Functional B3LYP Research Articles

Detection of Tetrachlorobutadiene Isomers Using Density Functional Theory Methods

The study aims to build upon previous research by incorporating Density Functional Theory (DFT), specifically using the B3LYP functional, to improve the computational methodology for analyzing chlorobutadiene (TCBD) compounds. DFT is chosen for its ability to account for electron correlation effects beyond the mean-field approximation, a limitation found in earlier approaches such as the Hartree-Fock (HF) method. By incorporating electron correlation, DFT provides a more accurate description of molecular properties, making it highly suitable for analyzing complex molecular structures like those found in chlorobutadienes. The methodology adopted in the study comprises four key steps. First, the molecular structure of each isomer was created. Next, the geometry of the isomers was optimized using DFT methods to ensure the most stable configurations for further analysis. The third step involved computing the vibrational frequencies of the molecules using the B3LYP functional, with different basis sets applied depending on the isomer under study. Finally, the simulated infrared (IR) spectra generated through DFT were compared with existing data from the literature to validate the findings and assess the accuracy of the computational model. The study focuses on nine different Tetrachlorobutadiene (TCBD) isomers, each with unique configurations of hydrogen and chlorine atoms. These structures were visualized using Molden software, and the IR spectra for each isomer were obtained using DFT, specifically the B3LYP and B3LYP-D3BJ functionals. The analysis of the IR spectra revealed characteristic peaks corresponding to various functional groups within the TCBD molecules. Notable vibrational modes include C-Cl stretching, C=C stretching and bending, and C-H stretching and bending, which are essential in identifying the chemical composition of the isomers. A comparative analysis was conducted between DFT and the previously employed Hartree-Fock (HF) method.

Discovery of iron-oxo-catalyzed oxidation of fluorophenyl systems to carbonyls or epoxides: reactive intermediates determined mechanism.

Carbonyl and epoxide compounds play crucial roles in organic synthesis, and the utilization of metal catalysis offers distinct advantages. However, the catalysis of their synthesis by high-valent iron-oxo remains a challenge. In this study, we investigated iron-oxo-catalyzed phenyl systems in detail. Our results show that the carbon atoms on the aromatic ring are positively charged by replacing a hydrogen atom with a fluorine atom, which leads to different catalytic mechanisms. Specifically, the cationic intermediate formed via a double-electron transfer in the low-spin (LS) state of a non-fluorinated benzene ring transforms into a radical intermediate via single-electron transfer when fluorine substitution occurs. Further computational investigations revealed that different intermediates in LS drive the formation of different products. The carbocation intermediate strongly favors the generation of carbonyl compounds through the migration of the ipso - hydrogen (known as the "NIH shift"). In contrast, the radical intermediate exhibits kinetic advantages in this pathway, leading to the formation of epoxides. This research provides theoretical support and facilitates the exploration of innovative pathways for carbonyl and epoxide synthesis. Computing was performed via Gaussian 09 software. Geometric optimization, transition state search, and intrinsic reaction coordinate (IRC) analysis were conducted via the hybrid functional B3LYP and the 6-311G(d,p) basis set. Single-point energy calculations were performed via a higher-level basis set, def2-TZVP. Multiwfn 8.0 and VMD 1.9.1 software are utilized for spin density and molecular frontier orbital analysis, as well as for graphically representing key intermediates.

Understanding Anionic Hyperporphyrins: TDDFT Calculations on Peripherally Deprotonated meso-Tetrakis(4-hydroxyphenyl)porphyrin.

Presented herein is a DFT/TDDFT study of meso-tetrakis(4-hydroxyphenyl)porphyrin (H2[THPP]) and its O-deprotonated tetraanionic form; the latter was modeled as both a free tetraanion and with various counterions. Based on our calculations, the experimentally observed hyperporphyrin spectra are attributed to an admixture of phenol/phenoxide character into the a2u-type HOMO of tetraphenylporphyrin. The admixture results in an elevation of the orbital energy of the HOMO in relation to other frontier orbitals, which accounts for the observed spectral redshifts. The calculations underscore differences in the performance of different exchange-correlation functionals. Thus, while the popular hybrid functional B3LYP greatly exaggerates the redshift of the far-red hyperporphyrin band of O-deprotonated H2[THPP], the range-separated functional CAMY-B3LYP predicts a more moderate redshift. The latter, however, fails to reproduce experimentally observed absorptions in the 550-600 nm range, potentially underscoring the still imperfect modeling of anionic hyperporphyrins.

