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Reticular chemistry has In the post-synthetic modification (PSM) of frameworks one of the most versatile tools to adapt the systems' physicochemical properties to the specific requirements which are imposed by their application in different contexts. We can safely say that PSM methodologies in all their variants are currently one of the main resources that reticular chemists turn to when they need to diversify a framework compositionally. Practically all these modifications require the integration of functional groups appended to the organic linkers in the framework, either by direct synthesis or by post-synthetic exchange. The reactivity of these tags allows, at a subsequent stage, covalent modification of the framework under conditions that ideally respect its structural integrity. In this perspective article we introduce the use of tetrazine-based linkers as intrinsically tagged alternatives to integrate PSM with click chemistry reactivity. This strategy is ideally suited to molecular frameworks, as it combines very mild modification conditions with direct control over the organisation of built-in appendices and the acknowledged potential of click chemistry to build framework libraries. [ABSTRACT FROM AUTHOR]

This study examines limestone properties and calcination process to enhance product quality. Limestone burning produces lime (CaO, calcium oxide) and carbon dioxide (CO2). Lime is a substance highly reactive and turns into slaked lime (Ca(OH)2, calcium hydroxide) when exposed to water. Six limestone samples from Tuscan Nappe sedimentary sequence, outcropping in the Monti d'Oltre Serchio area (NW Tuscany, Italy), were selected and calcined at different temperatures (800, 900, 1000 and 1100 °C). The obtained lime was slaked, and chemical, mineralogical and petrographic analyses were conducted to study its reactivity during slaking process. Key factors influencing lime reactivity were identified: calcination temperature/time and limestone characteristics (chemical and mineralogical composition). The lime reactivity was measured through the rate of lime hydration reaction. Results showed that higher reactivity in lime, lower calcination temperature. The increase in temperature and time leads to an increase of CaO grain size and, consequently, to a decrease in reactivity. Temperature increase has a more significant effect on the increasing of grain size and reactivity than time. The optimal calcination temperature was found to be 900 °C, like that of ancient limekilns. The study emphasized the close link between lime reactivity and chemistry/mineralogy of limestone. Overall, the research provides insights for improving limestone calcination processes and obtaining superior products. [ABSTRACT FROM AUTHOR]

We present the synthesis, structural characterization, and reactivity studies of a tetra‐zinc complex supported by the bisphenoxymethanone ligands and its transformation into various di‐zinc architectures. Our findings highlight the potential of these complexes in molecular recognition, supramolecular chemistry, and catalysis. [ABSTRACT FROM AUTHOR]

In this paper, we investigate two model reactions (an electrocyclic ring closure and a tautomerism equilibrium) in different sized fullerene cages to explore the intricate details of the confinement effect in chemistry and in chemical reactivity. Fullerene cages offers, with their unique geometry and electronic properties, an ideal theoretical model to explore confinement-induced alterations in reaction pathways and energy barriers. Computational results demonstrate that the induced confinement may significantly influence the thermodynamics and kinetics of the chemical processes under study through a comparative investigation of reactions in various fullerene cage sizes and their occurrence in gas phase. This theoretical investigation intends to improve our knowledge of molecular confinement events, while also highlighting the potential use of fullerene cages as adjustable nanoreactors for regulating and improving chemical reactivity. [ABSTRACT FROM AUTHOR]

The electronic properties, coordination chemistry and reactivity of metal complexes of a planar (C2v symmetric) acridane‐derived geometrically constrained phosphine, P(NNN), are described. On complexation to metal centers, the phosphine was found to adopt a distorted trigonal pyramidal structure with a high barrier to pyramidal inversion (22.3 kcal/mol at 298 K for Au[P(NNN)]Cl). Spectroscopic data and theoretical calculations carried out at the density functional level of theory indicate that P(NNN) is a moderate σ‐donor, with significant π‐acceptor properties. Despite the distortion undergone by the phosphorus atom on coordination to metal centers, the P(NNN) ligand retains its ability to react with small molecule substrates with polar E−H bonds (MeOH, NH2Ph, NH3). It does so in a concerted fashion across one of the P−N bonds, and reversibly in the case of amine substrates. This cooperative bond activation chemistry may ultimately prove beneficial in catalysis. [ABSTRACT FROM AUTHOR]

Since the dawn of photochemistry 150 years ago, photoreactions have been conducted under polychromatic light. However, despite the pivotal role that photokinetics should naturally play for such reactive photosystems, the literature lacks a comprehensive description of that area. Indeed, one fails to identify explicit model integrated rate laws for these reactions, a characteristic type for their kinetic behavior, or their kinetic order. In addition, there is no consensus in the community on standardized investigative tools to evaluate the reactivity of these photosystems, nor are there venues for the discussion of such photokinetic issues. The present work is a contribution addressing some of these knowledge gaps. It proposes an unprecedented general formula capable of mapping out the kinetic traces of photoreactions under polychromatic light irradiation. This article quantitatively discusses several reaction situations, including the effects of initial reactant concentration and the presence of spectator molecules. It also develops a methodology for standardizing actinometers and defines and describes both the spectral range of highest reactivity and the photonic yield. The validity of the model equation has been proven by comparing its results to both theoretical counterparts and those generated by fourth-order Runge-Kutta numerical calculations. For the first time, a confirmation of the Φ-order character of the kinetics under polychromatic light was established. [ABSTRACT FROM AUTHOR]

Context: In this study, we have investigated the structure, reactivity, bonding, and electronic transitions of DPA and PDTC along with their Ni-Zn complexes using DFT/TD-DFT methods. The energy gap between the frontier orbitals was computed to understand the reactivity pattern of the ligands and metal complexes. From the energies of FMO's, the global reactivity descriptors such as electron affinity, ionization potential, hardness (η), softness (S), chemical potential (μ), electronegativity (χ), and electrophilicity index (ω) have been calculated. The complexes show a strong NLO properties due to easily polarization as indicated by the narrow HOMO–LUMO gap. The polarizability and hyperpolarizabilities of the complexes indicate that they are good candidates for NLO materials. Molecular electrostatic potential (MEP) maps identified electrophilic and nucleophilic sites on the surfaces of the complexes. TDDFT and NBO analyses provided insights into electronic transitions, bonding, and stabilizing interactions within the studied complexes. DPA and PDTC exhibited larger HOMO–LUMO gaps and more negative electrostatic potentials compared to their metal complexes suggesting the higher reactivity. Ligands (DPA and PDTC) had absorption spectra in the range of 250 nm to 285 nm while their complexes spanned 250 nm to 870 nm. These bands offer valuable information on electronic transitions, charge transfer and optical behavior. This work enhances our understanding of the electronic structure and optical properties of these complexes. Methods: Gaussian16 program was used for the optimization of all the compounds. B3LYP functional in combination with basis sets, such as LanL2DZ for Zn, Ni and Cu while 6-311G** for other atoms like C, H, O, N, and S was used. Natural bond orbital (NBO) analysis is carried out to find out how the filled orbital of one sub-system interacts with the empty orbital of another sub-system. The ORCA software is used for computing spectral features along with the zeroth order regular approximation method (ZORA) to observe its relativistic effects. TD-DFT study is carried out to calculate the excitation energy by using B3LYP functional. [ABSTRACT FROM AUTHOR]

