Basis Set Level Research Articles

Structural characterisation of a cyanomesogen by X-ray diffraction and computational methods

The work reports the structural analysis of a cyanomesogen namely, p-cyanobenzylidene p-nonyloxyaniline belonging to the Schiff base class of compounds. It exhibits a partial bilayer/inter-digitated smectic Ad phase and a nematic phase. Polarising Optical Microscopy (POM) and Differential Scanning Calorimetry (DSC) studies have been carried out to study phase sequence and transition temperatures. Micro-structural parameters, like molecular length, spacing, crystallite size, activation energy and micro-strain, have been estimated and pair correlation function (PCF) studies have been done for exhibited mesophases using the X-ray diffraction technique. The study investigated the surface, electronic and optical properties of a compound by computational studies like Density Functional Theory (DFT) and Hirshfeld surface analysis (HSA) methods using the DFT B3LYP/6-311++G(d,p) level basis set. The results reveal that the polarity associated with the polar groups and alkoxy chain lengths, contributes majorly to the mesomorphic characteristics and stability. The Highest Occupied Molecular Orbitals (HOMO) and Lowest Unoccupied Molecular Orbitals (LUMO) analyses of the DFT optimised molecule give electronic and geometrical parameters, atomic charge distribution, polarisability factors which are used to interpret the characteristics of the mesophases and their suitability for electro-optical and non-linear optical applications of the compound in terms of the predicted data.

Theoretical interpretation of electron delocalization potential of the substituent in o-hydroxynaphthalidene-p-substituted anilines for prospective molecular electronics applications

The delocalization phenomenon plays a vital role in the electron transport properties of a molecule, which is essential for developing molecular-based electronics. The current work examined the delocalization potential of five theoretically designed low molecular weight anils, o-hyroxynaphthalidene-p-substitutedanilines(NP-X) with the substituent X(X = -CH3, -NO2, -OCH3, and –Cl) being placed in phenyl ring at the p- position to its functional moiety, azomethine linkage and compared with the compound without substitution(X = H). The geometric optimization through DFT with B3LYP/6-311G (d, p) level basis set indicated the anils to be coplanar. Theoretical FTIR could discriminate the aromatic and aliphatic C-H vibrational frequencies and confirm the vectorial flow of the electrons when the o-OH group and p-NO2 group were placed at the two extreme ends of anil, further supported by Natural Bond Orbital analysis. Atomic charge analysis indicated the significant effect on the charge of azomethine carbon atom. It followed the order: OCH3 < CH3 < H < Cl < NO2 parallel with the σp values of the corresponding substituent. The molecular electrostatic potential mapping identified azomethine nitrogen as an electron-rich centre. The global and local reactivity parameters indicated the highest tendency of NO2 substituted compound to accept electrons among the other compounds. The HOMO–LUMO energy gap of the NP-X predicted from Natural Localized Molecular Orbital analysis was found to be NP-H: 4.02 eV, NP-CH3: 3.94 eV, NP-NO2: 3.69 eV, NP-OCH3: 4.18 eV, NP-Cl: 4.10 eV. The overall studies corroborated the optimized delocalization in NP-NO2 with the lowest HUMO-LUMO gap, which would be better suited for developing molecular-based electronic devices than others. The importance of the electron delocalization phenomenon in searching for a molecular probe to develop molecular electronics device applications has been discussed.Graphical

Biological evaluation of a novel Schiff base ligand as an antioxidant agent: Synthesis, characterization and DFT computations of its Ni(II) and Cu(II) complexes

