Gauge Independent Atomic Orbital Method Research Articles

Linking quinoline ring to 5-nitrofuran moiety via sulfonyl hydrazone bridge: Synthesis, structural characterization, DFT studies, and evaluation of antibacterial and antifungal activity

In the present work, we report the synthesis, structural characterization, and computational studies of (E)-N'-((5-nitrofuran-2-yl)methylene)quinoline-8-sulfonohydrazide (QNF) as a potential antimicrobial drug candidate. To design the target molecule, we utilized a molecular hybridization technique that connects two antimicrobial pharmacophores (quinoline and 5-nitrofuran rings) with a sulfonyl hydrazone moiety. QNF was synthesized by the condensation of quinoline-8-sulfonohydrazide with 5-nitrofuran-2-carbaldehyde, and characterized by various spectral techniques including single-crystal X-ray crystallography. QNF was extensively evaluated for its antibacterial and antifungal activity. The inhibition capacity of QNF on Candida albicans filamentation and biofilm formation was further investigated. Biofilm inhibition of QNF against C. albicans was supported by molecular docking studies in the binding site of agglutinin-like sequence 3 (Als3). Drug-like profile of QNF was confirmed by in silico calculation of its significant physicochemical properties. Additionally, the optimized geometrical structure, natural bond orbital calculations, frontier molecular orbital and molecular electrostatic potential analysis of QNF were carried out using the density functional theory method at the B3LYP with 6–31+G(d,p) basis set. The predictions of 1H and 13C NMR chemical shift values were performed using the gauge-independent atomic orbital method. Structural parameters and NMR values obtained experimentally were compared with the calculated values.

Quantum chemistry of cocaine and its isomers II: Spectroscopy

We investigate the potential of spectroscopic methods to distinguish enantiomers, with the example of the naturally occurring r-cocaine and its s-cocaine enantiomer. We compute conventional spectra in the infrared and ultraviolet frequency range by applying density functional theory and validate the results by comparing them to experimental data available for r-cocaine. Using the B3LYP functional, the calculated IR frequencies and intensities agree well with experimental spectra, and the corresponding normal modes have been analyzed. 1H and 13C NMR experimental chemical shifts have been well reproduced using the gauge independent atomic orbital method. However, In the UV/Vis range, the M06-L functional shows a significant improvement compared to B3LYP.The enantiomeric behavior of the r-cocaine and s-cocaine isomers cannot be reproduced unless the conformational effects are considered. Consequently, we compute a weighted average spectra for the ten lowest conformations up to 3.39 kcal/mol. Simulated Vibrational Circular Dichroïsm (VCD) and Electron Circular Dichroïsm (ECD) spectra of both isomers exhibit spectra with pronounced features of identical magnitude, making their identification unambiguous.

Polyoxygenated Cyclohexenes from Uvaria grandiflora with Multi-Enzyme Targeting Properties Relevant in Type 2 Diabetes and Obesity.

Shikimic acid-derived polyoxygenated cyclohexene natural products commonly occurring in several species of the Uvaria represent natural products with promising biological activities. While a number of derivatives have been reported from Uvaria grandiflora (U. grandiflora), further studies are needed to discover additional bioactive congeners, particularly derivatives with multi-protein target inhibitory properties implicated in diseases such as diabetes and obesity. In this paper, isolation and identification of a new highly oxygenated cyclohexene, uvagrandol (1), along with the known compound (-)-zeylenone (2) from the DCM sub-extract of U. grandiflora following in vitro and in silico assessment of their enzyme inhibitory properties against α-glucosidase, dipeptidyl peptidase IV, porcine lipase, and human recombinant monoacylglycerol lipase are reported. The structure of 1 was elucidated using 1D and 2D NMR data analysis. The absolute configuration of 1 was established by quantum chemical calculations via the Gauge-Independent Atomic Orbital (GIAO) NMR method followed by TDDFT-Electronic Circular Dichroism (ECD) calculations. The structures of the eight possible stereoisomers were optimized by means of DFT calculations (B3LYP/6-31+G[d,p] in vacuum), and then their isotropic shielding tensors were obtained using the GIAO method at mPW1PW91/6-31G(d,p) in chloroform. Through DP4+, the isomer of configuration (1S,2S,3R,6R) for 1 was predicted with 96.3% probability. Compounds 1 and 2 significantly inhibited the four target enzymes in vitro. Binding studies through molecular docking simulations showed strong binding affinities for (-)-zeylenone (2), thus validating the in vitro results. Our findings suggest the potential of polyoxygenated cyclohexenes, in particular (-)-zeylenone (2), in anti-diabetic and anti-obesity drug discovery.