The typical initiating events of a core disruptive accident (CDA) in small sodium-cooled fast reactors (SFR) are evaluated with the computational code, SAS4A. CDA is one of the hypothetical events in the safety assessment of the SFR, as the SFR has the potential to experience power excursion due to the sodium voiding and the core degradation. To improve the safety of future SFRs, the development of SFRs with low void reactivity has been promoted. Small SFRs can have a negative void coefficient of reactivity. The analysis of the CDA event sequence in small SFRs is valuable for the investigation of the reactor characteristics for the future R&D of SFRs. The event progression during ULOF and UTOP, which are the typical initiating events of CDA, is investigated through the numerical analysis. The event progression of these accidents in the low void reactivity reactor is found to be slow due to the effective insertion of the negative reactivity feedback and the absence of significant positive reactivity insertion. No power excursion occurs in the initiating phase. In ULOF, the cladding melt and motion behavior becomes more important for the evaluation of the event progression due to its positive reactivity. [ABSTRACT FROM AUTHOR]

In this study, we focus on the theoretical calculation of global and local chemical reactivity descriptors for chiral carbon dots derived from pyrene and amino acids through ADPT (auxiliary density perturbation theory) linear response implemented in deMon2k software. We assessed the presence of hydroxyl, hydrosulfide groups, and nitrogen heteroatoms in the graphitic system of carbon dots. After optimizing the geometries, global chemical reactivity descriptors were computed using both traditional and analytical approaches. It has been observed that the presence of nitrogen heteroatoms increases the overall nucleophilic character of CDs, reduces the HOMO–LUMO gap and generates more nucleophilic and electrophilic reactive sites throughout the aromatic system. The position of nitrogen atoms was found to influence the planarity of the graphitic system, potentially compromising properties related to intramolecular electron transfer. Thiol groups at the edges of the CDs were identified to enhance the nucleophilic character of the pyrene fragment, exhibiting a more positive charge compared to the oxygen of the alcohol group. Amino acid fragments exhibit stereoselective reactivity, however, in the model systems examined here, their reactivity is surpassed by the pyrene fragment, which is highly reactive due to its planar conjugate system. These findings could contribute significantly to the structural design and understanding of properties for carbon dots developed for various technological applications. [ABSTRACT FROM AUTHOR]

In alkyllithium chemistry the highest reactivity has historically been linked to the smallest degree of aggregation possible. Since tert‐butyllithium is known to form a monomer in tetrahydrofuran solution, using just stoichiometric amounts of the lewis base to selectively form a dimeric species seemed irrational. In this study, we showed a considerable increase of the reactivity of t‐BuLi when using stoichiometric amounts of THF in the non‐polar solvent n‐pentane in order to enable the deprotonation of simple methyl silanes and other low C−H−acidic substrates. In this context, we were able to obtain the corresponding aggregates of t‐BuLi with the ligand THF in suspension and as crystalline solids and investigate them by single crystal X‐ray structural analysis, in situ FTIR spectroscopy and quantum chemical calculations. Furthermore, we were able to explain the enhanced reactivity of t‐BuLi with stoichiometric amounts of THF on the basis of structural features of the bridged dimer obtained under these conditions. With these findings, we present a new target in the aggregation of alkyllithium reagents: the selectively formed "frustrated" aggregates! [ABSTRACT FROM AUTHOR]

In this article, we report on advanced molecular dynamics simulations of the atomistic DMASnBr 3 –water interface, which, coupled with a grand-canonical formulation of adsorbates and defects, elucidate the surface chemistry and reactivity of this novel water-stable perovskite and highlight the role of small electron bipolarons in photocatalytic hydrogen production. We find that the extremely acidic nature of the surface Br atoms does not allow for significant adsorption of protons at the interface under charge-neutral conditions. However, when electrons are accumulated on the surface, the formation of a small electron bipolaron in the form of a Sn-Sn dimer provides the required electron localization to drive adsorption of H, which is assimilated on surface Sn atoms as hydride. Finally, we estimate a favourable alignment between the bipolaron energy level and the H + /H 2 redox level, which suggests the occurrence of a feasible route for hydrogen evolution, bypassing the common reaction mechanism. • Poor adsorption of protons at the DMASnBr 3 –water interface rules out common reaction mechanisms for H 2 production. • Small electron bipolarons alter the reactivity of the surface, inducing H adsorption as surface hydride. • An alternative route for photocatalytic H 2 production is proposed from the alignment of energy levels at the interface. [ABSTRACT FROM AUTHOR]

In light of its ubiquitous presence in the interstellar gas, the chemistry and reactivity of the HCO+ ion requires special attention. The availability of up-to-date collisional data between this ion and the most abundant perturbing species in the interstellar medium is a critical resource in order to derive reliable values of its molecular abundance from astronomical observations. This work intends to provide improved scattering parameters for the HCO+ and He collisional system. We have tested the accuracy of explicitly correlated coupled-cluster methods for mapping the short- and long-range multi-dimensional potential energy surface of atom–ion systems. A validation of the methodology employed for the calculation of the potential well has been obtained from the comparison with experimentally derived bound-state spectroscopic parameters. Finally, by solving the close-coupling scattering equations, we have derived the pressure broadening and shift coefficients for the first six rotational transitions of HCO+ as well as inelastic state-to-state transition rates up to j = 5 in the 5–100 K temperature interval. [ABSTRACT FROM AUTHOR]

Accurate dosimetric verification is becoming increasingly important in radiotherapy. Although polymer gel dosimetry may be useful for verifying complex 3D dose distributions, it has limitations for clinical application due to its strong reactivity with oxygen and other contaminants. Therefore, it is important that the material of the gel storage container blocks reaction with external contaminants. In this study, we tested the effect of air and the chemical permeability of various polymer-based 3D printing materials that can be used as gel containers. A methacrylic acid, gelatin, and tetrakis (hydroxymethyl) phosphonium chloride gel was used. Five types of printing materials that can be applied to the fused deposition modeling (FDM)-type 3D printer were compared: acrylonitrile butadiene styrene (ABS), co-polyester (CPE), polycarbonate (PC), polylactic acid (PLA), and polypropylene (PP) (reference: glass vial). The map of R2 (1/T2) relaxation rates for each material, obtained from magnetic resonance imaging scans, was analyzed. Additionally, response histograms and dose calibration curves from the R2 map were evaluated. The R2 distribution showed that CPE had sharper boundaries than the other materials, and the profile gradient of CPE was also closest to the reference vial. Histograms and dose calibration showed that CPE provided the most homogeneous and the highest relative response of 83.5%, with 8.6% root mean square error, compared with the reference vial. These results indicate that CPE is a reasonable material for the FDM-type 3D printing gel container. [ABSTRACT FROM AUTHOR]

Coordination chemistry and frustrated Lewis pair (FLP) chemistry have been most commonly studied using monodentate Lewis acids. In this paper, we examine the corresponding reactions employing the 1,1- and 1,2-bis-boranes, PhCH2CH(B(C6F5)2)21 and Me3SiCH(B(C6F5)2)CH2B(C6F5)22, respectively. Coordination of isocyanide to these species results in the formation of the products RCH(B(C6F5)2CNtBu)CH2(B(C6F5)2CNtBu) (R = Ph 3, Me3Si 4). The rearrangement of 1 to give the 1,2-bis-borane adduct 3 was probed and attributed to a donor-induced retrohydroboration and subsequent hydroboration. The analogous reaction of 1 is evident in efforts to use the Gutman–Beckett method to assess its Lewis acidity. However, in combination with tBu3P, bis-boranes 1 and 2 form FLPs and react with H2 to give [tBu3PH][PhCH2CH(B(C6F5)2)2(μ-H)] 5a and [tBu3PH][Me3SiCH(B(C6F5)2)CH2(B(C6F5)2)(μ-H)] 6, respectively. Reactions of 1 and 2 with various donors and PhCCH were shown to give deprotonation and addition products, depending on the nature of the base. However, in the case of 1, products resulting from retrohydroboration, and subsequent hydroboration are evident. Several of these alkyne products are crystallographically characterized. [ABSTRACT FROM AUTHOR]

