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The authors previously developed a divide-and-conquer (DC)-based non-local excited-state calculation method for large systems using dynamical polarizability [Nakai and Yoshikawa, J. Chem. Phys. 146, 124123 (2017)]. This method evaluates the excitation energies and oscillator strengths using information on the dynamical polarizability poles. This article proposes a novel analysis of the previously developed method to obtain further configuration information on excited states, including excitation and de-excitation coefficients of each excitation configuration. Numerical applications to simple molecules, such as ethylene, hydrogen molecule, ammonia, and pyridazine, confirmed that the proposed analysis could accurately reproduce the excitation and de-excitation coefficients. The combination with the DC scheme enables both the local and non-local excited states of large systems with an excited nature to be treated. [ABSTRACT FROM AUTHOR]

High-accuracy molecular force field models suited for hot gases and plasmas are not as abundant as those geared toward ambient pressure and temperature conditions. Here, we present an improved version of our previous electron-density based force field model that can now account for polarization effects by adjusting the atomic valence electron contributions to match ab initio calculated Mulliken partial charges. Using a slightly modified version of the Hohenberg–Kohn theorem, we also include an improved theoretical formulation of our model when applied to systems with degenerate ground states. We present two variants of our polarizable model, fitted from ab initio reference data calculated at CCSD(T)/cc-pVTZ and CCSD(T)/CEP-31G levels of theory, that both accurately model water dimer interaction energies. Further improvements include the additional interaction components with fictitious non-spherically symmetric, yet atom-centered, electron densities and fitting the exchange and correlation coefficients against analytical expressions. The latter removes all unphysical oscillations that are observed in the previous non-polarizable variant of our force field. [ABSTRACT FROM AUTHOR]

The recent ωLH22t range-separated local hybrid (RSLH) is shown to provide outstanding accuracy for the notorious benchmark problem of the two lowest excited-state potential energy curves for the amino group twist in 4-(dimethylamino)benzonitrile (DMABN). However, the design of ωLH22t as a general-purpose functional resulted in less convincing performance for triplet excitations, which is an important advantage of previous LHs. Furthermore, ωLH22t uses 8 empirical parameters to achieve broad accuracy. In this work, the RSLH ωLH23ct-sir is constructed with minimal empiricism by optimizing its local mixing function prefactor and range-separation parameter for only 8 excitation energies. ωLH23ct-sir maintains the excellent performance of ωLH22t for the DMABN twist and charge-transfer benchmarks but significantly improves the errors for triplet excitation energies (0.17 vs 0.24 eV). Additional test calculations for the AE6BH6 thermochemistry test set and large dipole moment and static polarizability test sets confirm that the focus on excitation energies in the optimization of ωLH23ct-sir has not caused any dramatic errors for ground-state properties. Although ωLH23ct-sir cannot replace ωLH22t as a general-purpose functional, it is preferable for problems requiring a universally good description of localized and charge-transfer excitations of both singlet and triplet multiplicity. Current limitations on the application of ωLH23ct-sir and other RSLHs to the study of singlet-triplet gaps of emitters for thermally activated delayed fluorescence are discussed. This work also includes the first systematic analysis of the influence of the local mixing function prefactor and the range-separation parameter in an RSLH on different types of excitations. [ABSTRACT FROM AUTHOR]

A fully numerical homogenization technique for the retrieval of the effective surface susceptibilities of a periodic composite metasurface is developed in this work. We utilize the so-called dual field-flux finite element formulation scheme to accurately calculate the eigenmodes of a composite periodic metasurface, a scheme that possesses a crucial advantage: The capability of evaluating all field components and their derivatives accurately and with the same order of approximation is a requirement for our proposed technique. Next, we derive the generalized sheet transition condition equations for a general bianisotropic metasurface, which correlate the field components on either sides of the metasurface with its surface susceptibilities. At this point, we establish a new field averaging scheme for the acquisition of the average field components of the modes supported by the metasurface. Combining this computational information, we derive a set of linear algebraic equations based on the GSTCs and the average electromagnetic fields and numerically solve it, so as to obtain the effective surface susceptibilities of a bianisotropic metasurface. Comparison with the results of other techniques in the literature shows very good agreement, relatively to the resonance behavior of the returned values and their position at the frequency spectrum. The advantages that distinguish the proposed technique over other related methods are its foundation on the intrinsic modal information of the eigenmodes supported by the metasurface and its independence of any wave excitation schemes or involvement of analytical polarizability calculations. [ABSTRACT FROM AUTHOR]

The use of oriented external electric fields (OEEFs) to promote and control chemical reactivity has motivated many theoretical and computational studies in the last decade to model the action of OEEFs on a molecular system and its effects on chemical processes. Given a reaction, a central goal in this research area is to predict the optimal OEEF (oOEEF) required to annihilate the reaction energy barrier with the smallest possible field strength. Here, we present a model rooted in catastrophe and optimum control theories that allows us to find the oOEEF for a given reaction valley in the potential energy surface (PES). In this model, the effective (or perturbed) PES of a polarizable molecular system is constructed by adding to the original, non-perturbed, PES a term accounting for the interaction of the OEEF with the intrinsic electric dipole and polarizability of the molecular system, so called the polarizable molecular electric dipole (PMED) model. We demonstrate that the oOEEF can be established by locating a point in the original PES with unique topological properties: the optimal barrier breakdown or bond-breaking point (oBBP). The essential feature of the oBBP structure is the fact that this point maintains its topological properties for all the applied OEEFs, also for the unperturbed PES, thus becoming much more relevant than the commonly used minima and transition state structures. The PMED model proposed here has been implemented in an open access package and is shown to successfully predict the oOEEF for two processes: an isomerization reaction of a cumulene derivative and the Huisgen cycloaddition reaction. [ABSTRACT FROM AUTHOR]

The influence of fluctuating charges or charge flow on the dynamic linear response properties of isolated molecules from the TS42 database is evaluated, with particular emphasis on dipole polarizability and C6 dispersion coefficients. Two new descriptors are defined to quantify the charge-flow contribution to response properties, making use of the recoupled dipole polarizability to separate isotropic and anisotropic components. Molecular polarizabilities are calculated using the "frequency-dependent atom-condensed Kohn–Sham density functional theory approximated to second order," i.e., the ACKS2ω model. With ACKS2ω, the charge-flow contribution can be constructed in two conceptually distinct ways that appear to yield compatible results. The charge-flow contribution is significantly affected by molecular geometry and the presence of polarizable bonds, in line with previous studies. We show that the charge-flow contribution qualitatively reproduces the polarizability anisotropy. The contribution to the anisotropic C6 coefficients is less pronounced but cannot be neglected. The effect of fluctuating charges is only negligible for small molecules with at most one non-hydrogen atom. They become important and sometimes dominant for larger molecules or when highly polarizable bonds are present, such as conjugated, double, or triple bonds. Charge flow contributions cannot be explained in terms of individual atomic properties because they are affected by non-local features such as chemical bonding and geometry. Therefore, polarizable force fields and dispersion models can benefit from the explicit modeling of charge flow. [ABSTRACT FROM AUTHOR]

First-principles calculations for electrochemistry require accurate treatment of both electronic structure and solvation. The perturbative GW approximation starting from density functional theory (DFT) calculations accurately models materials systems with varying dimensionality. Continuum solvation models enable efficient treatment of solvation effects in DFT calculations, but their applications with beyond-DFT electronic structure methods such as GW have been limited. Here, we introduce the frequency-dependent liquid polarizability from a nonlocal continuum solvation model in the screened Coulomb interaction of full-frequency GW calculations with a solvated DFT starting point. We show that the liquid screening contributions substantially reduce the HOMO–LUMO gap of molecules by 3–5 eV, while solvent effects on the DFT starting point negligibly impact the GW gap. The resulting framework facilitates the simultaneous electronic and solvation accuracy needed for first-principles electrochemistry. [ABSTRACT FROM AUTHOR]