Impact of confining hydrogen molecule inside fullerenes: A glance through DFT study.

In this work, we have studied different properties of a series of fullerenes, from C24 to C50 by confining hydrogen molecule inside their cavity. The compression of the hydrogen molecule upon encapsulation is evidenced by its altered bond length, while a slight expansion of the fullerene cages due to H2 confinement is also noted. The chemical reactivity parameters of both the empty and H2 confined fullerenes are computed, alongside an examination of the energy components through energy decomposition analysis. Analysis of the absorption spectra indicated that both H2 encapsulated and empty fullerenes exhibited absorption in the UV region. Nevertheless, the inclusion of H2 within the fullerene cages appeared to have minimal influence on the reactivity parameters and absorption spectra, as evidenced by the comparison between the sets of empty and H2-confined fullerenes. The computational work including the geometry optimization, followed by the frequency analysis and other parameters has been achieved using Gaussian09 software. For doing these calculations, B3LYP and CAM-B3LYP functionals along with 6-311 + G(d,p) basis set is used. In addition, MULTIWFN software has been considered for studying bonding analysis and energy decomposition analysis for the systems.

Interaction of CO, CO2, CSO, H2O, N2O, NO, NO2, O2, ONH, and SO2 gases onto BNNT(m,n)_x, (m = 3, 5, 7; n = 0, 3, 5, 7; x = 3-9).

This research investigates two critical areas, providing valuable insights into the properties and interactions of boron nitride nanotubes (BNNTs). Initially, a variety of BNNT structures (BNNT(m,n)_x, where m = 3, 5, 7; n = 0, 3, 5, 7; x = 3-9) with different lengths and diameters are explored to understand their electronic properties. The study then examines the interactions between these nanotubes and several gases (CO, CO2, CSO, H2O, N2O, NO, NO2, O2, ONH, and SO2) to identify the most stable molecular configurations using the bee colony algorithm for global optimization. The primary findings highlight the impact of nanotube diameter on these properties. It was observed that smaller diameters result in a larger energy gap due to increased quantum confinement. Significant charge transfer, especially with CO, was detected, affecting the electronic structure of the nanotubes. The study highlighted that BNNTs exhibit the strongest adsorption tendencies for NO₂, O₂, and SO₂. These findings underscore the critical roles of nanotube diameter and charge transfer in sensor applications and demonstrate the comprehensive utility of various analytical methods in understanding BNNT-gas interaction mechanisms. The research employs a comprehensive computational framework based on density functional theory (DFT). Various DFT methods, such as PBE0, B3LYP(GD3BJ), CAM-B3LYP, HSE06i, M06-2X, and ωB97XD functionals, are utilized along with the Def2tzvp basis set for the calculations. Structural optimizations are performed to ensure accuracy, and modifications to the energy gaps are analyzed using conceptual DFT. Additionally, Total Density of States (TDOS) analyses are conducted. Charge transfer mechanisms are investigated through Natural Bond Orbital (NBO) analysis. The interactions between gases and nanotubes are characterized at critical points using the Quantum Theory of Atoms in Molecules (QTAIM) framework.