Our study was motivated by the urgent need to develop or improve antivirals for effective therapy targeting RNA viruses. We hypothesized that analogues of favipiravir (FVP), an inhibitor of RNA-dependent RNA polymerase (RdRp), could provide more effective nucleic acid recognition and binding processes while reducing side effects such as cardiotoxicity, hepatotoxicity, teratogenicity, and embryotoxicity. We proposed a set of FVP analogues together with their forms of triphosphate as new SARS-CoV-2 RdRp inhibitors. The main aim of our study was to investigate changes in the mechanism and binding capacity resulting from these modifications. Using three different approaches, QTAIM, QSPR, and MD, the differences in the reactivity, toxicity, binding efficiency, and ability to be incorporated by RdRp were assessed. Two new quantum chemical reactivity descriptors, the relative electro-donating and electro-accepting power, were defined and successfully applied. Moreover, a new quantitative method for comparing binding modes was developed based on mathematical metrics and an atypical radar plot. These methods provide deep insight into the set of desirable properties responsible for inhibiting RdRp, allowing ligands to be conveniently screened. The proposed modification of the FVP structure seems to improve its binding ability and enhance the productive mode of binding. In particular, two of the FVP analogues (the trifluoro- and cyano-) bind very strongly to the RNA template, RNA primer, cofactors, and RdRp, and thus may constitute a very good alternative to FVP. [ABSTRACT FROM AUTHOR]

In this study, for the first time, boron oxide nanoflake is analyzed as drug carrier for favipiravir using computational studies. The thermodynamic stability of the boron oxide and favipiravir justifies the strong interaction between both species. Four orientations are investigated for the interaction between the favipiravir and the B3O3 nanoflake. The Eint of the most stable orientation is −26.98 kcal/mol, whereas the counterpoise-corrected energy is −22.59 kcal/mol. Noncovalent interaction index (NCI) and quantum theory of atoms in molecules (QTAIM) analyses are performed to obtain insights about the behavior and the types of interactions that occur between B3O3 nanoflake and favipiravir. The results indicate the presence of hydrogen bonding between the hydrogen in the favipiravir and the oxygen in the B3O3 nanoflake in the most stable complex (FAV@B3O3-C1). The electronic properties are investigated through frontier molecular orbital analysis, dipole moments and chemical reactivity descriptors. These parameters showed the significant activity of B3O3 for favipiravir. NBO charge analysis transfer illustrated the charge transfer between the two species, and UV-VIS analysis confirmed the electronic excitation. Our work suggested a suitable drug carrier system for the antiviral drug favipiravir, which can be considered by the experimentalist for better drug delivery systems. [ABSTRACT FROM AUTHOR]

Boron/potassium nitrate (B/KNO3) is a type of critical energetic composite material (ECM). However, the inert oxide layer on the B surface of B/KNO3 hinders the contact between pure fuel and oxidant, thus limiting energy release This limitation could be eliminated by adding highly reactive Al powder. To discern the effects of Al powder size on the reaction process and reactivity of B/KNO3, this study prepared Al/B/KNO3/polyvinylidene fluoride (PVDF) energetic sticks using the direct ink writing (DIW) technology. This study characterized the macroscopic morphology and structure of the energetic sticks using a laser scanning microscope and a scanning electron microscope, examined the reaction process of the composites using a differential scanning calorimeter and a thermogravimetric analyzer, and observed the flame propagation behavior of energetic sticks and energetic architectures using a high-speed camera. Furthermore, it tested the pressure output characteristics of the energetic composites using a closed volume tank. The results show that adding Al powder can improve the combustion efficiency of B/Al composite fuels and reduce the agglomeration of the combustion products. The Al powder with various particle sizes affects various reaction stages of the composite. The combustion and pressure output tests suggest that adding Al powder with a particle size of 1 µm yielded high reactivity and that flame jump propagation appeared in energetic architectures when the channel spacing was below 10 mm. These findings provide a guide for modifying the B/KNO3 energetic composites and regulating the reactivity of energetic sticks. [ABSTRACT FROM AUTHOR]

Organic donor‐acceptor (DA) complexes have emerged in recent years as materials of choice for organic binary electronics. The reactivity descriptors derived from the conceptual DFT reveal imidazo[1,2‐a]pyridines as potential donors. Thus, four imidazo[1,2‐a]pyridines were reacted with tetracyanoethylene (TCNE) in 1 : 2 molar ratio to afford four new DA complexes. The spectral studies, namely IR, 1H, 13C, DEPT 135, 2D HMQC NMR, and HRMS were used to establish structures of the products. The UV‐vis. spectroscopy reveals intramolecular charge transfer. All the four compounds fluoresce giving excitation emission fluorescence spectra with a red shift ranging from 64 to 151 nm and quantum yields from 0.004 to 16.35. Unexpectedly, nitro group in one of the products does not act as quencher; instead, it enhances the quantum yield to make it highest in this series. The products exhibit electrical conductivity which increases with temperature. The FESEM and HRTEM images reveal distinct and homogenous surface morphology with holes which facilitate flow of electrons as manifested by electrical conductivity. The powder XRD and SAED results establish the polycrystalline nature of the products. The theoretical studies indicate an alternate donor acceptor stacking pattern. [ABSTRACT FROM AUTHOR]

DFT calculations of ground-state hydrazine and benzohydrazide derivatives were performed by using hybrid functional B3LYP and CAMB3LYP with 6–31G (d, p) as basis set. The electric dipole moment (μ) , polarizability (α) and molecular first hyperpolarizability (β) were characterized in these compounds. The HOMO–LUMO energy gaps and the global chemical reactivity descriptors were computed by B3LYP and CAMB3LYP using 6–31G (d,p), while the excitation energies have determined by time dependent DFT (TDDFT). Besides, the stability and charge delocalization were studied by natural bond orbital analysis. Topological analyses such as atom in molecule (AIM), natural bonding orbital (NBO) and molecular electrostatic potential (MEP) have used to compute intermolecular interactions and in particular hydrogen bonds. The obtained first-order hyperpolarizabilities in the range of 1.5 × 10 − 3 0 to 30.2 × 10 − 3 0 esu revealed that the hydrazine and benzohydrazide derivatives have better NLO properties. The low-energy gap of 3.53 eV generates an intramolecular charge transfer, leading to the enhancement of the NLO activity in these compounds. The HOMO and LUMO have negative energies, suggesting that stable compounds could be synthesized. The negative (red, orange and yellow) regions of the MEP are related to electrophilic reactivity. The AIM analysis is applied to classify and understand hydrogen bonding interactions in the molecules. Besides, the 2D NCI plots describe the nature of noncovalent interactions in the molecules. [ABSTRACT FROM AUTHOR]

