Local Reactivity Descriptors Research Articles

Synthesis and crystal structures of two 1H-benzo[d]imidazole derivatives: DFT and anticorrosion studies, and Hirshfeld surface analysis.

The title benzimidazole compounds, namely, 2-(4-methoxynaphthalen-1-yl)-1H-benzo[d]imidazole, C18H14N2O (I) and 2-(4-methoxynaphthalen-1-yl)-1-[(4-methoxynaphthalen-1-yl)methyl]-1H-benzo[d]imidazole ethanol monosolvate, C30H24N2O2·C2H6O (II), were synthesized by the condensation reaction of benzene-1,2-diamine with 4-methoxynaphthalene-1-carbaldehyde in the ratios 1:1 and 1:2, respectively. In I, the mean plane of the naphthalene ring system is inclined to that of the benzimidazole ring by 39.22 (8)°, while in II, the corresponding dihedral angle is 64.76 (6)°. This difference is probably influenced by the position of the second naphthalene ring system in II; it is inclined to the benzimidazole ring mean plane by 77.68 (6)°. The two naphthalene ring systems in II are inclined to one another by 75.58 (6)°. In the crystal of I, molecules are linked by N-H...N hydrogen bonds to form chains propagating along the a-axis direction. Inversion-related molecules are also linked by a C-H...π interaction linking the chains to form layers lying parallel to the ac plane. In the crystal of II, the disordered ethanol molecule is linked to the molecule of II by an O-H...N hydrogen bond. There are a number of C-H...π interactions present, both intra- and intermolecular. Molecules related by an inversion centre are linked by C-H...π interactions, forming a dimer. The dimers are linked by further C-H...π interactions, forming ribbons propagating along the b-axis direction. The interatomic contacts in the crystal structures of both compounds were explored using Hirshfeld surface analysis. The molecular structures of I and II were determined by density functional theory (DFT) calculations at the M062X/6-311+g(d) level of theory and compared with the experimentally determined molecular structures in the solid state. Local and global reactivity descriptors were computed to predict the reactivity of the title compounds. Both compounds were shown to exhibit significant anticorrosion properties with respect to iron and copper.

Chemical reactivity of 3-substituted-6,8-dimethylchromones towards 1H-benzimidazol-2-ylacetonitrile and 5-amino-2,4-dihydro-3H-pyrazol-3-one: Spectroscopic, theoretical and in silico ADME studies

The reactivity of 1H-benzimidazol-2-ylacetonitrile and 5-amino-2,4-dihydro-3H-pyrazol-3-one, as nucleophilic reagents, was examined towards some 3-substituted-6,8-dimethylchromones 2a-d. A diversity of novel pyrido[1,2-a]benzimidazoles, chromeno[2,3-b]pyridines, pyrazolo[3,4-b]pyridines and chromenopyrazolopyridines was efficiently synthesized through different chemical transformations; depending on the functional group present at C-3 position of the chromone moiety. With B3LYP/6–311 G(d,p) basis set in the ground state, density functional theory (DFT) is used to determine the molecular geometry of synthesized compounds. The reactivity of the current compounds was studied by global reactivity descriptors at the same level of theory. In order to forecast the reactive locations on the starting substrates 2a-d for nucleophilic and electrophilic attacks, Fukui functions (local reactivity descriptors) were computed at the same level of theory. On the other hand, molecular electrostatic potential (MEP) surface maps were used to identify the nucleophilic and electrophilic sites. Moreover, 1H and 13C NMR chemical shift values in the ground state was calculated using the Gauge-Including Atomic Orbital (GIAO) technique, and the predicted values were compared with the experimental results. To interpret the nonlinear optical (NLO) property of the synthesized compounds, the dipole moment, polarizability, and first hyperpolarizability values have been measured (in the range β = 0.38 × 1030 - 3.28 × 10−30 esu). First hyperpolarizabilities of the investigated compounds indicate promising candidates for nonlinear optical applications. Also, using web-based platforms, in silico ADME calculations were performed.

