Gauge-invariant Atomic Orbital Research Articles

Investigation on molecular and biomolecular spectroscopy of the novel 2BCA molecule to analyse its biological activities and binding interaction with nipah viral protein

The molecule of 2-Biphenyl Carboxylic Acid (2BCA), which contains peculiar features, was explored making use of density functional theory (DFT) and experimental approaches in the area of quantum computational research. The optimised structure, atomic charges, vibrational frequencies, electrical properties, electrostatic potential surface (ESP), natural bond orbital analysis and potential energy surface (PES) were obtained applying the B3LYP approach with the 6–311++ G (d,p) basis set.. The 2BCA molecule was examined for possible conformers using a PES scan. The methods applied for spectral analyses included FT-IR, FT-RAMAN, NMR, and UV–Vis results. Vibrational frequencies for all typical modes of vibration were found using the Potential Energy Distribution (PED) data. The UV–Vis spectrum was simulated using the TD-DFT technique, which is also seen empirically. The Gauge-Invariant Atomic Orbital (GIAO) approach was employed to model and study the 13C and 1H NMR spectra of the 2BCA molecule in a CDCL3 solution. The spectra were then exploited experimentally to establish their chemical shifts. To predict the donor and acceptor interaction, the NBO analysis was used. The electrostatic potential surface was employed to anticipate the locations of nucleophilic and electrophilic sites. Hirshfeld surfaces and their related fingerprint plots are exploited for the investigation of intermolecular interactions. Reduced Density Gradient (RDG) helps to measure and illustrate electron correlation effects, offering precise insights into chemical bonding, reactivity, and the electronic structure of 2BCA. According to Lipinski and Veber’s drug similarity criteria, 2BCA exhibits the typical physicochemical and pharmacokinetic properties that make it a potential oral pharmaceutical candidate. According to the findings of a molecular docking study, the 2BCA molecule has promise as a treatment agent for the Nipah virus (PDB ID: 6 EB9), which causes severe respiratory and neurological symptoms in humans.

Quantum chemical, spectroscopic and molecular docking studies on methyl 2-chloro-6-methyl pyridine-4-carboxylate: A potential inhibitor for irritable bowel syndrome.

The methyl 2-chloro-6-methyl pyridine-4-carboxylate (MCMP) was studied using quantum chemical density functional theory (DFT) approach. The DFT/B3LYP method with cc-pVTZ basis set was employed to obtain the optimized stable structure and vibrational frequencies. The potential energy distribution (PED) calculations were used to assign the vibrational bands. The 13C NMR spectrum of MCMP molecule was simulated by the Gauge-Invariant-atomic orbital (GIAO) method using DMSO solution and the corresponding chemical shift values were calculated and observed. The maximum absorption wavelength was obtained using TD-DFT method and were compared with the experimental values. The bioactive nature of the MCMP compound was identified using the FMO analysis. The possible sites of electrophilic and nucleophilic attack were predicted using the MEP analysis and local descriptor analysis. The pharmaceutical activity of the MCMP molecule is validated through the NBO analysis. The molecular docking analysis confirms that the MCMP molecule can be used in the drug designing for the treatment of irritable bowel syndrome (IBS).

Spectral, quantum chemical, biological activity, and molecular docking analysis of 1,8-dihydroxyanthraquinone: A target drug exploration

In this current effort, the 1H and 13C NMR spectra as well as quantum chemical computational effort of 1,8 DHAQ molecule analyzed based on density functional theory (DFT) with the help of Gauss-View 6.0.6 and Gaussian 09W program package. The molecular structure of 1,8 DHAQ optimized first through DFT/B3LYP hybrid functional/6-311++G (d,p) basis-set. The NMR (1H and 13C) isotropic chemical shift values of the titled molecule (TMS as reference) was examined through gauge-invariant-atomic orbital (GIAO) process in DMSO‑d6 polar solvent using above similar basis set, then was correlated with the experimental outcomes. All the findings of DHAQ molecule correlated very well with each other. Reduced Density Gradients (RDG Scatter plot) give an evidence of various non-covalent intramolecular interactions inside molecule. ELF and LOL analysis proof a chemical association of molecules. It also reveals the main localization & delocalization of boding and non-bonding electrons within molecule. An in-silico ADMET profiles (absorption, distribution, metabolism, excretion, and toxicity), bioactivity score, and drug-likeness (based on the Lipinski rules of five) of 1,8 DHAQ molecule was executed via various computational online server tools. This study predicts that titled molecule have noble physicochemical and pharmacokinetic properties. Furthermore, the inhibitory nature of the DHAQ molecule has estimated by means of molecular docking analysis using various selected target proteins. The molecular docking is an effective computational analysis in estimating the binding affinity and binding sites of ligand together with the target proteins, which is much effective for future structure-based drug designing. Thus, the formation of numerous hydrogen bonds and docked binding affinities depicts that hydroxy-substituted Anthraquinone might serve as main structure for the development of upcoming drugs. As a result, this effort provide a summary of the chemistry, biology, and toxicology of 1,8 DHAQ molecule, focusing on innovative drugs discovery for treatment of various cancer diseases in pharmaceutical industries.