[Display omitted] Adiabatic ionization energies for a series of acyclic and cyclic compounds containing M–M and M=M (M = C, Si, Ge, and Sn) bonds were calculated using DFT-TPSS/D3/def2-TZVPP and DFT-PBE0-DH/def2-TZVPP. Their changes when moving down group 14, as well as the influence of the substituent nature on them, were discussed. [ABSTRACT FROM AUTHOR]

We argue for an account of chemical reactivities as chancy propensities, in accordance with the 'complex nexus of chance' defended by one of us in the past. Reactivities are typically quantified as proportions, and an expression such as "A + B → C" does not entail that under the right conditions some given amounts of A and B react to give the mass of C that theoretically corresponds to the stoichiometry of the reaction. Instead, what is produced is a fraction α < 1 of this theoretical amount, and the corresponding percentage is usually known as the yield, which expresses the relative preponderance of its reaction. This is then routinely tested in a laboratory against the observed actual yields for the different reactions. Thus, on our account, reactivities ambiguously refer to three quantities at once. They first refer to the underlying propensities effectively acting in the reaction mechanisms, which in 'chemical chemistry' (Schummer in Hyle 4:129–162, 1998) are commonly represented by means of Lewis structures. Besides, reactivities represent the probabilities that these propensities give rise to, for any amount of the reactants to combine as prescribed. This last notion is hence best understood as a single case chance and corresponds to a theoretical stoichiometric yield. Finally, reactivities represent the actual yields observed in experimental runs, which account for and provide the requisite evidence for/against both the mechanisms and single case chances ascribed. [ABSTRACT FROM AUTHOR]

This work involved the synthesis of the novel antifungal compound pyrazole pyrazolium picrate (PPP), which was then examined using X-ray crystallography, FT-IR, FT-Raman, and UV-vis spectra. Quantum chemical computations were carried out by Density functional theory methods at B3LYP level. The presence of functional groups in PPP compound is confirmed by FT-IR and FT-Raman spectral analysis. The molecular properties, such as chemical reactivity descriptors HOMO-LUMO, Fukui, and MEP of the title compound were calculated to get insight into the stability and reactive site on the molecule. Hirshfeld surface analysis and fingerprint plots were used to calculate intermolecular interactions. The quantum theory of atoms in molecules (QTAIM) and the reduced density gradient (RDG) were carried out to study the intra and intermolecular interactions within the molecule particularly the properties of C–H...O and N–H...O hydrogen bonds. Natural bond orbital (NBO) analysis was used to examine the compound's electronic stability due to intermolecular and intramolecular interaction and charge delocalization. A molecular docking simulation was employed to explore the ligand-protein interaction, while drug-likeness and ADMET analysis were used to ascertain the biological properties of the title molecule. Antifungal testing was performed to investigate the compound's efficacy against fungicidal strains. [ABSTRACT FROM AUTHOR]

In this work, the mechanism of the formation of a radical from 1,2-dihydro-2-methyl-2-phenyl-3H-indole-3-one-1-oxyl has been studied theoretically by the B3LYP/6-31G(d) method as well as the global descriptors of its reactivity have been calculated. The formation of an inclusion complex (stoichiometry 1:1) between the radical form of 1,2-dihydro-2-methyl-2-phenyl-3H-indole-3-one-1-oxyl and the randomly methylated β-cyclodextrin was also studied by B3LYP-D3/6-31G(d) method. The results obtained show that the formation of the radical is ensured by the HAT mechanism according to the BDE energies obtained in vacuum and in water. Formation of the inclusion complex according to the two models C1 and C2 leads to an increase in solubility and improve antioxidant activity of 1,2-dihydro-2-methyl-2-phenyl-3H-indole-3-one-1-oxyl radical which is agreed well with experimental results. Finally, intermolecular interaction such us H-bonds and van Der Waals interactions are the major contribution of inclusion complex stability. [ABSTRACT FROM AUTHOR]

A new procedure based on the two parabolas model of the energy and the electronic density for fractional electron number is used with the assumption that the changes to the isolated values of these two quantities due to the presence of another interacting species can be incorporated through a multiplicative constant in the second order term. The expressions thus obtained for the chemical potential, hardness, Fukui function and dual descriptor reactivity indexes of conceptual density functional theory have the same form of those obtained through a first order perturbation approach within the grand canonical ensemble. The perturbation parameters are then evaluated by imposing the chemical potential and hardness equalization principles for the interaction between species A and B to form AB, and it is applied to show for a group of substituted ethenes that the condensed to atom perturbed local chemical potential and local hardness evaluated at the carbon atom that follows the Markovnikov's rule lead to better correlation with the activation energy of their reaction with HCl than the unperturbed descriptors. A similar situation is found for the correlation of the condensed to atom local chemical potential evaluated at N in the aniline molecules with the experimental p K a values. The results obtained indicate that through the perturbed descriptors, that introduce information of the electronic structure on each species of the other one with which it interacts allow one to obtain an improved description of their chemical reactivity. [ABSTRACT FROM AUTHOR]

The molecular structure of 3-diethoxyphosphoryl-28-[1-(1-deoxy-β-D-glucopyranosyl)-1H-1,2,3-triazol-4-yl]carbonylbetulin was investigated through various experimental and theoretical methods. X-ray diffraction, Hirshfeld surface, experimental and calculated FT-IR spectra analysis, molecular electrostatic potential (MEP) and molecular orbital (HOMO and LUMO) were used for the analyses. It was found that the introduction of a triazole substituent affects the arrangement of molecules in the crystal structure and the formation of hydrogen bonds. The Hirshfeld surface analysis shows that the red regions are concentrated near groups, which create hydrogen bonds, which means that the hydrogen bonds are strong. The analysis of HOMO and LUMO orbitals and the chemical reactivity descriptors shows that the compound is kinetically and chemically stable. A molecular electrostatic potential map was used to analyze the electrophilic and nucleophilic area in the molecule. [ABSTRACT FROM AUTHOR]

Borocarbonitride (BCN) materials are newly developed oxidative dehydrogenation catalysts that can efficiently convert alkanes to alkenes. However, BCN materials tend to form bulky B2O3 due to over‐oxidation at the high reaction temperature, resulting in significant deactivation. Here, we report a series of super stable BCN nanosheets for the oxidative dehydrogenation of propane (ODHP) reaction. The catalytic performance of the BCN nanosheets can be easily regulated by changing the guanine dosage. The control experiment and structural characterization indicate that the introduction of a suitable amount of carbon could prevent the formation of excessive B2O3 from BCN materials and maintain the 2D skeleton at a high temperature of 520 °C. The best‐performing catalyst BCN exhibits 81.9 % selectivity towards olefins with a stable propane conversion of 35.8 %, and the propene productivity reaches 16.2 mmol h−1 g−1, which is much better than hexagonal BN (h‐BN) catalysts. Density functional theory calculation results show that the presence of dispersed rather than aggregated carbon atoms can significantly affect the electronic microenvironment of h‐BN, thereby boosting the catalytic activity of BCN. [ABSTRACT FROM AUTHOR]