The use of global and local reactivity descriptors of conceptual DFT to describe toxicity of benzoic acid derivatives

The present study explores the use of global and local quantum reactivity descriptors and conceptual density functional theory (cDFT), as well as descriptors of atomic-quantum topology (QTAIM), to describe the structure–toxicity relationship (STR) for 37 compounds derived from benzoic acid, employing the median lethal dose logarithm (log LD50) as a parameter. The method was validated using a coefficient of determination (R2) of 0.8285 and a leave-one-out cross-validation (Q2LOO) of 0.7138, thus fulfilling the statistical criteria indicated for models generated in QSARINS software. The descriptors closely related to the toxicity of the compounds were EHOMO(N−1), ∇2ρ(r)(BCP2), ∇2ρ(r)(BCP5), QH4Hirshfeld, QYY(C1), and ∑q-meta. This finding both enabled the reactivity of the benzoic acid derivatives to be interpreted and facilitated an understanding of the potential chemical bonds with enzymes, such as serine, in a biological environment.

Exploring the Synergistic Effect of Tegafur-Syringic Acid Adduct Against Breast Cancer through DFT Computation, Spectroscopy, Pharmacokinetics and Molecular Docking Simulation

The most prevalent kind of cancer and the main reason for cancer-related deaths in women is breast cancer. Synergistic drug delivery plays an effective role in the treatment of cancer by targeting various proteins underlying different mechanism. In this present study, a thorough analysis of the tegafur syringic acid adduct compound using density functional theory, molecular docking and pharmacokinetic prediction has been done. The PED value was given to the estimated vibrational wavenumbers. The molecule’s UV-Vis absorption spectra in the gas phase and liquid phase (water), were exhibited as π→π* electronic transitions. In order to determine the stability and molecular reactivity of the molecule, the HOMO-LUMO energies, energy gap, molecular electrostatic potential surface and mulliken atomic charge distribution were determined. Natural bond orbital analysis was used to determine the molecule’s second order perturbation energy E(2) values and potential reactive location was revealed through local reactivity descriptors. The Hirshfeld surface analysis showed that H…H (40.9%), O…H/H…O (27.2%), C…C (8%), O…C/C…O (7.8%), F…H/H…F (5.9%), C…H/H…C (5.5%), and N…C/C…N (2.9%) have the highest percentage contributions of the most important interactions. Thermodynamic characteristics like enthalpy, specific heat capacity and entropy were calculated. The physiochemical, absorption, distribution, metabolism, excretion and toxicity (ADMET) properties were predicted and represented the safety profile of adduct compound and the docking studies exhibited the binding potential of the adduct against the breast cancer proteins and highest binding affinity was observed against GSK3β with docking score of −9.7 Kcal/mol.

Synthesis, Spectroscopic Analysis, Charge and Proton Transfer Interaction Studies, In-Vitro, and In-Silico Antimicrobial, Pharmacokinetics Studies of Piperazin-1-Ium 4-Aminobenzoate Monohydrate: A Density Functional Theory Approach

Piperazin-1-ium 4-aminobenzoate monohydrate (PPAB) single crystals were grown by slow evaporation method. The grown crystal PPAB has been characterized by single-crystal X-ray diffraction, FTIR, FT-Raman, and UV-visible analysis. The B3LYP method and 6-311G (d, p) basis set were used to optimize the structure. The title compound was investigated theoretically and experimentally by FT-IR, FT-Raman, and UV-Vis spectral analysis. The presence of various functional groups in the structure was elucidated by FTIR and FT-Raman spectral studies. The intermolecular interactions within the crystal structure were investigated using Hirshfeld surface analysis. The crystal packing diagram reveals interesting non-covalent interactions involving C–H···O, N–H···O, and N–H···N hydrogen bonds, leading to the generation of 3D supramolecular architecture. The charge transfer within the molecule was deeply analyzed by using the NBO approach. The molecular electrostatic potential (MEP) and the local reactivity descriptors, such as Fukui function (fk +, fk −) analyses were performed to determine the reactive sites within the molecule. The HOMO and LUMO analysis was used to determine the chemical reactivity and bioactivity of the molecule. Hole-electron analysis was performed to analyze the charge transfer in an excited state. Based on the hole-electron analysis, the inter-fragment charge transfer (IFCT) analysis establishes the amount of charge transfer among different fragments. Topological analyses, such as AIM, RDG, and ELF were carried out to identify the non-covalent interaction within the molecule. The molecular docking studies of the molecule are performed to investigate the binding affinity of the ligand with the protein receptor. Drug-likeness properties, such as Lipinski’s rule of five, adsorption, distribution, metabolism, excretion, and toxicity (ADMET) have been investigated by in silico web-based tools like SwissADME and ADMETlab.