Synthesis, characterization, vibrational analysis and computational studies of a new Schiff base from pentafluoro benzaldehyde and sulfanilamide

This work presents the characterization of (E)-4-(((perfluorophenyl)methylene)amino)benzenesulfonamide (PFNI) by spectral techniques and quantum chemical calculations. The structure was investigated by FT-IR, UV–Vis and NMR techniques. The geometrical parameters and energies have been obtained from Density functional theory (DFT) B3LYP (cc-pVDZ) basis set calculation. The geometry of the molecule was fully optimized, vibrational spectra were calculated and fundamental vibrations were assigned on the basis of potential energy distribution (PED) of the vibrational modes, calculated with VEDA program. 1H and 13C NMR chemical shifts of the molecule were calculated using Gauge-independent atomic orbital method (GIAO). The electronic properties such as excitation energies, wavelength performed by Time dependent density functional theory (TD-DFT) results complements with the experimental findings. NBO analysis has been performed for analyzing charge delocalization throughout the molecule. The calculation results were applied to simulate spectra of the title compound, which show excellent agreement with observed spectra. To provide information about the interactions between staphylococcus aureus (4EMW) protein and the novel compound theoretically, docking studies were carried out using autodock-4.

Synthesis, spectral analysis, and theoretical investigations of diphenyl fumarate

Diphenyl fumarate is synthesized from maleic anhydride and phenol under solvent-free conditions. The structure of the product is characterized by FTIR, 1H NMR, and 13C NMR. The molecular structure is optimized using the density functional theory approach at the B3LYP/6-311G(d,p) level and the structural parameters are analyzed. Theoretical vibrational frequencies are investigated at the same level; the 1H NMR and 13C NMR are simulated using the default gauge-independent atomic orbital method at the B3LYP/6-31G(d) level and the solvation model density implicit continuum solvation model for chloroform; chemical shifts are scaled using scaling factors available on the cheshirenmr.info website (accessed 12 September 2021). In addition, the UV-Vis absorption and fluorescence emission are simulated using the time-dependent method at the PBE38/6-311G(d,p) level. All the calculated spectral values are compared with the experimental data. A generally good agreement between the experimental and theoretical results is found. The results reveal diphenyl fumarate as a candidate substrate for small-molecule organic fluorophores with a large Stokes shift. This work provides a detailed experimental and theoretical study on the structural and spectral properties of diphenyl fumarate, and thus provides proof for the novel applications of diphenyl fumarate and its derivatives.

Spectroscopic and topological analysis and in vitro antimicrobial activity of phenothiazine

The vibrational spectral analysis of phenothiazine is done by experimental results and theoretical investigation for identifying its pharmaceutical nature. The experimentally observed vibrational wavenumbers are compared with the calculated vibrational frequencies. Natural bond orbital analysis interprets the intramolecular contacts of phenothiazine molecules. Ultraviolet-visible spectra of the phenothiazine have also been recorded and the electronic properties. The 1H and 13C nuclear magnetic resonance chemical shifts of the molecule have been calculated by the Gauge Independent Atomic Orbital method and compared with the experimental outcome. The interpreted frontier molecular orbital energies indicated the chemical stability of the molecules. Fukui function and Mulliken analysis on atomic charges of the phenothiazine have been discussed. Docking studies were performed for phenothiazine using the molecular docking software with 3 fungicidal active proteins. The stability of the title compound has been investigated via molecular dynamics simulations. The in-vitro analysis had done with fungal and bacterial pathogens, Aspergillus niger and E.Coli.