A theoretical framework is presented for the computation of the rovibrational polaritonic states of a molecule in a lossless infrared (IR) microcavity. In the proposed approach, the quantum treatment of the rotational and vibrational motions of the molecule can be formulated using arbitrary approximations. The cavity-induced changes in electronic structure are treated perturbatively, which allows using the existing polished tools of standard quantum chemistry for determining electronic molecular properties. As a case study, the rovibrational polaritons and related thermodynamic properties of H2O in an IR microcavity are computed for varying cavity parameters, applying various approximations to describe the molecular degrees of freedom. The self-dipole interaction is significant for nearly all light–matter coupling strengths investigated, and the molecular polarizability proved important for the correct qualitative behavior of the energy level shifts induced by the cavity. On the other hand, the magnitude of polarization remains small, justifying the perturbative approach for the cavity-induced changes in electronic structure. Comparing results obtained using a high-accuracy variational molecular model with those obtained utilizing the rigid rotor and harmonic oscillator approximations revealed that as long as the rovibrational model is appropriate for describing the field-free molecule, the computed rovibropolaritonic properties can be expected to be accurate as well. Strong light–matter coupling between the radiation mode of an IR cavity and the rovibrational states of H2O leads to minor changes in the thermodynamic properties of the system, and these changes seem to be dominated by non-resonant interactions between the quantum light and matter. [ABSTRACT FROM AUTHOR]

A large number of force fields have been proposed for describing the behavior of liquid water within classical atomistic simulations, particularly molecular dynamics. In the past two decades, models that incorporate molecular polarizability and even charge transfer have become more prevalent, in attempts to develop more accurate descriptions. These are frequently parameterized to reproduce the measured thermodynamics, phase behavior, and structure of water. On the other hand, the dynamics of water is rarely considered in the construction of these models, despite its importance in their ultimate applications. In this paper, we explore the structure and dynamics of polarizable and charge-transfer water models, with a focus on timescales that directly or indirectly relate to hydrogen bond (H-bond) making and breaking. Moreover, we use the recently developed fluctuation theory for dynamics to determine the temperature dependence of these properties to shed light on the driving forces. This approach provides key insight into the timescale activation energies through a rigorous decomposition into contributions from the different interactions, including polarization and charge transfer. The results show that charge transfer effects have a negligible effect on the activation energies. Furthermore, the same tension between electrostatic and van der Waals interactions that is found in fixed-charge water models also governs the behavior of polarizable models. The models are found to involve significant energy–entropy compensation, pointing to the importance of developing water models that accurately describe the temperature dependence of water structure and dynamics. [ABSTRACT FROM AUTHOR]

This study was planned to prepare new mixed ligand chelates derived from N‐(4,6‐dimethylpyrimidin‐2‐yl)‐3a,4,5,6,7,7a‐hexahydro‐1H‐benzimidazol‐2‐amine (BIP), and imidazole (I). They identified through CHN study, spectroscopic (NMR, FT‐IR, and UV–Vis), conductivity, magnetic susceptibility, mass analysis, and thermal analysis. Correlation between all results exposed that the BIP ligand performed as a bi‐dentate ligand through NN donation locations, where the co‐ligand shows as N–H monodentate. The optimization for the studied chelates led to the formation of distorted octahedral geometry for BIPICu and BIPIVO chelates, distorted (tetrahedral and square planar) geometry for BIPIAg and BIPIPd chelates, respectively, around the metal salt. The B3LYP level, B3LYP/6‐311G** level for the free ligand, and B3LYP/6–311G**‐LANL2DZ functional level for the solid chelates were used in density functional theory (DFT) calculations. The findings showed that DFT calculations produce conclusions that are consistent with those of the experiments. The resulting compounds' nonlinear optical properties were examined by calculating the hyperpolarizability (β) and molecular polarizability (α) parameters, which gave rise to several unexpected optical properties for the synthesized compounds. Using the agar well diffusion method, the antimicrobial activity of the produced compounds was experimentally confirmed against a subset of G+ and G− bacteria. To ascertain how these substances attach to the targeted protein binding sites, a molecular docking mechanism between the microbially resistant chelates and their suppressed microbial protein pocket receptors was investigated. Also, DNA binding estimated for studied structures was tested by electronic absorption spectrum, viscosity estimation, and gel electrophoresis. Data proposed that all tested compounds link with DNA using an intercalation, electrostatic, and covalent binding mechanism. Moreover, antioxidant performance for studied compounds was governed by radical scavenging techniques in vitro. In addition, an MTT assay has been worked out to explore in vitro cytotoxic impending. All the tested chelates assumed antimicrobial, antitumor, and antioxidant performances that cause them to suggest drugs. [ABSTRACT FROM AUTHOR]

The effective calculation of static nonlinear optical properties requires a considerably high accuracy at a reasonable computational cost, to tackle challenging organic and inorganic systems acting as precursors and/or active layers of materials in (nano‐)devices. That trade‐off implies to obtain very accurate electronic energies in the presence of externally applied electric fields to consequently obtain static polarizabilities (αij) and hyper‐polarizabilities (βijk and γijkl). Density functional theory is known to provide an excellent compromise between accuracy and computational cost, which is however largely impeded for these properties without introducing range‐separation techniques. We thus explore here the ability of a modern (double‐hybrid and range‐separated) Range‐Separated eXchange Quadratic Integrand Double‐Hybrid exchange‐correlation functional to compete in accuracy with more costly and/or tuned methods, thanks to its robust and parameter‐free nature. [ABSTRACT FROM AUTHOR]

This study utilizes Density Functional Theory (DFT) alongside the Chemical Bond Overlap (OP) Model and Quantum Theory of Atoms in Molecules (QTAIM) to reinterpret the well‐established trans effect in square‐planar Pt(II) complexes. Investigating ligand exchange mechanisms in trans‐[Pt(NH3)2${\rm Pt}{({\rm NH}_3)}_2$(H2O${\rm H}_2{\rm O}$)T] (T = F−${\rm F}^-$, NH3${\rm NH}_3$, Cl−${\rm Cl}^-$, CH3−${\rm CH}_3^-$, CO, CN−${\rm CN}^-$) via transition state localization and intrinsic reaction coordinate calculations, overlap descriptors (OP/TOP) such as density, repulsion, and polarizability are computed for Pt−T and Pt−L bonds for reactants and transition states. Through OP/TOP and QTAIM, key descriptors correlating are identified with the trans‐directing effectiveness of ligands, revealing higher electron density donation and more electron‐rich bonds in stronger trans‐directing ligands. This combined methodology offers insights into ligand trans‐directing character, enhancing understanding of their reactivity and bonding behavior. [ABSTRACT FROM AUTHOR]

Semiempirical quantum chemistry has recently seen a renaissance with applications in high-throughput virtual screening and machine learning. The simplest semiempirical model still in widespread use in chemistry is Hückel's π-electron molecular orbital theory. In this work, we implemented a Hückel program using differentiable programming with the JAX framework based on limited modifications of a pre-existing NumPy version. The auto-differentiable Hückel code enabled efficient gradient-based optimization of model parameters tuned for excitation energies and molecular polarizabilities, respectively, based on as few as 100 data points from density functional theory simulations. In particular, the facile computation of the polarizability, a second-order derivative, via auto-differentiation shows the potential of differentiable programming to bypass the need for numeric differentiation or derivation of analytical expressions. Finally, we employ gradient-based optimization of atom identity for inverse design of organic electronic materials with targeted orbital energy gaps and polarizabilities. Optimized structures are obtained after as little as 15 iterations using standard gradient-based optimization algorithms. [ABSTRACT FROM AUTHOR]

