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Through this paper, the authors propose using the quantum cluster equilibrium (QCE) theory to reinvestigate ammonia clusters in the liquid phase. The ammonia clusters from size monomer to hexadecamer were considered to simulate the liquid ammonia in this approach. The clusterset used to model the liquid ammonia is an ensemble of different structures of ammonia clusters. After studious research of the representative configurations of ammonia clusters through the cluster research program ABCluster, the configurations have been optimized at the MN15/6‐31++G(d,p) level of theory. These optimizations lead to geometries and frequencies as inputs for the Peacemaker code. The QCE study of this molecular system permits us to get the liquid phase populations in a temperature range of 190–260 K, covering the temperatures from the melting point to the boiling point. The results show that the population of liquid ammonia comprises mainly the ammonia hexadecamer followed by pentadecamer, tetradecamer, and tridecamer. We noted that the small‐sized ammonia clusters do not contribute to the population of liquid ammonia. In addition, the thermodynamic properties, such as heat of vaporization, heat capacity, entropy, enthalpy, and free energies, obtained by the QCE theory have been compared to the experiment given some relatively good agreements in the gas phase and show considerable discrepancies in liquid phase except the density. Finally, based on the predicted population, we calculated the infrared spectrum of liquid ammonia at 215 K temperature. It comes out that the calculated infrared spectrum qualitatively agrees with the experiment. [ABSTRACT FROM AUTHOR]

Despite its potential importance, the computational chemistry of adsorption processes for wastewater treatment has received negligible attention. Exploring the literature shows several limitations in applying quantum chemistry to study adsorption processes in wastewater treatment. The choice of suitable functionals of density functional theory (DFT) is one of the critical limits of the current application of quantum chemistry in wastewater treatment. Therefore, in this work, we performed a benchmark study of sixteen DFT functionals (including dispersions) to select the most suitable one. The def2-TZVP basis set has been used with the sixteen DFT functionals. The sixteen DFT functionals are benchmarked to the CCSD(T)/CBS level of theory. We used four different pollutants (p-aminobenzoic acid, aniline, p-chloro phenol, and phenol) adsorbed on coronene to perform this benchmarking. In addition to the coronene and the pollutant, four explicit water molecules are used to consider the environmental effects. The results show that the functional MN15 and PW6B95-D3 have the lowest mean absolute deviation relative to the CCSD(T)/CBS adsorption energies. Overall, the functionals MN15, PW6B95-D3, ωB97X-V, M05-2X-D3, M05-D3, and M06-2X-D3 are recommended for studying the adsorption processes. [ABSTRACT FROM AUTHOR]

Context: The search for highly efficient adsorbent materials remains a significant requirement in the field of adsorption for wastewater treatment. Computational study can highly contribute to the identification of efficient material. In this work, we propose a computational approach to study the adsorption of four cationic basic dyes, basic blue 26 (BB26), basic green 1 (BG1), basic yellow 2 (BY2), and basic red 1 (BR1), onto two models of graphene oxide as adsorbents. The main objectives of this study are the assessment of the adsorption capacity of the graphene oxide towards basic dyes and the evaluation of the environmental and temperature effects on the adsorption capacity. Quantum theory of atoms in molecules (QTAIM) analysis has been used to understand the interactions between the dyes and graphene oxides. In addition, adsorption free energies of the dyes onto graphene oxides are calculated in gas and solvent phases for temperatures varying from 200 to 400 K. As a result, the adsorption free energy varies linearly depending on the temperature, highlighting the importance of temperature effects in the adsorption processes. Furthermore, the results indicate that the environment (through the solvation) considerably affects the calculated adsorption free energies. Overall, the results show that the two models of graphene oxide used in this work are efficient for removing dyes from wastewater. Methods: We have optimized the complexes formed by the interaction of dyes with graphene oxides at the PW6B95-D3/def2-SVP level of theory. The SMD solvation model realizes the implicit solvation, and water is used as the solvent. Calculations are performed using the Gaussian 16 suite of program. QTAIM analysis is performed using the AIMAll program. Gibbs free energies as function of temperature are calculated using the TEMPO program. [ABSTRACT FROM AUTHOR]

In this work, we have studied the microsolvation of phenol in water. We started by identifying initial configurations of phenol-water clusters using classical molecular dynamics. The configurations are optimised at the ωB97XD/aug-cc-pVDZ level of theory. To understand the interaction between phenol and the solvating water molecules, we performed a quantum theory of atoms in molecules (QTAIM) analysis. The results show that the structures of phenol-water clusters are similar to those of neutral water clusters. The QTAIM analysis shows that the structures of phenol-water clusters are stabilised by strong OH··· O hydrogen bondings, weak CH··· O hydrogen bondings, and OH ⋯ π bonding interactions. The located structures of phenol-water clusters have been used to calculate the absolute hydration free energy and enthalpy of phenol for temperatures between 20 and 400 K. The hydration energies are calculated using the cluster continuum solvation model. It has been found that the explicit solvation has negligible effects on the hydration free energy and enthalpy of phenol. Furthermore, the hydration free energy of phenol is found to be linearly varying with increasing temperature, while the hydration enthalpy is found to be temperature independent. The estimated hydration free energy of phenol is slightly underestimated as compared to a previously reported experimental estimate. [ABSTRACT FROM AUTHOR]

The potential energy surfaces (PESs) of the neutral ethanol clusters is among the complex PESs of the neutral clusters. This is due to the fact that the ethanol monomer has three different isomers. In this work, we propose a systematic procedure to thoroughly explore the PES of the neutral ethanol hexamer that can be extended to other ethanol clusters. Thus, we started with a thorough exploration using the ABCluster code which uses the Lennard-Jones potential model. The resulting structures are further optimized at the APFD/6-31++g(d,p) level of theory {APFD refers to the initials of the first four authors in Austin et al. [J. Chem. Theory Comput. 8, 4989–5007 (2012)]}. Finally, 68 APFD structures have been fully re-optimized using the second order Møller-Plesset perturbation (MP2) method associated to the aug-cc-pVDZ basis set As a result, an isomer constituted of two trans ethanol monomers, two gauche+ ethanol monomers, and two gauche− ethanol monomers, is predicted to be the most stable structure using ABCluster. Full optimizations at the APFD/6-31++g(d,p) and MP2/aug-cc-pVDZ levels of theory confirm that this isomer is among the iso-energetic most stable structures of the ethanol hexamer. We found that most of the iso-energetic most stable structures are constituted of at least two different ethanol monomers. This highlights the importance of taking into account all the possible monomers in the exploration of the neutral ethanol clusters. In addition, we found that all the structures having their relative energies within 1.7 kcal mol−1 are cyclic structures. The results show that the most stable branched cyclic structures lies 1.7 kcal mol−1 above the most stable at the APFD/6-31++g(d,p) level of theory. [ABSTRACT FROM AUTHOR]

We investigated in this work the structures and relative population of large sized protonated ammonia clusters, H + ( NH 3 ) n , n = 18, 20, 25, 30. To this end, we generated initial geometries using the ABCluster code. The 30 most stable geometries for each of the clusters have been fully optimized at the APFD/6-31++g(d,p) level of theory. The results show that the proton is asymmetrically shared by two ammonia molecules to form the NH 4 + ⋯ NH 3 complex. The NH 4 + ⋯ NH 3 complex occupies the center of the structures, and it is gradually solvated with increasing cluster size. For n = 25 and n = 30, the first solvation shell of NH 4 + ⋯ NH 3 is completely filled with some ammonia molecules present in the second solvation shell. Besides, we have reported the relative population of the investigated clusters at the thermodynamic equilibrium. As a result, the three most stable structures dominate the population of the clusters. For each cluster size, we found that the IR spectra of these three most stable structures are in agreement with experiments. This agreement could be an indication of the reliability of our investigations. Overall, the structures of large sized protonated ammonia clusters are cage-like and exhibit an amorphous behavior. [ABSTRACT FROM AUTHOR]

Thermodynamics properties as well as infrared spectra of liquids can be determined using the quantum cluster equilibrium (QCE) theory. The QCE theory requires the knowledge of the structures of the clusters formed by the solvent molecules. In prelude to this determination, in this work, we studied the non-covalent bondings, the structures and the temperature-dependence of the clusters of dimethylformamide (DMF) from dimer to tetramer. To perform this study, we used classical molecular dynamics to sample initial geometries of DMF clusters. Then, optimisation of the geometries is carried out at the MP2/aug-cc-pVDZ level of theory. Besides, we carried out a quantum theory of atoms in molecule analysis. The results show that the structures of the DMF dimer exhibit a stacking configuration, and mainly stabilised by CH··· O hydrogen bondings. For the DMF trimer and DMF tetramer, the structures exhibit an amorphous behaviour. Moreover, it has been found that the CH··· O hydrogen bondings are the main non-covalent bondings in DMF clusters. CH··· C, CH··· N, N··· O, N··· C, C··· O and H··· H bonding interactions are also located in the studied DMF clusters. In addition, the temperature-dependence study shows that only isomers with relative energy within ∼ 1.0 kcal/mol have meaningful contribution to the population of DMF clusters. [ABSTRACT FROM AUTHOR]