Theoretical study of nimetazepam, a real-life chiral molecule without an asymmetric carbon atom

We investigate the potential energy landscape and the spectroscopic properties of the nimetazepam molecule using a density functional theory approach. Our calculations show that despite the lack of a chiral carbon atom or a stereochemically active bond, this molecule exhibits two conformational enantiomers, M and P. For the isomerization process we find an activation energy of 16.7 kcal/mol. The conformers are inseparable at room temperature, and consequently, the nimetazepam drug exists as a racemic mixture. The theoretical spectroscopic analysis of these enantiomers including IR, VCD, NMR, UV-Vis, and ECD has been performed, to identify suitable experimental techniques to detect the individual stereoisomers. The infrared spectrum of nimetazepam agrees well with the experimentally observed one, and vibrational bands have been assigned. Moreover, the 1H and 13C NMR experimental chemical shifts have been well reproduced using the gauge independent atomic orbital method. The calculations suggest a dynamic 1H NMR effect that can be used to follow the isomerization process. The TD-DFT approach enables us to simulate the UV-Vis spectra, and the obtained results coincide satisfactorily with the observed spectrum. The M and P conformers show a complementary behavior in their predicted VCD and ECD spectra.

An inexpensive density functional theory-based protocol to predict accurate 19 F-NMR chemical shifts.

Thanks to its advantages, 19 F-NMR is an increasingly popular technique for the structural characterization of F-containing molecules, among which polymers, materials, fluorophores, pharmaceuticals, and so forth. However, the computational calculation of the 19 F-NMR chemical shifts, both for prediction and interpretation of experimental spectra, remains a challenge. In this work a density functional theory (DFT) based protocol for the calculation of the chemical shifts is established within the framework of the gauge-independent atomic orbital method, upon verifying the performance of Hartree-Fock and 60 DFT functionals coupled with seven different basis sets. The benchmark is conducted using two sets of molecules, namely one used for testing methods and another used for probing; the former set consists of 134 molecules, the latter 50, yet both of them with F in different chemical environments. Following Bally-Rablen-Tantillo strategy, the scaling parameters and other statistical quantities were computed for each method upon least squares linear regression between experimental and computed chemical shifts. The designed computational workflow is computationally inexpensive and represents a significant improvement with respect to the current state of the art.

X-ray structure, surface analyses, spectroscopic characterization, antimicrobial activity and DFT studies of the triphenylphosphoranylidene derivative

The structure of 1-(2-hydroxyphenyl)-2-(triphenylphosphoranylidene)ethanone was crystallized. X-ray diffraction, FT-IR, NMR (1H, 13C, 31P) and theoretical DFT method were used for understanding structural, electronic, and spectroscopic properties. The theoretical calculation was performed by the DFT method with the B3LYP/6-311G(d, p) basis set. The commentate of both experimental and theoretical results, it was observed good agreement with each other. Vibrational modes and wavenumbers as well as their intensities were performed with the aid of the potential energy distribution (PED) analysis.1H, 13C, and 31P NMR spectra’s have been calculated by employing the gauge-independent atomic orbital method. Also, Hirshfeld and MEP surface analyses, HOMO–LUMO orbitals and Mulliken charge distribution of the triphenylphosphoranylidene derivative were performed. Antibacterial activities of the title compound were tested according to the minimal inhibitory concentration (MIC) method.

Evaluation of conformational and spectral behavior and prediction of biological activity and chemical reactivity descriptors of Levosimendan

The conformational behavior and structural stability of Levosimendan (LVM) is investigated by density functional theory. The spectroscopic properties are analyzed using 1H NMR, FT-IR and Raman techniques. The 1H NMR chemical shifts of the molecule are calculated by Gauge independent atomic orbital method and compared with the experimental results. The vibrational spectra have been interpreted with the aid of normal coordinate analysis. A comparison of normal modes of both the conformers has been made in terms of change in wavenumbers, intensities and potential energy distribution. Lipophilicity and aqueous solubility have been calculated to estimate the absorption and distribution properties of drug which dictate the success or failure rate of drug discovery and development. ‘Prediction of Activity Spectra for Substances’ analysis has been done to predict the possible biological activities of LVM. Molecular docking has been performed to investigate the potential of the LVM molecule to bind with human cardiac troponin C receptor. Several chemical reactivity descriptors such as ionization energy, electron affinity, chemical potential, global hardness and electrophilicity have been evaluated to understand the molecular properties. The possible electrophilic and nucleophilic reactive sites of the molecule are studied using molecular electrostatic potential surface and Fukui function.