Unraveling the mechanism: How does β-phosphoglucomutase from the haloacid dehalogenase superfamily catalyze the interconversion of β-d-glucose 1-phosphate and β-d-glucose 6-phosphate? A chemical perspective

The catalytic mechanisms of enzymes can be phylogenetically mapped corresponding to their catalytic structures. This mapping effectively elucidates the diversity of enzyme catalytic mechanisms and the emergence of new enzymatic activities within enzyme superfamilies. The haloacid dehalogenase (HAD) superfamily serves as an exemplary model system for comprehending the co-evolution of catalytic structures and mechanisms. This study delves into the mechanism underlying the functional divergence of β-phosphoglucomutase (β-PGM) from the phosphatase branch of the HAD superfamily, employing a chemical perspective. Through the construction and calculation of three models of varying scales using the Density Functional Theory method with B3LYP function, we aim to investigate the chemical mechanism driving this functional divergence of β-PGM from the HAD family. The computational results indicate that residues His20 and Lys76 in the second shell stabilize substrates and enhance the acid-base catalytic ability of Asp10. Additionally, residues Arg49, Ser116 and Asn118 facilitate substrate binding by engaging in close hydrogen bonding interactions with the substrates. Through cooperative action, these residues enable β-PGM to function as an efficient phosphoglucomutase. Through computational modeling and a chemical perspective, we unravel the mechanisms enabling β-PGM to convert β-d-glucose 1-phosphate to β-d-glucose 6-phosphate. Finally, based on the analysis of the evolutionary tree, we discussed and summarized the evolutionary relationships among different forms of metal cores of hydrolases.

Theoretical investigations of some isolated compounds from Calophyllum flavoramulum as potential antioxidant agents and inhibitors of AGEs

In this paper, we have attempted a theoretical calculation of some plant-isolated compounds as potential inhibitors of oxidative stress and Advanced Glycation Endproducts (AGEs). Herein, theoretical reactivity indices based on the CDFT theory were computed to explore the reactivity of five isolated products from Calophyllum flavoramulum. Global reactivity indices based on HOMO and LUMO energy such as electronic chemical potential, hardness, electrophilicity and the local reactivity descriptors Parr function, molecular electrostatic potentials(MEP), electrostatic potential (ESP) and thermodynamic parameters for the studied compounds are computed and discussed using DFT method and two functionals B3LYP and CAM-B3LYP with 6-31 G(d,p) basis set. The free radical scavenging activity mechanisms (HAT, SET-PT, and SPLET) of some of the isolated products with DPPH are also presented in this work. SET-PT mechanism of the antiradical activity is found to be thermodynamically favorable. Furthermore, a molecular docking study with RAGE receptor and AtGSTF2 enzyme was conducted, in which flavonoids 4 and 5 show a low binding affinity with −8.42 and −10.49 kcal/mol for RAGE, −8.67 and −9.00 kcal/mol for AtGSTF2. After the encouraging outcomes from the molecular docking study, the 4-AtGSTF2 and 5-RAGE complex were subjected to 200 ns molecular dynamics simulation using Desmond, where both studied systems exhibited remarkable stability throughout the 200 ns simulations. Also, the MM-GBSA method was measured by calculating the binding free energy using the individual energy components. Finally, the ADMET predictions were assessed to anticipate the behavior of a drug candidate within the human body.

Molecular, spectroscopic and thermochemical characterization of C2Cl3, C2F3 and C2Br3 radicals and related species.

This work reports a detailed theoretical study of the molecular parameters, harmonic vibrational frequencies, UV absorption spectra and standard enthalpies of formation for the radicals C2X3 (with X = F, Cl and Br) and a comparison with the corresponding determinations for the rest of the members of the family C2X n (with n = 2-4). Molecular properties were calculated using different levels of theory: density functional theory employing the B3LYP, X3LYP, BMK, M06-2X and M08-HX functionals combined with the basis sets 6-311++G(3df,3pd) and aug-cc-pVTZ, and the ab initio composite models G3B3 and G4. Structural and spectroscopic characterization of the C2F3, C2Cl3 and C2Br3 radicals, along with the estimation of the enthalpies of formation of C2F3 and C2Cl3, were derived here for the first time, to our knowledge. In particular, values of -220.9 ± 2.9, 230.8 ± 3.8 and 375.4 ± 5.9 kJ mol-1 were computed for enthalpies of formation of C2F3, C2Cl3 and C2Br3, respectively. Additionally, enthalpies of formation for related closed-shell molecules were obtained with less uncertainty compared to those found in the literature. The recommended values of -669.6 ± 3.8, -23.0 ± 4.6 and 155.3 ± 5.0 kJ mol-1 were derived for C2F4, C2Cl4 and C2Br4, while corresponding values of 0.6 ± 6.3, 228.1 ± 2.1 and 319.6 ± 5.4 kJ mol-1 were estimated for C2F2, C2Cl2 and C2Br2, respectively.