By condensation reaction in methanolic medium, a novel ligand using methoxy substituted amine and 5-bromosalicylaldehydic was synthesized. Then, its Cu- and Ni- complexes were also prepared under same experimental conditions. The final desired compounds, with high obtained yields, have been characterized and well discussed by EA-CHN, UV–Vis., FT-IR, NMR, SEM-EDX and MS spectrometry. The structure of the ligand was confirmed by X-ray crystallography showing an interesting intramolecular hydrogen bond and also intermolecular interactions (Br…CArom. and CH/π-type). The electronic properties were quantified by density functional theory (DFT) calculations using DFT- B3LYP/6-31 G (d,p) level basis set. The molecular structures, geometrical parameters, chemical reactivity, stability, molecular electrostatic potential (MEP) and Mulliken atomic charges were computed to identify the chemical reactive sites on the molecular surface. The antioxidant activities were studied theoretically involving various parameters such as bond dissociation enthalpy (BDE), ionization potentials (IPs), proton affinities (PA), proton dissociation enthalpy (PDE), electron transfer enthalpy (ETE) and radical stabilization energy (RSE). Experimentally, the antioxidant activities were also studied by using 2,2′-azinobis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS), ferric ion reducing antioxidant power (FRAP) and nitric oxide scavenging (SNP) methods. The computational study of antioxidant activity is well correlated with their experimental results.

Quantum Mechanics Characterization of Non-Covalent Interaction in Nucleotide Fragments.

Accurate calculation of non-covalent interaction energies in nucleotides is crucial for understanding the driving forces governing nucleic acid structure and function, as well as developing advanced molecular mechanics forcefields or machine learning potentials tailored to nucleic acids. Here, we dissect the nucleotides' structure into three main constituents: nucleobases (A, G, C, T, and U), sugar moieties (ribose and deoxyribose), and phosphate group. The interactions among these fragments and between fragments and water were analyzed. Different quantum mechanical methods were compared for their accuracy in capturing the interaction energy. The non-covalent interaction energy was decomposed into electrostatics, exchange-repulsion, dispersion, and induction using two ab initio methods: Symmetry-Adapted Perturbation Theory (SAPT) and Absolutely Localized Molecular Orbitals (ALMO). These calculations provide a benchmark for different QM methods, in addition to providing a valuable understanding of the roles of various intermolecular forces in hydrogen bonding and aromatic stacking. With SAPT, a higher theory level and/or larger basis set did not necessarily give more accuracy. It is hard to know which combination would be best for a given system. In contrast, ALMO EDA2 did not show dependence on theory level or basis set; additionally, it is faster.

Azine Based Oligoesteric Chemosensors for Cu2+ Ion Detection: Synthesis, Structural Characterization, and Theoretical Investigations.

Synthesized monomer and its three oligoesters were characterized by techniques such as 1H, 13C{1H}, IR, UV, GPC and applied to chemosensor applications. A series of metal ions was studied with fluorophores to evaluate the sensitivity towards Cu2+ ion. The fluorophores results exhibit the selective and sensitive "Turn off" fluorescence response with Cu2+ ion in DMF/H2O (1:1, pH: 7.4, fluorophore: 5µM) solution. Binding stoichiometry and binding constant of fluorophores were calculated using Stern-Volmer equation and Benesi-Hildebrand plots, respectively. Structure of fluorophores were studied using DFT, B3LYP/6-311 + + G(d,p) level basis set. Quenching mechanisms and electrical properties of fluorophores were explained with theoretical outcomes. Iodine doped and undoped oligoesters electrical conductivity were studied in solid-state and the conductivity was gradually increased with increase the contact time of iodine with oligoesters. At different frequencies and temperatures, the dielectric measurement was calculated using the two-probe method. Among all oligoesters, DMDAP exhibited high electrical conductivity and DMDMP has a higher dielectric constant value than other oligoesters.

Design of a new palladium(ii) halide complex as a bio-active material: synthesis, physico-chemical studies, DFT-computations and evaluation of anti-inflammatory, antioxidant and anti-gastric damage activities.