Inhibitory behavior and adsorption of asparagine dipeptide amino acid on the Fe(111) surface.

The inhibitory effect of asparagine (Asn) and its derivatives on iron (Fe) corrosion was studied by performing density functional theory (DFT) calculations. In this paper, the global and local reactivity descriptors of Asn in the protonated and neutral forms were evaluated. Also, the changes in reactivity were investigated when dipeptides were combined with Asn. Due to the increase in the reaction centers within their molecular structure, there was an enhancement in the inhibitory effect of these dipeptides. Moreover, the adsorption energies (Eads) and the adsorption configurations of Asn and small peptides (SPs) with most stability were determined on the surface of Fe(111). It was found that dipeptides had a chemical adsorption on these substrates. In the protonated forms, there was an enhancement in the absolute values of Eads between the inhibitors and the Fe(111) surfaces. Peptides were more likely to be adsorbed on the Fe surfaces, showing the great inhibitory effect of these moieties. The results of the current research demonstrate the possibility of utilizing SPs as efficient "green" corrosion inhibitors. DFT computations were undertaken by employing the BIOVIA Material Studio with B3LYP-D3 functional and 6-31 + G* basis set. The theoretical evaluation of the inhibitory effect of asparagine (Asn) dipeptides, and the potential analysis of small peptides to protect against the corrosion of Fe, was done.

Local reactivity descriptors of the important atoms in chelotropic reactions provide insight into their global variants along the reaction path

AbstractChelotropic reactions are widely used in organic synthesis. These reactions are of the pericyclic type where a π bond and a lone pair are transformed into a pair of sigma bonds; with both sigma bonds added to the same atom. This work presents an analysis of several representative chelotropic reactions. To study the reaction path, we have divided it into two parts, from the reactants to the transition state and from the transition state to the products which has allowed us to compare the behavior of the reactants in these two ranges of the path. To perform the analysis, global reactivity descriptors based on the conceptual‐density functional theory (DFT), such as electrophilicity and global softness, have been calculated. To analyze these descriptors, the corresponding local descriptors have been used. A model based on Sanderson's principle (electronegativity equalization principle), developed previously, has been used to calculate the local reactivity descriptors (atomic). The statistical methodology of multiple regression analysis has been used to determine which local variables are the most relevant for the global parameter under study (softness, and electrophilicity), also the principal component analysis has been used as a guide to estimate the number of variables to take into account in the analysis, finally this has led us to important correlations between global and local parameters which has allowed us to analyze the reactions of the study. Transition states of the reactions are aromatic as obtained from the nucleus independent chemical shift (NICS) and gauge including magnetically induced ring current (GIMIC) analysis.