Synthesis of Novel Phenylalanine Carboxamides Derivatives Bearing Sulfonamides Functionality and Their Molecular Docking, In Vitro Antimalarial, and Antioxidant Properties

AbstractA new series of phenylalanine‐derived carboxamides with sulfonamide functionality is designed, synthesized, and assessed for their in silico studies, in vitro antimalarial, and antioxidant activities. The interaction of 4‐nitrobenzene sulfonyl chloride with phenylalanine in a basic aqueous solution yielded an intermediate ((4‐nitrophenyl)sulfonyl)phenylalanine. The reaction of various cyclic amines with the intermediate, utilizing phenylboronic acid as the coupling agent, yielded the carboxamides derivatives. The derived‐carboxamides passed in silico test and fulfilled all the allowed ranges for molecular descriptors. Optimization was achieved before compounds were deployed as ligands in molecular docking studies using density functional theory utilizing the functional B3LYP and the basis set 6–31G**. The docking experiments were done on the active site of FKBP35 binding domain of Plasmodium falciparum for antimalarial impact whereas that of antioxidants was performed on the active site of PDB ID:IXAN. The computational antimalarial and antioxidant study demonstrated that the compounds displayed a high binding affinity with the target protein residues via hydrogen bonding, π‐π, π‐alkyl, π‐sigma, and π‐cation bonding interactions. Additionally, the new compounds were evaluated for in vitro antimalarial and antioxidant properties. The screening findings suggest that the new compounds exhibit effective antimalarial and antioxidant action compared to traditional medicines.

Growth of L-asparagine monohydrate organic single crystals: An experimental and DFT computational approach for nonlinear optical applications

Good optical quality of L-asparagine monohydrate (C4H8N2O3.H2O) organic single crystal has been grown by adopting natural slow evaporation process at room temperature from aqueous solutions. The lattice parameters obtained by powder X-ray diffraction data revealed orthorhombic crystal system of the harvested crystal. The morphology and planes of the crystal have been identified. The molecular vibrations and functional groups have been specified by Fourier transform infrared (FTIR) spectroscopy studies. Energy dispersive X-ray (EDX) study has been availed to find out the elements constituting the crystal. Scanning electron microscopy, (SEM), provided the surface morphology of the crystal. The dependence of dielectric properties on frequency and temperature have been investigated and the electronic polarizability (α) has been determined. UV–vis spectral analysis shows that the crystal possesses good optical transmittance in the visible part of the energy spectrum. The optical band gap and the Urbach energy have been determined from lower absorption edge. Third order nonlinear susceptibility χ(3), nonlinear refractive index (n2), and linear susceptibility χ(1) have been calculated by Miller's generalized rule. The first-principle computation of band structure of electrons and the electron density of states have been discussed, which suggest that the crystals possess direct band gap. Density Functional Theory (DFT) with B3LYP function by Gaussian09W software was utilized to calculate HOMO-LUMO energy gap as well as non-linear optical parameters namely, linear polarizability (α), hyperpolarizability (β and γ) and dipole moment (μ) of L-asparagine monohydrate crystal. All the findings prove that L-asparagine monohydrate is a promising NLO crystal.