To improve the performance of the third-order density-functional tight-binding method (DFTB3) for non-covalent interactions involving organic and biological molecules, a chemical-potential equalization (CPE) approach was introduced [J. Phys. Chem. A, 116, 9131 (2012)] and parameterized for the H, C, N, O, and S chemical elements [J. Chem. Phys., 143, 084123 (2015)]. Based largely on equilibrium structures, the parameterized DFTB3/CPE models were shown to exhibit improvements in molecular polarizabilities and intermolecular interactions. With more extensive analyses, however, we observe here that the available DFTB3/CPE models have two critical limitations: (1) they lead to sharply varying potential energy surfaces, thus causing numerical instability in molecular dynamics (MD) simulations, and (2) they lead to spurious interactions at short distances for some dimer complexes. These shortcomings are attributed to the employed screening functions and the overfitting of CPE parameters. In this work, we introduce a new strategy to simplify the parameterization procedure and significantly reduce free parameters down to four global (i.e., independent of element type) ones. With this strategy, two new models, DFTB3/CPE(r) and DFTB3/CPE(r†) are parameterized. The new models lead to smooth potential energy surfaces, stable MD simulations, and alleviate the spurious interactions at short distances, thus representing consistent improvements for both neutral and ionic hydrogen bonds. [ABSTRACT FROM AUTHOR]

K20 microwave dielectric ceramics SrLnAlO 4 (Ln = Eu, Gd, and Ho) were prepared at 1440–1520 °C. SrEuAlO 4 and SrGdAlO 4 crystallized into tetragonal K 2 NiF 4 -type structures. While SrHoAlO 4 was a mixture (SrHo 2 Al 2 O 7 , Ho 2 O 3 , and Sr 3 HoAl 2 O 7.5) due to the too-small radius of Ho3+ to bond in [HoO 9 ] dodecahedron. SrEuAlO 4 and SrGdAlO 4 exhibited near-zero τ f values of +1.7 and +4.3 ppm/°C and low ε r (19.37 and 19.14) along with contrasting Q × f values (70,030 and 5560 GHz). Compared with the modified molecular polarizability (α Corr) based on the bond valence deviation, the α obs values of SrEuAlO 4 and SrGdAlO 4 are much higher, indicating that their dielectric polarizabilities were underestimated, and this phenomenon was mainly influenced by rattling cations, which also causes their τ f with near-zero values. Due to the magnetic subsystem adversely affecting microwave dielectric losses, the worsened Q × f value of SrGdAlO 4 compared to that of SrEuAlO 4 is due to the high magnetic moment of Gd3+ (7.94 μ B). [ABSTRACT FROM AUTHOR]

The surface tensions of molten oxides depend strongly on the structural relaxation of the surface region. The mechanism of surface structural relaxation for molten oxide slags is complex. The surface tension of calcium aluminate slag is minimal at an intermediate composition, although the critical reason has not been identified. Here, two novel approaches were used to evaluate the features of surface ionic structures in the molten state for the range of 25–50 mol% Al2O3: (1) X‐ray absorption analysis of oxygen and cationic elements in glass samples after surface relaxation treatment, and (2) molecular dynamics simulations, based on a polarizable‐ion model, of the ionic distribution in a molten slag with vacuum/melt interfaces. The results indicate that bridging oxygen (BO) ions are preferred to non‐BOs in the surface region. In calcium aluminate slag, BOs are formed by connecting two AlO4 tetrahedrons with charge compensation of two Al3+ ions with one Ca2+ ion. Additionally, the above approaches were used to qualify the effect on the surface ionic structure of adding 1–20 mol% SiO2 to the calcium aluminate slag. The results indicated that the SiO4 tetrahedrons incorporate the vertex connection with AlO4 tetrahedrons to form BOs in the surface region. [ABSTRACT FROM AUTHOR]

The intensity of light scattered by liquids has been studied for over a century since the valuable microscopic information about the molecules can be obtained, such as the anisotropy of the molecular polarizability tensor or preferred orientations of neighboring molecules. However, in modern dynamic light scattering experiments, the scattering intensity is usually disregarded, unlike in dielectric spectroscopy, which can be considered as a complementary experimental method, where the dielectric strength is routinely evaluated. The reason lies partly on the fact that the exact form of the equations relating the macroscopically measured light scattering intensity to the microscopic properties of the molecules is debated in the literature. Therefore, as a first step, we compare anisotropy parameters from the literature, calculated from light scattering intensities using different equations, with quantum chemical calculations for over 150 medium-sized molecules. This allows us to identify a consistent form of equations. In a second part, we turn to the depolarized light scattering spectra of 13 van der Waals liquids and some mixtures thereof, recorded with a combination of Tandem–Fabry–Perót and Raman spectroscopies, giving direct access to the reorientational dynamics of the molecules. We discuss how the strength of the structural α-relaxation is connected to the anisotropy parameter, what implication this has for the shape of the α-relaxation, how the components of a mixture—also for the case of ionic liquids—can be identified in this way, and how orientational correlation parameters can be extracted. Additionally, we point out for the example of n-alkanes that for highly flexible molecules, the reorientational motion might not be the decisive source of the depolarized scattered light. We also show that light scattering might serve as a sensitive tool to check the accuracy of a conformer ensemble obtained by quantum chemical calculations. [ABSTRACT FROM AUTHOR]

This study investigates the supramolecular interactions between perylene diimides (PDI) and nucleotides, specifically adenosine monophosphate (AMP) and cytidine monophosphate (CMP). Ten complexes (complex 1 (l-ala-PDI-AMP), complex 2 (B-ala-PDI-AMP), complex 3 (GLY-PDI-AMP), complex 4 (IMI-PDI-AMP), complex 5 (PYR-PDI-AMP, complex 6 (l-ala-PDI-CMP), complex 7 (B-ala-PDI-CMP), complex 8 (GLY-PDI-CMP), complex 9 (IMI-PDI-CMP), and complex 10 (PYR-PDI-CMP), were simulated using the B3LYP/6-31G(d,p) level of DFT method. The study explores NMR, IR, UV, hyperpolarizabilities, frontier molecular orbitals (FMOs), density of states (DOS), noncovalent interactions (NCI), iso-surface analysis, atom in molecule (AIM), dipole moment (µ), electron density distribution map (EDDM), transition density matrix (TDM), molecular electrostatic potential (MEP), and electron–hole analysis (EHA) using differential functional theory (DFT). The weak bonds formed were visualized using Discovery Studio Visualizer. The electronic properties of the complexes were examined through natural bond orbital (NBO) and natural population analysis (NPA), leading to nonlinear optics (NLO) study. Complex 6 demonstrates the highest NLO activity with γ static of 17,424,700.00, and complex 10 exhibits the weakest NLO activity with second dipole hyperpolarizability (γ static) at 25,116.10. Moreover, global reactivity factors for complexes 1–5 show EA ranging from 6.53 to 7.7, and ionization potential (IP) spans 7.8–8.8. Global hardness values highlight complex 4 as the hardest (η = 0.55) and complex 1 as the softest (η = 0.51). Electronegativity (X) varies from 7.28 to 8.25, with complex 3 being the most electronegative. Chemical potential (μ) ranges from − 7.9 to − 8.25, global softness (σ) identifies complex 1 as the softest (0.2575) and complex 4 as the hardest (0.435). Electrophilicity (ω) ranges from 33.30 to 61.87. Complexes 6–10 show EA from 6.7 to 7.53. IP values range from 8.4 to 8.6, with complexes 7 and 10 highest. Global hardness spans 0.53 to 0.85. X ranges from 7.55 to 8.06, with complex 7 the most electronegative. μ varies from − 7.55 to − 8.06, and complex 7 has the lowest. From σ values, complexes 9 and 10 are the softest. ω ranges from 35.53 to 60.78, with complex 7 the most electrophilic. [ABSTRACT FROM AUTHOR]