Structural insights, spectral, flourescence, Z-scan, C-H…O/N-H…O hydrogen bonding and AIM, RDG, ELF, LOL, FUKUI analysis, NLO activity of N-2(Methoxy phenyl) acetamide

Quantum chemical calculations of geometries and vibrational wavenumbers of N-2(methoxy phenyl)acetamide(N2MPA) in the ground state were carried out by using density functional theory (DFT/B3LYP) method with 6-31G (d,p) basis set. The scaled harmonic vibrational frequencies have been compared with experimental FT-IR spectra. Theoretical vibrational spectra of the title compound were interpreted by means of potential energy distributions (PEDs) using MOLVIB program. The experimental 1H and 13C NMR chemical shifts were investigated and then compared with computed NMR data using the gauge – invariant atomic orbital (GIAO) method. The optical nature of the grown crystal was evaluated by using the UV-Vis optical transmittance spectrum. The lower wavelength absorption range and various optical constant for instance, energy band gap, absorption and extinction coefficient, refractive index, susceptibility and Urbach energy values were evaluated. The colourless crystal of N2MPA was grown by slow-evaporation technique. The nonlinear optical (NLO) properties of N2MPA have been investigated using Z-scan technique. The emission behavior of N2MPA was analyzed by fluorescence spectral analysis. Thermal stability of N2MPA was studied by TG-DTA analysis. The HOMO and LUMO energy levels are constructed and the corresponding frontier energy gaps are determined to realize the charge transfer within the molecule. The molecular electrostatic potential(MESP), natural bond orbital(NBO) analysis and topological analysis such as electron localization function(ELF), reduced density gradient(RDG), localized orbital locator(LOL), atoms in molecule(AIM) and FUKUI function analysis have been used to evaluate the intermolecular interaction, especially the hydrogen bonds. Fingerprint plots of Hirshfeld surfaces were used to locate and analyze the percentage of hydrogen bonding interactions.

Quantum chemical and molecular docking studies on N-tert-butoxycarbonyl (Boc)-3-aminomethyl pyridine: A potential bioactive agent for the treatment of amyotrophic lateral sclerosis

The novel N-tert-butoxycarbonyl (Boc)-3-aminomethyl pyridine (NBAMP) was analyzed by density functional theory (DFT) quantum chemical method. The B3LYP method with 6–311++ G (d,p) basis set were employed to obtain the optimized structure, vibrational wavenumbers, electronic properties and the molecular electrostatic potential surface (MEP). The vibrational frequencies were assigned using the potential energy distribution (PED) calculation. UV-Vis spectrum was simulated by TD-DFT method, which is also observed experimentally. The 13C NMR spectrum of NBAMP molecule was simulated and observed using Gauge-Invariant-atomic orbital (GIAO) method with DMSO solution and their chemical shifts were calculated and observed. The natural bond orbital analysis (NBO) was used to predict the donor-acceptor interactions. The reactive sites were obtained by fukui function analysis. The nucleophilic and electrophilic sites were predicted by molecular electrostatic potential surface (MEP). The mulliken atomic charge distribution was calculated for NBAMP molecule. Intra-molecular charge transfer was predicted by frontier molecular orbitals (FMO) and NBO. To identify the potential applications of the NBAMP molecule, the molecular docking analysis was carried out and the molecular docking results revealed that the NBAMP molecule may be useful for drug designing in the treatment of amyotrophic lateral sclerosis.