DFT calculations of structural, chemical, electronic and thermodynamic properties of Rifampicin and Oxalic Acid

The thermodynamic properties of the compounds contribute to the theoretical analysis of the results of favorable energies that are subject to interaction. In this work, through the DFT study, the comparison of the functionals ωB97XD and B3LYP. Geometry optimization calculations and vibrational frequencies were performed for the individual ions and for the interactions. In all cases, all calculated vibrational frequencies are positive, confirming the optimized geometry obtained as a minimum on the potential energy surface. The calculations were carried out in solvent, considering the solvation effect in methanol using the IEFPCM (Integral Equation Formalism of the Polarizable Continuum Model) method. The present work aims to carry out a theoretical study, for in-depth investigations of structural, electronic and thermodynamic properties. In usability in the calculation of the thermodynamic properties, Rifampicin (RIF) and Oxalic Acid (OXA) and the interaction between RIF-OXA in the protonated form protonated RIF with charge +1 and deprotonated OXA with charge -1. In this context, the most favorable thermodynamic parameters in the interaction calculated RIF+-OXA- the values of ∆EZPVE+BSSE, ∆G298 and ∆H in kcal/mol more favorable are -19.62, -14.81 and -25,77.

New charge transfer complex between melamine and 4-nitrobenzoic acid: Synthesis, spectroscopic characterization, and DFT studies

The charge transfer (CT) complex [MA(NBA)] was synthesized by combining melamine (MA) as the electron donor with 4-nitrobenzoic acid (NBA) as the acceptor in a stoichiometric ratio of 1:1. The complex was characterized using IR, NMR, and UV–vis spectroscopy, as well as elemental analysis. Computational analysis was carried out by density functional theory (DFT) studies using the B3LYP function with basis set 6–311 G (d, p) in the gas phase and DMSO. DFT calculations were in good agreement with the experimental data, providing further evidence of the complex's structure and stability. The gap energy (∆Eg) value for the [MA(NBA)] complex is 4.019 eV. This outcome provides strong proof of the charge transfer process occurring from the donor part (mainly HOMO) to the acceptor part (mainly LUMO), leading to the formation of the CT complex. Thermodynamic and molecular quantum parameters were also calculated to understand the stability and reactivity of the charge transfer complex and to show the spontaneity of the complex formation.

Cocrystal screening of benznidazole based on electronic transition, molecular reactivity, hydrogen bonding, and stability.

Screening of cocrystals of active pharmaceutical ingredients is important in the development of pharmaceutical compounds because it improves bioavailability, stability, solubility, and many other physicochemical properties. In this work, quantum chemical calculations were utilized for the computational evaluation of the cocrystal screening of benznidazole (BZN) API via hydrogen bonding with four coformers (maleic acid, malonic acid, oxalic acid, and salicylic acid), and they contain carboxylic groups. The nitrogen of the imidazole ring in benznidazole and the carboxylic group of the coformer form a hetero-synthon connected by a strong hydrogen bond. The strength of the hydrogen bonding interaction O-H…N was measured using various tools. It was found that in comparison to BZN cocrystals with malonic acid, oxalic acid, and salicylic acid, the O-H…N interaction in the BZN-maleic acid cocrystal had higher interaction energy, indicating it had stronger hydrogen bonding. The strength of the hydrogen bond O-H…N for synthons was discovered to be more beneficial than the C-H…O interaction, as confirmed by ESP analysis. The BZN-salicylic acid cocrystal was found to be more reactive and polarizable, whereas the BZN-malonic acid cocrystal was more stable. Cocrystals of benznidazole exhibited better physicochemical characteristics than API benznidazole, as indicated by electron transition properties between the most significant orbitals. The computational evaluation for the screening of benznidazole cocrystals was performed in Gaussian 16 software using density functional theory (DFT) with the hybrid functional B3LYP and the basis set 6-311 + + G(d,p). The UV-Vis absorption spectrum in solvent water was analyzed using the TD-DFT/6-311 + + G(d,p) method to determine the influence of the solvent in cocrystals using a polarizable continuum model. The strength of the hydrogen bonding interactions O-H…N in each of those mentioned cocrystals was used to screen the cocrystals using tools such as thermodynamic probability, ESP analysis, QTAIM analysis, and NBO analysis. The pairing energy of interaction was measured by determining H-bond donor ( ) and H-bond acceptor ) parameters for hydrogen bonds from maxima and minima on the ESP surface. GaussView 06 software was used to create, visualize, and plot the optimized structure of the cocrystal and HOMO-LUMO orbitals. The AIMALL (10.05.04) software package generated the molecular graph for intra- and intermolecular interactions. The RDG-scatter plot, MEP map, and ELF plot were rendered from Multiwfn 8.0 and VMD 1.9.1 software.