In this work, we reported structures and relative stabilities of the neutral ammonia eicosamer at the APFD/6-31++g(d,p) level of theory. Furthermore, we have examined the temperature dependence isomer distribution and reported the relative population of the ammonia eicosamer for temperatures ranging from 20 to 400 K. Moreover, a theoretical infrared (IR) spectroscopic study is performed to confirm our results. As a result, several stable structures have been identified as isomers of the ammonia eicosamer. The most stable structure is a cage-like isomer with two central solvated ammonia molecules. It is found that cage-like isomers with central solvated ammonia molecules are more stable than other types of structures. Besides, two fused tetrameric cyclic structures belonging to the C2 symmetry point group are also located. Moreover, other reported isomers exhibit an amorphous behavior with no definite symmetry. When considering the temperature dependence isomer distribution, we found that only cage-like isomers contribute to the population of the ammonia eicosamer. The most stable isomer dominates the population of the cluster for all the investigated temperatures. Our analysis shows that only the IR spectra of isomers that contribute to the relative population have their peaks in agreement with the experiment. This agreement could be an indication of the reliability of our proposed structures of the ammonia eicosamer and their relative stability. [ABSTRACT FROM AUTHOR]

Theoretical understanding of thiophene clusters is very important for molecular understanding of thiophene as solvent and for determining the thermodynamics properties of the solvent. However, no investigations on thiophene clusters have been reported previously in the literature. We have performed in this work an ab initio computational study to understand the interactions taking place in thiophene clusters using the thiophene pentamer. We started by generating possible structures using classical molecular dynamics followed by full optimization at the ab initio MP2/aug‐cc‐pVDZ level of theory. Relative energies and temperature‐dependent isomer distribution of the investigated structures have been reported. Finally, we have performed a quantum theory of atoms in molecule (QTAIM) analysis to identify all non‐covalent bondings that are responsible for the stability of the structures of the thiophene pentamer. The results show that six different types of non‐covalent interactions could be found in thiophene pentamer depending on the structure. [ABSTRACT FROM AUTHOR]

We provide in this work, the absolute solvation enthalpies and the absolute solvation free energies of the proton in ammonia explicitly versus temperature. As a result, the absolute solvation free energy of the proton remains quite constant for temperatures below 200 K. Above this temperature, it increases as a linear function of the temperature: ΔGam(H+, T) = -1265.832 + 0.210 T. This indicates that a temperature change of 100 K would induce a solvation free energy change of 21 kJ mol-1. Thus, ignoring this free energy change would lead to a bad description of hydrogen bonds and an unacceptable error higher than 3.7 pKa units. However, the absolute solvation enthalpy of the proton in ammonia is not significantly affected by a temperature change and, the room temperature value is -1217 kJ mol-1. The change of the solvation enthalpy is only within 3 kJ mol-1 for a temperature change up to 200 K. [ABSTRACT FROM AUTHOR]

Structures of protonated ammonia clusters (H+(NH3)n) are very important for the determination of pKa's and solvation energies of the proton in ammonia. In this work, their structures were investigated at M06-2X/6-31++g(d,p) level of theory, for n = 10-16 and for temperatures ranging from 0 to 400 K. In the cluster community, this is the first theoretical study on the protonated ammonia clusters larger than the nonamer. We noted that the population of the investigated clusters is reproduced by branched cage or cage like structures at low temperatures, while branched linear and branched cyclic or branched double cyclic isomers are the only isomers responsible for the population at higher temperatures. In these isomers, the proton is highly and entirely solvated at the center of the cluster. In addition, protonated ammonia clusters are all Eigen structures and the first solvation shell of the related ammonium ion core is saturated by four ammonia molecules. Moreover, infrared (IR) spectra of all isomers have been investigated and these spectra show good agreement with the experiment. This allowed us to assign experimental peaks and to provide the constitution of the populations of the various clusters. [ABSTRACT FROM AUTHOR]

In this study, we have investigated the potential energy of surfaces of the various glycine tautomers, also the interaction between Cu 2 + cation with these glycine tautomers in both the gas and solvent phases and for the first time, the glycine- Cu 2 + (NH 3) n = 3 − 6 clusters in the gas-phase. For the studied clusters, we reported their temperature-dependent conformer distributions, along with the binding energies per ammonia molecule and clustering energies. After comparing the binding energies obtained computationally by using the DLPNO-CCSD(T)/CBS level of theory to those obtained from ten DFT functionals (M06, M06HF, M06-2X, M08HX, MN15, MN12SX, ω B97XD, PW6B95D3, TPSSH, APFD), as well as from the ab initio MP2 method, we selected the DFT functional, M08HX, in conjunction with the aug-cc-pVDZ basis set, as our method of choice. Evidence emerged from our study that the solvation medium and the presence of the Cu 2 + cation influence the stability of glycine tautomers. The relative stability of Gly- Cu 2 + (NH 3) n clusters in the gas phase is influenced by the coordination of the Cu 2 + cation. The study of the relative population in the gas phase of the Gly- Cu 2 + (NH 3) n = 3 − 6 clusters, predicts that for cluster size n = 4 , the structure of the more compact penta-coordinated Cu 2 + ion dominates at low temperatures. Conversely, the conformers for the less compact tetra-coordinated Cu 2 + cation are prevalent at high temperatures. For cluster size n = 6 with more ammonia molecules per cluster, the conformers containing the compacted is penta-coordinated Cu 2 + cation, are predominant at all temperatures. Binding energies computed for ionic interactions of the Gly- Cu 2 + complexes, resulted in the following values at room temperature: the binding electronic energy (Δ E n), binding enthalpy (Δ H n) and binding free energy (Δ G n) of ionic interaction are respectively -218.3, -218.4, -211.6 kcal/mol in the gas phase and -93.8, -94.9, -85.2 kcal/mol in the solvent phase. In order to extrapolate this also to the Gly- Cu 2 + ammonia clusters, a suitable function of best fit was applied. The computational prediction of binding electronic energy, binding enthalpy and binding free energy, per ammonia molecule in the gas phase, at saturation, produced the values -25.9, -26.1 and -17.0 kcal/mol, respectively. We therefore recommend this function fit for further study of such systems. • The results are accurate with functional DFT M08HX, M06-2X and WB97XD for the study of such clusters. • The solvation medium and the presence of the Cu2+ ion influence the stability of glycine tautomers. • The relative stability of Gly-Cu2+(NH 3) n clusters in gas is influenced by the ionic and hydrogen bonds. • The Cu2+ ion is penta- and hexa-coordinated in Glycine-Cu2+(NH 3) n=3-6 depending on the temperature. • The binding energies per ammonia molecule at n = ∞ are predicted by fitting the data with a fit function. [ABSTRACT FROM AUTHOR]

Dimethylsulfoxide (DMSO) clusters are crucial for understanding processes in liquid DMSO. Despite its importance, DMSO clusters have received negligible attention due to the complexity of their potential energy surfaces (PESs). In this work, we explored the PESs of the DMSO clusters from dimer to decamer, starting with classical molecular dynamics, followed by full optimizations at the PW6B95-D3/def2-TZVP level of theory. In addition, the binding energies, the binding enthalpy per DMSO, and the quantum theory of atoms in molecules (QTAIM) analysis of the most stable isomers are reported. Temperature effects on the stability of the isomers have also been assessed. After thoroughly exploring the PESs of the DMSO clusters, 159 configurations have been used to apply the quantum cluster equilibrium (QCE) theory to liquid DMSO. The quantum cluster equilibrium theory has been applied to determine the liquid properties of DMSO from DMSO clusters. Thus, using the QCE, the population of the liquid DMSO, its infrared spectrum, and some thermodynamic properties of the liquid DMSO are predicted. The QCE results show that the population of the liquid DMSO is mainly dominated by the DMSO dimer and decamer, with the contribution in trace of the DMSO monomer, trimer, tetramer, pentamer, and octamer. More interestingly, the predicted infrared spectrum of liquid DMSO is in qualitative agreement with the experiment. • 159 isomers of the DMSO clusters from dimer to decamer located using DFT. • Relative energies and binding energies of the clusters are calculated. • Non-covalent interactions in DMSO clusters are studied using QTAIM analysis. • Application of quantum cluster equilibrium (QCE) theory to liquid DMSO. • Prediction of IR spectrum of liquid DMSO using QCE is in agreement with experiment. [ABSTRACT FROM AUTHOR]