Computational Study of Novel 2,3-Bis[(1-methyl-1H-imidazole-2-yl)sulfanyl]quinoxaline: Structural Aspects, Spectroscopic Investigation, HOMO-LUMO, MESP, NLO, ADMET Predictions and Molecular Docking Studies as Potential Biotin Carboxylase and Antibiotics Resistant Aminoglycoside Phosphotransferase APH(2")IVA Enzyme Inhibitor

In this paper, a complete quantum chemical calculation has been done to describe the relevant structural aspects of novel 2,3-bis[(1-methyl-1H-imidazole-2-yl)sulfanyl]quinoxaline with combination of DFT/B3LYP method 6-311++G(d,p) basis set in gas phase and in solvent phase. The molecular structure was examined by using IR, 1H & 13C NMR and UV-visible techniques and solvent effect on spectroscopic properties are also discussed. The vibrational assignments are analyzed by PED using Gauss View 5.0 and VEDA 4.0 program. The 1H NMR and 13C NMR chemical shifts are calculated using the gauge-independent atomic orbital method (GIAO method) in gas phase and in solvents (water, DMSO and chloroform). The UV spectrum is calculated by using TD-DFT/6-311++G(d,p) method in gas phase and in solvent (water, DMSO and chloroform) using IEF-PCM model. With the help of theoretical calculations chemical activities, electrophilic/nucleophilic nature and sites in the molecule, molecular and chemical properties that cannot be obtained by experimental way are obtained. Accordingly, molecular electrostatic potential (MESP), hardness (η)/softness (S) parameters, net charges analyses are investigated to gain electrophilic and nucleophilic nature. Also the sites in molecule and Fukui function analysis are discussed. The dipole moment (μ), polarizability (αtot), anisotropic polarizability (Δα) and first-order hyperpolarizability (βtot) of the title compound are reported and results shows that the material is capable to generate non-linear effect (NLO). The in silico study of all th e biological and ADMET properties of title molecule are also discussed and compared with reference drug ciprofloxacin antibiotics. The title molecule and reference drug ciprofloxacin docked with biotin carboxylase enzyme (PDB ID: 2V59) of E. coli and aminoglycoside phosphotransferase APH(2")IVA (PDB ID: 4DFU) of Enterococcus casseliflavus receptor with the help of Molegro molecular viewer 2.5 program and binding affinity (ΔG) were determined by ParDock server.

Spectroscopic (FTIR, UV-Vis and NMR), theoretical investigation and molecular docking of substituted 1,8-dioxodecahydroacridine derivatives

Recently, substituted 1,8-dioxodecahydroacridine derivatives have been investigated and found to possess a wide variety of biological and pharmacological activities. Two of these biologically relevant N-heterocyclic scaffolds, 2-(9-(4-methoxyphenyl)-3,3,6,6-tetramethyl-1,8-dioxo-1,2,3,4,5,6,7,8- -octahydroacridin-10(9H)-yl)succinic acid (MTDOSA) and 2-(3,3,6,6-tetramethyl- 9-(4-nitrophenyl)-1,8-dioxo-1,2,3,4,5,6,7,8-octahydroacridin-10(9H)-yl)- succinic acid (NTDOSA), have been studied in ground and first excited state using DFT method employing B3LYP/6-311++G(d,p) level of theory. Quantum chemical calculations of geometrical structure and vibrational wavenumbers of MTDOSA and NTDOSA were carried out using DFT method. The experimental FT-IR spectra of the compounds were recorded in the range 4000?400 cm-1 and comprehensively interpreted on the basis of potential energy distribution. The global reactivity descriptors are calculated and discussed. Moreover, 1H- and 13C-NMR spectral data have been calculated using the gauge independent atomic orbital method and compared with experimental spectra. The docking studies reveal that the compounds MTDOSA and NTDOSA have strong binding affinity toward the target protein 5KLH. Thus, the compounds have a possible use as an antileishmanial drug.