De novo Drug Design and Repurposing to suppress Liver Cancer via VEGF-R1 Mechanism: Comprehensive Molecular Docking, MolecularDynamics Simulations and ADME Estimation

Aims: The aim is to halt the progression of liver cancer [Hepatocellular carcinoma] by suppressing the VEGF-R1 receptor using Myricetin and its de novo-designed analogues. Background: VEGF/VEGFR autocrine signalling promotes the growth, progression, and metastasis of Hepatocellular carcinoma, making the development of molecularly targeted therapies highly feasible. Invasive and metastatic behaviours in various cancers, including hepatocellular carcinoma [HCC], are closely monitored through the use of VEGF signalling pathway inhibitors. Specifically in HCC, VEGFR-1 facilitates the invasive capabilities of cancer cells primarily by triggering the epithelial-mesenchymal transition [EMT] process. VEGFR-1 significantly influences the activity of proteolytic enzymes that are critical for the invasive behaviour of HCC cells. Notably, a novel mechanism has been discovered where VEGFR-1 activation leads to the upregulation of MMP-9, thereby enhancing the invasiveness of HCC cells. The scientists, in their study, have elaborated on the various antiangiogenic agents developed for the treatment of HCC. They have highlighted clinical trials that explore the efficacy of these treatments, which include the application of monoclonal antibodies and small-molecule kinase inhibitors designed to target specific pathways involved in tumour angiogenesis and growth. Objective: Creating a pharmaceutical chemistry table regarding ‘’Structure-Activity Relationship of New Compounds on anticancer’’. To do so, Myricetin and its de novo designed structured variants were used in molecular docking, molecular dynamics, cluster analyses, and 1H NMR estimation to specifically understand and enhance the mechanism of suppressing the VEGF-R1 receptor. Method: Proper ligand [Myricetin and its analogues] and receptor [VEGF-R1] preparations, and optimizations were done using the density functional theory [DFT]/B3LYP function along with the 6-31G[d,p] basis set principle in the latest software programs such as Gaussian 09, Gauss View 6.0 and Avogadro. Then using PyRx and Autodock Vina 1.1.2., many molecular docking trials were achieved with 100 posed simulations in each run. An extensive cluster analysis was performed to identify the most optimal docking poses with the highest accumulation and most favourable binding interactions, ensuring the accuracy of the study. The docking configurations that exhibited the most precise and advantageous binding energies were chosen as initial structured data for subsequent Molecular Dynamics [MD] simulations for each drug candidate. To verify the molecular docking results, MD runs were achieved in our supercomputers and the trajectory analyses were made. The data confirmed what was found in molecular docking results, verifying the high efficiency of the druggable molecules’ inhibition towards VEGF-R1. Result: Amine-derivatized Myricetin has a significantly high docking score [-10.56 kcal/mol] and great inhibition constant compared to pristine Myricetin [-4.77 kcal/mol] itself while Fluorinederivatized Myricetin [-6.45 kcal/mol] has an affinity towards VEGF-R1 between the first two molecules. Thus, the structure-activity relationship concerning pharmaceutical chemistry aspects of all the molecules studied, yielded us a great insight into what Myricetin’s organic structure possesses towards inhibiting the progression of Liver Cancer. Also, ADME studies showed that both Amine and Fluorined-derivatized Myricetin molecules are good drug candidates. Conclusion: This study highlighted the significant potential of Myricetin as an anti-cancer drug when modified with specific functional groups. Through comprehensive in silico computational analyses, our research group enhanced Myricetin's inhibitory capabilities by derivatizing its Hydroxyl group with Amine and Fluorine, resulting in improved docking scores and inhibition constants. The findings from molecular docking and molecular dynamics simulations provide a promising foundation for future in vitro and in vivo investigations of this molecule as a potential drug in cancer research.

