Theoretical investigations on the molecular structure, vibrational spectra, HOMO-LUMO and NBO analysis of 5-chloro-2-((4-chlorophenoxy)methyl)benzimidazole

TD-DFT calculations, dipole moments, and solvatochromic properties of 2-aminochromone-3-carboxaldehyde and its hydrazone derivatives

2-Aminochromone-3-carboxaldehyde (ACC) and its hydrazones (ACMHCA and ACMNPHTCA) with semicarbazide hydrochloride and N-phenylthiosemicarbazide were synthesized and characterized by elemental analysis and spectral studies. The solvatochromic behavior of the title compounds in various solvents showed distinct bathochromic shifts on going from nonpolar to polar solvents, suggesting intramolecular-charge-transfer (ICT) solute-solvent interactions. The ground and excited state dipole moments of ACC, ACMHCA, and ACMNPHTCA were determined experimentally by the solvatochromic shift method using the Bilot-Kawski, Lippert-Mataga, Bakhshiev, Kawski-Chamma-Viallet functions, and a microscopic Reichardt's solvent polarity parameter (ENT). All the investigated molecules showed a substantial increase in the dipole moment upon excitation to the emitting state. The experimental results were generally consistent with the values obtained by the TD-DFT, B3LYP/6-311G++(d,p) method. Molecular electrostatic potential (MEP) mapping and natural charge and natural bonding orbital (NBO) analysis were performed and the results were discussed. The 1H NMR chemical shifts of the prepared compounds were simulated by the gage independent atomic orbital (GIAO) method and compared with their experimental chemical shift values. The biological activity data were correlated with the frontier molecular orbitals. The photovoltaic behavior of the title compounds showed there was sufficient electron injection.

Computational and theoretical chemistry of newly synthesized and characterized 2,2'-(5,5'-(1,4-phenylene)bis(1H-tetrazole-5,1-diyl))bis-N-acetamides

Energetic heterocycles, including pyridines, triazoles, and tetrazoles, exhibit greater density, heats of formation, and oxygen balance compared to their carbocyclic counterparts, making them a promising approach for synthesizing novel bis-tetrazole acetamides. Synthesized compounds A-F, some of which feature a chlorine atom attached to the phenyl ring, serve as valuable synthons for aryl coupling reactions. Analysis via 1H-NMR and 13C-NMR spectroscopy, as well as density functional considerations through B3LYP functional correlation with 6-311 +  + G(d) and 6-31G(d) basis set, revealed the observed LUMO/HOMO energies and charge transfer within the molecule. Additionally, the dipole moment, chemical hardness, softness, ionization potential, local reactivity potential via Fukui indices and thermodynamic properties (entropy, enthalpy, and Gibbs free energy) of the molecule were calculated through density functional theory studies. In addition, Molecular Docking studies were conducted to investigate the anti-cancer potential of synthesized heterocyclic compounds against caspase 3, NF-KAPPA-B and P53 protein. Molecular docking analysis demonstrated a potent interaction between 2,2'-(5,5'-(1,4-phenylene)bis(1H-tetrazole-5,1-diyl))bis-N-(2,4-dinitrophenyl) acetamides (6d) and TP53 and NF-KAPPA-B with binding energies of - 11.8 kJ/mol and - 10.9 kJ/mol for TP53 and NF-KAPPA-B, respectively. Similarly, 2,2'-(5,5'-(1,4-phenylene)bis(1H-tetrazole-5,1-diyl))bis-N-(2-chlorophenyl) acetamides (6f) exhibited a strong interaction with caspase-3 with binding energy of -10.0 kJ/mol, indicating their potential as therapeutic agents against these proteins. Furthermore, the findings of current study was further strengthen by 100 ns molecular dynamics (MD) simulations. Finally, theoretical studies of oxygen balance and nitrogen percentage suggest that these molecules can be utilized as energetic materials.

Spectral and Theoretical Studies of Benzimidazole and 2-Phenyl Substituted Benzimidazoles

This chapter discusses about the spectral and theoretical aspects of selected benzimidazole and 2-phenyl substituted benzimidazole molecules. The synthesis of these benzimidazoles was reported in many methods by the reaction between o-phenylenediamine with formic acid, aromatic aldehydes and N-benzylbezene-1,2-diamine in presence of oxidant tert-butyl hydroperoxide (TBHP). The spectral analysis of these molecules mainly such as UV-visible, fluorescence in solvents will be included in this chapter and discussed about the absorption, fluorescence maximum, conjugation, transition. Further the optimized structure of these molecules will be given using Gaussian 09 W (DFT 6-31G method). And also will be discussed about structural parameters, highest occupied molecular orbital (HOMO) – lowest unoccupied molecular orbital (LUMO) energy energy values, natural bond orbital (NBO), molecular electrostatic potential map (ESP). Many benzimidazole molecules having tautomers in the structure will be explained with the help of theoretical parameters to describe the structural properties.

Spectroscopic and theoretical characterization of 2-(4-methoxyphenyl)-4,5-dimethyl-1H-imidazole 3-oxide

The optimized molecular structure, vibrational frequencies, corresponding vibrational assignments of 2-(4-methoxyphenyl)-4,5-dimethyl-1H-imidazole 3-oxide have been investigated experimentally and theoretically. Gauge-including atomic orbital (1)H NMR chemical shifts calculations were carried out and compared with experimental data. The HOMO and LUMO analysis is used to determine the charge transfer within the molecule. The stability of the molecule arising from hyper-conjugative interaction and charge delocalization has been analyzed using NBO analysis. The calculated geometrical parameters are in agreement with that of similar derivatives. Molecular electrostatic potential was performed by the DFT method. Mulliken's net charges have been calculated and compared with the atomic natural charges. First and second hyperpolarizability are calculated in order to find its role in non-linear optics. Molecular docking is also reported.