Synthesis, characterization, DFT and molecular docking studies for novel 1,5-diphenylpenta-1,4-dien-3-one O-benzyl oximes

The main objectives of this study are: (a) to synthesize novel 1,5-diphenylpenta-1,4-dien-3-one O-benzyl oximes in an efficient way, (b) to investigate the synthesized molecules computationally via DFT calculations, (c) to compare computationally obtained data with experimental results and (d) to perform molecular docking calculations for the newly synthesized compounds and heat shock protein HSP90A N-terminal domain to determine the binding affinities of the investigated molecules and to reveal possible receptor–ligand interactions. In the first part of the study, syntheses and characterizations of the investigated compounds have been carried out. In this part, the target compounds have been synthesized and characterized successively. In the synthesis of target compounds from corresponding oximes, ultrasound has been used alternatively and results showed that the usage of ultrasound considerably increases the reaction rate and the efficiency. In the second part, detailed density functional theory calculations have been performed on the investigated compounds with the use of Becke, three-parameter, Lee–Yang–Parr hybrid functional and various basis sets. In this part, geometry optimizations, frequency analyses, NMR spectral analyses, frontier molecular orbital calculations, and molecular electrostatic potential map calculations have been performed. In NMR spectral analyses, both continuous set of gauge transformations (CSGT) and gauge-independent atomic orbital (GIAO) methods have been used and the obtained results with the use of various basis sets have been compared. Results showed that in NMR calculations, GIAO method is more successful than CSGT method and can provide satisfactory results even with small basis sets. In the third part of the study, molecular docking calculations have been performed on the investigated compounds and HSP90A N-terminal domain. Results showed that investigated molecules show a good binding affinity for HSP90A N-terminal domain. The binding affinities were found to be in the range of − 8.7 to − 10.1 kcal/mol.

Toward the comprehensive calculations on the relationship between 1 H, 13 C, 31 P chemical shifts, 2 JPH , and the bonding structure of different phosphoryl benzamides.

A comprehensive investigation was performed on 1 H, 13 C, and 31 P nuclear magnetic resonance (NMR) chemical shifts (CSs) of phosphoryl benzamide derivatives (C6 H5 C(O)NHP(O)R1 R2 ), (R1 , R2 =aziridine [L1 ], azetidine [L2 ], pyrrolidine [L3 ], piperidine [L4 ], azepane [L5 ], 4-methylpiperidine [L6 ], propane-2-amine [L7 ], and 2-methylpropane-2-amine [L8 ]) by the gauge-independent atomic orbital method (GIAO) to find the most accordant level of theory with the experimental values. To achieve this goal, all the structures were optimized using the B3LYP, BP86, PBE1PBE, M06-2X, MPWB1K, and MP2 methods with 6-31+G* basis set. Computed structural parameters demonstrate that BP86 has the best agreement to the experimental values between the other methods. The def2-TZVP and aug-cc-pVDZ basis sets were also employed to inspect the effect of different types of basis sets with higher polarization and diffuse functions. The correlation between the empirical and computational values attests that 6-31+G* basis set is the optimum case regarding minimization of the costs and results. The comparison between calculated and experimental CSs at all mentioned combinations illustrated that in accordance with structural results, the best level of theory in CSs is also BP86/6-31+G*. Besides, 2 JPH values were computed with an acceptable agreement to experimental data at the optimum level of theory. The dependency between 2 JPH and the bonding structure of studied ligands was also scrutinized by the Natural Bond Orbital (NBO) analysis that interprets the relationship between the electronic properties and 2 JPH values.