Colorless single crystals of the zero-dimensional hybrid compound, (C6H10N2)2[PdCl6]·2H2O were acquired through the slow evaporation technique. The crystal structure was explored using SC-XRD, which demonstrates that the material crystallizes in the centrosymmetric space group P1̄ of the triclinic system. The density functional theory method at the B3LYP/Lan2mb basis set level was employed to establish the optimized geometry and vibrational frequencies of the title compound. An acceptable correspondence was observed between the results obtained through calculation and the experimental data, including the structure, and IR spectra. The optical characteristics revealed a direct band gap energy of 2.35 eV, validating the semiconductor characteristics of this new material. The results suggest strong agreement with the experimental data and validate the involvement of metal orbitals in defining the HOMO-LUMO boundary. Simultaneous TGA-DTA shows that this material remains solid up to 210 °C. Beyond these temperatures, a gradual decomposition process occurs, extending up to 440 °C and unfolding in several steps. This process entails the liberation of diverse compounds, encompassing organic molecules, and the evaporation of chlorine ions, ultimately leading to the formation of palladium oxide (PdO) as the final product. When given to rats with gastric ulcers at a dose of 100 mg kg-1, these compounds inhibit the key enzyme responsible for neutrophil infiltration as myeloperoxidase (MPO) by 38.7%. The compound also alleviates cellular damage induced by free radicals, demonstrated by a notable 48.3% decrease in thiobarbituric acid reactive substance rates (TBARS) compared to untreated rats. Additionally, these compounds bring about a substantial 30.6% reduction in the surface area of ulcers.

Structure directing interactions in the crystals of o-hydroxyaryl/naphthyl derived aldimines: X-ray structure, Hirshfeld surface analysis, DFT and Molecular docking studies

We have synthesized and thoroughly analyzed many intermolecular interactions present in (E)-1-(((3-nitrophenyl)amino)methylene)naphthalen-2(1H)-one (a), (E)-5-(diethylamino)-2-(((3-nitrophenyl)imino)methyl)phenol(b) and (E)-2-(((3-nitrophenyl)imino)methyl)phenol (c). Compounds a (keto-amine tautomeric form) and b, which have one molecule in the asymmetric unit, crystallize in the monoclinic crystal system with space groups P21/n and C2/c, respectively. Compound C, on the other hand, crystallizes in an orthorhombic crystal structure with the space group Pca21. The structural analysis showed that the construction of ring motifs to stabilize the crystal packing involves several interactions, including pi stacking interactions, NH…O, and CH…O interactions. Hirshfeld surface analysis has been used to examine their solid-state structures, including the evaluation of several energy frameworks. The results show that hydrogen bonds play a major role in the formation of the molecular sheets, and that electrostatic energy contribution dominates stability. Using fingerprint plots, it was possible to examine the variations and commonalities in the target compounds' relative contributions from noncovalent interactions. In addition, B3LYP hybrid functional with 6- 311 G (d, p) level basis set was used in the density functional theory computations to optimize the structural coordinates. Through the examination of the molecular electrostatic potential surface, the chemically active areas of the target imine molecules were located. Additionally, using the internal ribosome entry site of the Hepatitis C virus ED42 (PDB-ID 3T4B), molecular docking of the title compounds was performed based on PASS analysis and literature findings.

Convergent abinitio analysis of the multi-channel HOBr + H reaction.

High-level potential energy surfaces for three reactions of hypobromous acid with atomic hydrogen were computed at the CCSDTQ/CBS//CCSDT(Q)/complete basis set level of theory. Focal point analysis was utilized to extrapolate energies and gradients for energetics and optimizations, respectively. The H attack at Br and subsequent Br-O cleavage were found to proceed barrierlessly. The slightly submerged transition state lies -0.2kcal mol-1 lower in energy than the reactants and produces OH and HBr. The two other studied reaction paths are the radical substitution to produce H2O and Br with a 4.0kcal mol-1 barrier and the abstraction at hydrogen to produce BrO and H2 with an 11.2kcal mol-1 barrier. The final product energies lie -37.2, -67.9, and -7.3kcal mol-1 lower in energy than reactants, HOBr + H, for the sets of products OH + HBr, H2O + Br, and H2 + BrO, respectively. Additive corrections computed for the final energetics, particularly the zero-point vibrational energies and spin-orbit corrections, significantly impacted the final stationary point energies, with corrections up to 6.2kcal mol-1.