Antitumor and antimicrobial effect of syringic acid urea cocrystal: Structural and spectroscopic characterization, DFT calculation and biological evaluation

The syringic acid urea (SYRAUA) cocrystal was produced at room temperature using a slow evaporation approach. The SYRAUA formed as orthorhombic crystal with the Cmca space group. It was undertaken to perform structural, spectroscopic (FTIR), and optical research. For SYRAUA, the structural and different spectroscopic parameters were calculated with quantum mechanics utilizing the B3LYP/6–31++G (d, p) approach. The XRD results were related with the optimized geometrical parameters and found there is a close agreement. SYRAUA's FT-IR spectrum was analysed using the data collected in the 4000–400 cm−1 region. There is decent agreement between the calculated and recorded wavenumbers. The 200–600 nm region of the UV–Visible absorption spectrum was noted showed the presence of two absorption peaks. The NBO approach was used to analyse the charge transfer in the cocrystal, and Mulliken charge analysis was used to confirm the identity of the involved atoms. To comprehend the reactive location in SYRAUA, the molecule electrostatic potential and local reactivity descriptors were determined. The non-linear optical characteristics were determined and found that it possesses 70% NLO activity compared with urea. Hirshfeld surface and finger print analysis were used to examine the inter and intramolecular interaction of the SYRAUA. When the SYRAUA was tested for antimicrobial activity, it was discovered to have zone of clearance. Molecular docking outcomes support that SYRAUA may exhibit inhibitory activity against caspase 3,7 and 9. Amongst the three caspases the SYRAUA showed higher docking affinity to caspase 9 with the binding score of -8.4 Kcal/mol. Further the drug likeness of the SYRAUA were assessed through Lipinski's rule and the pharmacokinetic parameters and those predicted values showed good safety profile of SYRAUA cocrystal.

Phytochemical components of Allium Jesdianum flower as effective corrosion-resistant materials for Fe(1 1 0), Al(1 1 1), and Cu(1 1 1): DFT study

As anticorrosive materials, natural products such as flower extracts are widely used. In lieu of using the whole product, it is better to apply the isolated phytochemical active component among all existing components in the flower as anticorrosive. Therefore, identifying the component or components responsible for anticorrosion paves the road for its experimental synthesis and effective application. In the present investigation, a comprehensive investigation of three phytochemicals present in Allium Jesdianum (AJ) flower, namely Methyl heptadecanoate (Palmitic acid), Ethyl (9Z,12Z)-octadeca-9,12-dienoate (a-Linolenic acid), and Icosan-1-ol (1-Ecosanol) was characterized using computational methods (DMol3, and Monti Carlo (MC) simulations) to determine the inhibition potentials for corrosion, chemical reactivities, and adsorption behaviors. Isolated forms were characterized by local and global reactivity descriptors such as the energies and distributions of the highest occupied molecular orbitals (HOMOs), Lowest unoccupied molecular orbitals (LUMOs), their gaps, hardness (h), global softness (s), global electronegativity (χ), chemical potential (μ), electrophilicity (ω), nucleophilicity (ε), electron-accepting power (ω-), electron-donating power (ω+), and net electrophilicity (Δω±). A further investigation has been made into the adsorption of three types of industrial metals, namely Fe(110), Al(111), and Cu(111). Based on the most stable adsorption configurations, the three phytochemicals adsorbed parallel to all surfaces. Adsorbate and surfaces interact primarily via chemisorption. In line with this result, the radial distribution function (RDF) has been analyzed. Computed parameters illustrated 1-Ecosanol's superiority over other phytochemicals and justified the reason behind its efficiency.

Experimental and theoretical studies of a thiourea derivative: 1-(4-chloro-benzoyl)-3-(2-trifluoromethyl-phenyl)thiourea