Spectroscopic investigation and density functional theory prediction of first and second order hyperpolarizabilities of 1-(4-bromophenyl)-3-(2,4-dichlorophenyl)‑prop-2-en-1-one

This work presents the spectroscopic analysis and nonlinear optical (NLO) behaviour of 1-(4-Bromophenyl)-3-(2,4-dichlorophenyl)‑prop-2-en-1-one (DCBC). The motivation behind choosing chalcone derivative DCBC for NLO studies is its crystallization in non-centrosymmetric structure, excellent second harmonic generation efficiency (SHG) and flexibility in structure of chalcones due to donor-acceptor groups. The compound was characterized by FT-IR, FT-Raman, UV–vis and NMR techniques. The structural and spectroscopic features of the molecule were calculated using density functional theory (DFT) employing B3LYP/6–311++G(d,p) basis set and compared with the experimental values. The complete vibrational assignments were made on the basis of potential energy distribution (PED). The Natural Bond Orbital (NBO) analysis of DCBC has been done in order to provide the detailed insight into the nature of electronic conjugation between the bonds in this molecule. The second-order perturbation theory analysis of Fock matrix in the NBO basis of the molecule shows the strong intramolecular hyperconjugative interactions between σ (Cl3-C28) to σ*(C26-C28), n(1)(Cl3) to σ*(C26-C28) and π(C6-C8) to π*(C5-C13) resulting in large stabilization energies leading to large delocalization. A time-dependant variant of DFT (TD-DFT) is applied to calculate the electronic properties such as oscillator strengths, absorption maxima and HOMO and LUMO energies. The HOMO-LUMO energy gap is found to be 3.882 eV and is used to calculate global reactivity parameters. Isotropic chemical shifts were calculated using gauge invariant atomic orbital (GIAO) method and these matched well with the experimental results, indicating the accuracy of calculation method. Molecular Electrostatic Potential (MEP) surface has been depicted to know the chemically active regions of the molecule. The nonlinear optical properties of title molecule were addressed theoretically by the determination of two contributions, vibrational and electronic, to polarizability (α) and the first and the second order hyperpolarizabilities (β and γ). The electronic first and second order hyperpolarizabilities of DCBC determined by Finite Field approach method are found to be 17.805 × 10−30 and 6.0 × 10−41 e.s.u. respectively. These values are comparable to other chalcones and organic NLO materials which indicate that the studied molecule is responsive to nonlinear optical (NLO) effect and has enhanced applicability in the development of nonlinear optical devices.

Structural, vibrational spectroscopy, molecular docking, DFT studies and antibacterial activity of (E)-N1-(3-chlorobenzylidene)benzene-1,4-diamine

In this work, (E)-N1-(3-chlorobenzylidene)benzene-1,4-diamine (CBD) compound was synthesized with good yield. The spectral studies were recorded by FT-IR, FT-Raman, NMR and UV-Vis to determine structural parameters. The geometrical parameters were optimized using DFT calculations at 6-311++G(d,p) basis set. The calculated structural parameters of the molecule were in line with the experimental data. The molecular orbitals of the compound were investigated through highest occupied molecular orbital (HOMO), lowest unoccupied molecular orbital (LUMO) analysis. The hyper conjugative interaction energy E(2) along with donor, acceptor electron densities (EDs) were determined by natural bond orbital (NBO) analysis. The molecular electrostatic potential (MEP), mulliken atomic charges, non-linear optical (NLO) properties and potential energy surface (PES) scan were also calculated. The 1H and 13C NMR chemical shifts calculated using Gauge invariant atomic orbital (GIAO) method were compared with the experimental NMR chemical shifts. Thermogravimetry (TG) and Differential Scanning Calorimetry (DSC) were carried out to characterise the thermal behaviour and stability of CBD molecule. In addition, PreADMET tool was also used to estimate ADME and Toxicity of CBD compound. The compound screened against four pathogens two gram positive and two gram negative had shown good anti-bacterial behaviour. The molecular docking studies executed against anti-bacterial target topoisomerase DNA gyrase enzyme (2XCT) emphasized good binding behaviour over the standard drug. Communicated by Ramaswamy H. Sarma

Synthesis, quantum mechanical calculations, molecular docking, Hirshfeld surface analysis and ADMET estimation studies of (E)-3-(anthracene-10-yl)-1-(napthalen-1-yl)prop-2-en-1-one