Computation methods or molecular simulations can be used to identify materials with high adsorption capacity for wastewater treatment rapidly. They can also provide complementary insights into the dynamics of adsorption processes. In addition, molecular simulations can be used to understand the adsorption mechanism and the interaction between contaminants and adsorbents. Considering their applicability in wastewater treatment, computational methods have been widely used for adsorption studies. Due to affordability, most of these methods are based on density functional theory (DFT) calculations. However, molecular dynamics and Monte Carlo simulations have also been used to get insights into the adsorption of pollutants. With the growth of artificial intelligence, machine learning-based approaches have also been used to predict the adsorption capacity of materials. Despite the importance of computational methods in wastewater treatment, no review article summarizes the methods used in the literature. Therefore, we undertake to summarize, classify, and provide a detailed description of computational methods used in the adsorption studies for wastewater treatment. For each method, we review some outstanding works using the method and provide the advantages and limits of the method. Finally, future directions and possible improvements of the computational methods are suggested as perspectives. • Summary of computational methods used in wastewater treatment. • Detailed description of computational methods or molecular simulations. • Advantages and limits of current computational methods. • Outstanding works reported using computational methods or molecular simulations. • Possible improvements of current computational methods are provided. [ABSTRACT FROM AUTHOR]

Understanding the proton transfer processes in acetonitrile is subjected to the knowledge of the structures of protonated acetonitrile clusters, H+(MeCN)n. Despite their importance, there is no clearly reported investigation of the structures of the protonated acetonitrile clusters, unlike the protonated water clusters or the protonated ammonia clusters. In this work, we thoroughly explored the potential energy surfaces (PESs) of the protonated acetonitrile clusters up to the decamer (n = 10) using three incremental levels of theory. We started by exploring the PESs of the protonated acetonitrile clusters using classical molecular dynamic to generate initial structures. Then, the generated structures have been fully optimized using a density functional theory (DFT) functional, MN15, associated to the 6-31++G(d,p) basis set. Finally, to gain more insights on the location of the global minima energy structures, all the structures of clusters up to the heptamer (n = 7) have been fully re-optimized at the MP2/aug-cc-pVDZ level of theory. As a result, we reported several local and global minima energy structures of the protonated acetonitrile clusters that have not been reported previously. The results show that the structures of the protonated acetonitrile clusters are stabilized by strong H+⋯N hydrogen bonds, anti-parallel dimers, dipole–dipole and CH⋯N interactions. Moreover, we noted that planar and branched isomers are the most favored for clusters lower than the hexamer, while larger-sized clusters favored compact isomers. To derive temperature effects on the stability of the investigated structures, we have reported the temperature-dependent isomer distributions of all the investigated clusters. [ABSTRACT FROM AUTHOR]

The hydrogen bond network of ethanol clusters is among the most complex hydrogen bond networks of molecular clusters. One of the reasons of its complexity arises from the number of possible ethanol monomers (there are three isoenergetic isomers of the ethanol monomer). This leads to difficulties in the exploration of potential energy surfaces (PESs) of ethanol clusters. In this work, we have explored the PES of the ethanol hexamer at the MP2/aug‐cc‐pVDZ level of theory. We have provided structures and their relative stability at 0 K and for temperatures ranging from 20 to 400 K in the gas phase. These structures are used to compute the theoretical infrared (IR) spectrum of the ethanol hexamer at the MP2/aug‐cc‐pVDZ level of theory. As a result, 98 different structures have been investigated, and six isomers are reported to be the most isoenergetically stable structures of the ethanol hexamer. These isomers are folded cyclic structures in which the stability is enhanced by the implication of CH⋯O interactions. Our investigations show that the PES of the ethanol hexamer is very flat, yielding several isoenergetic structures. Furthermore, we have noted that several isomers contribute to the population of the ethanol hexamer at high temperatures. As far as the IR spectroscopic study is concerned, we have found that the IR spectra of the most stable structures are in good agreement with the experiment. Considering this agreement, these structures are used to assign the experimental peaks in the CH‐stretching region. We concluded that the stability of the structures of the ethanol hexamer is related both to OH⋯O hydrogen bonds and CH⋯O interactions. Overall, we have found that the IR spectrum of the ethanol hexamer, calculated from the contribution of all the possible stable structures weighted by their probability, excellently reproduce the experimental spectrum of the ethanol hexamer. [ABSTRACT FROM AUTHOR]

Structures and relative stabilities of neutral acetonitrile clusters up to decamer have been investigated. We used the ABCluster code to thoroughly explore the potential energy surfaces (PESs) of the acetonitrile clusters and to generate initial geometries, which are further fully optimized at the MN15/6‐31++G(d,p) level of theory. Our exploration yielded several new local and global minima structures of the acetonitrile clusters. We located new global minimum structures of the acetonitrile pentamer to decamer. The results show that the PESs of the acetonitrile clusters are very flat, yielding several isoenergetic structures. Our investigations also revealed that the stability of the acetonitrile clusters is due both to CH⋯N and dipole–dipole interactions. Structures stabilized by the latter are found to be more stable than those stabilized by the former at low temperatures. Furthermore, we examined the effect of temperature on the stability of the structures of the acetonitrile clusters for temperatures in the range 20 to 400 K. We found that several structures contribute to the population of the clusters at high temperatures, and also that a significant contribution to the population comes from isomers that lie within 2.0 kcal/mol from the most stable one. In addition, we used the most stable structures to compute the binding energies of the acetonitrile clusters and to assess the performance of some DFT functionals (MN15, ωB97XD, PW6B95D3, and B2PLYP) in comparison with the MP2 method associated to the aug‐cc‐pVTZ basis set in calculating the binding energies. We found that the MN15 functional performs better than ωB97XD and PW6B95D3, and that MN15 is less sensitive to the basis set change. We also used an extrapolation scheme to calculate the binding energies of the acetonitrile clusters at the highly accurate W1BD, CBS‐QB3, and G4MP2 levels of theory. The resulting binding energies are recommended for future benchmarking of the acetonitrile clusters. [ABSTRACT FROM AUTHOR]

The absolute solvation energies (free energies and enthalpies) of the proton in ammonia are used to compute the pKa of species embedded in ammonia. They are also used to compute the solvation energies of other ions in ammonia. Despite their importance, it is not possible to determine experimentally the solvation energies of the proton in a given solvent. We propose in this work a direct approach to compute the solvation energies of the proton in ammonia from large‐sized neutral and protonated ammonia clusters. To undertake this investigation, we performed a geometry optimization of neutral and protonated ammonia 30‐mer, 40‐mer, and 50 mer to locate stable structures. These structures have been fully optimized at both APFD/6‐31++g(d,p) and M06‐2X/6‐31++g(d,p) levels of theory. An infrared spectroscopic study of these structures has been provided to assess the reliability of our investigation. Using these structures, we have computed the absolute solvation free energy and the absolute solvation enthalpy of the proton in ammonia. It comes out that the absolute solvation free energy of the proton in ammonia is calculated to be −1192 kJ mol–1, whereas the absolute solvation enthalpy is evaluated to be −1214 kJ mol–1. © 2019 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

We have revised the structures of neutral water clusters, (H2O)n=2–30, with the affordable M06-2X functional, presenting up to 25 isomers for each cluster size. Besides, relative energies, relative free energies and binding energies of all the investigated clusters are also provided. Temperature dependent isomer distributions of the clusters are also presented. As a result, significant new local minima structures are located on the PESs of water clusters. When available our global minima structures are in agreement with the CCSD(T)/CBS reports. We noted that the cage isomer with a central solvated water molecule starts to be the global minimum structure from n = 17. In addition, we found that from n = 19, the cage isomers are the global minimum structure or they are among the most stable structures, on the PESs of water clusters. From the water 26-mer till 30-mer (excluding the 29-mer), the most stable structures are cage isomers with two central solvated water molecules. Moreover, these cage isomers dominate the population of clusters for temperatures ranging from 20 to 400 K. As far as the energetic study is concerned, binding energies of neutral water clusters are computed using M06-2X, APFD, MN15 and ωB97XD functionals associated with the aug-cc-pVTZ (aVTZ) basis set for n = 2–30. As a result, the MN15/aVTZ binding energies are reported to be in good agreement with the CCSD(T)/CBS benchmark results for n = 2–10. The mean absolute deviation (MAD) for n = 2–10 is calculated to be 1.0 kcal mol−1. [ABSTRACT FROM AUTHOR]