Molecular docking, molecular dynamics simulations and binding free energy studies of interactions between Mycobacterium tuberculosis Pks13, PknG and bioactive constituents of extremophilic bacteria

Mycobacterial pathogens present a significant challenge to disease control efforts globally due to their inherent resistance to multiple antibiotics. The rise of drug-resistant strains of Mycobacterium tuberculosis has prompted an urgent need for innovative therapeutic solutions. One promising way to discover new tuberculosis drugs is by utilizing natural products from the vast biochemical space. Multidisciplinary methods can used to harness the bioactivity of these natural products. This study aimed to evaluate the antimycobacterial efficacy of functional crude extracts from bacteria isolated from gold mine tailings in South Africa. Bacterial strains were identified using 16S rRNA sequencing. The crude extracts obtained from the bacteria were tested against Mycobacterium tuberculosis H37Rv, Mycobacterium smegmatis mc2155, and Mycobacterium aurum A+. Untargeted HPLC-qTOF and molecular networking were used to identify the functional constituents present in extracts that exhibited inhibitory activity. A virtual screening workflow (VSW) was used to filter compounds that were strong binders to Mycobacterium tuberculosis Pks13 and PknG. The ligands returned from the VSW were subjected to optimization using density functional theory (DFT) at M06-2X/6-311++ (d,p) level of theory and basis set implemented in Gaussian16 Rev.C01. The optimized ligands were re-docked against Mycobacterium tuberculosis Pks13 and PknG. Molecular dynamics simulation and molecular mechanics generalized born surface area were used to evaluate the stability of the protein–ligand complexes formed by the identified hits. The hit that showed promising binding characteristics was virtually modified through multiple synthetic routes using reaction-driven enumeration. Three bacterial isolates showed significant activity against the two strains of Mycobacterium, while only two, Bacillus subtilis and Bacillus licheniformis, exhibited activity against both Mycobacterium tuberculosis H37Rv, Mycobacterium smegmatis mc2155, and Mycobacterium aurum A+. The tentatively identified compounds from the bacterial crude extracts belonged to various classes of natural compounds associated with antimicrobial activity. Two compounds, cyclo-(L-Pro-4-OH-L-Leu) and vazabitide A, showed strong binding against PknG and Pks13, with pre-MD MM-GBSA values of − 42.8 kcal/mol and − 47.6 kcal/mol, respectively. The DFT-optimized compounds exhibited the same docking scores as the ligands optimized using the OPSL-4 force field. After modifying vazabitide A, its affinity to the Pks13 binding site increased to − 85.8 kcal/mol, as revealed by the post-MD MM-GBSA analysis. This study highlights the potential of bacteria isolates from gold mine tailings as a source of new scaffolds for designing and optimizing anti-Mycobacterium agents. These agents synthesized in-silico can be further tested in-vitro to evaluate their efficacy.

Experimental and Theoretical Approach for the Corrosion Deceleration of Mild Steel in Hydrochloric Acid Medium by Two Sulfonamide Derivatives

AbstractIn the pursuit to find corrosion inhibitors of superior efficacy, N‐(pyrimidin‐2‐yl)‐4‐[(quinazoline‐4‐yl)amino]benzene‐1‐sulfonamide (PQS) and N‐(4‐methylpyrimidin‐2‐yl)‐4‐[(quinazoline‐4‐yl)amino]benzene‐1‐sulfonamide (MQS) are the two new sulfonamides employed, which have decelerating effect on mild steel (MS) corrosion in a medium 0.5 M HCl and were found to have an efficiency of 98.7 % and 96.8 % respectively (303 K for 40 ppm concentration) deliberated through the electrochemical techniques (PDP and EIS). The inhibitory efficacy relies on the temperature of the solution and inhibitor concentration. PQS had greater stability than MQS at higher temperatures which is indicative in the obtained experimental data. The relative adsorption process was in consonance with the Langmuir adsorption isotherm. The SEM, EDS, FT‐IR, and AFM analysis validated PQS and MQS to form a barrier on MS, opposing corrosion. The potential energy surfaces (PES) scan and a theoretical study for PQS and MQS were probed employing density functional theory (DFT) at B3LYP/6‐311+G(d, p) basis set level that explicated the formation of a complex between the sulfonamides and MS. The corrosion inhibition efficiency of PQS and MQS inferred from experimental and theoretical data comply, making them credible corrosion inhibitors.