The cocrystals and salts of sorbic acid (SA), nicotinamide (NIA), piperazine (PIP) and 2,6-diaminopyridine (2,6-DAP) were synthesized for the first time and characterized by XRD, FT-IR, DSC and TG. The solubility of SA and its multicomponent crystals in aqueous solution at 37 °C was measured. The results showed that the formation of the multicomponent crystals of SA increased its equilibrium solubility in water. Ternary phase diagrams (TPDs) of SA–NIA in ethanol were constructed at 20 °C and 30 °C. The results show that as the temperature increases, the preparation region of the pure SA–NIA cocrystal becomes larger, and the shape of the TPD remains unchanged. To further reveal the causes of salt or cocrystal formation, intermolecular interactions were evaluated using the Hirshfeld surface (HS), molecular atomic quantum theory (AIM) and independent gradient model (IGM). The chemical reactivity of molecules was discussed differently using molecular electrostatic potential (MEP) analysis, frontier orbital analysis and global electron reactivity descriptors. [ABSTRACT FROM AUTHOR]

A new class of spirocyclic imines (SCIs) has been theoretically investigated by applying a variety of quantum chemical methods and basis sets. The uniqueness of these compounds is depicted by various peculiarities, e.g., the incidence of planar six-membered rings each with two imine groups (two π bonds) and the incorporation of the isosteres carbon, silicon, or germanium spiro centers. Additional peculiarities of these novel SCIs are mirrored by their three-dimensionality, the simultaneous occurrence of nucleophilic and electrophilic centers, and the cross-hyperconjugative (spiro-conjugation) interactions, which provoke charge mobility along the spirocyclic scaffold. Substitution of SCIs with strong electron-withdrawing substituents, like the cyano group or fluorine, enhances their docking capability and impacts their reactivity and charge mobility. To gain thorough knowledge about the molecular properties of these SCIs, their structures have been optimized and various quantum chemical concepts and models were applied, e.g., full NBO analysis and the frontier molecular orbitals (FMOs) theory (HOMO-LUMO energy gap) and the chemical reactivity descriptors derived from them. For the assessment of the charge density distribution along the SCI framework, additional complementary quantum chemical methods were used, e.g., molecular electrostatic potential (MESP) and Bader's QTAIM. Additionally, using the aromaticity index NICS (nuclear independent chemical shift) and other criteria, it could be shown that the investigated cross-hyperconjugated sila and germa SCIs are spiro-aromatics of the Heilbronner Craig-type Möbius aromaticity. [ABSTRACT FROM AUTHOR]

The unsymmetrical diborane(4) derivative [(d(CH2P(iPr)2)abB)–Bpin] (1) proved to be a versatile PBP boryl pincer ligand precursor for Co(I) (2a, 4a), Rh(I) (2–3b) and Ir(I/III) (2–3c, 5–6c) complexes, in particular of the types [(d(CH2P(iPr)2)abB)M(PMe3)2] (2a–c) and [(d(CH2P(iPr)2)abB)M–PMe3] (2b–c). Whilst similar complexes have been obtained before, for the first time, the coordination chemistry of a homologous series of PBP pincer complexes, in particular the interconversion of the five- and four-coordinate complexes 2a–c/3a–c, was studied in detail. For Co, instead of the mono phosphine complex 2a, the dinitrogen complex [(d(CH2P(iPr)2)abB)Co(N2)(PMe3)] (4a) is formed spontaneously upon PMe3 abstraction from 2a in the presence of N2. All complexes were comprehensively characterised spectroscopically in solution via multinuclear (VT-)NMR spectroscopy and structurally in the solid state through single-crystal X-ray diffraction. The unique properties of the PBP ligand with respect to its coordination chemical properties are addressed. [ABSTRACT FROM AUTHOR]

Semicarbazide (OC(NH2)(N2H3)) and thiosemicarbazide (SC(NH2)(N2H3)) are well-known for their coordination complex formation ability. They contain nonbonding electrons in the form of heteroatoms (N, O and S) and π-electrons in the form of >C=O and >C=S through they strongly coordinate with the metal atoms and ions. Because of their association with this property, the Semicarbazide (SC), thiosemicarbazide (TSC) and their derivatives are widely used for different applications. They serve as building blocks for synthesis of various industrially and biologically useful chemicals. The SC, TSC and they derivatives are also serve as strong aqueous phase corrosion inhibitors. In the present reports, the coordination ability and corrosion protection tendency of Semicarbazide (SC), thiosemicarbazide (TSC) and their derivatives is surveyed and described. These compounds are widely used as inhibitors for different metals and alloys. Through their electron rich sites they adsorb on the metal surface and build corrosion protective film. Their adsorption mostly followed the Langmuir adsorption isotherm. Through their adsorption they increase the value of charge transfer resistance and decrease the value of corrosion current density. Computational studies adopted in the literature indicate that SC, TSC and their derivatives adsorb flatly and spontaneously using charge transfer mechanism. [ABSTRACT FROM AUTHOR]

Fagaramide (FA) alkaloid was investigated experimentally using FT-IR, FT-Raman and NMR (1H and 13C) spectra, also theoretically studied using density functional theory (DFT) calculations. To obtain the ground state geometry and vibrational frequencies of FA molecule, DFT calculations were performed at the B3LYP/6-31++G(d,p) level. The potential energy distribution (PED) analysis of the title molecule was obtained with the help of normal co-ordinate analysis (NCA) and these assignments were compared with the experimental FT-IR and FT-Raman spectrum. The natural bond orbital (NBO), reduced density gradient (RDG) and Hirshfeld surface analysis were applied to evaluate the relative strength of hydrogen bond interaction and to represent their effect on the stabilization of molecular arrangements. Electron localization function (ELF) and localized orbital locator (LOL) maps were generated to show electron delocalization in the molecule. The reactivity of the molecule was studied by the investigation of frontier molecular orbital analysis, density of states (DOS), molecular electrostatic potential (MEP) and chemical reactivity descriptors. Furthermore, through molecular docking, the anti-inflammatory activity of FA was studied and discussed. A molecular dynamic simulation (MDS) was employed to explore biomolecular stability. [ABSTRACT FROM AUTHOR]

The phosphate units have been theoretically investigated through density functional theory (DFT) calculations. Ionization potential (I), electron affinity (A), electrophilicity index (ω), chemical potential (µ), hardness (η), softness (S), and dipole moment (P) have been optimized. The obtained results revealed that the [PO4]3- (Q0) units act as electron donors, while the [P4O10]0 (Q3) unit acts as an electron acceptor. The passage from one unit to the other implies an increase in the number of bridging oxygens (BO) consistent with the variation of Mulliken charges. Moreover, the analysis of the optimized contours of the electrostatic potential has indicated that the electrophilic attack is more expected on the P-O-P bonds. The infrared and Raman spectra have been also predicted and the change of symmetric and asymmetric vibrational bands of the phosphate units with the number of bridging oxygens has been investigated. [ABSTRACT FROM AUTHOR]

This study investigates the crystal structure, physicochemical properties, and pharmacokinetic profile of Ethyl 2-amino-6-methyl-4,5,6,7-tetrahydrothieno[2,3-c]pyridine-3-carboxylate (EAMT) as a potential therapeutic agent. The crystal structure was analyzed using Hirshfeld surface analysis in conjunction with the quantum theory of atoms in molecules (QT-AIM). Non-covalent interactions were evaluated through reduced-density gradient reduction, revealing that the EAMT crystal is stabilized by hydrogen bonds between EAMT molecules in the crystal and between EAMT molecules and water molecules. The molecular electrostatic nature of interactions was examined using MESP, while global and local descriptors were calculated to assess the compound's reactivity. Molecular docking with the Adenosine A1 receptor was performed and validated through a 50 ns molecular dynamics simulation (MDS). Results suggest that EAMT influences protein structure, potentially stabilizing specific secondary structure elements. The compactness analysis showed a slightly more compact protein conformation and a marginally increased solvent exposure in the presence of the EAMT ligand, as indicated by Rg and SASA values. The total binding free energy (ΔG total) was determined to be −114.56 kcal/mol. ADMET predictions demonstrated EAMT's compliance with Lipinski's and Pfizer's rule of five, indicating good oral availability. The compound may exhibit low-potency endocrine activity. In conclusion, EAMT presents potential as a therapeutic candidate, warranting further exploration of its molecular interactions, pharmacokinetics, and potential safety concerns. [ABSTRACT FROM AUTHOR]