Structural characterization, photoluminescence, computational studies and bioassay of newly synthesized N-(3-oxo-3-morpholino-1-phenyl-propyl) benzo sulfonamide with multifunctional application

N-(3-oxo-3-morpholino-1-phenyl-propyl) benzo sulfonamide (BMS) (C19H22N2O4S) has been synthesized and characterized by FT-IR, 1H and 13C NMR, and ESI-mass spectrometric methods. The 2-D NMR (COSY, HSQC, DEPT and TOCSY spectra) of BMS is recorded to study the correlation between protons and carbons. The optimized geometry, harmonic vibrational frequencies and infrared intensities are calculated using B3LYP/6-311++(2d,p) basis set on the Gaussian. 13C and 1H NMR chemical shifts are calculated using the gauge independent atomic orbital method with B3LYP/6-311++(2d,p) basis set. The detailed analysis of experimental NMR chemical shifts as well as IR vibrations is supported by quantum chemical calculations using the Gaussian approach. The HOMO and LUMO energy calculation and Mulliken charges were calculated by the DFT approach. The UV–Vis and photoluminescence study confirms the light emitting nature of the molecule. BMS showed better antimicrobial activities against resistant and non-resistant strains. Further, the anticancer activity of the compound is studied against the PC-3 cancer cell line in comparison to mitoxantrone. Comparative docking study of BMS with mitoxantrone and doxorubicin has been carried out on the p53 tumor suppressor-DNA complex. Effective binding is observed at ARG-248, which is an experimentally proved mutated site of the p53 protein.

Synthesis, Spectroscopic Characterization, and Time-Dependent DFT Calculations of 1-Methyl-5-phenyl-5H-pyrido[1,2-a]quinazoline-3,6-dione and Its Starting Precursor in Different Solvents.

In this study, 2‐mercapto‐3‐phenyl‐2,3‐dihydro‐1H‐quinazolin‐4‐one (1), which exists as a thiol and thione tautomer, was treated with acetylacetone to give the target compound, namely, 1‐methyl‐5‐phenyl‐5H‐pyrido[1,2‐a]quinazoline‐3,6‐dione (2). The spectroscopic data, including UV/Vis, IR, 1H NMR, 13C NMR, and mass data, of this compound were recorded. The molecular structures of the starting material (1) and the product (2) were optimized by using density functional theory (DFT) by employing the B3LYP exchange correlation with the 6‐311G (d, p) and 6‐31G++ (d, p) basis sets. The electronic spectra were determined based on time‐dependent DFT calculations in three different solvents (i.e., chloroform, ethanol, and acetonitrile) starting from the same solvated run of the optimized geometry with the same two basis sets. The solvent effects were considered based on the polarizable continuum model (PCM), and the energetic behavior of the compounds and the total static dipole moment (μ) in different solvents were examined in the two basis sets; the results showed that the total energy of the compounds decreased upon increasing the polarity of the solvent. Time‐dependent DFT calculations were performed to analyze the electronic transitions for various excited states that reproduced the experimental band observed in the UV/Vis spectrum. A study on the electronic properties, such as the HOMO and LUMO energies, was performed by the time‐independent DFT approach. Using the gauge‐independent atomic orbital method (GIAO), the 1H NMR chemical shifts were calculated and correlated with the experimental ones. The computed results showed that the introduction of different dielectric media had a slight effect on the stability and reactivity of the title compound as well as on the Milliken atomic charges and the molecular geometry. Besides, the molecular electrostatic potential of target product 2 was evaluated in different solvents.

FT-IR, UV–visible, and NMR Spectral Analyses, Molecular Structure, and Properties of Nevadensin Revealed by Density Functional Theory and Molecular Docking

ABSTRACTNevadensin 2-(4-methoxyphenyl)-5,7-dihydroxy-6,8-dimethoxy-4H-1-benzo-pyran-4-one] is a natural bioactive flavonoid compound that has the potential to become a novel “natural lead” in the field of drug discovery program. The molecular structure, vibrational frequencies, and corresponding vibrational assignment of nevadensin have been investigated experimentally and theoretically by employing the B3PW91/6–311++G(d,p) method. The fundamental vibrational wave numbers as well as their intensities were calculated, and a good correlation between experimental and scaled calculated wave numbers had been accomplished. The ultraviolet spectrum of the studied molecule was recorded in the region 200–500 nm, and the electronic properties were predicted by the time-dependent density functional theory approach. 1H and 13C NMR spectra have been calculated by employing the gauge-independent atomic orbital method. Nevadensin has been reported to exhibit antimicrobial activities against both Gram-positive and Gram-negative bacteria and also against the fungal pathogens, highlighting the pharmacological importance of the molecule.