The solvatochromic effect of functionalized 6-aminoracil derivatives in light of DFT: FT-IR, TD-DFT, NBO, and FMO studies

Uracil-based compounds have increasing attention in material design for different applications as well as pharmaceutical purposes. Accordingly, the key electronic reasons underlying the solvatochromic effect and possible activity features by using quantum chemical computations should be explored in detail. This work focuses on the structural, electronic, and optical properties of the aminouracil derivatives to explore the key electronic-related properties that affect the solvatochromism features. The molecular geometries of the 1,3-dimethyl-5-(arylazo)-6-aminouracil derivatives were optimized using the DFT method at the B3LYP/6–31++G(d,p) basis set level. The solvent-phase simulations of the studied derivatives were utilized using the PCM (Polarized Continuum Model). The TD-DFT approach was employed to enlighten UV–visible characteristics such as possible electronic transitions, energies, and oscillator strengths. The NBO (Natural Bond Orbital) method was used to predict the possible intramolecular charge transfer and delocalization, as well as the interactions between donor-acceptor molecular orbitals. TD-DFT computations revealed that the bonded group within the arylazo ring would affect solvatochromic properties such as electronic excitation energies and transitions in the UV-Vis regions. The NBO analysis revealed that the electron movement from the lone pair of N atoms on the uracil unit to neighbor unfilled orbitals contributed to reducing the stabilization energy.

Role of Non‐Covalent Interactions on Acid Strength Measurement of Liquid Acids using Phosphine Oxide NMR Probe

AbstractThe 31P NMR Chemical Shifts(δP) of Trimethylphosphine Oxide (TMPO) conjugated with ten common liquid molecular acids have been calculated employing the Density Functional Theory (DFT) based computational method. These shifts have been correlated with the intrinsic acid strength parameter, Deprotonation Energy (DPE), of the underlying acids and the complexation energy of TMPO (ΔΕ). The acids, anions, and conjugated complexes were modeled with PW91 functional and 6‐31++G(d,p) basis set. The NMR calculations were performed on the relaxed structures as single‐point calculations using the Gauge Including Atomic Orbital (GIAO) method at the MP2 level and TZVP basis set. Poor linearity was observed in the correlation of δP with respect to DPE (R2=0.867), while strong linearity was seen with the complexation energy ΔΕ (R2=0.967). We have hypothesized the unreliable modeling of anions and Non‐Covalent Interactions (NCI) to be the factors affecting the linear trend of δP with respect to DPE. To support our hypothesis, we have presented Reduced Density Gradient (RDG) Maps and 31P NMR Tensor spatial orientation data of the Acid‐TMPO conjugates.

Effects of intramolecular hydrogen bonding on nuclear magnetic resonance, electron paramagnetic resonance and molecular docking studies: Mexiletine molecule.

In this study, the molecular structure of the mexiletine molecule was investigated. Since the Mexiletine molecule is a drug active ingredient, its molecular structure and spectroscopic properties are important. The effects of intramolecular hydrogen bonding on Nuclear Magnetic Resonance Parameters (NMR), Electron Paramagnetic Resonance (EPR) parameters and molecular docking studies were examined in the mexiletine molecule. The effects of intramolecular hydrogen bonding on EPR parameters and molecular docking studies are the most important steps for this study. Conformational space scanning required for molecular structure calculations was carried out with the Molecular Mechanic Force Field method. DFT method with 6-311 + + G(d,p) basis set level was used to obtain the most stable structure among the conformations. NMR parameters (1H and 13C chemical shift values) were also performed using the same basis set as the DFT method. The radicals created to calculate the Electron Paramagnetic Resonance parameters were modeled using the DFT/B3LYP/6-311 + + G(d,p) method basis set level. Molecular Docking studies were carried out with the Autodock vina program.