We calculate the bound state energies of the hydrogen atom in semiclassical dense hydrogen plasmas modeled by the effective screened interaction potential developed by Ramazanov et al. [Phys. Rev. E 92, 023104 (2015)]. It is shown that the quantum degenerate and exchange-correlation effects of plasma electrons do not play significant roles in the region where the system exhibits bound states. The bound-continuum critical transition lines and the distribution of the ground state energies in the plasma density-temperature phase diagrams are obtained, both with and without taking into account the screening effect of the plasma ions. The dipole transition oscillator strengths and static dipole polarizabilities of the electron-ion subsystems in semiclassical dense hydrogen plasmas are calculated in a wide range of plasma parameters. [ABSTRACT FROM AUTHOR]

Very recently, N-heterocyclic carbenes (NHCs) have found a wide range of applications in the fields of catalysis and nonlinear optics. Herein, we have employed 1,3-bis-(1(S)-benzyl)-4,5-dihydro-imidazol-based carbene as a reference molecule and substituted one H atom from each CH2 of the benzyl groups in both sides by CH3, NH2, and CF3 to study the thermodynamic and opto-electronic properties of NHCs theoretically. It was observed that the enthalpy (H), Gibb's free energy (G), specific heat capacity (Cv), and entropy (S) increase significantly in the presence of the electron-withdrawing groups compared to the electron-donating groups. The IR active in-plane bending vibrations of the CH (NHC) group are shifted to the higher frequency region for the considered substituted molecules compared to the reference carbene. The analysis of the electronic properties shows that the CH3-substituted carbene is more reactive for catalytic activities compared to other NHCs. The calculated nonlinear optical (NLO) properties reveal that the NH2-substituted NHC has the largest hyperpolarizability value whereas the CH3-substituted NHC has the largest dipole moment and polarizability among all, making them potential candidates for the development of NLO materials. [ABSTRACT FROM AUTHOR]

Novel glass-free low-temperature cofiring NaCaLn(MoO 4) 3 (Ln = Nd, Sm) ceramics were prepared by a conventional solid-state reaction method, and their sintering characteristics, phase composition, micro-morphology and microwave dielectric properties were comprehensively investigated. The pure tetragonal scheelite structure of NaCaLn(MoO 4) 3 (Ln = Nd, Sm) ceramics were disclosed by the XRD patterns. The extremely dense micro-morphology was revealed in the SEM images, which corresponds to the density measurements results. Those results showed that the change of ε r values is closely related to relative density and molecular polarizability. The change in Q × ƒ value are considered influenced by both grain size and packing fraction. In addition, the largest contribution of Mo–O bonds to the Q × ƒ of NaCaLn(MoO 4) 3 (Ln = Nd, Sm) ceramics was revealed by P–V–L theory. The best dielectric properties were obtained at 850 °C and 875 °C for NaCaNd(MoO 4) 3 and NaCaSm(MoO 4) 3 , respectively: ε r = 11.06, Q × ƒ = 58,442 GHz, τ ƒ = −37.7 ppm/°C and ε r = 11.02, Q × ƒ = 47,190 GHz, τ ƒ = −43.8 ppm/°C. Furthermore, the good compatibility of these two ceramics with silver powder indicated that they have potential for LTCC applications. [ABSTRACT FROM AUTHOR]

A fluorometric method based on boron, bromide-codoped carbon dots (BBCNs) was developed for the first time for the highly selective detection of p-nitroaniline (PNA) in wastewater samples. It should be noted that the introduction of bromine greatly increases the molecular polarizability of the probe, which can regulate the energy level matching between the probe and PNA, resulting in the interaction between BBCNs and PNA. In the presence of PNA, the fluorescence of BBCNs is obviously quenched and accompanied by a red shift of the fluorescence band, which might be attributed to the formation of aggregates caused by the polar adsorption of BBCNs and PNA. It is beneficial for constructing a highly selective sensing platform for PNA determination compared to its isomers (o-nitroaniline and m-nitroaniline) through atomic bromine-mediated polarization of the BBCNs. With the help of this mechanism, an excellent linear range of 0.5–300 μM with a low detection limit of 0.24 μM toward PNA was obtained. This work further confirms that there is a significant relationship between the nature of doping elements and the optical and physicochemical properties of fluorescent materials. [ABSTRACT FROM AUTHOR]

In the present research, a new ferrocene‐appended linear donor‐π‐acceptor (D‐π‐A) ester chromophore Fc‐(C6H4)2‐COOC2H5 (2) was synthesized and characterized using various spectroscopic techniques. The molecular structure of chromophore 2 was determined using single‐crystal X‐ray diffraction analysis, revealing its crystallization in the monoclinic crystal system with the P21/n space group. The chromophore Fc‐C6H4‐COOC2H4 (1) was utilized to compare its photophysical and nonlinear optical characteristics with those of 2. Cyclic voltammetry revealed a single‐electron transfer mechanism from Fe2+↔Fe3+. The emission solvatochromism studies show a polarized excited state in response to increasing solvent polarity, indicating charge transfer processes. Interestingly, in mixed aqueous media (THF/H2O), the chromophores exhibit intensified fluorescence due to restricted intra‐molecular rotation (RIR), despite weak emission in THF solvent. Chromophore 2 demonstrated 1.5 times higher second harmonic generation (SHG) efficiency than 1, attributed to its extended π‐conjugation from an additional phenyl ring and reduced antiparallel alignments. Despite its centrosymmetric crystal packing, chromophore 2 exhibited SHG efficiency due to non‐covalent interactions (C−H⋅⋅⋅π) in the crystal lattice. Density Functional Theory (DFT) calculations, employing various functionals, provided insights into dipole moment and first hyperpolarizability, with B3LYP‐hybrid functional underestimating hyperpolarizability values owing to long‐range charge transfer interactions within the D‐π‐A systems, aligning closely with experimental findings. [ABSTRACT FROM AUTHOR]

The geometrical structures, stabilities, electronic properties and nonlinear optical response of the halogen doped bimetallic LinClK (n = 1–6) clusters were studied within the density functional theory. Based on the dissociation energy, second order energy difference and GH-L (HOMO-LUMO gap), the LinClK (n = 2, 4, 6) clusters are more stable. According to their ionization energies, the clusters can be classified as a superalkali. From the NBO analysis, the clusters are excess electron systems. The obtained first static hyperpolarizability (βo) values are in the range of 1.56 × 104 − 4.33 × 104 au while the second static hyperpolarizability vary within 2.47 × 106 au to 13.9 × 106 au for the LinClK (n = 1–6) superalkalis that are slightly higher than the nonlinear optical response of halogen doped monometallic clusters. More importantly, the Li5ClK is transparent in the deep UV region (λ < 300 nm) among the superalkalis indicating that the Li5ClK superalkali can be a candidate structure as new member of NLO materials. [ABSTRACT FROM AUTHOR]