The inhibitory effect of di-imine-SB namely ((N1Z, N4E)-N1, N4-bis (4 (dimethylamino) benzylidene) butane 1,4-diamine) on X65-steel in 1 M HCl has been investigated experimentally and theoretically. The electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), and weight loss outcomes display the anticorrosion properties of "di-imine- SB". The inhibitory efficiency exceeds 90% at the optimal concentration of 1 × 10–3 M "di-imine- SB". The metal surface was examined further using scanning electron microscope (SEM) and energy dispersive X-ray (EDX). The effectiveness of the di-imine-SB is returned into its adsorption on X65-steel surface and found in agreement with Langmuir adsorption isotherm. According to the standard Gibbs free energy of adsorption (Δ G ads ∘) , di-imine-SB adsorption tends to be chemical rather than physical, it increases the activation energy ( E a ) of metal dissolution reaction and makes it hard to occur. The PDP data suggested anodic and cathodic type of the di-imine-SB inhibitor. Meanwhile, increasing the resistance of X65-steel to 301 Ω cm2 after adding 1 mM of di-imine-SB confirms its protective effect. Whereas, the positive value of the fraction of electron transference (ΔN, 0.746), confirms the affinity of di-imine-SB to share electrons to the partially filed 3d-orbital of Fe forming strong protective film over X65-steel surface. Aided by Monte Carlo (MC) simulation, the calculated adsorption energy (Eads) suggests excessive adsorption affinity of di-imine-SB on metal surface over the corrosive chlorides and hydronium ions. A good correlation between the theoretical hypothesis and the experimental inhibition efficiency has been achieved. The comparative study showed the superior of the di-imine-SB as potential corrosion inhibitor compared with those reported before. Finally, global reactivity descriptors; electron affinity (A), ionization potential (I), electronegativity (χ), dipole moment (µ), global hardness (η ), electrophilicity index and, Fukui indices were also calculated and found well correlated to the reactivity of di-imine-SB. [ABSTRACT FROM AUTHOR]

A class of organomanganese hydrogenation catalysts was recently rediscovered. These are simple dinuclear Mn(I) carbonyl compounds with phosphido (PR2−) and hydrido (H−) bridges. This class of compounds has been known since the 1960's, and they have rich coordination chemistry and reactivity. Given their recently discovered potential for catalytic applications, a fresh look at this class of compounds was necessary. Hence, this Review comprehensively covers the synthesis, reactivity, and catalysis of this interesting class of molecules. [ABSTRACT FROM AUTHOR]

A clay-based adsorbent (CBA) was purified from a sustainable precursor (raw clay, RC), which was obtained from the Amazon region in Brazil. The CBA was characterized using X-ray diffraction (XRD), Fourier Transform Infrared spectroscopy (FTIR), Brunauer-Emmet-Teller surface area (SBET, RC = 23.386 m2.g−1, CBA = 33.020 m2.g−1), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDS), thermogravimetric analysis (TGA), cation exchange capacity (CEC, CBA = 44.75 cmol/kg), and point of zero charge analyses (pHPZC, CBA = 2.20). Subsequently, CBA was used to adsorb basic yellow 2 (BY2) dye from aqueous solutions. A CBA dosage (1 g/L), initial concentration of dye (C0 = 15 mg/L), and pH (5.6) were ideal conditions for the BY2 dye removal of ~ 98%. The BY2 kinetics was better represented by the pseudo-first-order (PFO) model while the BY2 equilibrium was well represented by the Sips model, with a maximum adsorption capacity of qms = 18.04 mg/g at 28 °C. The negative values of ΔG° and ΔH° showed that the studied process is spontaneous and exothermic, while the values of isosteric heat (∆Hst, -16 to -20 kJ/mol) suggest a predominance of physical interactions. The molecular chemical reactivity of BY2 was investigated using quantum chemical descriptors calculated based on Density Functional Theory (DFT) optimization of the dye molecule, and the results revealed a large energy gap value (4.3900 eV) and considerable chemical hardness (η = 2.1950 eV). Therefore, the correlation between DFT and experimental results consistently sustains that BY2 dye tends to be adsorbed on the CBA surface by electrostatic interactions, thus, this is the possible adsorption mechanism of this process. [ABSTRACT FROM AUTHOR]

Polyols are groups of organic compounds which contain carbon and are randomly linked to other atoms, especially carbon-carbon and carbon-hydrogen. These compounds are mainly used as reactants to make other polymers. Among biopolymers, lignin is regarded as the base of a new polymer in polyol construction. The present study aimed to investigate the effects of amine type (diethylenetriamine and ethylenediamine) on the modification of lignin-based polyols, so as to provide an alternative to petroleum polyols and, in turn, increase functional groups and reduce their harm to humans' health and the environment. To this aim, first, lignin was extracted from raw liquor. Next, the extracted lignin was reacted with diethylenetriamine (DETA) and ethylenediamine (EDA). Finally, the Mannich method was used for the reaction between amine lignin and propylene carbonate. The results of the Fourier Transform Infrared (FTIR) spectroscopy analysis showed that modification with DETA led to more structural change in lignin and peak 1100 indicates the presence of C-O bond related to urethane bonds in modified lignin. Moreover, adding propylene carbonate to aminated lignin did not result in much change in the results of the FTIR analysis. Additionally, urethane bonds can be seen in the results of GPC at 400°C-500°C. Furthermore, a slight decrease in thermal stability was observed in lignin modified with amine and propylene carbonate, compared to the raw lignin sample. [ABSTRACT FROM AUTHOR]

Tuberculosis is the leading bacterial killer worldwide. 8-Nitro-4H-benzo[e][1,3]thiazin-4-ones are a potent class of antitubercular agents with a new mechanism of action. BTZ043 and PBTZ169 (macozinone) have progressed to clinical studies. Herein, we give a comprehensive account of this important class of potential new drugs to treat tuberculosis. We present an overview of recent developments in the field of antitubercular benzothiazinones (BTZs) and summarize our own contributions. The review covers synthesis, structures and reactivity, mechanism of action, in vitro activity and structure activity relationships (SARs), physicochemical and pharmacokinetic properties as well as a brief summary of in vivo models and clinical studies. We address bioavailability issues and the challenge of the potentially toxic nitroaromatic moiety, including reactivity towards nucleophiles in vivo and highlight possible directions of further research into BTZs through chemical modification. [ABSTRACT FROM AUTHOR]