SON KULLANMA TARİHİ GEÇMİŞ BİR İLACIN İNHİBİSYON ETKİNLİĞİ ÜZERİNE PROTONASYONUNUN DEĞERLENDİRİLMESİNE YÖNELİK TEORİK BİR YAKLAŞIM

The quantum theoretical calculations were performed to elucidate the corrosion inhibition efficiency of an expired drug. For this purpose, molecular orbital analysis, which is used in the analysis of chemical interactions and gives detailed data about the electronic structure of molecules, was used to gain insight into the electronic properties of the selected drug molecule in neutral and aqueous form. The calculations were carried out at the (B3LYP) 6-311G**(d,p) basis set level utilizing density functional theory (DFT) to examine the relationship between the molecular structure and inhibition efficiency of the corresponding drug molecule. Various quantum chemical descriptors such as highest occupied molecular orbital energy (HOMO), lowest unoccupied molecular orbital energy (LUMO), energy gap (ΔE), dipole moment (μ), ionization potential (I), electron affinity (A), electronegativity (χ), hardness (η), softness (σ), back donation (ΔEback- donation) and fraction of electrons transferred (ΔN) were calculated and correlated to the inhibition efficiency. The most probable nucleophilic and electrophilic reactive sites of studied drug molecule were analyzed through computed Fukui indices. Overall, obtained theoretical data indicate that the quantum chemical parameters correlate well with the inhibition performance.

Photovoltaic properties of novel reactive azobenzoquinolines: experimental and theoretical investigations

Abstract In this work, synthesis, characterization, DFT, TD-DFT study of some novel reactive azobenzoquinoline dye structures to elucidate their photovoltaic properties. The azobenzoquinoline compounds were experimentally synthesized through a series of reaction routes starting from acenaphthene to obtained aminododecylnaphthalimide and finally coupled with diazonium salts to get the desired azobenzoquinoline. Azo dye synthesized differ in the number of alkyl chains designated as (AR1, AR2, AR3, and AR4) which were experimentally analyzed using FT-IR and NMR spectroscopic methods. The synthesized structures were modelled for computational investigation using density functional theory (DFT) and time-dependent density functional theory (TD-DFT) combined with B3LYP and 6-31+G(d) basis set level of theory. The results showed that the HOMO-LUMO energy gap was steady at approximately 2.8 eV as the alkyl chain increases, which has been proven to be within the material energy gap limit for application in photovoltaic. The highest intramolecular natural bond orbital (NBO) for the studied compounds is 27.60, 55.06, 55.06, and 55.04 kcal/mol for AR1, AR2, AR3, and AR4 respectively and the donor and acceptor interacting orbitals for the highest stabilization energy (E (2)) are LP(1)N 18 and π*C 16−O 19 respectively. The photovoltaic properties in terms of light-harvesting efficiency (LHE), Short circuit current density (J SC), Gibbs free energy of injection (ΔG inj), open-circuit voltage (V OC) and Gibbs free energy of regeneration (ΔG reg) were evaluated to be within the required limit for DSSC design. Overall, the obtained theoretical photovoltaic results were compared with other experimental and computational findings, thus, are in excellent agreement for organic solar cell design.

Comparative QSAR Modeling for Predicting Anticancer Potency of Imidazo[4,5-b]Pyridine Derivatives Using GA-MLR and BP-ANN Techniques

Background: Prediction of toxicity of imidazo[4,5-b]pyridine derivatives is carried out using GA-MLR and BPANN methods. Objective: A quantitative structure-property relationship (QSPR) was determined based on methods, including genetic algorithm-multiple linear regression (GA-MLR) and backpropagation artificial neural network (BP-ANN). These methods were employed for modeling and predicting the anticancer potency of imidazo[4,5-b]pyridine derivatives. Materials and Methods: A dataset of imidazo[4,5-b]pyridine derivatives was randomly divided into two groups, training and test sets consisting of 75% and 25% of data points, respectively. The optimized conformation of compounds was obtained using the DFT-B3LYP method and 6-31G* basis sets level with Gaussian 09 software. A large number of molecular descriptors were calculated using Dragon software. The QSAR models were optimized using multiple linear regressions (MLR). Results: The most relevant molecular descriptors were obtained using the genetic algorithm (GA) and backward stepwise regression. The predictive powers of the GA-MLR models were studied using leaveone- out (LOO) cross-validation and an external test set. Conclusion: The obtained results of statistical parameters showed the BP-ANN model to have better performance compared to the GA-MLR model. To assess the predictive ability of QSAR models, many statistical terms, such as correlation coefficient (R2), leave-one-out cross-validation (LOOCV), root mean squared error (RMSE), and external and internal validation were used. The results of validation methods demonstrate the QSAR model to be robust and with high predictivity.