The 1-(4-chloro-benzoyl)-3-(2-trifluoromethyl-phenyl)thiourea compound was synthesized by a two-step reaction and a single crystal of it was obtained by recrystallization method. Its structure was elucidated by elemental analyzes, FT-IR, 1H NMR, and 13C NMR techniques, and its molecular and crystal structure was also determined by single-crystal X-ray diffraction analysis. The Hirshfeld surface analyzes of the crystal structure indicate that the most important contributions for crystal packing are from H···H (23.8%), H···S/S···H (14.5%), H···F/F···H (14.3%), C···H/H···C (14.2%), and Cl···F/F···Cl (9.0%). In addition, energy-framework calculations are used to analyze and visualize the three-dimensional topology of the crystal packing. The electrostatic energy framework is dominant over the dispersion energy framework. The density functional theory method with the basis set of B3LYP/6-311G(d,p) has been employed to obtain the optimized structural geometry, Mulliken charges, molecular electrostatic potential, frontier molecular orbitals, the total density of states, reduced density gradient analysis and natural bond orbitals. The experimental crystal structure parameters and optimized structure parameters are very similar. The HOMO–LUMO energy gap of the compound is 3.5307 eV. Different global chemical reactivity descriptor parameters were also calculated. Nonlinear optical properties such as anisotropy of polarizability, mean polarizability, static dipole moment, and first-order hyperpolarizability values were theoretically determined. The Fukui functions as electron density-based local reactivity descriptors were also calculated to explain the chemical selectivity or the reactivity site in the molecule. Molecular docking studies were also carried out to determine the inhibitory action of the title compound against the main protease (6LU7) of a new coronavirus (COVID-19).

Local reactivity descriptors to decipher the electrochemical hydrogenation of unsaturated carboxylic acids

We explain the intricate interplay between electronic properties and reactivity during the electrochemical hydrogenation of biobased unsaturated (di)acids under acidic and neutral conditions.

Gallic acid-cholesterol conjugate: Synthesis spectroscopic characterization and quantum chemical calculations-an experimental and theoretical approach

Gallic acid is the major constituent in fruits Phyllanthusemblica (amla), of the family phyllanthaceae. Gallic acid was first methylated to 3,4,5 trimethoxygallic acid, which upon esterification using steglich method with cholesterol resulted in the product (3S,8S,10R,13R,17R) -10,13-dimethyl-17-((R)-6-methylheptan-2-yl)-2,3,4,7,8,9,10,11,12,13,14,15,16,17-tetradecahydro - 1H - cyclopenta[a]phenanthren-3-yl 3,4,5-trimethoxybenzoate. The synthesized compound has been characterized by 1H NMR, 13C NMR, UV, FT-IR and mass spectroscopy. Density functional theory (B3YLP) using a 6-31G (d,p) basis set has been used for quantum chemical calculations. The reactive site and reactivity within the molecule are rendered by global and local reactivity descriptors, whereas AIM (Atom in a molecule) approach illustrated weak molecular interactions within the molecule. The energies of HOMO and LUMO and frontier orbital energy gap are calculated by time dependent DFT approach using the IEFPCM model. A small value for the HOMO-LUMO energy gap indicates easier charge transfer within the synthesized compound. The nucleophilic and electrophilic reactivity is determined by MEP (molecular electrostatic potential) studies. The values calculated for polarizability, dipole moment, and first hyperpolarizability are used to depict the NLO (nonlinear optical) property of the synthesized compound.

DFT Analysis, ADME, antibacterial activity and molecular docking studies of 2-(3-aryl-1,2,4-oxadiazol-5-yl)-n-phenylacetamide derivatives

Quantum computational study based on density functional theory (DFT/B3LYP) using basis set 6-311G (d,p) a number of global and local reactivity descriptors have been computed to predict the reactivity and the reactive sites on the 2-(3-aryl-1,2,4-oxadiazol-5-yl)-n-phenylacetamideoxadiazole derivatives. The molecular geometry and the electronic properties such as frontier molecular orbital (HOMO and LUMO), ionization potential (I) and electron affinity (A) are investigated to get a better insight of the molecular properties. Molecular electrostatic potential (MEP) for all compounds were determined to check their electrophilic or nucleophilic reactivity. The in silico pharmacokinetics showed that nearly all derivatives obeyed Lipinski rule of 5 with low toxicity and metabolic stability. The antibacterial activity was carried out against B. subtilis, S. aureus, P.aeruginosa and E. coli , displaying considerable inhibition . MurE ligases, (PDB: 7b6k) participating in the intracellular steps of bacterial peptidoglycan biosynthesis, are taken as targets for molecular docking studies using Flare GUI software. The docking outcome revealed that these 1,2,4-oxadiazole analogues have highest LF rank score in the range -12.9 to -6.0 which shows that they act as potent antibacterial agents.