Spectroscopic investigation (FT-IR and FT-Raman), vibrational assignments, HOMO-LUMO, NBO, MEP analysis and molecular docking study of 2-(4-hydroxyphenyl)-4,5-dimethyl-1H-imidazole 3-oxide

In this work, the vibrational spectral analysis was carried out using FT-IR and FT-Raman spectroscopy of 2-(4-hydroxyphenyl)-4,5-dimethyl-1H-imidazole 3-oxide. The computations were performed at DFT levels of theory to get the optimized geometry and vibrational frequencies of the normal modes of the title compound using Gaussian09 software. The complete vibrational assignments of frequencies were made on the basis of potential energy distribution. The calculated HOMO and LUMO energies show the chemical activity of the molecule. The stability of the molecule arising from hyper-conjugative interaction and charge delocalization has been analyzed using NBO analysis. The hyperpolarizability values are reported and the first hyperpolarizability of the title compound is 19.61 times that of standard NLO material urea. From the MEP plot, the negative charge covers the nitro group and the positive region is over the hydroxyl group and N-H part of the imidazole ring. The calculated (1)H NMR results are in good agreement with experimental data. Molecular docking study is also reported.

Infrared spectrum, structural and optical properties and molecular docking study of 3-(4-fluorophenyl)-5-phenyl-4,5-dihydro-1H-pyrazole-1-carbaldehyde

The optimized molecular structure, vibrational frequencies, corresponding vibrational assignments of 3-(4-fluorophenyl)-5-phenyl-4,5-dihydro-1H-pyrazole-1-carbaldehyde have been investigated experimentally and theoretically. The title compound was optimized using at HF and DFT levels of calculations. The B3LYP/6-311++G(d,p) (5D,7F) results and in agreement with experimental infrared bands. The normal modes are assigned using potential energy distribution. The stability of the molecule arising from hyper-conjugative interaction and charge delocalization has been analyzed using natural bonding orbital analysis. The frontier molecular orbital analysis is used to determine the charge transfer within the molecule. From molecular electrostatic potential map, it is evident that the negative electrostatic potential regions are mainly localized over the carbonyl group and mono substituted phenyl ring and are possible sites for electrophilic attack and, positive regions are localized around all para substituted phenyl and pyrazole ring, indicating possible sites for nucleophilic attack. First hyperpolarizability is calculated in order to find its role in nonlinear optics. The geometrical parameters are in agreement with experimental data. From the molecular docking studies, it is evident that the fluorine atom attached to phenyl ring and the carbonyl group attached to pyrazole ring are crucial for binding and the results draw us to the conclusion that the compound might exhibit phosphodiesterase inhibitory activity.

Synthesis, interaction with DNA and antiproliferative activities of two novel Cu(II) complexes with norcantharidin and benzimidazole derivatives

Two novel complexes [Cu(L)2(Ac)2]·3H2O (1) (L=N-2-methyl benzimidazole demethylcantharate imide, C16H15N3O3, Ac=acetate, C2H3O2) and [Cu(bimz)2(DCA)] (2) (bimz=benzimidazole, C7H6N2; DCA=demethylcantharate, C8H8O5) were synthesized and characterized by elemental analysis, infrared spectra and X-ray diffraction techniques. Cu(II) ion was four-coordinated in complex 1, Cu(II) ion was five-coordinated in complex 2. A large amount of intermolecular hydrogen-bonding and π-π stacking interactions were observed in these complex structures. The DNA-binding properties of these complexes were investigated using electronic absorption spectra, fluorescence spectra, viscosity measurements and agarose gel electrophoresis. The interactions between the complexes and bovine serum albumin (BSA) were investigated by fluorescence spectra. The antiproliferative activities of the complexes against human hepatoma cells (SMMC7721) were tested in vitro. And the results showed that these complexes could bind to DNA in moderate intensity via partial intercalation, and complexes 1 and 2 could cleave plasmid DNA through hydroxyl radical mechanism. Title complexes could effectively quench the fluorescence of BSA through static quenching. Meanwhile, title complexes had stronger antiproliferative effect compared to L and Na2(DCA) within the tested concentration range. And complex 1 possessed more antiproliferative active than complex 2.

Quantum chemical vibrational study, molecular property, FTIR, FT-Raman spectra, NBO, HOMO-LUMO energies and thermodynamic properties of 1-methyl-2-phenyl benzimidazole

The solid phase FT-IR and FT-Raman spectra of 1-methyl-2-phenyl benzimidazole (MPBZ) have been recorded in the condensed state. In this work, experimental and theoretical study on the molecular structure, quantum chemical calculations of energies and vibrational wavenumbers of MPBZ is presented. The vibrational frequencies of the title compound were obtained theoretically by DFT/B3LYP calculations employing the standard 6-311+G(d,p) and 6-311++G(d,p) basis set for optimized geometry and were compared with Fourier transform infrared spectrum (FTIR) in the region of 4000-400 cm(-1) and with Fourier transform Raman spectrum in the region of 4000-100 cm(-1). Complete vibrational assignments, analysis and correlation of the fundamental modes for the title compound were carried out. The vibrational harmonic frequencies were scaled using scale factor, yielding a good agreement between the experimentally recorded and the theoretically calculated values. The study is extended to calculate the HOMO-LUMO energy gap, NBO, mapped molecular electrostatic potential (MEP) surfaces, polarizability, Mulliken charges and thermodynamic properties of the title compound.