Synthesis, crystal structure and computational analysis of 2,7-bis-(4-chloro-phen-yl)-3,3-dimethyl-1,4-diazepan-5-one.

In the title compound, C19H20Cl2N2O, the seven-membered 1,4-diazepane ring adopts a chair conformation while the 4-chloro-phenyl substituents adopt equatorial orientations. The chloro-phenyl ring at position 7 is disordered over two positions [site occupancies 0.480 (16):0.520 (16)]. The dihedral angle between the two benzene rings is 63.0 (4)°. The methyl groups at position 3 have an axial and an equatorial orientation. The compound exists as a dimer exhibiting inter-molecular N-H⋯O hydrogen bonding with R 2 2(8) graph-set motifs. The crystal structure is further stabilized by C-H⋯O hydrogen bonds together with two C-Cl⋯π (ring) inter-actions. The geometry was optimized by DFT using the B3LYP/6-31 G(d,p) level basis set. In addition, the HOMO and LUMO energies, chemical reactivity parameters and mol-ecular electrostatic potential were calculated at the same level of theory. Hirshfeld surface analysis indicated that the most important contributions to the crystal packing are from H⋯H (45.6%), Cl⋯H/H⋯Cl (23.8%), H⋯C/C⋯H (12.6%), H⋯O/O⋯H (8.7%) and C⋯Cl/Cl⋯C (7.1%) inter-actions. Analysis of the inter-action energies showed that the dispersion energy is greater than the electrostatic energy. A crystal void volume of 237.16 Å3 is observed. A mol-ecular docking study with the human oestrogen receptor 3ERT protein revealed good docking with a score of -8.9 kcal mol-1.

Synthesis, characterization, DFT, vibrational analysis (FT-IR and FT-Raman), topology and molecular docking studies of 3,3′-((1E,1′E)-((sulfonylbis(4,1-phenylene)) bis (azaneylylidene)) bis (methaneylylidene)) diphenol

The 3,3′-((1E,1′E)-((sulfonylbis(4,1-phenylene)) bis (azaneylylidene)) bis (methaneylylidene)) diphenol (D3H) was characterized by experimental and theoretical approaches. Titled compound FT-IR, FT-Raman, NMR (1H), UV–vis and fluorescence spectral analysis were developed in experimentally. After that, theoretical computations at the DFT/WB97XD/cc-pVDZ basis set level were carried out. The experimental geometrical parameters and the theoretical geometrical parameters were compared and well matched. The frequencies calculated using FT-Raman and FT-IR matched those obtained from experiments. The potential energy distributions analysis was calculated. Comparisons were made between the theoretical and experimental NMR chemical shifts. Absorption wavelengths in the UV–Vis spectrum were measured experimentally and compared to those predicted by TD-DFT. It is optical material, because its showed good fluorescence spectrum. The frontier molecular orbital, natural bond orbital analysis, molecular electrostatic potential, electron localized function, reduced density gradient and localized orbital locator, were carried out and thoroughly explained. According on the results of docking tests, the greatest possible binding energy score is -7.52 kcal/mol.

Streamlining and Optimizing Strategies of Electrostatic Parameterization.