The electronic properties, absorption spectra, and nonlinear optical properties of triamantane substituted with alkali metals were investigated. Upon the substitution of triamantane via alkali metals affect the absorption capacity drastically that also reflect form EHOMO-ELUMO (H–L) gap. Compared to triamantane, which has H–L gap of 9.06 eV, the designed molecule 9 has the H–L gap (3.474 eV). Alkali metal substitution at different position in triamantane reviled that specific position is important for enhancing the first order hyperpolarizability (βtot) value. Out of different molecules, 9 has a highest first hyperpolarizability among the designed molecules. Calculated results reviled that the lower crucial transition energy (ΔE = 1.648 eV) is responsible for the significant increase in first hyperpolarizability (βtot). We have also calculated frontier molecular orbitals (FMO), transition density matrix (TDM), and densities of states (DOS) at same level of the theory. The absorption shifts from ultraviolet to visible was observed when triamantane was substituted via alkali metal. It is also observed form spectra that as the size of the alkali metal atoms increases the red shift takes place. [ABSTRACT FROM AUTHOR]

An analytical implementation of static dipole polarizabilities within the generalized Kohn–Sham semicanonical projected random phase approximation (GKS-spRPA) method for spin-restricted closed-shell and spin-unrestricted open-shell references is presented. General second-order analytical derivatives of the GKS-spRPA energy functional are derived using a Lagrangian approach. By resolution-of-the-identity and complex frequency integration methods, an asymptotic O ( N 4 ⁡ log (N)) scaling of operation count and O ( N 3 ) scaling of storage is realized, i.e., the computational requirements are comparable to those for GKS-spRPA ground state energies. GKS-spRPA polarizabilities are assessed for small molecules, conjugated long-chain hydrocarbons, metallocenes, and metal clusters, by comparison against Hartree–Fock (HF), semilocal density functional approximations (DFAs), second-order Møller–Plesset perturbation theory, range-separated hybrids, and experimental data. For conjugated polydiacetylene and polybutatriene oligomers, GKS-spRPA effectively addresses the "overpolarization" problem of semilocal DFAs and the somewhat erratic behavior of post-PBE RPA polarizabilities without empirical adjustments. The ensemble averaged GKS-spRPA polarizabilities of sodium clusters (Nan for n = 2, 3, ..., 10) exhibit a mean absolute deviation comparable to PBE with significantly fewer outliers than HF. In conclusion, analytical second-order derivatives of GKS-spRPA energies provide a computationally viable and consistent approach to molecular polarizabilities, including systems prohibitive for other methods due to their size and/or electronic structure. [ABSTRACT FROM AUTHOR]

An investigation of electro‐optical and nonlinear optical properties of pure and halogenated (−Cl, −Br) hexahexyloxytriphenylene (HAT6) molecule is presented employing a density functional theory (DFT) approach. The effect of halogenation on HAT6 molecule is studied by introducing single and double halogens (Cl, Br) in its molecular geometry. The geometries are optimized progressively to achieve stability using B3LYP method with 6‐311 basis sets. The physical properties encompassing electro‐optical, thermodynamic, and electronic properties of single molecule of HAT6 are computed using DFT method. The introduction of halogens to discotic HAT6 molecule to an augmentation in molecular polarizability, rendering halogenated HAT6 a suitable candidate for nonlinear optical devices due to its π–π conjugation and improved optical parameters. The UV‐Vis spectra indicate the predominant absorptions and changes in absorption depend on the halogenations of the HAT6 molecule. Also, the halogenation effect leads to a significant reduction in the energy bandgap directly associated with electron‐electron correlation, facilitating straightforward tuning. [ABSTRACT FROM AUTHOR]

A correction notice has been issued for a study published in the journal Nanomaterials. The correction addresses errors in the method of obtaining mean values for near-field enhancement (NFE) and optical chirality density (OCD) over the surface of spherical nanoparticles. The corrections involve recalculating values in several figures and a table to avoid overweighting values in the poles. Additionally, errors in Figure 3 and Figure 4a,b have been acknowledged and corrected. The correction notice provides a more accurate understanding of the research findings. The authors apologize for any inconvenience caused and confirm that the original publication has been updated. [Extracted from the article]

The kinetics and mechanism of osmium(VIII)-catalyzed oxidation of paracetamol (PAM) with N-bromosuccinimide (NBS) in acidic medium have been studied at a constant ionic strength of 0.50 M. The reaction is characterized by 1:1 stoichiometry. The main products were identified by spot test and IR and UV-visible spectroscopy. The activation parameters of the rate-determining step were computed and discussed, and the thermodynamic parameters were also calculated. First-order kinetics with respect to Os(VIII) was observed for the oxidation of paracetamol. The reaction rate decreased with increase in the acidity and NBS concentration. Variation of the ionic strength had no significant effect on the reaction rate. A plausible mechanism has been proposed on the basis of the kinetic studies, reaction stoichiometry, and product analysis. Quantum chemical study of the oxidation of paracetamol with NBS was performed in the framework of the density functional theory (DFT) using B3LYP/6-31G(d,p) basis set. The DFT studies included computation of various structural parameters, viz. electrostatic potential, electrophilicity, chemical potential, chemical hardness, thermodynamic properties at various temperatures, nonlinear optical (NLO) properties, Mulliken charges, electric dipole moments, polarizability, and first static hyperpolarizability, as well as natural bond orbital (NBO) and atom in molecule (AIM) analysis. [ABSTRACT FROM AUTHOR]

We investigate the polarizability of the negative ions of hydrogen and positronium embedded in nonideal classical plasmas using correlated exponential wavefunctions. The interactions among the charged particles in plasmas have been taken care of by a pseudopotential, derived from a solution of Bogolyubov's hierarchy equations. The effects of nonideality of plasma on the ground state energies and the static and dynamic dipole polarizabilities of the negative ions have been studied in detail for wide range of nonideality. The results show interesting features. [ABSTRACT FROM AUTHOR]

Hydrogels have broad application prospects in drug delivery due to their biocompatibility, high water content and three-dimensional structure. However, the regulation of drug release from hydrogels is an important issue in medical applications. At the same time, water also has an important impact on drug release. In this study, a hydrogel with hydrogen bond and ion dipole interaction (PAHDP) was prepared by introducing catechol group into polymer to regulate drug release. Ten model drugs were selected to explore the relationship and mechanism of action among polymer, drug and water. The results showed that PAHDP had excellent adhesion and safety. Drug release test showed that 10 kinds of drugs had different drug release trends, and the release amount was negatively correlated with drug polarizability and LogP. In addition, in vitro transdermal test and pharmacokinetic results showed that the hydrogel based on PAHDP achieved increased or decreased blood drug concentration, and the area under the concentration-time curve (AUC) of >1.5 times showed its potential to regulate drug release. The mechanism study showed that the hydrogen bond and ion dipole interaction between polymer and drug were affected by drug polarizability and LogP, and the distribution of water in different states was changed. Hydrogen bond and ion dipole interactions synergistically control drug release. Therefore, the mussel inspired PAHDP hydrogel has the potential to become a controllable drug delivery system. [Display omitted] [ABSTRACT FROM AUTHOR]

Phosphoric acid influenced the crystal structure of hexamine p-nitrophenol and their physico-chemical properties. Supermolecular assembly of hexamine, p-nitrophenol, phosphoric acid and water (HNPP) crystal was grown through slow evaporation process in acetone–water solvent. The HNPP crystal exhibits both second harmonic generation (SHG) and third order nonlinear consequences. Single crystal XRD reveals that the HNPP crystal belongs to monoclinic system with space group P21/c. To confirm structure, computational/investigational IR and UV–visible spectra were analysed. The molecular absorption, transparency and optical energy gap of HNPP was measured from experiments and compared to calculate TD-DFT quantities. The UV spectral wavenumbers of molecule were evaluated and the appropriate FMO intermolecular transitions into α (↑ ) and β(↓) offsets were assigned. The HNPP crystal is being used for the fluorescence spectral analysis. The powder SHG effect was obtained from Kurtz and Perry procedure is 0.73 times superior to standard urea. As well as, the static first hyperpolarizability value is 3.8 times superior to urea. Z-scan technique revealed that the HNPP possess third order nonlinear efficiency. The NLO and MEP, as well as Fukui functions were used to discuss the charge of the global molecule and local atoms respectively. [ABSTRACT FROM AUTHOR]