Synthesis, crystallographic characterization, spectroscopic (FT-IR, UV-Vis, NMR) and density functional studies of (E)-3-(anthracene-10-yl)-1-(napthalen-1-yl)prop-2-en-1-one (3ANP) have been reported. The molecular structure obtained from single crystal X-ray diffraction method of the investigated compound was compared with theoretical values by DFT method at B3LYP with 6-311G(d,p) basis set. The 3ANP crystallizes in triclinic space group P1 with a = 8.3426(5), b = 10.4643(6), c = 11.3925(6). Hirshfeld surface analysis was performed to confirm the existence of intra- intermolecular and other interactions using Crystal Explorer. In addition to the optimized geometrical structure, molecular electrostatic potential (MEP), natural bond orbital (NBO) analysis, non-linear optical (NLO) property, HOMO, LUMO, mulliken population analysis have been investigated. The electronic properties of the compound were examined using TD-DFT calculations. The calculated vibrational frequencies have been compared with the experimental FT-IR values. Gauge invariant atomic orbital (GIAO) method was used to calculate 1H and 13C NMR chemical shifts in the ground state and was compared with the experimental NMR spectra. Further, the analysis using rules for drug-likeness and ADMET prediction revealed the druggability of the compound. Molecular docking showed the binding energy of -9.4 Kcal/mol and other interactions of 3ANP molecule with protein PDB ID: 1FCQ.

Comparison of Computational and Previous Experimental Studies on Naphthyl Pyridyl Pyrazole (NPP)

The naphthyl pyridyl pyrazole (NPP) was the subject of a theoretical inquiry. The data determined through the calculations were supported by experimental results from 1HNMR and X-Ray techniques. Geometrical parameters and optimized energies for the NPP molecule were determined via density functional theory (DFT) at the B3LYP 6-311++G (d, p) level of theory. The vibrational spectra were obtained and the fundamental vibrations were assigned. 1HNMR chemical shifts were recorded by using the gauge-invariant atomic orbital (GIAO) method. Further, electronic properties such as HOMO and LUMO energies were determined via time-dependent density functional theory (TD-DFT). The results of the calculations were found to be comparable to the experimental results obtained.

Study of the Addition Mechanism of 1H-Indazole and Its 4-, 5-, 6-, and 7-Nitro Derivatives to Formaldehyde in Aqueous Hydrochloric Acid Solutions.

The reaction of NH-indazoles with formaldehyde in aqueous hydrochloric acid has been experimentally studied by solution and solid-state nuclear magnetic resonance (NMR) and crystallography. The mechanism of the formation of N1-CH2OH derivatives was determined. For the first time, 2-substituted derivatives have been characterized by multinuclear NMR. Theoretically, calculations with gauge-invariant atomic orbitals (GIAOs) at the Becke three-parameter (exchange) Lee–Yang–Parr B3LYP/6-311++G(d,p) level have provided a sound basis for the experimental observations. The first X-ray structures of four (1H-indazol-1-yl)methanol derivatives are reported.

Conformational, spectroscopic, electronic and Molecular docking Studies on 2-methoxy-4-methyl-5-nitropyridine: A potential bioactive agent

The molecular geometry, vibrational bands, electronic properties and NMR spectra of 2 methoxy 4 methyl 5 nitropyridine (MMNP) were studied using density functional theory (DFT) calculations. The MMNP molecule was optimized using the DFT/B3LYP approach with the cc-pVTZ basis set to acquire the stable geometry. The potential energy distribution (PED) simulation was used to assign the obtained vibrational wavenumbers of the MMNP molecule. The chemical shift of 13C and 1H NMR spectrum was derived using the Gauge-Invariant-atomic orbital (GIAO) approach using DMSO solution and compared with the observed shifts. To investigate the electronic absorption spectral features of the MMNP molecule, the UV-Vis spectrum was simulated and observed. The hyperconjugation and intramolecular charge transfer were predicted using FMO and NBO analysis. Mulliken atomic charge distribution, Molecular Electrostatic potential (MEP) surface and the local reactivity analysis were used to spot out the reactive sites of the MMNP molecule. Moreover, the MMNP molecule acts as a potent inhibitor against bladder cancer so that the title molecule may be used in the drug designing for the treatment of bladder cancer.