Molecular modelling and simulation were used to examine the efficacy of iron nanoparticles (Fe3O4–NPs) in removing amoxicillin (AMX) from aqueous media and determine the optimal conditions. Fe3O4–NPs were initially ascertained using scanning electron microscopy, and Fourier transform infrared spectroscopy. The molecular optimisation modelling via DFT confirmed AMX molecule has chemical potential (–3.59), and electrophilicity index (2.14). The results established that a small chemical hardness = 3.0 eV and molecular energy gap of 6.01 eV, which makes it reactive. The molecule of the antibiotics could interact and be absorbed by the lactase enzyme. The parameters: pH (3–7), time (15–80 min), Fe3O4–NPs dosage (0.1–1.0 g/L), and antibiotic concentration (10–100 mg/L) were studied. The impact of optimum variables pH3, and dosage (0.5 g/L) for adsorption of AMX molecules onto coated Fe3O4–NPs translated to 98% efficiency at 60 mg/l of AMX and 60 min. The adsorption data fitted the Langmuir (R2: 0.9245) with minimal error metrics RMSE ≤ 1.2 when compared to the Freundlich isotherm R2 (0.88) and intraparticle diffusion model R2 (0.58). The maximum adsorption capacity of AMX to Fe3O4–NPs corresponds to 6.47 mg/g with a corresponding adsorption constant of 2.8. Furthermore, AMX adsorption onto Fe3O4–NPs followed pseudo-second-order at R2 (0.9999), with an adsorption constant (k = 3.6 × 10−2g/mg.min). [ABSTRACT FROM AUTHOR]

Context: Micro-hydration of the aminobenzoic acid is essential to understand its interaction with surrounding water molecules. Understanding the micro-hydration of the aminobenzoic acid is also essential to study its remediation from wastewater. Therefore, we explored the potential energy surfaces (PESs) of the para-aminobenzoic acid-water clusters, ABW n , n = 1 - 10 , to study the microsolvation of the aminobenzoic acid in water. In addition, we performed a quantum theory of atoms in molecules (QTAIM) analysis to identify the nature of non-covalent bondings in the aminobenzoic acid-water clusters. Furthermore, temperature effects on the stability of the located isomers have been examined. The located structures have been used to calculate the hydration free energy and the hydration enthalpy of the aminobenzoic acid using the cluster continuum solvation model. The hydration free energy and the hydration enthalpy of the aminobenzoic acid at room temperature are evaluated to be −7.0 kcal/mol and −18.1 kcal/mol, respectively. The hydration enthalpy is in perfect agreement with a previous experimental estimate. Besides, temperature effects on the calculated hydration enthalpy and free energy are reported. Finally, we calculated the gas phase binding energies of the most stable structures of the ABW n clusters using twelve functionals of density functional theory (DFT), including empirical dispersion. The DFT functionals are benchmarked against the DLPNO-CCSD(T)/CBS. We have found that the three most suitable DFT functionals are classified in the following order: PW6B95D3 > MN15 > ω B97XD. Therefore, the PW6B95D3 functional is recommended for further study of the aminobenzoic acid-water clusters and similar systems. Methods: The exploration started with classical molecular dynamics simulations followed by complete optimization at the PW6B95D3/def2-TZVP level of theory. Optimizations are performed using Gaussian 16 suite of codes. QTAIM analysis is performed using the AIMAll program. [ABSTRACT FROM AUTHOR]

Quantum cluster equilibrium theory (QCE) has been widely used to determine the properties of pure and binary mixture of liquids. The main limitation of the application of QCE is the exploration of different possible clusters formed by the solvent molecules. Therefore, in this study, we applied the QCE theory to predict liquid properties of ethanol after thorough exploration of the potential energy surfaces (PESs) of the ethanol clusters from dimer to hexamer. The exploration started by generating possible structures using classical molecular dynamics followed by optimizations at the MP2/aug-cc-pVDZ level of theory. 484 different configurations of the ethanol clusters have been finally used in the QCE theory. The results show that the population of liquid ethanol is constituted from the contribution of hexamer, pentamer, and tetramer. In addition, we noted that the ethanol monomer, dimer and trimer do not contribute to the population of liquid ethanol. Furthermore, based on the predicted population of the liquid ethanol, we calculated its infrared spectrum at different temperatures. The calculated infrared spectrum is found to be in qualitative agreement with experiment. Some thermodynamic properties, such as the heat capacity, are also predicted to be in good agreement with experiment. • Quantum cluster equilibrium (QCE) theory is applied to study the liquid ethanol. • 484 different configurations of the ethanol clusters have been used. • Analysis of the population of the liquid ethanol is proposed. • QCE predicted infrared spectrum of liquid ethanol in agreement with experiment. • Thermodynamics properties of the liquid ethanol are proposed. [ABSTRACT FROM AUTHOR]

In this work, we have investigated the electronic, optoelectronic, optical, and thermodynamic properties of the parent molecules diphenanthro [3,4,5,6-efghi:3′,4′,5′,6′-uvabc]ovalene (C48H18), tribenzo[jk,mn,pq]dibenzo [5,6:7,8] pentapheno [2,1,14,13,12-stuvabcd] ovalene (C60H22), and its derivatives formed by through functionalization with chlorine and potassium atoms. All calculations were performed using Density Functional Theory (DFT) (HSE, ωB97XD, and CAM-B3LYP) and time-dependent density functional theory (TD-DFT), associated with the 6-31G(d) basis set. The results show that the molecules functionalized with potassium atoms have small gap energy values, which gives them good applications in electronics. These same molecules present a non-centrosymmetric architecture with a first hyperpolarizability value higher than that of the reference molecule for nonlinear optics, which is the paranitroaniline molecule. The high values of the average electric field, of the susceptibility, of the refractive index, and the small value of the dielectric constant of the molecules functionalized with potassium allow us to say that these molecules have good optoelectronic and photonic applications. [ABSTRACT FROM AUTHOR]

Molecular modeling can considerably speed up the discovery of materials with high adsorption capacity for wastewater treatment. Despite considerable efforts in computational studies, the molecular modeling of adsorption processes has several limitations in reproducing experimental conditions. Handling the environmental effects (solvent effects) and the temperature effects are part of the important limitations in the literature. In this work, we address these two limitations using the adsorption of phenol onto coronene as case study. In the proposed model, for the solvent effects, we used a hybrid solvation model, with n explicit water molecules and implicit solvation. We increasingly used n = 1 to n = 12 explicit water molecules. To account for the temperature effects, we evaluated the adsorption efficiency using the adsorption free energy for temperatures varying from 200 to 400 K. We generated initial configurations using classical molecular dynamics, before further optimisation at the ω B97XD/aug-cc-pVDZ level of theory. Polarisable continuum solvation model (PCM) is used for the implicit solvation. The adsorption free energy is evaluated to be -1.3 kcal/mol at room temperature. It has been found that the adsorption free energy is more negative at low temperatures. Above 360 K, the adsorption free energy is found to be positive. [Display omitted] • A new methodology to compute the adsorption free energy of a pollutant is proposed. • The adsorption free energy of phenol onto coronene is calculated as case study. • Adsorption free energy is evaluated for 200–400 K to assess temperature effects. • N = 1–12 explicit water molecules are used to assess the solvent effects. • The adsorption free energy is found to be linearly increasing with temperature. [ABSTRACT FROM AUTHOR]

Understanding of clusters of dimethylsulfoxide (DMSO) is important in several applications in Chemistry. Despite its importance, very few studies of DMSO clusters, (DMSO) n , have been reported in comparison to systems such as water clusters or methanol clusters. In order to provide further understanding of DMSO clusters, we investigated the structures and non-covalent interactions of the (DMSO) n , n = 5. Therefore, the potential energy surface (PES) of the DMSO pentamer has been examined using classical molecular dynamics. The structures generated using classical molecular dynamics are further optimized at the PW6B95D3/aug-cc-pVDZ level of theory. To comprehend the non-covalent bondings in the DMSO pentamer, we carried out a quantum theory of atoms in molecule (QTAIM) analysis. In addition, the effects of temperature on the structural stability is investigated between 20 and 500 K. It comes out that seven different kind of non-covalent bondings can be found in DMSO pentamers. [Display omitted] • Potential energy surface of the DMSO pentamer has been explored using PW6B95D3 • QTAIM analysis is performed to identify Non-covalent interactions in DMSO pentamer • Seven different non-covalent bondings have been located in DMSO pentamers • Temperature effects on the stability of the located isomers have been assessed [ABSTRACT FROM AUTHOR]