Computational studies based on Density Functional Theory (DFT) and time-dependent DFT (TD-DFT) were used to determine molecular and thermodynamic parameters, optoelectronic and electronic properties, as well as chemical descriptors, UV–vis spectra and nonlinear optical response of the chromophores of 2-Styrylquinoline (M01) and 2-(3-nitrostyryl)quinoline (M02). We evaluated the impact of the substitution of the hydrogen atom in M01 by the nitro group (NO2) to obtain the molecule M02. The results show very good optoelectronic properties with respect to very high electric fields of the order of 1.43 × 109 Vm−1 for M01 up to 5.26 × 109 Vm−1 for M02. The energy gap decreases from 3.94 eV for M01 to 3.56 eV for M02; which suggest that they are semiconductors. In addition, these two molecules exhibit ionization potential (IP) and electron affinity (EA) quite close to those of Alq3 and could therefore be good candidates for the manufacture of Organic Light-Emitting Diodes (OLED). The chemical descriptors were assessed and allowed us to discuss the stability and reactivity of our molecules. Thus, the addition of the nitro group to the virgin 2-Styrylquinoline decreases the reactivity and stability of the 2-Styrylquinoline. The analysis of the IR and Raman vibrational spectra shows several peaks between 100 cm−1 and 3200 cm−1 of which the most intense for the molecule M01 are attributed to the stretching mode of the C–H bond in the phenyl ring and the C=C double bond in the quinoline ring. For the M02 molecule, stronger peaks were assigned to the stretching mode of the O–N and N–C bonds. The analysis of the UV–vis spectra showed that the maximum absorption wavelength of M01 is 334.80 nm and that of M02 is 375.37 nm; both located in the ultraviolet. The high values of first ( β T ) and second ( γ ¯ ) hyperpolarizability showed that both molecules have very good nonlinear optical properties and thus can be used for second and third harmonic generation. [ABSTRACT FROM AUTHOR]

Fluorite-structured Ce 1- x Y x O 1- x /2 (x = 0, 0.1, 0.3, 0.5) ceramics were prepared by the solid-phase reaction method. The XRD analysis reveals that the maximum solid solubility of Y3+ in CeO 2 is less than 60%. With increasing x , the ε r decreased from 24.02 to 18.87, and the τ f decreased from −50.0 ppm/°C to −66.7 ppm/°C. The largest Q × f value of 75,661 GHz is obtained at x = 0.3. The decrease in ε r is due to the reduction of ionic polarizability per unit volume and the weakening of the cationic rattling effect. The existence of Ce3+ and the rattling effect of Ce4+ are the reasons for ε r being larger than ε r (C-M) in Ce 1- x Y x O 1- x /2 ceramics. The trends of τ f and ε r values are similar and consistent with the ion polarizability dilution mechanism. The Q × f of Ce 1- x Y x O 1- x /2 ceramics is related to lattice energy, FWHM, and oxygen vacancy concentration. [ABSTRACT FROM AUTHOR]

The electronic, hydrophobic and global reactivity parameters of modeled 28 different 5,8- quinolinequinone derivatives have been calculated using DFT (B3LYP)/6-31G(d,p) method and basis set. The molecular descriptors are chosen molecular polarizability, dipole moment, frontier molecular orbital energy, molecular volume, ionization potential, electron affinity, electronegativity, molecular hardness, molecular softness, electrophilic index, molar refractivity, octanol–water partition coefficient, entropy and capacity of heat. The relations between molecular descriptors have been investigated dependent on their correlations. QSAR/QSPR models have been derived for anti-proliferative and anti-inflammatory activity of these 5, 8-quinolinequinone derivatives. The dependence of the electronegativity parameter on both electronic and thermochemical parameters is found to be the best correlated parameter. [ABSTRACT FROM AUTHOR]

New organic dyes (H1-H6) for their promising applications as dye sensitized solar cell (DSSCs) were theoretically designed from 6,6′-di(thiophen-2-yl)-4,4′-bipyrimidine (TB) moiety in acceptor (A), π-spacer, and donor (D) type architecture to create A-π-D-π-D-π-A framework. After their benchmarking study against various exchange correlation (XC) and long-range corrected (LC) functional, the CAM-B3LYP produced accurate results so as selected for further density functional theory (DFT) and time dependent DFT (TD-DFT) studies. The frontier molecular orbitals (FMOs) were analyzed for their electron transfer properties, and their energies of the highest occupied molecular orbital (EHOMO) and the lowest unoccupied molecular orbital (ELUMO) were used to assess various electronic properties. Their energy differences (EH-L) ranged between 1.69 and 2.03 eV indicating their good responsiveness to electron injection (Ginj) being the values greater than 0.2 eV. The maximum absorbance of the dyes was reported around the 388–406 nm while their starting material (TB) had this value to be 371 nm. This redshift was significant with an intensification of electron-withdrawing groups on the dye structures. The dyes were evaluated for their device related parameters like their light harvesting efficiency, open circuit voltage, exciton binding energies, and exciton life times which were found in their promising values. The dyes were analyzed for their linear (α), first (βtotal), and second (γtotal) order nonlinear responses and were found to have significantly higher responses, not only against their starting materials but also those reported in literature for standard molecules (urea and p-nitric acid). Among the dyes under study, dye H4 exhibits the highest molecular polarizability (α) and hyperpolarizability (β and γ) values thanks to two CN substituted units on each ends. These dyes are most likely to have possible optical and photonic uses. Also, according to the results of the current theoretical research, all of these dyes may function as effective photosensitizer for their DSSC application. [ABSTRACT FROM AUTHOR]

Theoretical study of the photophysical/photochemical properties of 1H‐benzimidazole and its derivatives was carried out using APFD, B3LYP, CAM‐B3LYP and PBE0 density functionals with 6‐311+G(2d,p) basis set. The effects of ethanol, 1,4‐dioxane, acetonitrile and water was investigated by means of Integral Equation Formalism of the Polarizable Continuum Model (IEPCM) in the framework of Self‐Consistent Reaction Field (SCRF). The results obtained show that S2 state of the 1H‐benzimidazole molecule is more acidic than the S0 state as the N5−H11 bond length increased to ~ 1.01 Å. At B3LYP/6‐311+G(2d,p) level of theory, the excitation energy of 1H‐bensimidazole molecule in ethanol from S0 to the S2 state was calculated to be 273 nm (4.54 eV). The electronic energy for this transition was calculated to be 0.131 a.u. and observed to occur between π→π* orbitals. Calculations with the PBE0, APFD and B3LYP functionals reproduced the experimental dipole moment in 1,4‐dioxane, with values of 4.09, 4.09 and 4.07 Debye respectively. However, the dipole moments of the 2‐ethyl‐7‐nitro‐5‐substituted‐1H‐benzimidazoles were calculated to be higher for electron donating groups (EDGs) than those bearing electron withdrawing groups (EWGs). In addition, the molecular polarizability was observed to increase with decreasing energy gap. Local excitation (LE) and charge‐transfer (CT) were observed to mediate the mechanisms of electronic excitation in 2‐ethyl‐7‐nitro‐5‐substituted‐1H‐benzimidazoles. [ABSTRACT FROM AUTHOR]