Accurate characterization of electrostatic interactions is crucial in molecular simulation. Various methods and programs have been developed to obtain electrostatic parameters for additive or polarizable models to replicate electrostatic properties obtained from experimental measurements or theoretical calculations. Electrostatic potentials (ESPs), a set of physically well-defined observables from quantum mechanical (QM) calculations, are well suited for optimization efforts due to the ease of collecting a large amount of conformation-dependent data. However, a reliable set of QM ESP computed at an appropriate level of theory and atomic basis set is necessary. In addition, despite the recent development of the PyRESP program for electrostatic parameterizations of induced dipole-polarizable models, the time-consuming and error-prone input file preparation process has limited the widespread use of these protocols. This work aims to comprehensively evaluate the quality of QM ESPs derived by eight methods, including wave function methods such as Hartree-Fock (HF), second-order Møller-Plesset (MP2), and coupled cluster-singles and doubles (CCSD), as well as five hybrid density functional theory (DFT) methods, used in conjunction with 13 different basis sets. The highest theory levels CCSD/aug-cc-pV5Z (a5z) and MP2/aug-cc-pV5Z (a5z) were selected as benchmark data over two homemade data sets. The results show that the hybrid DFT method, ωB97X-D, combined with the aug-cc-pVTZ (a3z) basis set, performs well in reproducing ESPs while taking both accuracy and efficiency into consideration. Moreover, a flexible and user-friendly program called PyRESP_GEN was developed to streamline input file preparation. The restraining strengths, along with strategies for polarizable Gaussian multipole (pGM) model parameterizations, were also optimized. These findings and the program presented in this work facilitate the development and application of induced dipole-polarizable models, such as pGM models, for molecular simulations of both chemical and biological significance.

Evaluating the in vitro antidiabetic, antibacterial and antioxidant properties of copper(II) Schiff base complexes: An experimental and computational studies

In recent years, metal-based compounds have been explored as potential remedies for majorhealth issues such as diabetes, bacterial infections, and oxidative stress, which impact the general well-being of humans globally. Diabetes, bacterial infections, and oxidative stress are major health concerns affecting millions worldwide. Researchers have been exploring the use of metal-based compounds as potential treatments for these conditions. In our quest towards identifying biologically viable metal-based compounds, three novel Cu(II) complexes were synthesized from halogen-substituted ON donor Schiff base ligands. These ligands were obtained by condensing 2-hydroxybenzldehyde with three different halogen-substituted anilines. The ligands and their complexes were characterized using various spectroscopic techniques such as 1H and 13C nuclear magnetic resonance, Fourier Transform-Infrared, Ultraviolet–visible spectra, elemental analysis, mass spectrometry, and single-crystal X-ray spectroscopy to elucidate their structures. The compounds were screenedfor antidiabetic (α-glucose and α-amylase enzymes inhibition assay), antioxidant (2,2-diphenyl-1-picrylhydrazyl(DPPH), ferric reducing antioxidant potential (FRAP) assay, and nitric oxide(NO) radical scavenging), and antimicrobial activities. The pharmacological activity revealed that the efficacy of the ligands was enhanced upon coordination, and CuL3 is more potent among the complexes, having higher inhibition activity on α-glucosidase (IC50 = 100.1 μM) than the control, whose IC50 is 112.4 μM on the same enzyme. For radical scavenging activity, the results showed that the complexes have higher scavenging activity on DPPH radicals than their ligands and the control. For the FRAP assay, the complexes show higher activity than their ligands. Similarly, NO radical scavenging activity results indicate the ligands have higher activity than their complexes, while the complexes outperformed the control at all concentrations tested. The In vitro antibacterial results on some selected Gram-positive and Gram-negative bacteria revealed the complexes have higher antibacterial activity than their corresponding ligands, with CuL3 taking the lead, showing a MIC value of 4 g/mL on some of the bacteria tested. Also, density functional theory calculations at different levels of DFT and basis sets were used to investigate the optimized geometry, electronic structure (energy of HOMO and LUMO, Mulliken atomic charge, dipole moment, hardness, and softness, electrophilicity, and spectral properties) of the synthesized compounds. Molecular docking studies were carried out to investigate the binding affinity of the receptor proteins to other proteins and to establish the mechanism of action at the active sites.