Spectroscopic analysis, DFT studies and molecular docking of 2,3‐dichloro‐benzylidine‐(2‐trifluoromethyl‐phenol)‐amine

Abstract2,3‐dichloro‐benzylidine‐(2‐trifluoromethyl‐phenol)‐amine (2DBTP) has been synthesized and characterized by various spectroscopic techniques including FT‐IR, FT‐Raman, UV‐Vis and 1H, 13C NMR spectroscopy. The equilibrium geometry and harmonic vibrational frequencies were investigated by density functional theory (DFT) at B3LYP/6‐311++G(d,p) basis set. The vibrational wavenumber assignments were made on the basis of total energy distribution (TED) calculations using Veda 4 program. The harmonic wavenumbers calculated at DFT were in line with the experimental values. The non‐linear optical properties (NLO) were calculated. Stability of the molecule arises from hyperconjugative interactions and charge delocalization was analyzed by natural bond orbital (NBO) analysis. Molecular electrostatic potential (MEP), mulliken atomic charges were also calculated. The energy gap of the molecule was found by HOMO and LUMO calculation. TD‐DFT calculations have been carried out on the optimized geometry to further understand the electronic transitions in the UV‐Vis spectrum of the compound. In addition, the 1H and 13C NMR chemical shift values of 2DBTP in the ground state were also calculated using Gauge invariant atomic orbital (GIAO) method. The molecular docking solved the binding mode of 2XCT complex with the ligand. The investigated molecule revealed the inhibition activity of the ligand against anti‐bacterial protein topoisomerase DNA gyrase enzyme (PDB ID: 2XCT).

Towards Elucidating Structure-Spectra Relationships in Rhamnogalacturonan II: Computational Protocols for Accurate 13C and 1H Shifts for Apiose and Its Borate Esters.

Apiose is a naturally occurring, uncommon branched-chain pentose found in plant cell walls as part of the complex polysaccharide Rhamnogalacturonan II (RG-II). The structural elucidation of the three-dimensional structure of RG-II by nuclear magnetic resonance (NMR) spectroscopy is significantly complicated by the ability of apiose to cross-link via borate ester linkages to form RG-II dimers. Here, we developed a computational approach to gain insight into the structure–spectra relationships of apio–borate complexes in an effort to complement experimental assignments of NMR signals in RG-II. Our protocol involved structure optimizations using density functional theory (DFT) followed by isotropic magnetic shielding constant calculations using the gauge-invariant atomic orbital (GIAO) approach to predict chemical shifts. We evaluated the accuracy of 23 different functional–basis set (FBS) combinations with and without implicit solvation for predicting the experimental 1H and 13C shifts of a methyl apioside and its three borate derivatives. The computed NMR predictions were evaluated on the basis of the overall shift accuracy, relative shift ordering, and the ability to distinguish between dimers and monomers. We demonstrate that the consideration of implicit solvation during geometry optimizations in addition to the magnetic shielding constant calculations greatly increases the accuracy of NMR chemical shift predictions and can correctly reproduce the ordering of the 13C shifts and yield predictions that are, on average, within 1.50 ppm for 13C and 0.12 ppm for 1H shifts for apio–borate compounds.

Structure, Spectroscopic Investigation, Molecular Docking and In vitro Cytotoxicity Studies on 4,7-dihydroxycoumarin: A Breast Cancer Drug

Coumarin derivatives are broadly used as anti-inflammatory, antioxidants, anticancer, and antiviral drugs in recent years. In particular, hydroxy coumarins have great importance because of their various biological and pharmacological purposes. The quantum chemical studies of 4,7-dihydroxycoumarin (DHC) have been performed using the cc-pVTZ level of basis set. The DHC molecular structure has been optimized and the computed frequency assignments have been correlated well with the experimental results. The experimental [Formula: see text]C NMR shifts of DHC have been compared with the computed [Formula: see text]C NMR in the dimethyl sulfoxide (DMSO) solution using the Gauge-invariant atomic orbital (GIAO) method. The electron delocalization within the DHC is shown by highest occupied molecular orbitals (HOMO)-lowest unoccupied molecular orbitals (LUMO) energy analysis, and the resulting small energy gap value reveal the molecule’s bioactive characteristics. The natural bond orbital (NBO) analysis approves the bioactive property of the DHC molecule. The DHC compound has a cytotoxic impact on the MCF-7 breast cancer cell line, according to in vitro cytotoxicity studies. The docking study approves that the DHC works as a new inhibitor of breast cancer targeted proteins such as epidermal growth factor receptor (EGFR), estrogen receptor (ER), and progesterone receptor (PR). Thus, this work covers the approach for the evolution of new drugs against breast cancer.