Polarizability is a key factor when it comes to an accurate description of different ionic systems. The general importance of including polarizability into molecular dynamics simulations was shown in various recent studies for a wide range of materials, ranging from proteins to water to complex ionic liquids and for solid–liquid interfaces. While most previous studies focused on bulk properties or static structure factors, this study investigates in more detail the importance of polarizable surfaces on the dynamics of a confined ionic liquid in graphitic slit pores, as evident in modern electrochemical capacitors or in catalytic processes. A recently developed polarizable force field using Drude oscillators is modified in order to describe a particular room temperature ionic liquid accurately and in agreement with recently published experimental results. Using the modified parameters, various confinements are investigated and differences between non-polarizable and polarizable surfaces are discussed. Upon introduction of surface polarizability, changes in the dipole orientation and in the density distribution of the anions and cations at the interface are observed and are also accompanied with a dramatic increase in the molecular diffusivity in the contact layer. Our results thus clearly underline the importance of considering not only the polarizability of the ionic liquid but also that of the surface. [ABSTRACT FROM AUTHOR]

Property-optimized Gaussian basis sets of split-valence, triple-zeta valence, and quadruple-zeta valence quality are developed for the lanthanides Ce–Lu for use with small-core relativistic effective core potentials. They are constructed in a systematic fashion by augmenting def2 orbital basis sets with diffuse basis functions and minimizing negative static isotropic polarizabilities of lanthanide atoms with respect to basis set exponents within the unrestricted Hartree–Fock method. The basis set quality is assessed using a test set of 70 molecules containing the lanthanides in their common oxidation states and f electron occupations. 5d orbital occupation turns out to be the determining factor for the basis set convergence of polarizabilities in lanthanide atoms and the molecular test set. Therefore, two series of property-optimized basis sets are defined. The augmented def2-SVPD, def2-TZVPPD, and def2-QZVPPD basis sets balance the accuracy of polarizabilities across lanthanide oxidation states. The relative errors in atomic and molecular polarizability calculations are ≤8% for augmented split-valence basis sets, ≤ 2.5% for augmented triple-zeta valence basis sets, and ≤1% for augmented quadruple-zeta valence basis sets. In addition, extended def2-TZVPPDD and def2-QZVPPDD are provided for accurate calculations of lanthanide atoms and neutral clusters. The property-optimized basis sets developed in this work are shown to accurately reproduce electronic absorption spectra of a series of L n C p 3 ′ − complexes (Cp′ = C5H4SiMe3, Ln = Ce–Nd, Sm) with time-dependent density functional theory. [ABSTRACT FROM AUTHOR]

The effect of hydrogen bonds on the NLO properties was not considered as essential, in particular in pyridine hydrazone systems. Yet, we show in the present study that a control of these photoswitches depends on the strength of hydrogen bonds. In this study, we investigate a selection of 18 E/Z pyridine hydrazone photoswitch molecules to explore the impact of resonance-assisted hydrogen bond (RAHB) on the NLO properties in the E/Z isomers. Using quantum calculations at the ωB97XD/6-311+g(d) level of theory, we determine various electronic parameters, reactivity descriptors, bond length alternation (BLA) values, nuclear independent chemical shift (NICS) aromaticity indices, QTAIM topology, energy of hydrogen bond (EHB), RAHB, and linear and nonlinear optical properties for these molecules. The agreement between the quantum calculations and experimental spectra is illustrated through TD-DFT calculations, showing small deviations. Contrary to conventional expectations, our findings demonstrated that the delocalization strength of the electrons and NLO properties of the Z isomers are significantly enhanced by the presence of a resonance-assisted hydrogen bond. The Z-isomer exhibited a lower excited state energy, weaker energy gap, smaller BLA value, larger dipole moment variations for the first excited state, higher ΦE→Z, and electron delocalization at the quasi-cycle closed (RAHB) compared to the E-isomer. Furthermore, we find that the hyperpolarizability value of the title photoswitches increases as the wavelength of the incident light decreases, i.e., β(695) > β(1064) > β(1340) > β(∞), and the dispersion has less effect at λ = 1064 and 1340 nm. Additionally, we observe a strong relation between the photoisomerization quantum yield (ΦEZ) and static hyperpolarizability (β) of the first and second isomer, where ΦEZ is proportional to β of the second isomer and inversely proportional to b of the first isomer. This inverse trend between static hyperpolarizability and photoisomerization quantum yields is attributed to the electron-withdrawing character of substituents on the Ar ring. Our research provides valuable insights into optimizing the 2nd-order NLO properties of pyridine hydrazone photoswitch molecules. By understanding the influence of hydrogen bonding on the delocalization strength of the electrons (RAHB) and the shape-dependent NLO performance, we gain the ability to design and synthesize novel photoswitch molecules with enhanced NLO characteristics. [ABSTRACT FROM AUTHOR]

Two novel pregnane–cholesterol and cholesterol–cholesterol prodrugs have been synthesized. The synthetic route involved preparation of 2-(cholest-5-en-3-yloxycarbonyl)benzoic acid (2) by the esterification of cholesterol (1) with phthalic anhydride. The pregnane–cholesterol prodrug (4) was synthesized by treating 2-(cholest-5-en-3-yloxycarbonyl)benzoic acid (2) with 3β-hydroxypregna-5,16-dien-20-one (3), and cholesterol–cholesterol prodrug (5) was synthesized by treating acid 2 with cholesterol. The synthesized compounds have been characterized with the help of spectroscopic techniques like 1H and 13C NMR, FT-IR, UV-visible spectroscopy, and mass spectrometry. The prodrugs have shown potential cytotoxic effect in cervical cancer cell line HeLa. Compounds 2 and 4 were found to be effective prodrugs, the latter being the most effective. It showed less than 10% cell viability at 1 µM concentration, which signifies that these prodrugs may help to reduce cancer burden in human populations. Quantum chemical calculations of compounds 2–5 were performed in the ground state using the DFT of B3LYP level with 6-31G(d,p) basis set. The electronic properties such as HOMO and LUMO energies were determined by the time-dependent DFT approach. Intramolecular interactions have been identified by the AIM (Atoms in Molecules) approach. The reactivity and reactive sites within the synthesized prodrugs were examined with reactivity descriptors (global and local). The calculated dipole moments, polarizabilities, and first static hyperpolarizabilities indicated that the synthesized compounds might behave as good nonlinear optical materials. The probable reaction paths of prodrugs were calculated with molecular electrostatic potential (MEP) surface analysis. [ABSTRACT FROM AUTHOR]

This study examines the molecular interactions and thermal characteristics of supramolecular hydrogen-bonded liquid crystals, utilizing FTIR and thermal analysis techniques. Our investigation focuses on the hydrogen-bonded liquid crystal system of p, n-alkoxy benzoic acid: nonyl-p-hydroxy benzoate (nOBA: 9HB), specifically with 'n' values of 6, 7, and 8. The intermolecular interactions between the COOH donor of liquid crystal p-n alkoxy benzoic acid and the OH acceptor of non-liquid crystalline compound nonyl-p-hydroxybenzoate (9HB) result the supramolecular system through hydrogen bonding. The existence and applicability of newly formed systems depend on the strength of the bond formed between the molecules and the stability of the complex system. Here, the molecular vibration method of FTIR and thermal analysis techniques are employed to characterize the supramolecular systems (nOBA: 9HB, where n = 6,7, and 8). Results obtained from this investigation explain how the presence of hydrogen bonds influences the molecular and thermal properties of liquid crystal complexes towards the improvement of device performance and their utility in biological applications. [ABSTRACT FROM AUTHOR]