Understanding the origin of reactivity, mechanism and regioselectivity of the [3+2] cycloaddition reaction between nitrile imine and pyrrolopyrazine

AbstractIn this work, we have performed a computational study on the [3+2] cycloaddition (32CA) reaction between nitrile imine and pyrrolopyrazine within molecular electron density theory (MEDT) using B3LYP and M06‐2X DFT functionnals together with 6‐31G(d,p) basis set. This study shows that the popular B3LYP is the appropriate functional for performing this study. The analysis of energy profiles indicates that this 32CA reaction favours kinetically the formation of a single product as observed experimentally. The favour cycloadduct (P1) is formed through a moderate polar stepwise mechanism, in which the first step is the determining one that is characterised by a moderate polarity and the second step by a highly polar character, while the unfavoured one is formed via a nonpolar one‐step asynchronous mechanism. Solvent effects do not change the regioselectivity, but it increases the activation energies. Thermodynamic parameters analysis indicates that this 32CA reaction is characterised by an exothermic and endergonic characters favouring the formation of cycloadduct (P1), as observed experimentally. Conceptual DFT (CDFT) reactivity indices analysis shows that pyrrolopyrazine 2 reacts as a nucleophile, while nitrile imine 3 as an electrophile. Local reactivity descriptors, such as Parr functions and dual descriptors, show that this 32CA reaction is regioselective leading to the formation of P1. Analysis of ELF electron density demonstrated that the interaction between the high electron density reactive centre with that of low electron density leads to the formation of P1 cycloadduct. The obtained results using MEDT method are in great agreement with what observed in the experimental data.

Reactivity of 9-anilinoacridine Derivatives as Potent Anticancer Agents: A DFT Approach

Background: Anticancer activity of 9-anilinoacridine derivatives has been well reported. Although, the DNA-drug sequence-specific binding of these compounds may be affected by the substituent(s) on the aniline ring, it is still unclear which substituent (NH2 or CH2–OH) on the anilino ring of the compound is the critical element. A good understanding of chemical properties such as steric, lipophilic and electronic properties at the molecular level may provide important background for mutagenic and carcinogenic properties. Objectives: The present study is an attempt to understand the reactive nature of some selected 9-anilinoacridine derivatives in both gas and solvent phases and to predict their anticancer activity by QSAR analysis. Methods: Full geometry optimizations of all derivatives were carried out at gradient corrected DFT using DMol3 program. We used DNP basis set in combination with BLYP to study all the derivatives. The molecular mechanics parameters used for QSAR analysis were calculated using Hyperchem software. Results: We found Compound (31) (R=COOC6H5) as the most stable compound and compound (6) (R1= NO2) as the most reactive one in both gas and solvent phases. Fukui function (f+) values of all the atoms showed that N10 is the most reactive atom in each of the molecule which indicates that N10 is the preferred site for nucleophilic attack. The final QSAR model with four parameters (electrophilicity, hardness, surface area, and molar refractivity) is capable of predicting anticancer activity of the compounds against leukemic HL-60 cell lines with r2 = 0.91 and 0.88 in both gas and solvent phases, respectively. Conclusion: The global and local reactivity descriptors, such as hardness, chemical potential, electrophilicity index, Fukui function, and local philicity were calculated to understand the reactive nature and reactive sites of the compounds. The comparative QSAR study with the help of DFT and MM + techniques provides the importance of the selected descriptors in predicting the activity of the selected derivatives.