Molecular simulations of adsorption processes have received considerable attention. Despite the attention, exploration of the literature shows serious limitations, among which solvent and temperature effects are the most important. In this work, we propose a computational approach to study the adsorption of aniline (as an example of pollutant) from wastewater using coronene as adsorbent. We identified all possible adsorption sites using classical molecular dynamics for further optimization at the ω B97XD/aug-cc-pVDZ level of theory. Three different solvation schemes have been explored: implicit solvation of aniline + coronene, explicit solvation of aniline + coronene, and implicit-explicit solvation of aniline + coronene. For the explicit solvation, we used six water molecules, while the implicit solvation is performed using the PCM (polarizable continuum medium) solvation model. For each of the four cases (gas phase and the three solvation schemes), the adsorption free energy is evaluated as function of temperature from 200 K to 400 K. The results show that solvation has a considerable effects on the adsorption free energy. Furthermore, we noted that the adsorption free energy varies from −39.5 kJ mol−1 at 200 K to 27.7 kJ mol−1 at 400 K using the implicit-explicit solvation of aniline + coronene. This result highlights the importance of considering temperature effects in molecular simulations study of adsorption processes. [Display omitted] • DFT study of the adsorption free energy of aniline onto coronene. • New methodological approach to compute adsorption free energy. • Temperature effects on the adsorption free energy. • Four solvation schemes to account for the environmental effects. [ABSTRACT FROM AUTHOR]

[Display omitted] • Potential energy surfaces of the DMSO clusters. • Relative stability for temperatures ranging from 50 to 500 K. • QTAIM analysis for non-covalent interactions in DMSO clusters. • Eight different types of non-covalent interactions have been identified. • DFT benchmarking of ten functionals against MP2/CBS and DLPNO-CCSD(T)/CBS. Dimethylsulfoxide (DMSO) is one of the most used solvents in industries and in Chemistry. Understanding the dynamics of the solvent is subjected to the understanding of interactions in DMSO clusters. Despite its importance, a very few studies have been reported on DMSO clusters. In this work, we have explored thoroughly the potential energy surfaces (PESs) of the DMSO clusters from dimer to tetramer at the MP2/aug-cc-pVDZ level of theory. In order to understand the non-covalent interactions in DMSO clusters, we have performed a quantum theory of atoms in molecules (QTAIM) analysis. The QTAIM analysis showed that there are eight different types of non-covalent interactions stabilizing the DMSO clusters. The CH ⋯ O hydrogen bonding and H ⋯ H bonding are found to be the strongest and the weakest non-covalent interactions in DMSO clusters, respectively. In addition, we have reported the temperature-dependent isomer distribution of all the investigated clusters for temperatures ranging from 50 to 500 K. To allow affordable investigations of medium and large sized DMSO clusters in future investigations, we have assessed the performance of ten functionals of the density functional theory (DFT) in calculating the binding energies of the DMSO clusters. The ten DFT functionals (M05, M05-2X, M06, M06-2X, M08HX, PBE0, ω B97XD, PW6B95D3, APFD and MN15) have been benchmarked to MP2/CBS and DLPNO-CCSD(T)/CBS. The functionals PW6B95D3 and ω B97XD are recommended for further affordable investigations of the DMSO clusters. [ABSTRACT FROM AUTHOR]

Understanding of the furan solvent is subjected to the knowledge of the structures of the furan clusters and interactions taking place therein. Although, furan clusters can be very important to determine the dynamics and the properties of the furan solvent, there has been only a few investigations reported on furan dimer. In this work, we have explored the potential energy surfaces (PESs) of the furan clusters using two incremental levels of theory. Structures have been initially generated using classical molecular dynamics followed by full optimization at the MP2/aug-cc-pVDZ level of theory. The results show that the most stable structure of the furan dimer has a stacking configuration while that of the trimer has a cyclic configuration. We have noted that the structures of the furan tetramer have no definite configurations. In addition, we have performed a quantum theory of atoms in molecule (QTAIM) analysis to identify all possible non-covalent interactions of the furan clusters. The results show that six different types of non-covalent interactions can be identified in furan clusters. We have noted that the CH⋯C and CH⋯O hydrogen bondings are the strongest non-covalent interactions while the H⋯H bonding interaction is found to be the weakest. Furthermore, we have assessed the performance of ten DFT functionals in calculating the binding energies of the furan clusters. The ten DFT functionals (M05, M05-2X, M06, M06-2X, M08HX, PBE0, ω B97XD, PW6B95D3, APFD and MN15) have been benchmarked to DLPNO-CCSD(T)/CBS. The functionals M05-2X and M06 are recommended for further affordable investigations of the furan clusters. [Display omitted] • Structures and relative stability of the furan clusters. • QTAIM analysis for non-covalent interactions in furan clusters. • Six different types of non-covalent interactions have been identified. • Temperature-dependent isomer distribution of furan clusters. • DFT benchmarking of ten functionals against DLPNO-CCSD(T)/CBS. [ABSTRACT FROM AUTHOR]

[Display omitted] • Exploration of the potential energy surfaces of small thiophene clusters. • Non-Covalent interactions stabilizing thiophene clusters. • Benchmarking of eleven DFT functionals for further investigations. • M05-2X and M06 are recommended for the study of larger-sized thiophene clusters. Theoretical understanding of the thiophene solvent is subjected to the knowledge of the structures and the interactions taking place in thiophene clusters. Despite the importance of the thiophene clusters in understanding the thiophene solvent, there are not many reported studies on thiophene clusters. In this work, we have performed quantum chemical computations to understand the nature and number of non-covalent interactions that stabilize the structures of the thiophene clusters. For this purpose, we have started by exploring the potential energy surfaces (PESs) of the thiophene dimer, trimer, and tetramer, using classical molecular dynamics in order to generate initial guessed structures. These generated structures were then optimized at the MP2/aug-cc-pVDZ level of theory. As a result, it is found that the thiophene dimer prefers the sandwich/stacking configuration over the T-shaped configuration while for the thiophene trimer, only the cyclic configuration has been located. After locating the stable structures of the thiophene dimer, trimer and tetramer, we have performed a quantum theory of atoms in molecules (QTAIM) analysis on the investigated structures. The results show that six different non-covalent interactions have been identified in thiophene clusters: C ⋯ C (or π ⋯ π) bonding, CH ⋯ C (or CH ⋯ π) hydrogen bonding, CH ⋯ S hydrogen bonding, C ⋯ S (or π ⋯ S) bonding, S ⋯ S bonding and H ⋯ H bonding interactions. In addition, we have assessed the performance of eleven functionals of the density functional theory (DFT) in calculating the binding energies of the thiophene clusters. It is found that the functionals M052X and M06 showed the best performance with DLPNO-CCSD(T)/CBS used as reference. [ABSTRACT FROM AUTHOR]

• Efficiency of new generation adsorbents and their adsorption capacities. • Equilibrium isotherms and kinetic modelling for fluoride adsorption. • Thermodynamic studies for adsorption of fluoride onto novel adsorbents. • Molecular modelling and simulation. • Knowledge gap and future perspectives. Water is essential for life and is threatened by the pollution and contamination generated by human activity and industries. Fluoride contamination of water is a serious problem in the world. The review article highlights on new generation adsorbents including carbon-based adsorbents, nano-adsorbents, bio-sorbents, inorganic materials, modified and composite adsorbents for purification of fluoride from water. It was indicated from the review that a Zinc oxide nanoparticles is the best adsorbents for the removal of fluoride from aqueous media, with a capacity adsorption (q max) of 100 mg/g. The f l u o r i d e uptake best-fit both the Langmuir and Freundlich isotherm models as well as a pseudo second order kinetic model. A wide range of values for the thermodynamic parameters (both negative and positive) were reported for fluoride across different studies. Kinetic and thermodynamic, molecular modelling and simulations, knowledge gaps and future prospects are also presented. [ABSTRACT FROM AUTHOR]

[Display omitted] • Aniline as a toxic aromatic uptake from industrial effluents was reviewed. • The different empirical findings on the equilibrium isotherms, kinetics and thermodynamics. • Molecular modelling and simulation of aniline adsorption. • Azo-linked porous organic polymer is the best adsorbents for the removal of aniline. • The best fit kinetic model for aniline adsorption is the pseudo-second-order model. This review aims to report the efficiency of the adsorption of industrial pollutants, aniline, from wastewater. It was observed from the review that an Azo-linked porous organic polymer (AZO-POP-1) is the best adsorbents for the removal of aniline from aqueous media, with a capacity adsorption (q max) of 1059 mg/g. In terms of factors that affect the efficiency of adsorbents, temperature seems to be the most influential. Aniline uptake best-fit both the Langmuir and Freundlich isotherm models as well as a pseudo second order kinetic model. Different potential adsorbents have been examined through simulations, usually using density functional theory (DFT) or ab-initio method. Most of the time they are simulated in the gas phase, but for a realistic adsorption model, they should be simulated in the solvent phase. Although some studies have been reported on molecular modeling of aniline adsorption using a different range of computational approaches, there are still a lot of issues to be addressed. These issues include the solvent effects which are not properly modeled, the calculation of adsorption energy which is not taking the environment into account, and possibly the temperature effects. [ABSTRACT FROM AUTHOR]