Unimolecular isomerizations of C6H6•+ radical cations: a computational study.

Eighteen concerted isomerization reactions of various C6H6•+ radical cation (RC) species are studied and found to proceed via well-defined transition states, whose relative positions along the reaction pathway generally agree with Hammond's postulate. From the barrier heights, the rate coefficients of these reactions are estimated by using transition state theory, and the activation energies are computed. Through combination among themselves, these 18 isomerizations yielded 15 multi-step conversion routes of various C6H6•+ species to the lowest energy benzene radical cation isomer 1, which routes are compared. Use is made of DFT with the B3LYP and M06-2X functionals, along with the CBS-QB3 approach to arrive at better energies. From the barrier heights for each of the concerted reactions, canonical transition state theory was applied to evaluate rate coefficients k over the temperature range 200-500K. The Arrhenius activation energies were computed using the plot of ln k vs. 1/T.

B3LYP and B3PW computations of BaSnO3 and BaZrO3 perovskite (001) surfaces

By means of the B3LYP and B3PW hybrid exchange-correlation functionals, as it is included in the CRYSTAL computer code, we performed ab initio computations for BaSnO3 and BaZrO3 perovskite (001) surfaces. For BaSnO3 and BaZrO3 perovskite (001) surfaces, with a few exceptions, all atoms of the upper surface layer relax inwards, all atoms of the second surface layer relax outwards, and all third layer atoms, again, relax inwards. The relaxation of BaSnO3 and BaZrO3 (001) surface metal atoms for upper two surface layers, for both BaO and BO2-terminations, as a rule, are considerably larger than the relaxation of relevant oxygen atoms. The BaO (1.30 eV) and ZrO2-terminated (1.31 eV) BaZrO3 (001) surface energies are almost equal. The BaZrO3 perovskite BaO (4.82 eV) and ZrO2-terminated (4.48 eV) (001) surface Г-Г band gaps are reduced regarding the respective bulk Г-Г band gap value (4.93 eV). The B–O chemical bond populations in BaSnO3 and BaZrO3 perovskite bulk always are smaller than near their SnO2 and ZrO2-terminated (001) surfaces, respectively.

Supramolecular structure, DFT calculation and vibrational characterization of melamin-1-ium oxalurate monohydrate

Crystallization from an aqueous solution of melamine with parabanic acid was taken in a molar ratio of 1:1 leads to the formation of melamin-1-ium oxalurate monohydrate (MOX) crystals. The compound crystallizes in the centrosymmetric space group P21/n of the monoclinic system with four molecules per unit cell. The molecular geometry and vibrational frequencies of MOX in the ground state have been calculated by using the density functional hybrid function B3LYP 6–31+G(d) basis set. The results of optimized molecular structure are presented and compared with the experimental X-ray diffraction data. Furthermore, Fourier Transform Infrared (FT-IR) and Raman Spectra were used to conduct vibrational characterization to study the compound's structural groups. The calculated Highest Occupied Molecular Orbital (HOMO) and Lowest Unoccupied Molecular Orbital (LUMO) energies show that charge transfer occurs in the molecule and other related electronic properties have also been calculated. Besides, Molecular Electrostatic Potential (MEP) was performed to identify the possible electrophilic and nucleophilic sites. First order hyperpolarizability results establish the nonlinear response of the grown MOX crystal with respect to the electric field. Further, the crystal packing behaviour of MOX was studied quantitatively with the aid of Hirshfeld surface analysis.