Spectroscopic (FT-IR, FT-Raman, UV, 1H and 13C NMR) insights, electronic profiling and DFT computations on ({(E)-[3-(1H-imidazol-1-yl)-1-phenylpropylidene] amino}oxy)(4-nitrophenyl)methanone, an imidazole-bearing anti-Candida agent

AbstractThe anti-Candida agent, ({(E)-[3-(1H-imidazol-1-yl)-1-phenylpropylidene]amnio}oxy(4-nitropheny) methanone (IPAONM), was subjected to comprehensive spectroscopic (FT-IR, FT-Raman, UV–Vis 1H and 13C NMR) characterization as well as Hartree Fock and density functional theory computation studies. The selected optimized geometric bond lengths and bond angles of the IPAONM molecule were compared with the experimental values. The calculated wavenumbers have been scaled and compared with the experimental spectra. Mulliken charges and natural bond orbital analysis of the title molecule were calculated and interpreted. The energy and oscillator strengths of the IPAONM molecule were calculated by time-dependent density functional theory (TD-DFT). In addition, frontier molecular orbitals and molecular electrostatic potential diagram of the title compound were computed and analyzed. A study on the electronic properties, such as HOMO, HOMO-1, LUMO and LUMO+1 energies was carried out using TD-DFT approach. The 1H and 13C NMR chemical shift values of the title compound were calculated by the gauge independent atomic orbital method and compared with the experimental results.

Structure, spectroscopic analyses (FT-IR and NMR), vibrational study, chemical reactivity and molecular docking study on 3,3'-((4-(trifluoromethyl)phenyl)methylene)bis(2-hydroxynaphthalene-1,4-dione), a promising anticancerous bis-lawsone derivative

Lawsone (2-hydroxy-1,4-naphthoquinone)has been evaluated to possess a wide range of biological and pharmacological activities. The interesting structural pattern of lawsone coupled with its so-called multifaceted pharmacological potential have made this scaffolds useful in certain chemical processes, particularly in synthesizing ligands for metal complexations, and also few of its derivatives have shown a number of biological activities. The equilibrium geometry of 3,3′-((4-(trifluoromethyl)phenyl)methylene)bis(2-hydroxynaphthalene-1,4-dione) (1; TPMHD), a promising anticancerous lawsone derivative, has been determined and analyzed at DFT method employingB3LYP/6-311++G(d,p) level of theory. The reactivity descriptors such as Fukui functions and HOMO–LUMO gap are calculated and discussed. The infrared spectra of TPMHD(1) are calculated and compared with the experimentally observed ones. Moreover, 1H and 13C NMR spectra have been calculated by using the gauge independent atomic orbital method. The docking studies reveal that the TPMHD has strong binding affinity toward target protein 2SHP. Thus the compound has a possible use as a drug in cancer therapy. The study suggests further investigation on TPMHD for their in-depth biological and pharmaceutical importance.

Experimental and quantum chemical studies on poriferasterol – A natural phytosterol isolated from Cassia sophera Linn. (Caesalpiniaceae)

Poriferasterol, a biologically relevant phytosterol, has been isolated and identified first-time from Cassia sophera Linn. (family: Caesalpiniaceae) based on detailed spectral studies. Exhaustive theoretical studies on the molecular structure, vibrational spectra, HOMO, LUMO, MESP surfaces and reactivity descriptor of this plant-derived natural molecule have been performed. The experimentally observed FT-IR spectrum of the title compound has been compared with spectral data obtained by DFT-B3LYP/6-311 + G (d,p) method. The UV–visible spectrum of the title compound has also been recorded and the electronic properties, such as frontier orbitals and band gap energy are measured by TD-DFT approach. The 1H and 13C NMR spectrum has been calculated by using the gauge independent atomic orbital method and compared with the observed data.