We have investigated the structures, electronic properties, hole and electron mobilities of perfluorinated, perchlorinated and percyanated coronene molecules, using the density functional theory (DFT) and Time Dependent DFT (TDDFT) at the B3LYP-D3/6-311++G(d,p) and ω B97XD/6-311++G(d,p) levels and Markus-Hush charge transfer theory. The calculated geometric parameters for coronene and perchlorocoronene are in good agreement with the experimental data. Our theoretical investigations have shown that B3LYP-D3 functional is suitable to well define vibrational assignments for studied molecules. The quantified effect of the complete substitution of peripheral hydrogen atoms with cyanide groups for the key properties relevant for optoelectronic and photonics such as electron affinities, ionization energies, HOMO-LUMO energies, reorganisation energies, optical absorption spectra, and electron mobilities were discussed. Compared to perfluorination and perchlorination, the percyanation of coronene considerably increases the adiabatic/vertical electron affinities (AEAs/VEAs), the electron mobilities, the HOMO-LUMO gap and reduces the LUMO energy level thus indicating an ambipolar behavior and air-stable material. We have discussed the possible implications of cyanide groups as important substitutes for the design of the new organic compounds useful in electronics. [ABSTRACT FROM AUTHOR]

• Review on structures and hydrogen bond networks of ammonia clusters. • Review on spectroscopy, temperature effects, solvent effects on ammonia clusters. • Future directions and what remains unknown on ammonia clusters. Understanding the behaviour of liquid ammonia is subjected to understanding the hydrogen bond networks in ammonia clusters as well as their interactions. In comparison to water clusters, hydrogen bond networks of ammonia clusters have received less attention. Nevertheless, from the available literature, one can draw some understanding of the hydrogen bond networks in ammonia clusters. In this work, we reviewed what we know on ammonia clusters regarding their structures and hydrogen bond networks, their spectroscopy, the temperature and solvent effects on the stability of their structures as well as on their hydrogen bond networks. In addition, we have also discussed the application of the ammonia clusters to determine the solvation free energy and enthalpy of the proton in ammonia. Besides, their application to the determination of the proton transfer free energy from water to ammonia has been also discussed. As part of what we don't know, we presented some perspectives for future investigations on ammonia clusters as well as their potential application in understanding some processes. [ABSTRACT FROM AUTHOR]

[Display omitted] • Cluster continuum proton solvation model in acetonitrile. • Solvation free energy and solvation enthalpy of the proton in acetonitrile. • Estimated solvation free energy in agreement with experimental estimate. • Structures and relative stability of acetonitrile clusters in the solvent phase. • New global and local minima energy structures in the solvent phase. Solvation free energy of the proton in solution is used to describe proton transfer processes in that solution. In addition, the solvation free energy of the proton is involved in several chemical and biological processes. Although several methodological approaches have been used to estimate the solvation free energy of the proton in solutions (mainly in water), there is no consensus estimate of the solvation free energy of the proton. In this work, we have reported the solvation free energy of the proton in acetonitrile using the cluster continuum solvation model. To compute the solvation free energy of the proton within this model, one needs the structures of neutral and protonated acetonitrile clusters. Thus, we thoroughly explored the potential energy surfaces (PESs) of the clusters in the solvent phase using several incremental levels of theory. We generated initial structures using classical molecular dynamics. Then the generated structures have been successively optimized at the MN15/6-31++G(d,p) and MP2/aug-cc-pVDZ levels of theory. Finally, single point extrapolations to the complete basis set (CBS) limit have been performed at the MP2 level of theory. As results, the solvation free energy (respectively enthalpy) of the proton in acetonitrile is estimated to be −1022.0 kJmol−1 (respectively −1056.5 kJmol−1) at the MP2/CBS level of theory. The calculated solvation free energy of the proton in acetonitrile is found to be in excellent agreement with the experimental estimate based on the tetraphenylarsonium-tetraphenylborate (TATB) approach. [ABSTRACT FROM AUTHOR]

The absolute solvation energies (free energy and enthalpy) of the proton in solution is of great importance for biological and chemical processes in that solution. The absolute solvation free energy of the proton is used to compute the p K a (acids proton dissociation constant) of organic compounds. Furthermore, these absolute solvation energies are used in the development of continuum solvation models and force fields. They are also used to determine the absolute solvation energies of other ions. Despite their importance, the absolute solvation energies of the proton cannot be determined experimentally. In the last century, several methodological approaches have been proposed to determine the absolute solvation energies of the proton in solution. In this review, we present recent and important methodologies used in the last two decades to evaluate the absolute solvation energies of the proton in solutions. In addition, we reviewed and discussed the absolute solvation energies of the proton in water, methanol, ammonia, acetonitrile, dimethylsulfoxide (DMSO), ethanol and other solvents reported in the literature in the last two decades. Finally, featured directions and methodologies which could be very promising are presented and discussed as perspectives. • Recent advances in the determination of proton solvation free energy and enthalpy • Summary of proton solvation methodological approaches • Future directions in the determination of proton solvation free energy and enthalpy [ABSTRACT FROM AUTHOR]

• Structures and relative stability of water clusters (n = 2–9) in the solvent phase for the first time. • New global and local minima energy structures that have not been reported in the gas phase. • Influence of the solvent on the structures of the water clusters. Most of biological and chemical processes occur in aqueous solution. To consider this solvent effects, theoretical investigations including explicit water molecules forming clusters are often considered. These clusters have been extensively investigated in the gas phase to understand their structures, energetics, dynamics, and several other properties. However, their structures, energetics, hydrogen bond networks and many other properties in the solvent phase remained unknown. In this work, we have investigated the effects of solvent on the structures, energetics and hydrogen bond networks of the water clusters from dimer to nonamer. We have explored thoroughly the potential energy surfaces (PESs) of the considered water clusters at classical level to generate initial geometries. The generated geometries have been fully optimized in the solvent phase (represented by a dielectric continuum medium) at the MN15/6-31++G(d,p) level of theory. For the description of the dielectric continuum medium we used the integral equation formalism polarized continuum model (IEF-PCM). The results show that the hydrogen bond network in the solvent phase is different from that in the gas phase due to further interaction with the dielectric continuum medium. Several structures located in the solvent phase are found to be unstable in the gas phase. Nevertheless, we have found that the global minimum structures in both phases have the same shape although their hydrogen bond lengths are different. [ABSTRACT FROM AUTHOR]

Proton transfer at the interface of solvents are of great importance in chemistry and biology. Despite their importance, there are very rare computational models that do describe the proton transfer processes. In this work, we propose a simple and affordable yet efficient model to compute the proton transfer free energy and enthalpy. We applied the proposed model to the calculation of the water-ammonia as well as water-acetonitrile proton transfer free energy and enthalpy. To compute the water-ammonia proton transfer free energy and enthalpy within this model, we need the structures of neutral and protonated water clusters as well as the structures of neutral and protonated ammonia clusters optimized in the solvent phases. Thus we started by exploring the potential energy surfaces (PESs) to locate the most stable structures of the clusters involved in the model. We initially generated the geometries using the ABCluster code followed by full optimization at the MN15/6–31++G(d,p) level of theory combined with the polarized continuum model. As a result, we have reported the global minima energy structures of the investigated clusters in the solvent phase. At room temperature, the water-ammonia (respectively water-acetonitrile) proton transfer free energy and enthalpy are evaluated to be −109.9 and −104.2 kJ mol−1 (respectively 60.2 and 58.0 kJ mol−1), respectively. The calculated water-ammonia as well as water-acetonitrile proton transfer free energy and enthalpy are found to be in good agreement with experimental values when available. • Efficient and affordable model to calculate proton transfer free energy and enthalpy • Water-Ammonia and water-acetonitrile proton transfer free energy and enthalpy • Global minima structures of neutral and protonated ammonia clusters in solution • Global minima structures of neutral and protonated acetonitrile clusters in solution. [ABSTRACT FROM AUTHOR]

The class of insecticides known as neonicotinoid insecticides has gained extensive application worldwide. Two characteristics of neonicotinoid pesticides are excellent insecticidal activity and a wide insecticidal spectrum for problematic insects. Neonicotinoid pesticides can also successfully manage pest insects that have developed resistance to other insecticide classes. Due to its powerful insecticidal properties and rapid plant absorption and translocation, dinotefuran, the most recent generation of neonicotinoid insecticides, has been widely used against biting and sucking insects. Dinotefuran has a wide range of potential applications and is often used globally. However, there is growing evidence that they negatively impact the biodiversity of organisms in agricultural settings as well as non-target organisms. The objective of this review is to present an updated summary of current understanding regarding the non-target effects of dinotefuran; we also enumerated nano- and bio-based mitigation and management strategies to reduce the impact of dinotefuran on non-target organisms and to pinpoint knowledge gaps. Finally, future study directions are suggested based on the limitations of the existing studies, with the goal of providing a scientific basis for risk assessment and the prudent use of these insecticides. [ABSTRACT FROM AUTHOR]