Highlights: Theoretical studies were performed on [RuNOTSP]+, TSPH2, and its anion TSP2− using the DFT/B3LYP method. Cationic complex [RuNOTSP]+ and TSPH2 were investigated mechanistically for ctDNA interaction. Spontaneous ctDNA binding via a static mechanism with two steps was reported. Detailed kinetic data are reported and relative reactivity is [RuNOTSP]+/TSPH2 = 3/1. The ruthenium effect on affinity and mechanism is reported. The ruthenium center improves the reaction rate through coordination affinity, but does not change its mechanism. Molecular docking was used to predict the binding between [RuNOTSP]+ and TSPH2 and the receptors. DNA cleavage studies are correlated with kinetic data. This work aimed to evaluate in vitro DNA binding mechanistically of cationic nitrosyl ruthenium complex [RuNOTSP]+ and its ligand (TSPH2) in detail, correlate the findings with cleavage activity, and draw conclusions about the impact of the metal center. Theoretical studies were performed for [RuNOTSP]+, TSPH2, and its anion TSP−2 using DFT/B3LYP theory to calculate optimized energy, binding energy, and chemical reactivity. Since nearly all medications function by attaching to a particular protein or DNA, the in vitro calf thymus DNA (ctDNA) binding studies of [RuNOTSP]+ and TSPH2 with ctDNA were examined mechanistically using a variety of biophysical techniques. Fluorescence experiments showed that both compounds effectively bind to ctDNA through intercalative/electrostatic interactions via the DNA helix's phosphate backbone. The intrinsic binding constants (Kb), (2.4 ± 0.2) × 105 M−1 ([RuNOTSP]+) and (1.9 ± 0.3) × 105 M−1 (TSPH2), as well as the enhancement dynamic constants (KD), (3.3 ± 0.3) × 104 M−1 ([RuNOTSP]+) and (2.6 ± 0.2) × 104 M−1 (TSPH2), reveal that [RuNOTSP]+ has a greater binding propensity for DNA compared to TSPH2. Stopped-flow investigations showed that both [RuNOTSP]+ and TSPH2 bind through two reversible steps: a fast second-order binding, followed by a slow first-order isomerization reaction via a static quenching mechanism. For the first and second steps of [RuNOTSP]+ and TSPH2, the detailed binding parameters were established. The total binding constants for [RuNOTSP]+ (Ka = 43.7 M−1, Kd = 2.3 × 10−2 M−1, ΔG0 = −36.6 kJ mol−1) and TSPH2 (Ka = 15.1 M−1, Kd = 66 × 10−2 M, ΔG0 = −19 kJ mol−1) revealed that the relative reactivity is approximately ([RuNOTSP]+)/(TSPH2) = 3/1. The significantly negative ΔG0 values are consistent with a spontaneous binding reaction to both [RuNOTSP]+ and TSPH2, with the former being very favorable. The findings showed that the Ru(II) center had an effect on the reaction rate but not on the mechanism and that the cationic [RuNOTSP]+ was a more highly effective DNA binder than the ligand TSPH2 via strong electrostatic interaction with the phosphate end of DNA. Because of its higher DNA binding affinity, cationic [RuNOTSP]+ demonstrated higher cleavage efficiency towards the minor groove of pBR322 DNA via the hydrolytic pathway than TSPH2, revealing the synergy effect of TSPH2 in the form of the complex. Furthermore, the mode of interaction of both compounds with ctDNA has also been supported by molecular docking. [ABSTRACT FROM AUTHOR]

The piperidine put deep attention to research due to their pharmacological activity and hence drug designing. The derivatives of piperidine have important activities against cancers and tumor disease. Cancer is the most difficult disease in the world (WHO) which is basically considered to be the uncontrolled growth of abnormal cells. In present communication structural and vibrational features of piperidine derivatives 3-(hydroxymethyl)-3-methyl-2,6-diphenylpiperidin-4-one has been computed based on theoretical quantum chemical approach. The primary aspects of piperidine derivatives 3-(hydroxymethyl)-3-methyl-2,6-diphenylpiperidin-4-one structure has been calculated by using optimized geometry, spectroscopic behavior, chemical reactivity and molecular docking analysis. The info about coupled of modes were founded in vibrational features of the molecule. The stability of the chemical reactivity of 3-(hydroxymethyl)-3-methyl-2,6-diphenylpiperidin-4-one was predicted by using HOMO-LUMO energy gap. The molecular electrostatic surface potential (MESP) plot utilizes overall picture of accretion of charges on separate atoms in molecule which very useful predict the nucleophilic and electrophilic charge center. The pharmacological importance of piperidine derivatives 3-(hydroxymethyl)-3-methyl-2,6-diphenylpiperidin-4-one is established by calculated biological activity. The inhibition properties and chemical reactivity of piperidine derivatives 3-(hydroxymethyl)- 3-methyl-2,6-diphenylpiperidin-4-one are well-known by chemical reactivity descriptors by using HOMO-LUMO energies. The inhibition potentials of piperidine derivatives 3-(hydroxymethyl)- 3-methyl-2,6-diphenylpiperidin-4-one are established by calculated lipophilicity, aqueous solubility, and binding affinity. The docking of molecule has been also performed with suitable target. [ABSTRACT FROM AUTHOR]

In this report sulfadiazine (SDZ) has been experimentally and quantum chemically investigated. Computational analysis was carried out theoretically using the density functional theory (DFT) approach/B3LYP and 6-311++G(d,p) level to obtain optimized geometrical structure and vibrational modes analysis and other various calculations. A detailed description of the intermolecular interactions of the crystal surface were carried out by means of Hirshfeld surface analysis and fingerprint plots. Exploration of electron excitation from occupied to unoccupied orbitals in a single electron pair occurs, with dimethyl sulfoxide (DMSO) and MeOH as solvents and electron density distribution (EDD) and hole density distribution (HDD) maps were drawn in an excited state. The molecule reactivity region MEP, molecular stability, natural bond orbital (NBO), HOMO–LUMO, dipole moment (μ), polarizability (α), and hyperpolarizability (β) nonlinear optical (NLO), have all been taken into account. NBO analysis was carried out and the hybridization of atoms that form bonds was evaluated. The charge transfer of the title molecule has been examined by TD-DFT method The UV–Vis spectrum was obtained by employing the TDDFT/PCM method and compared with experimental spectra. Calculated HOMO→LUMO energy gap and charge transfer in the molecule was investigated. Chemical descriptors indicate the reactivity of the molecule as a whole, and Fukui function calculations were used to examine the reactive locations of the compound. The electrophilicity index was calculated and the bio-activity of the molecule was studied. However, biological research like drug-likeness and molecular docking are also done on the molecule. [ABSTRACT FROM AUTHOR]

Many sciences are described by two conceptually different but complementary theories, one visual and insightful the other better suited to computation. Chemistry has a powerful computational theory in quantum mechanics, but its visual and insightful theory of valence has never been properly developed. The rigorous theory of valence described here takes the atom as its fundamental particle. As the theory has no knowledge of the atom's internal structure, the valence is not associated with the electron, hence it is free to adopt fractional values. Each atom is characterized by two experimental properties: its valence determined from the compositions of observed compounds, and its size determined from its observed coordination numbers. These two properties are able to describe a surprising amount of chemistry. The amount of valence an atom typically uses to form a bond determines both the conditions under which bonds can be formed and their resulting properties. A valence definition of electronegativity removes the need to distinguish between ionic and covalent bonds by defining the more nuanced concept of bond polarization, clearing up much of the confusion found in popular bonding models. The theory is compatible with the physical picture provided by quantum mechanics but not with the physically unrealistic ionic model. It can be used for analyzing, modeling, and teaching of chemical structure and reactivity, but having no knowledge of the internal structure of the atom it cannot be used to calculate energies or any of the properties that depend on the energy; for that quantum mechanics must be used. [ABSTRACT FROM AUTHOR]