DFT study of difluoro & trifluoro bi-cyclohexane based dimer for application in electronic and optical devices

This investigation outlines a comprehensive analysis of the electronic and optical characteristics of difluoro and trifluoro bi-cyclohexane-based dimers in different conformations, specifically focusing on two distinct molecules: 4-(2,2,-difluorocyclopropyl)-4′-propyl-1,1′-bi(cyclohexane) and 4-propyl-4′-(1,2,2,-trifluorocyclopropyl)-1,1′-bi(cyclohexane). Utilizing Density Functional Theory (DFT) with advanced functionals M06-2X and B3LYP paired with a 6-311G(d,p) basis set, this study probes the interaction energy, orbital behaviors, and non-linear optical (NLO) properties across two primary molecular orientations such that in-plane and stacked.Our findings reveal that both configurations exhibit remarkable non-linear optical properties as evidenced by significant change in values of polarizability and hyperpolarizability, with the latter suggesting enhanced suitability for NLO applications. This study also ventures into frontier molecular orbital analysis, offering predictive insights into the chemical reactivity and charge transfer phenomena intrinsic to these molecular systems.

Benzo[6,7]cyclohepta[1,2-d]pyrazolo[1,5-a]pyrimidines: Regioselective synthesis of a Novel Ring System, DFT-based NMR prediction, local reactivity indexes, and MEP analysis

Novel benzo[6,7]cyclohepta[1,2-d]pyrazolo[1,5-a]pyrimidines were prepared as a new ring system utilizing a regioselective protocol. A mixture of the appropriate 3,5-diamino-1H-pyrazoles and benzosuberone-based enones in ethanolic potassium hydroxide solution was heated at reflux for 5 h to produce the novel benzosuberone-fused pyrazolo[1,5-a]pyrimidines in 87–94 % yields. Both spectral data as well as elemental analyses were used to establish the structure of the novel products. Theoretical calculation of chemical shifts of NMR spectra is a powerful tool in analyzing experimental spectra for known substrates as well as elucidating the chemical structure for unknown ones. Using the DFT-GIAO approach under the B3LYP and mPW1PW91 functions, as well as a variety of basis sets, including 6–31G(d,p), 6–31+G(d), 6–311G(d), 6–311+G(d,p), 6–311++G-(d,p), and 6–311+G(2d,p), the chemical shifts of 1H- and 13C NMR in DMSO were calculated. The results that are most similar to the experimental observations are obtained from the computation of the chemical shift values under the 6–31G(d,p) or 6–31+G(d,p) basis sets and mPW1PW91 when using the multistranded approach. By identifying the preferred regions for electrophilic and nucleophilic attack, DFT-based FMO, global descriptors, local reactivity indexes, and MEP mapping were applied at the B3LYP function using the 6–31+G(d,p) basis set to provide additional insight into the regioselectivity in the desired reaction as well as the plausible mechanism for the formation of new products.

Analysis of electronic properties and sensing applications in Graphene/BC3 heterostructures

Many research studies have been conducted into the applications of the heterostructures of graphene (Gr) and boron carbide (BC3) in real-world devices after they were synthesized successfully by researchers. Thanks to their unique electronic attributes and high surface-to-volume ratio, the above-mentioned two-dimensional nanosheets (NSs) such as have enjoyed the interest of many research groups and scientists. Within this piece of research, the electronic and structural attributes of pure Gr (PGr), pure BC3 (PBC3) and their in-plane heterostructures were investigated by employing the DFT along with the density functionals B3LYP and WB97XD. The results demonstrated that by increasing the concentration of the B-C, there was a gradual increase in the bandgap. Also, the structural stability of the NSs was good and the cohesive energy was favourable. In addition, the adhesion attributes of these NSs were investigated towards two toxic gasses, namely CO and SO2. Amongst the heterostructures, after exposure to CO and SO2, the adhesion energy of GBC3I was greater, which was approximately −0.487 eV and −0.229 eV, respectively. Following the adhesion of SO2 onto the surface of the NSs, apart from the PGr, there was a significant change in their electronic attributes such as conductance, workfunction, Fermi level, the LUMO, the HOMO and the bandgap. However, following the adhesion of CO, the above-mentioned attributed remained almost the same. Based on the NBO and Mulliken charge analysis, there was a charge transport from the gasses to the NSs. Despite the fact that the adhesion energies for CO were relative higher than the adhesion energies for SO2for the NSs, the analysis of the MEP maps, the charge transport and the electronic attributes demonstrated that the NSs can be used as promising nanosensors for the detection of SO2 rather than CO.