Angle-resolved one and Two-Photon absorption spectrum in twisted bilayer graphene quantum dots

In this paper, one-photon absorption (OPA) spectrum and two-photon absorption (TPA) spectrum and its electronic excitation, charge transfer, partial density of states (PDOS) and magnetic induction current density of zigzag edge twisted bilayer graphene quantum dots (Z-TwBLG-QDs) with different twisted angles which were divide into two pattern of Moiré superlatrate (MS) are qualitativly and quantitativly analyed by using density functional theory (DFT), excited state wave function, single electron approximation, and gauge-invariant atomic orbital (GIAO) method. The inter-layer local excitation in the electronic transition and intra-layer charge transfer dominated by MS and anti-symmetric electron-hole pair density induced by PDOS are discussed. The twisted angle is decisive to the absorption spectrum, large twisted angle will lead to the red shift of the absorption spectrum. The two-photon transition shows that the twisted angle can regulate the TPA cross section and the boundary effect of Z-TwBLG-QDs in a specific wavelength range. The edge effect of two-step transition can be enhanced by MS with specific twisted angles. The physical mechanism of twisted angle regulating electron transition behavior is revealed by magnetic induction current density analysis.

Synthesis, crystal structure, spectroscopic, quantum chemical investigation, molecular docking and ADMET prediction of 2(E)-3-(anthracen-9-yl)-1-(1-methyl-1H-pyrrol-2-yl) prop-2-en-1-one

In the present study, 2(E)-3-(anthracen-9-yl)-1-(1-methyl-1H-pyrrol-2-yl) prop-2-en-1-one (3AMP) crystal was grown by slow evaporation method. The single crystal X-ray diffraction analysis and density functional theory (DFT) calculations were carried out for 3AMP crystal. The 3AMP crystallizes in orthorhombic space group Pbca with a = 14.818 (8) Å, b = 9.796 (5) Å, c = 23.239 (11) Å. Hirshfeld surface and finger print plots were analyzed to confirm the existence of intra-, inter-molecular and other weak interactions using Crystal Explorer. The optimized molecular structure and harmonic wavenumbers were calculated by DFT method using B3LYP functional with 6-31G(d,p) basis set. The FT-IR, 1H, 13C NMR and UV–Vis spectra of 3AMP were recorded and analyzed. The optimized geometrical parameters, calculated wavenumbers by DFT method were compared with the experimental results. Natural bond orbital (NBO) analysis was carried out to evaluate the intra- and inter-molecular interactions in the crystal. The energy gap for 3AMP was calculated as 3.156 eV. Molecular electrostatic potential (MEP), Mulliken atomic charges and non-linear optical (NLO) properties for the title crystal were calculated. In addition, gauge invariant atomic orbital (GIAO) method was used to calculate the 1H and 13C NMR chemical shifts in the ground state. To obtain the electronic transitions in UV–Vis spectra of the title molecule in DMSO and ethanol solvents, TD-DFT calculations were performed on the optimized geometry. Furthermore, the compound was subjected to in silico ADMET evaluation. Molecular docking study was carried out to determine the interactions of ligand with the protein Hyaluronidase (PDB ID: 1FCQ).

Spectroscopic Studies (FT-IR, FT-Raman and UV-Vis), NBO Analysis, HOMO-LUMO, First Order Hyperpolarizability and Docking Studies of 4-[4-(Bromo-Phenylimino)-Methyl]-2-Ethoxy Phenol

The FT-IR, FT-Raman and UV-Vis spectra of 4-[4-(bromo-phenylimino)-methyl]-2-ethoxy phenol (4BPMEP) were recorded and analyzed. The optimized geometrical parameters were calculated. The total energy distribution (TED) analysis was used to find the complete vibrational assignments. The UV-Vis spectra were recorded and analyzed. The hyper conjugative interaction energy E(2) and donor (i), acceptor (j) electron densities (EDs) were calculated by natural bond orbital (NBO) analysis. The band gap energy of 4BPMEP was calculated by highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) analysis. The electronic transition was studied by UV-Vis analysis of 4BPMEP with B3LYP/6-311++G(d,p) level of basis set. The non - linear optical (NLO) behavior, molecular electrostatic potential (MEP) and thermodynamic properties were also calculated. In addition, Gauge invariant atomic orbital (GIAO) method was used to calculate 1H and 13C NMR chemical shift values of 4BPMEP in the ground state at B3LYP/6-311++G(d,p) basis set. To establish the information about interactions between topoisomerase DNA gyrase enzymes and the novel compound, docking studies were carried out by Schrödinger software.