Cool flame oxidation of hydrocarbon fuels produces substantial intermediates with various levels of chemical reactivity, which can be used for combustion control of advanced engines with low-temperature combustion. Previous investigation has evaluated the performance of low-temperature reforming under high fuel-rich conditions, whereas the potential of a broader scope of reforming conditions (especially fuel-lean scenarios) is not clear. In this work, cool flame oxidation as a reforming way was proposed to investigate the effect of reforming products from various reforming conditions on ignition characteristics of typical operating conditions, and the role of the reforming products from typical reforming conditions on ignition characteristics of different operating conditions was clarified under engine-relevant conditions. The results show that the reforming products via cool flame oxidation are more sensitive to reforming temperature than pressure and equivalence ratio. Residence time also plays an important role in reforming products, and depending on the oxidation degree, two kinds of reforming products can be identified, i.e. mild reforming and severe reforming, manifesting distinct chemical reactivity. Meanwhile, it is found that different from the previous findings of very fuel-rich reforming conditions, the ignition delay time of different blends is significantly shortened under most operating conditions, except for some scenarios (e.g. the negative temperature coefficient region) manifesting a "cross-point" behavior. Moreover, the promotion on ignition processes becomes enhanced under higher temperature, higher pressure, leaner mixture, and severe reforming conditions. Globally, cool flame oxidation as a reforming way can reduce the ignition delay time by 30 ~ 50% under engine-relevant conditions. The current work can provide new perspectives of cool flame oxidation as an effective way to control advanced engine combustion processes. [ABSTRACT FROM AUTHOR]

Today's environmental needs require the reduction of the weight of vehicles, thus reducing fuel consumption and associated emissions. For this reason, the use of light alloys is being studied, which, due to their reactivity, must be protected before use. In this work, the effectiveness of a hybrid sol-gel coating doped with various organic environmentally friendly corrosion inhibitors applied to an AA2024 lightweight aluminium alloy is evaluated. Some of the inhibitors tested are pH indicators, acting as both corrosion inhibitors and optical sensors for the surface of the alloy. Samples are subjected to a corrosion test in a simulated saline environment and characterised before and after the test. The experimental results regarding their best inhibitor performance for their potential application in the transport industry are evaluated. [ABSTRACT FROM AUTHOR]

Aluminum (Al) powder is widely used in solid propellants. In particular, nano-Al has attracted extensive scholarly attention in the field of energetic materials due to its higher reactivity than micro-Al. However, the existence of aluminum oxide film on its surface reduces the heat release performance of the aluminum powder, which greatly limits its application. Hence, this paper used iron, a component of solid propellant, to coat micron-Al and nano-Al to improve the heat release efficiency and reactivity of Al powder. SEM, TEM, EDS, XRD, XPS, and BET were used to investigate the morphological structure and properties of pure Al and Fe/Al composite fuels of different sizes. The results show that Fe was uniformly coated on the surface of Al powder. There was no reaction between Fe and Al, and Fe/Al composite fuels had a larger specific surface area than pure Al, which could better improve the reactivity of pure Al. Besides, the catalytic effects of pure Al and Fe/Al composite fuels of different sizes on ammonium perchlorate and ammonium nitrate were explored. The results show that the catalysis of pure Al powder could be greatly improved by coating Fe on the surface of Al powder. Especially, the micron-Fe/Al composite fuel had a higher catalytic effect than the pure nano-Al powder. Hence, Fe/Al composite fuels are expected to be widely used in solid propellants. [ABSTRACT FROM AUTHOR]

Obtaining rate constants and branching ratios for the atmospheric degradation of organic compounds is crucial for their environmental assessment and for a deeper understanding of their atmospheric chemistry and reactivity. The theoretical prediction of such quantities is a challenging endeavor that grows with conformational complexity. In this work, we have theoretically calculated the rate constants and branching ratios for the tropospheric OH‐initiated oxidation reactions of the CH3OCF2CHF2 hydrofluoroether and its primary product, the HC(O)OCF2CHF2 fluorinated ester. The calculations were performed with a cost‐effective multiconformer transition state theory protocol employing the recently developed constrained transition state randomization method. The calculated k(HO⋅+CH3OCF2CHF2)=1.6×10−14cm3molecule−1s−1 rate constant lies within the error bars of the recommended experimental value, while the calculated rate coefficient of k(HO⋅+HC(O)OCF2CHF2)=2.6×10−14cm3molecule−1s−1 represents, to our knowledge, the first determination of this reaction's rate constant. The results provide new insight and elucidate the main mechanistic issues discussed in recent experimental work while they also encourage the use of this protocol in investigations of the tropospheric reactivity of other fluorinated organic compounds. [ABSTRACT FROM AUTHOR]

In this work, 2-thioxo -3 N-(2-ethoxyphenyl -5[4′-methyl -3′N-(2′-ethoxyphenyl) thiazol-2′(3′H)-ylidene] thiazolidin-4-one (E2Th2) was synthesized and its molecular structure determined by FT-IR, UV-Vis and NMR spectroscopic techniques along with a single crystal X-ray diffraction study. Quantum chemical calculations were performed to better understand its structural, spectroscopic and electronic properties such as HOMO and LUMO energy gap, MEP and global reactivity descriptors. Theoretical calculations were performed using density functional theory (DFT) based on the B3LYP/6-311G (d,p). Vibrational frequencies were assigned on the basis of PED and electronic transitions are calculated according to time-dependent density functional theory (TD-DFT). The HOMO and LUMO analysis are used to determine the charge transfer within the molecule. The NLO activity evaluation was based on the determination of the dipole moment, polarizability (α), first-order hyperpolarizability (β) and the second-order hyperpolarizability (γ) which were calculated using the same level of theory. The hyper-hardness descriptor (Γ) was explored and correlated with the NLO properties. Additionally, the stability of the molecule occurring from hyper-conjugative interaction, intramolecular hydrogen bond and charge delocalization were quantified using NBO analysis. The repulsive, attractive, and van der Waals strong and weak interactions were revealed by RDG and HS analyses. Finally, results have shown that the title compound can be used as attractive future NLO material. [ABSTRACT FROM AUTHOR]

The molecular structure of the compound, spectroscopic investigations (Fourier transform infrared, FT-Raman and nuclear magnetic resonance), as well as the frontier energy level and molecular electrostatic potential (MEP) analysis of 3-hydroxy-3′,4′,5,7-tetramethoxyflavone (3H7TMFN), were all examined using density functional theory (DFT) methods. Comparisons were made between predicted DFT geometrical parameters and experimental values and also the same was performed between the theoretical vibrational wavenumbers and observed data. Chemical reactivity of 3H7TMFN was studied using DFT/PBEPBE approach that included frontier orbital energies, MEP surface map, optical characteristics and chemical descriptors. Additionally, the cytotoxic activity of the bioactive ligand was checked against human cancer cell lines A549 and MCF-7 in vitro by the MTT assay. Hence, the docking and in vitro activity against cancer cell lines display positive results and the present ligand performance appears to be a promising way for anticancer agents with better efficacy. [ABSTRACT FROM AUTHOR]