Combined experimental, computational studies (synthesis, crystal structural, DFT calculations, spectral analysis) and biological evaluation of the new homonuclear complex Di-µ-benzoato-bis [benzoatodipyridine-cobalt (II)

A binuclear cobalt(II) benzoate complex with pyridine as auxiliary ligands has been synthesized and identified by UV–Vis, IR spectroscopy, and TG-DTA analysis. The molecular structure of the complex was determined by single-crystal X-ray diffraction (SCXRD). Thermogravimetric analysis shows two steps decomposition of the present complex. The Co (II) ions are in a distorted octahedral environment [CoN2O4]. The crystal structure was stabilized by different intramolecular/ intermolecular interactions, including Van der Waals, hydrogen bonding, donor-acceptor, and π-π interactions between the pyridine rings. Furthermore, all density functional theory (DFT) calculations have been performed in the gas phase using the GGA-BLYP functional and the TZP basis set, and for the Time-Dependent Density Functional Theory (TD-DFT) calculations, several functionals have been used, namely the GGA BLYP and PBE, the hybrids B3LYP and PBE0, the SAOP potential model, and finally the range-separated CAMY-B3LYP functional with the TZP basis set. Good consistency was observed between the calculated and the experimental results. The bond dissociation energies (BDE) were calculated using the fragment analysis. The intermolecular interactions were investigated through the Molecular Electrostatic Potential (MEP) and supported by Hirshfeld charges analysis. To characterize the non-covalent interactions in the complex, (NCI plot) index has been computed and supported by AIM analysis. Also, the global and local reactivity descriptors have been calculated to highlight the reactive sites in the molecular structure. Moreover, the antimicrobial activity was evaluated by agar disk diffusion assay against seven pathogenic strains, and the antioxidant activity was estimated using four different techniques. In addition, the in vitro anti-inflammatory activity was assessed by the albumin denaturation method.

Bonding nature, nucleophilic reactivity and electron excitation of NLO active 2,6 dichloroindophenol sodium salt (polar and non polar solvents) with topology analysis- bacterial pathogens study

2,6 Dichloroindophenol sodium salt was an aromatic compound evaluated by DFT through experimental and computation using various solvents used in solvation analysis investigation. FT-IR studies are used to identify the various functional groups, which are then compared with simulated spectra. The estimated vibrational wavenumbers were scaled using a suitable scaling factor after the optimized geometrical parameters were determined. The plotted FT-IR, FT-Raman; and UV–vis spectra are correlated with experimental calculations. Measured and computed spectra are found to be quite similar. NBO (Natural Bond Analysis) research explains how charges transferred occur in a molecule. NBO analysis indicates that the greatest second-order perturbation energy E(2) = 25.77 kcal/mol is associated with electron delocalization from the donor π (C13-C15) to π* (O4-C17) acceptor interaction. Local reactivity descriptor stipulates the molecule's reactive areas. The stability, hardness, and softness are studied by Highest Occupied Molecular Orbital (HOMO) and Lowest Unoccupied Molecular Orbital (LUMO). FMO (Frontier Molecular Orbital) divulge kinetic stabilization and reactivity of DCIP (2,6 Dichloroindophenol sodium salt). Reactive descriptors and molecular reactivity of DCIP were significantly changed by the solvents. The material under analysis has outstanding NLO (Non-linear Optical) properties. ELF (Electron Localization Function), LOL (Localised Orbital Locator) and RDG (Reduced Density Gradient) were performed and reported. Molecular docking is used to investigate specific biological data of DCIP. Two bacterial targets interact with a protein ligand. Whereas to ascertain the biological properties drug-likeness and ADMET were utilised. The outcome of the ADMET experiments showed that the structure under investigation possesses antibacterial properties. To test the substance's effectiveness against various bacterial strains, antibacterial tests were carried out.

Spectroscopic and quantum chemical investigations to explore the effect of intermolecular interactions in a diuretic drug: Hydrochlorothiazide