Experimental and Theoretical Approach to Novel Polyfunctionalized Isoxazole

A novel, fast, and straightforward procedure for the synthesis of di- and trifunctionalized isoxazoles starting from 2-ethoxymethylenemalononitrile with different ratios of hydroxylamine in the presence of sodium acetate is described in this paper. The current method’s features include the availability of the starting materials, moderate reaction conditions, and the simplicity of the workup. The structures are characterized using different spectroscopic studies, such as infrared (IR), <sup>1</sup>H/<sup>13</sup>C nuclear magnetic resonance (NMR), and elemental analysis, in addition to X-ray single-crystal determination. The gauge-invariant atomic orbital (GIAO) <sup>1</sup>H and <sup>13</sup>C NMR chemical shift values of 5-aminoisoxazole-4-carbonitrile and 3,5-diaminoisoxazole-4-carboxamide are calculated in the ground state using the density functional theory (DFT) with the 6-311+G(d, p) basis set and are compared with the experimental data, in addition to the calculation of the molecular electrostatic potential (MEP) distribution, and the frontier molecular orbitals (FMOs) for the synthesized isoxazoles are illustrated theoretically.

Spectroscopic, quantum chemical and molecular docking studies on 1-amino-5-chloroanthraquinone: A targeted drug therapy for thyroid cancer

The DFT studies of the 1-Amino-5-chloro-anthraquinone (ACAQ) molecule have been carried out with extensive and accurate investigations of detailed vibrational and spectroscopic investigations and validated by experimentally. The optimized molecular structure and harmonic resonance frequencies were computed based on DFT/B3LYP method with 6-311G++(d,p) basis set using the Gaussian 09 program. The experimental and calculated vibrational wavenumbers were assigned on the basis of PED calculations using VEDA 4.0 program. The 13C NMR isotropic chemical shifts of the molecule were calculated using Gauge-Invariant-Atomic Orbital (GIAO) method in DMSO solution and compared with the experimental data. The absorption spectrum of the molecule was computed in liquid phase (ethanol), which exhibits л to л* electronic transition and compared with observed UV–Vis spectrum. Frontier molecular orbitals analysis shows the molecular reactivity and kinetic stability of the molecule. The Mulliken atomic charge distribution and molecular electrostatic potential surface analysis of the molecule validate the reactive site of the molecule. The natural bond orbital analysis proves the bioactivity of the molecule. Molecular docking analysis indicate that ACAQ molecule inhibits the action of c-Met Kinase protein, which is associated with the thyroid cancer. Hence, the present study pave the way for the development of novel drugs in the treatment of thyroid cancer.

Spectroscopic, Quantum chemical and Molecular docking Studies on Methyl 6-aminopyridine-3-carboxylate: A potent bioactive agent for the treatment of sarcoidosis

In the present study, the structural and spectroscopic investigations of Methyl 6-Aminopyridine-3-carboxylate (MAPC) molecule were performed using density functional theory (DFT) quantum chemical calculations. Molecular docking analysis was used to find out the inhibitory nature of the title molecule. The most stable molecular structure was predicted using conformational analysis at DFT/B3LYP level of cc-pVTZ basis set. The optimization was carried out using DFT/B3LYP method with cc-pVTZ basis to find out the most stable molecular structure of the molecule. The optimized molecular structure was used to determine the vibrational frequencies, which were assigned and compared with the experimentally observed vibrational frequencies. The Gauge-Invariant-atomic orbital (GIAO) method was used to calculate the 13C NMR isotropic chemical shift values of the molecule in DMSO solution and compared with experimental data. The ultraviolet-visible spectra of the molecule were used to find out the electronic properties of the molecule and are confirmed experimentally. The HOMO-LUMO energies, energy gap, chemical potential (μ) electronegativity (χ), hardness (η) and softness (S) values were calculated which results in the stability and molecular reactivity of the molecule. The second order perturbation energy E(2) values of the molecule were calculated using natural bond orbital analysis, which indicates the bioactivity of the molecule. Mullikan atomic charge distribution was calculated. Molecular Electrostatic potential (MEP) surface was computed and visualized by GaussView 05. The obtained lower binding energy and intermolecular energy values of MAPC ligand docked with HLA-DRB1 protein compared to the other selected proteins confirms that the title molecule can be useful for treatment of sarcoidosis disease. Hence, the present study paves the way for the development of novel drugs associated with sarcoidosis disease.