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

Synthesis, DFT Calculations, In Silico Studies, and Antimicrobial Evaluation of Benzimidazole-Thiadiazole Derivatives

In this study, a series of new benzimidazole-thiadiazole hybrids were synthesized, and the synthesized compounds were screened for their antimicrobial activities against eight species of pathogenic bacteria and three fungal species. Azithromycin, voriconazole, and fluconazole were used as reference drugs in the mtt assay. Among them, compounds 5f and 5h showed potent antifungal activity against C. albicans with a MIC of 3.90 μg/mL. Further, the results of the antimicrobial assay for compounds 5a, 5b, 5f, and 5h proved to be potent against E. faecalis (ATCC 2942) on the basis of an acceptable MIC value of 3.90 μg/mL. The cytotoxic effects of compounds that are effective as a result of their antimicrobial activity on healthy mouse fibroblast cells (L929) were evaluated. According to HOMO-LUMO analysis, compound 5h (with the lower ΔE = 3.417 eV) is chemically more reactive than the other molecules, which is compatible with the highest antibacterial and antifungal activity results. A molecular docking study was performed to understand their binding modes within the sterol 14-α demethylase active site and to interpret their promising fungal inhibitory activities. Molecular dynamics (MD) simulations of the most potent compounds 5f and 5h were found to be quite stable in the active site of the 14-α demethylase (5TZ1) protein.

Heterojunction solar cell based on donor-acceptor pi-conjugated naphthalene bisbenzimidazole, perylene bisbenzimidazole, and naphthalene imidazole: A spectroscopic, microscopic and DFT assessment

This study represents detailed vibrational analysis of naphthalene bisbenzimidazole (NBBI), perylene bisbenzimidazole (PBBI), and naphthalene imidazole (NI) by vibrational spectroscopic (Fourier Transform Infrared (FT-IR) and Raman), Atomic Force Microscopic (AFM) and quantum chemical studies for the first time. These sorts of compounds provide an opportunity to build potential n-type organic thin film phototransistors which can be used as organic semiconductors. Optimized molecular structures and vibrational wavenumbers of these molecules in their ground states have been calculated by Density Functional Theory (DFT) using B3LYP functional with 6-311++G(d,p) basis set. Finally, theoretical UV-Visible spectrum was predicted and Light Harvesting Efficiencies (LHE) were evaluated. AFM analysis revealed that PBBI has the highest surface roughness thus exhibits an increase in high Jsc value and high conversion efficiency.

Synthesis, Molecular Docking, Dynamics, Quantum-Chemical Computation, and Antimicrobial Activity Studies of Some New Benzimidazole-Thiadiazole Hybrids

In this study, some new compounds, which are 2-aminothiadiazole derivatives linked by a phenyl bridge to the 2-position of the benzimidazole ring, were designed and synthesized as antimicrobial agents. The structures of the compounds were elucidated by ¹H and ¹³C NMR spectroscopy, high-resolution mass spectrometry, and elemental analysis. The antifungal activities of the synthesized compounds were tested on Candida albicans, Candida krusei, Candida glabrata, and Candida parapsilosis. Compound 5f is more active against C. albicans and C. glabrata than standard fluconazole and varicanazole. Compounds were also evaluated for their counteracting activity against Gram-positive Escherichia coli, Serratia marcescens, Klebsiella pneumoniae, and Pseudomonas aeruginosa and Gram-negative Enterococcus faecalis, Bacillus subtilis, and Staphylococcus aureus. Compounds 5c and 5h had minimum inhibitory concentrations against E. faecalis close to that of the standard azithromycin. Molecular docking studies were performed against Candida species' 14-α demethylase enzyme. 5f was the most active compound against Candida species, which gave the highest docking interaction energy. The stabilities of compounds 5c and 5f with CYP51 were tested using 100 ns molecular dynamics simulations. According to the theoretical ADME calculations, the profiles of the compounds are suitable in terms of limiting rules. HOMO-LUMO analysis showed that 5h is chemically more reactive (represented with the lower ΔE = 3.432 eV) than the other molecules, which is compatible with the highest antibacterial activity result.

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.

Non-linear optical properties of polystyrene and polyvinyl alcohol composites with 4-methoxy-1-naphthol

The analysis of the NLO properties of 4-methoxy-1-naphthol (4M1N) reveals that this molecule has the value of polarizability tensor, α, more than 340% greater than that obtained, at the same level of theory, for urea molecule. This improvement grows to 500% when the second-order hyperpolarizability is considered. Calculations performed within LR-PCM-B3LYP/6-311+G(3d,2p) model proved that embedding of 4M1N in the polymer matrix significantly improved these results suggesting applications of 4M1N as the cheap and effective NLO material. The molecule was also studied, both theoretically and experimentally, to determine its full vibrational characterisation and structural description. Calculations were performed with HF, MP2, SVWN and B3LYP methods, in two, varying in size, basis sets, to find optimized structures, conformational isomers and UV–VIS, IR and Raman spectra. The accordance of simulated oscillation and absorption spectra with experimental ones is very good; IR values are slightly red-shifted. NBO charge distribution analysis was made to generate frontier orbitals and find most reactive parts of the molecule.

Synthesis of an oligomer ruthenium complex and its catalysis in the oxidation of alcohols

The catalyst showed high efficiency in the oxidation of alcohols to ketones or acids and can be recycled several times.

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.