Hydrochlorothiazide (HCTZ) being a diuretic drug widely used in anti-hypertensive therapy as it lowers the blood pressure by reducing the reabsorption of electrolytes in kidney resulting an increment of urine output and lowering the blood pressure. The purpose of the present work is to study the structural, vibrational and chemical properties of HCTZ based on its monomeric, dimeric and trimeric models by utilizing computational methods and experimental techniques. Density functional theory (DFT) with functional B3LYP and 6-311++G (d, p) basis set was used for a detailed computational study. Monomeric, dimeric and trimeric models of HCTZ have been studied for a better understanding of inter- and intramolecular hydrogen bonding. FT-IR (400–3800 cm−1) and FT-Raman (100–3600 cm−1) spectroscopy have been utilized for the characterization of HCTZ. The shifting in wavenumber of NH2 and OSO group were observed in dimer and trimer due to the formation of intermolecular hydrogen bonding. Quantum theory of atoms in molecules (QTAIM) along with natural bond orbital (NBO) analysis were performed to examine the nature and strength of hydrogen bonding which showed that all the interactions were medium and partially covalent in nature; transition from LP(3)O15 → σ*(H46 → N32) and LP(3)O39 → σ*(H74 → N51) were responsible for the formation of O15•••H46 and O39•••H74 H-bonds, respectively. HOMO-LUMO energies predicted the chemical reactivity and stability of the molecule and the energy gap for dimer (4.6240 eV) and trimer (4.0493 eV) was found to be lesser than the monomer (5.0888 eV) which showed that the dimer and trimer have predicted more chemical reactivity in comparison to monomer. The most electronegative electrostatic potential was observed around the OSO group and the most electropositive potential around the amide group from MEPS analysis. Global as well as local reactivity descriptors have predicted the reactivity and hence, stability of the title molecule.

Investigation of Corrosion Inhibition Potential of Triazolopyrimidinones via Density Functional Theory and Monte-Carlo Simulations

The protection of metal parts from corrosion is important to save the cost of production of goods and lives. Twelve triazolopyrimidinone derivatives were investigated for their ability to inhibit the corrosion of metal via density functional theory and Monte Carlo (MC) simulation approaches. The electronic properties and global and local reactivity descriptors were computed at the B3LYP/6-31G(d) level of theory, using Spartan 14 software. The Mulliken charge distribution and electrostatic potential (ESP) maps were used to locate the reactive sites. The adsorption of the compounds on the surface of the stable Fe(110) was investigated in an aqueous solution using the adsorption locator module on Material Studio software. The values of energies of their frontier molecular orbitals and other reactivity descriptors suggest that these molecules displayed good corrosion inhibition potentials. The Mulliken charge distribution and electrostatic potential maps showed that they can donate electrons to the metal and at the same time accept electrons via back-donation, also rationalized by the values of their electron back-donation calculated. The molecules interacted well with Fe(110) surface in an aqueous medium, as revealed by the MC results.

Investigation of the substituted—titanium nanocages using computational chemistry

We are investigated substitution effects of titanium heteroatoms on band gap, charge and local reactivity of C20-nTin heterofullerenes (n = 1–5), at different levels and basis sets. The C18Ti2-2 nanocage is considered as the most kinetically stable species with the widest band gap of 2.86 eV, in which two carbon atoms are substituted by two Ti atoms in equatorial position, individually. The charges on carbon atoms of C20 are roughly zero, while high positive charge (1.256) on the surface of C19Ti1 prompts this heteofullerene for hydrogen storage. The positive atomic charge on Ti atoms and negative atomic charge on their adjacent C atoms implies that these sites can be influenced more readily by nucleophilic and electrophilic regents, respectively. We examined the usefulness of local reactivity descriptors to predict the reactivity of Ti–C atomic sites on the external surface of the heterofullerenes. The properties determined include Fukui function (F.F.); f (k) and local softness s (k) on the surfaces of the investigated hollow cages. Geometry optimization results reveal that titanium atoms can be comfortably incorporated into the CC network of fullerene. It is most likely associated with the triple-coordination characteristic of titanium atoms, which can well match with the sp2-hybridized carbon bonding structure. According to the values of f (k) and s (k) for the C15Ti5 heterofullerene; the carbon atoms in the cap regions exhibit a different reactivity pattern than those in the equatorial portion of the heterofullerene. The titanium impurity can significantly improve the fullerene's surface reactivity and it allows controlling their surface properties. The band gap of C20-nTin …..(H2)n structures is decreased with increasing n. Hence, C15Ti5 is found as the best hydrogen adsorbent.