We investigated classical and quantum rotational partition functions, rotational energies and rotational entropies for linear-, spherical- and symmetric-top molecules in a canonical system within a wide range of temperatures under the rigid rotor approximation. We then derived the temperature, T limit , below which classical approach is not valid and the complex quantum approach is strongly recommended. This temperature certainly increases with the inertia moment of the molecule and follows an exact combination of three decreasing exponential functions for linear- and spherical-top molecules when rotational partition functions are considered. However, another good news is that contrary to what is being commonly known, quantum approach is not needed at all for energetic rotational parameters, whatever the temperature. Therefore, there is no real frontier between the classical and quantum approaches when energetic rotational parameters are concerned, though the frontier is naturally a bounded decreasing sequence converging to zero when rotational partition functions are rather concerned. Particularly, classical approach (as implemented in several quantum chemistry computational codes) fails describing rotational partition functions for light molecules or molecules at low temperatures. As a matter of fact, we noted that as far as the partition function is concerned, T limit = 100 3 θ for linear-top molecules and T limit = 25 θ for spherical-top molecules, with θ the characteristic rotational temperature. Moreover, all the closed-forms expressions proposed in the whole literature fail drastically approaching quantum and exact results for light molecules or molecules at low temperatures. In regard of the importance of partition functions in the evaluation of rate constants for chemical reactions and accurate intensities lines in spectroscopy, we proposed two new accurate and simple analytic expressions of the rotational partition functions of linear-top and spherical-top molecules, valid for light molecules or at low temperatures. These new closed-forms reproduce excellently the exact values and are exceptionally better than previous proposed closed-forms in the literature, and they are therefore strongly recommended for light molecules or at low temperatures. [ABSTRACT FROM AUTHOR]

We investigated theoretically the structures and relative stabilities of the solvated copper(II) ion in ammonia, Cu2+(NH3)n, n = 1–10. Besides, we reported the temperature dependence of the isomer distribution of the studied clusters. Distances dCu2+–N for the solvated copper(II) ion in ammonia were discussed. Several significant new isomers and new global minimum energy structures of these clusters were pointed out. A satisfactory relative stability rule of the various isomers of this cluster is proposed and we expect it to be extended to other metal ions solvated in other media. It is worth mentioning that the only possible coordination numbers of the solvated copper(II) ion in ammonia are 4, 5 and 6 and these coordination numbers are strongly influenced by the temperature. The theoretical approach used in this work leads to equatorial distances dCu2+–N, in excellent agreement with experimental results. As far as the temperature dependence of the isomer distribution is concerned, compact and highly coordinated structures dominate the population of the studied clusters at all temperatures. For n = 2–5, the most stable isomers dominate exclusively the population of the clusters, irrespective of the temperature. For n ≥ 6, two to three isomers contribute to the population of the clusters. After reporting binding energies, clustering energies, clustering enthalpies and clustering free energies of the studied clusters, we proposed anticipated results for n > 10 through highly correlated fit functions with very low root mean square errors. We also confirm here our previous claim that clustering free energies at modest or higher cluster sizes (n > 7) for solvated metals could not depend on the metal type (alkaline earth, transition metals, ...). [ABSTRACT FROM AUTHOR]

Iron plays a key role in the evolution of living systems and so it is an essential element in a wide range of biological phenomena, energy transduction mechanisms, and oxygen carriers. In this work, we investigated various isomers of the Fe2+(NH3)n=1–10 complex in the singlet, triplet and quintet spin states in the gas phase and their relative stabilities in a wide range of temperatures (0 K and 25–400 K). All the calculations are performed at the M06-2X/6-31++G(d,p) and MP2/6-31++G(d,p) levels of theory. It emerges from this work that although M06-2X could not in all cases be suitable for investigating the structural parameters of this complex in the singlet spin state, it gives excellent relative energies as compared to MP2 results and therefore could be recommended for evaluating the solvation free energy of the ferrous ion rather than the time consuming MP2 method. In addition, with a few exceptions, structures obtained at the MP2 and M06-2X levels of theory are very similar. The solvated ferrous ion in the singlet, triplet and quintet spin states in ammonia is hexa-coordinated, irrespective of the temperature. This result slightly contrasts the reported finding concerning the hydrated ferrous ion for which the CN is ∼6 around 215 K and less at a higher temperature of 305 K. Furthermore, the quintet spin state structures dominate exclusively lower spin state ones at all temperatures in such a way that no natural spin-crossover is possible between the quintet spin state and the lower spin states in the clusters of Fe2+(NH3)n=1–10. However, the spin-crossover is naturally possible around 200 K between the singlet and the triplet spin states for n≥ 6, and the latter is preferred at high temperatures while the former is preferred at lower temperatures. We also pointed out that the available clustering energies at modest or higher cluster sizes (n ＞ 7) for solvated metal ions neither depend on the spin state of the metal, or on the type of metal (alkaline earth, transition metals,…), or on the ligand type (ammonia, water,…). Thus, the solvation energies of metal ions did not depend on their spin states. We also anticipated that the solvation free energy or enthalpy of the ferrous ion in ammonia could be determined by clustering up to n = 9 or 10. [ABSTRACT FROM AUTHOR]

The possible isomers of [Mg(NH3)n = 1 − 10]+ clusters have been investigated using both M06‐2X/6‐31++G(d,p) and MP2/6‐31++G(d,p) levels of theory. The isomeric distribution for each n size has been studied as a function of temperatures ranging from 25 to 400 K. To the best of our knowledge, for clusters size n > 6, this is the first theoretical study available in the literature. From the calculated values in the considered clusters and using a fitting procedure, we have evaluated the binding energies (−14.0 kcal/mol), clustering energies (−10.1 kcal/mol), clustering free energies (−2.8 kcal/mol), and clustering enthalpies (−10.3 kcal/mol). On the basis of our structural and infrared (IR) spectroscopy outcomes, we find that the first solvation shell can hold up to six ammonia molecules. © 2019 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

[Display omitted] • The removal of Hg from environmental water by advanced oxidation processes. • The removal of Hg from environmental water by adsorption. • Thermodynamic molecular modelling and simulation of Hg adsorption. • Hg adsorption mechanism, kinetics and column adsorption studies. • Regeneration and reusability studies. The review discusses the removal of mercury (Hg) from wastewater by advanced oxidation processes (AOPs) and adsorption. The Hg adsorption in batch and column method was described, and the mechanism was explained, followed by the equilibrium and kinetic modelling. Furthermore, thermodynamic molecular modelling and simulation of Hg adsorption were discussed. The results showed that the removal of Hg from the aqueous solution by AOPs was successfully applied. Some of the future perspectives include enhancing the efficiency of the AOPs for the removal of Hg. The efficiency of available technologies for the removal of heavy metals in general and Hg in particular, depend on three criteria, namely efficacy, cost, suitability, and conditions of application. Langmuir and Freundlich isotherm models are best-fit and also pseudo second order kinetic model. [ABSTRACT FROM AUTHOR]

Horticultural crops are used for a variety of purposes, including nourishment and aesthetics. Human nutrition relies heavily on these plants for carbohydrates, proteins, organic acids, vitamins, and minerals. Drought, flood, nutrient inadequacy, heat, light, metal stress, and other abiotic stresses restrict crop plant development and output. A variety of tactics are used to improve abiotic stress tolerance, including the production of genetically modified cultivars by incorporating gene constructions to improve performance under stress. Nanotechnology is a multifaceted field that could be applied in every branch of research comprising medicine, industry and agriculture. Soil and water nanoremediation, plant nanoprotection and plant nanonutrition are some of the agricultural applications. To accomplish sustainable progress in horticultural plants challenged with various environmental challenges, numerous definitive directions have been developed to secure public acceptance and convenient utilization of nanoparticles. Even with the rapid increase in nanoparticle use in several applications, there is still a dearth of information on the actual outcomes of nanoparticle interaction with plants. This review assesses the role of nanomaterials in horticultural crops under abiotic stress, with a focus on recent research. In addition, this review focuses on explaining the broad roles of several nanoparticles in enhancing abiotic stress tolerance in horticulture plants. [ABSTRACT FROM AUTHOR]