Context: To comprehend the microscopic property alterations within the ConMoS cluster (n=1–5), this study investigates its internal interactions, electronic characteristics, and orbital correlations employing density functional theory. Structural optimization and theoretical analysis of the cluster are conducted using the Gaussian09 software package, considering various spin multiplicities and employing the B3LYP/def2tzvp quantum chemical method as the computational standard. The outcomes reveal the optimization of the cluster, resulting in 21 stable configurations while continually acquiring energy from the external environment. Analysis of the interaction region indicator functions, the independent gradient model based on Hirshfeld partition, the localized orbital indicator functions, and the electron localization function reveals a trend toward chemical bonding interactions within the interatomic interaction regions. Moreover, the interatomic forces exhibit a high likelihood of engaging in covalent bonding interactions. Both Co and Mo atoms display greater electron delocalization, facilitating the exchange of electrons with the external environment. The paper discuss electron space range, hardness and softness, polarizability, dipole moment, Mulliken population analysis, density of states, HOMO-LUMO diagram, and UV-Vis spectra. Configuration 5a exhibits the broadest electron delocalization and the highest reactivity. It maintains structural stability in external conditions and displays the most polarized molecules. Metal atoms in this cluster exhibit superior mobility compared to non-metal atoms. We elucidate the electron density aggregation region within the cluster. Configuration 1a demonstrates the highest correlation with molar absorption coefficient for its peak. Analyzing the HOMO and LUMO orbital delocalization index and center-of-mass distances revealed that the front orbits of configuration 5a exhibited a broad distribution in space and the minimum center-of-mass distance. Methods: This study presents a theoretical investigation of Co-Mo-S clusters employing density functional theory (DFT). DFT is a prevalent method for exploring the electronic structure and characteristics of atoms, molecules, and solids. The paper examines cluster attributes encompassing interatomic interactions, electronic properties, and frontier orbitals. Gaussian09 software is employed for optimizing cluster structures, while the analysis is augmented using Multiwfn wave function analysis software. By harnessing these theoretical and computational tools, it aims to delve deeper into cluster properties, yielding valuable insights. [ABSTRACT FROM AUTHOR]

The design of organic molecules as drug molecules holds tremendous promise for success in both the present and future. Among the various types of compounds, heterocyclic compounds play a crucial role as they are extensively found in nature and are vital for life's processes. Their widespread presence and importance make them invaluable in the field of drug discovery and development. In this study, we present a thorough examination of 4-methylthiazole compounds (MTs) that are synthesized using a simple, straightforward protocol. Our analysis aims to provide a comprehensive understanding of these compounds. Various techniques, including proton and carbon NMR, mass spectrometry, FT-IR, and UV spectroscopy, are employed to perform an in-depth characterization of the MTs. The molecular structures of the synthesized substances, namely 6, 7, and 9, are investigated using density functional theory (DFT) with 6-311++G(d,p) as the basis set. By utilizing the DFT/B3LYP technique, the polarizability (α0) and first hyperpolarizability (β0) values are determined. Notably, the computed results for β0 suggested the potential presence of non-linear optical (NLO) behavior in all the molecules. Furthermore, the energies of the highest occupied molecular orbital (HOMO), the lowest unoccupied molecular orbital (LUMO), and the molecular electrostatic potential (MEP) are calculated and thoroughly examined to gain insights into the reactive sites of the molecules. The MEP surface is used to comprehend the locations of reactivity within the molecule. Additionally, the Mulliken atomic charges of carbon, oxygen, and nitrogen atoms are calculated using the same basis set. The anti-inflammatory and anti-diabetic properties of MTs are evaluated using protein denaturation and α-amylase inhibitory methods, respectively. Remarkably, the MTs demonstrated greater effectiveness compared to the standard drugs diclofenac and acarbose, respectively, indicating their potential as potent therapeutics for inflammation and diabetes treatment. [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]

Switchable nonlinear optical (NLO) materials have widespread applications in electronics and optoelectronics. Thermo-switches generate many times higher NLO responses as compared to photo-switches. Herein, we have investigated the geometric, electronic, and nonlinear optical properties of spiropyranes thermochromes via DFT methods. The stabilities of close and open isomers of selected spiropyranes are investigated through relative energies. Electronic properties are studied through frontier molecular orbitals (FMOs) analysis. The lower HOMO-LUMO energy gap and lower excitation energy are observed for open isomers of spiropyranes, which imparts the large first hyperpolarizability value. The delocalization of π-electrons, asymmetric distribution and elongated conjugation system are dominant factors for high hyperpolarizability values of open isomers. For deep understanding, we also analyzed the frequency-dependent hyperpolarizability and refractive index of considered thermochromes. The NLO response increased significantly with increasing frequency. Among all those compounds, the highest refractive index value is observed for the open isomer of the spiropyran 1 (1.99 × 10−17 cm2/W). Molecular absorption analysis confirmed the electronic excitation in the open isomers compared to closed isomers. The results show that reversible thermochromic compounds act as excellent NLO molecular switches and can be used to design advanced electronics. [ABSTRACT FROM AUTHOR]

The FT–IR, FT–Raman and UV–Vis spectra of 2E-1-(3-bromothiophene-2-yl)-3-(1, 3-benzodioxol-5-yl)prop-2-en-1-one (BTBD) have been performed experimentally and simulated theoretically. The present investigation focuses mainly on quantum chemical calculations and the spectral characteristics of the molecule. The observed and theoretical wavenumbers have been assigned to respective vibrational modes through potential energy distribution (PED). The non-linear optical (NLO) properties have been explored through the calculation of the first hyperpolarizability of the BTBD compound. In the MEP map, it is evident that the negative site located the carbonyl group and the positive site over the CH2 group of 1, 3-benzodioxol, and all hydrogen atoms. From the HOMO–LUMO orbital investigation, the HOMO is caped on the C = O and C–C excluding the thiophene ring. The UV-Visible spectrum, the electronic properties which include wavelength, excitation energies, and oscillator strength were simulated via the DFT method. The antifungal ability of the molecule is predicted through in vitro evaluation toward four fungal strains. The NBO analysis confirms the hyper conjugative interaction and stabilization energy E (2). The in vitro anti-inflammatory activity was done via the protein denaturation assay method at various concentrations. Molecular docking studies were carried out to predict the active binding residues of the target. [ABSTRACT FROM AUTHOR]

2-Bromo-3-nitroacetophenone (I) and 2-Bromo-4-nitroacetophenone (II), which are structural isomers of each other, were characterized using proton/carbon NMR, FT-IR, and density functional methods. The effects of the substituents on the molecular geometry parameters were investigated by comparing the optimized molecular structures obtained by computational methods with root mean square error calculations. The potential energy surface scan of the torsion angle between the bromoacetone group and the ring revealed that the lowest energy conformation is at 110°. The molecules' chemical reactivity and kinetic stability in different solvents were studied using frontier molecular orbital analyses. NMR core assignments and IR vibration assignments revealed similarities between the isomers. At the computational level that we determined to be sufficient in accuracy and precision for molecular geometry and spectrum calculations, it was found that the average polarizability of the compounds are approximately five times, and the total high-level polarizability are approximately four times greater than the reference compound when their nonlinear optical properties are theoretically calculated. [ABSTRACT FROM AUTHOR]

We have investigated liquid crystalline p-azoxyanisole and azobenzene based compounds using reported experimental crystal structure data and molecular dynamic study to understand the underlying reasons why p-azoxyanisole shows mesophase and not azobenzene compounds. Simulated moduli and molecular polarizabilities of PAA are in agreement with the reported experimental values. This study also gives an insight to understand the structure–property relation in these compounds. For the first time, topological data analysis has been carried out using two-dimensional plot that is generated using platon and.cif files of different compounds. [ABSTRACT FROM AUTHOR]