Optoelectrical, electronic, and thermodynamic properties of {6}cycloparaphenylene ({6}CPP) and its derivative, N,N-dimethyl-diaza{6}cycloparaphenylene (DMDA{6}CPP), are theoretically investigated in this work. Using the density functional theory (DFT) and time-dependent DFT (TD-DFT) supported by the APFD and B3LYP-D3 functionals and the 6-311++G (d,p) basis set, the new compound, DMDA{6}CPP, revealed an optical band gap E opt = 1.20 eV. With the lowest energy transition excited state recorded at λ = 1029 nm and associated light-harvesting efficiency (LHE) = 25 % , this derivative demonstrates good characteristics as absorber material in organic solar cell (OSC) devices. The analysis of its charge transport abilities exhibits a ratio of hole/electron reorganization energies λ h / λ e = 0.68 , providing very consistent information on good hole transport abilities. Moreover, this derivative of {6}CPP registered amazing linear and NLO properties with polarizability and first-order hyperpolarizability α = 626.7 a.u and β = 10195.8 a.u, respectively. These values are far higher than those of both para-nitro aniline (p-NA) and urea commonly used as reference molecules in linear and nonlinear optics, positioning this molecule as a perfect candidate for NLO applications and optoelectronics. Molecular atomization energy calculation, spectra analysis, and thermodynamic descriptor calculations have also revealed a very stable structure. [ABSTRACT FROM AUTHOR]

[Display omitted] • Solvated ferrous ion in methanol is hexa-coordinated. • Accurate free energy and enthalpy of the solvated ferrous ion in methanol available. • Binding and clustering energies of the solvated ferrous ion in methanol available. The accurate determination of the solvation free energies or solvation enthalpies of ferrous ion in a given medium is subject to the determination of the most favored structures of the ferrous ion in this medium. In this work, we investigated structures, relative stabilities, clustering energies, binding energies, solvation enthalpies and solvation free energies of the ferrous ion in methanol for temperatures ranging from 20 K to 400 K. It is pointed out that the coordination number of the solvated ferrous ion in methanol is six, but could decrease slightly when the temperature increases. The temperature dependence of the relative stability of different isomers obtained proves that, for T ranging from 20 K to 400 K, the population is dominated by one structure and we noted the presence of fourfold coordinated structures for n > 6. Solvation energies of ferrous ion in methanol were computed following an hybrid solvation scheme. Finally, the solvation free energy of ferrous ion in methanol at room temperature (298.15 K), is −2066.1 kJ mol−1 and the corresponding solvation enthalpy is −2103.5 kJ mol−1. Taking into account the temperature effects, the solvation free energies are more affected by the change of temperature mainly for temperature higher than 200 K. However, the effect of temperature is insignificant on the solvation enthalpies. At the saturation, the binding electronic energy per methanol molecule, the binding enthalpy per methanol molecule and the binding free energy per methanol molecule of the solvated ferrous ion in methanol are −142.1, −140.3 and −104.0 kJ mol−1, respectively. For the clustering energies, we reported −6.9, −6.8 and -3.4 kJ mol−1 corresponding respectively to the clustering electronic energy, the clustering enthalpy and the clustering free energy of the solvated ferrous ion in methanol. [ABSTRACT FROM AUTHOR]

We studied the absorption capacity, optoelectronic and non-linear optical (NLO) properties of graphene oxide nanosheet (GON) and its doped derivatives with aluminum (-Al) atoms. The investigations have been performed using three functionals (B3LYP, B3LYP-D3 and ωB97XD) of the density functional theory (DFT) associated to the basis set 6-31+G(d,p). Aluminum atoms were incorporated into GON at different sites in order to search for suitable candidates that could lead to the enhancement of NLO properties and decrease the band gap value of pristine graphene oxide. As per our molecular investigations, several doped molecular design schemes based on push–pull models of GON were proposed. The best electronic and NLO configurations responses highlight the doped derivatives which were obtained by replacement of carbon atoms which support the functional groups present on the honeycomb lattice of GON with –Al atoms. [Display omitted] • The global reactivity descriptors of the graphene oxide nanosheet and its aluminum-doped derivatives were calculated. • The linear and nonlinear optical parameters of the graphene oxide nanosheet and its aluminum-doped derivatives were calculated. • The light harvesting efficiency (LHE) of the nanosheet of graphene oxide and its aluminum-doped derivatives was calculated. • We found some specific doping positions of the aluminum atom within the graphene oxide nanosheet capable of increasing its intrinsic properties. [ABSTRACT FROM AUTHOR]

• Electrocatalytic performance of the MOFs for CO 2 conversion to value-added products can be boosted by other components. • Effects, principles, and techniques of CO 2 RR, and the mechanism involving C1, C2, C2 + product formations were commented. • MOF composites are efficient electrocatalysts to promote CO 2 reduction. • Challenges facing MOF composites and prospects to boost their activities were discussed. Carbon dioxide (CO 2) levels in the atmosphere are quickly increasing as a consequence of anthropogenic activities, which present grave hazards and dangerous circumstances to not only humanity but also the ecosystem. Currently, electrochemical CO 2 conversion to chemical/fuels remains one of the best methods for minimizing CO 2 concentrations. Metal-organic frameworks (MOFs) composite materials have been considered as new class of highly-performed electrocatalysts for CO 2 reduction reaction (CO 2 RR) due to their wide surface area, higher porosity, chemical tunability and excellent stability. This article presents major approaches for electrochemical CO 2 RR to value-added product. These were followed by discussing the recent advancements in MOF composite electrocatalysts for CO 2 RR including active sites MOF-supported electrocatalysts, metal-nanoparticles-supported MOFs, conductive supported MOFs composites, and polyoxometalate-based MOF composites. Lastly, some challenges currently facing MOF composites for CO 2 RR as well as anticipated future advances were discussed. Research hotspot lies in the creation of highly effective CO 2 RR electrocatalyst such as ligand engineering in MOFs. It is believed that the current study will contribute to accelerating the fabrication of efficient MOF composite materials for abating the CO 2 emission in the ecosystem and to highlight the necessity for further research to address significant environmental sustainability concerns. [ABSTRACT FROM AUTHOR]

Furfural contamination of water is a serious problem in the world. The review article highlights on furfural ecotoxicology and the associated molecular mechanisms involved in its toxicity, efficacy of novel adsorbents for the removal of furfural from polluted water, adsorption capacities of adsorbents under different conditions, such as surface area, concentration, adsorption capacity, pH, time, temperature, applicable isotherm models, characterization and percentage removal of furfural. It was showed from the review that CTAB-bentonite is the best adsorbents for the removal of furfural (q max = 538 mg/g) from aqueous media.A wide range of values for the thermodynamic parameters (both negative and positive) were reported for furfural across different studies. Furfural uptake best-fit both for the Langmuir and Freundlich isotherm models as well as a pseudo second order kinetic model. Additionally, the review also highlighted the molecular modelling and simulations of furfural adsorptions and detail about its future prospects. Among the different treatment options, advanced oxidation processes (AOPs) are likely promising for efficient degradation of furfural in water and wastewater. [Display omitted] • Ecotoxicology effects of furfural. • Adsorption and Advanced oxidation processes (AOPs) removal of furfural from industrial effluents. • Empirical results on equilibrium isotherms, kinetics and thermodynamics. • Molecular modelling and simulation of furfural adsorption. [ABSTRACT FROM AUTHOR]

• This study discussed recent progress in UiO-66 MOF as adsorbents for CO 2 adsorption. • Recent advances in the performance of the UiO-66 MOF membranes for CO 2 separation were discussed. • It presents recent advances in the performance of the UiO-66 MOF catalysts for CO 2 conversion to value-added products. • Different design engineering of UiO-66 MOF materials and challenges associated with structural and morphology controls are discussed. • Some insights into new research dimensions in UiO-66 MOFs for environmental remediations, and CO 2 conversion applications are discussed. UiO-66 (UiO denotes the Oslo University where it was first reported) is an archetypical Zr-based metal-organic framework with numerous exceptional attributes, including larger surface area, well-ordered porous structures, stability, and flexible tailorability. It has found extensive applications in carbon dioxide (CO 2) adsorption and separation and CO 2 conversion to value-added chemicals/fuels. This study presents a detailed combined application of UiO-66 for CO 2 utilization covering adsorption, separation, and conversion to important chemical products. Prior to these, various aspects, including structural integrity, design and defect engineering of UiO-66 materials, and challenges associated with structural and morphology controls, were discussed. The study further discussed the corresponding performance of UiO-66 as adsorbents for CO 2 uptakes, as membranes for CO 2 separation, and as catalyst and photocatalysts for CO 2 conversion to various alcohol and hydrocarbons, light olefins, and oxygenates, thereby suggesting the current research advancements in the implementation of UiO-66 materials for these applications. This was followed by the insight into integrated approaches for CO 2 separation/adsorption onto UiO-66 materials. Finally, this study identifies the associated weaknesses and strengths and treatment strategies, challenges/knowledge gaps to enable fostering and exploring new dimensions and directing specific research for large/industrial-scale applications. [ABSTRACT FROM AUTHOR]