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[Display omitted] • Complete vibrational assignments of 216 vibration modes of cholesterol in gas phase and ethanol solution are reported. • AIM calculations predicted intra-molecular interactions between CH 3 /CH 3 , CH 3 /CH 2 and CH 2 /CH 2 groups. • NBO studies predicted that the OH group and the four fused rings play important roles in the stability of cholesterol. • Electronic spectra at different ethanol concentrations suggest that positions of maxima increase with the solution concentration. • Frontier orbitals predicted low reactivity of cholesterol in ethanol probably due to its high ω value in this medium. In this investigation, the experimental FT-IR and FT-Raman spectra of cholesterol in the solid phase and in ethanol solution have been combined with the B3LYP/6–311++G** calculations and the scaled quantum mechanical force field (SQMFF) methodology, normal internal coordinates and transferable scaling factors to obtain the complete vibrational assignments of 216 vibration modes expected. Hence, complete vibrational assignments for that steroid of greatest biological importance are reported for first time in gas phase and ethanol solution together with its scaled force constants. Changes in the positions of some bands and in force constants values are observed in the different media due to the predicted intra-molecular interactions between CH 3 /CH 3 , CH 3 /CH 2 and CH 2 /CH 2 groups by atoms in molecules (AIM) calculations. The 1H- and 13C NMR chemical shifts of normal and deuterated cholesterol in aqueous solution confirm that the H atom of OH group is involved in the formation of H bonds in solution. Studies of experimental electronic spectra of cholesterol in different concentrations of ethanol revealed that the positions of peaks maxima increase conform increase the solution concentration. The natural bond orbital (NBO) analyses reveal that the polar OH group and the four fused rings play important roles in the stability and properties of cholesterol than the large hydrophobic moiety. Frontier orbitals predicted low reactivity of cholesterol in ethanol probably due to its high ω value in this medium. [ABSTRACT FROM AUTHOR]

• Unveiled odd–even sensitivity in liquid crystal compounds using DFT analysis. • Revealed distinctive molecular configurations and NLO properties influenced by spacer units. • Charge distribution mapping elucidated electronic intricacies. • Raman spectra reveal distinct intensity patterns linked to spacer parity. In this article, a comprehensive investigation into a series of liquid crystalline compounds belonging to the α,ω-bis(4-alkylanilinebenzylidene-4′-oxy)alkane (m.OnO.m) family has been conducted to unravel their intricate molecular characteristics. The computational investigations employing DFT/B3LYP/6-311G(d,p) level delve into the odd–even effect, exploring how the presence of spacer units influences the structural, electronic, and vibrational properties of these compounds. Optimization analyses reveal the minimum energy configurations, offering valuable insights into spatial arrangements and symmetry. Visualization of molecular structures emphasizes a distinctive odd–even effect, with compounds exhibiting either U-shaped or Z-shaped configurations based on the parity of spacer units. Charge distribution maps further elucidate electronic intricacies, showcasing the interplay of charges among different atoms. Thermodynamic properties and frontier orbital analysis providing a nuanced understanding of the compounds behavior. NLO parameters exhibited a consistent odd–even effect. Potential Energy Distribution (PED), IR, and Raman spectra analysis, provided a detailed symphony of stretching, bending, and torsional motions. UV–Vis absorption spectra uncover distinctive electronic transitions within each compound. In essence, this research sheds light on the profound impact of spacer units, shaping the structural, electronic, and vibrational characteristics of the liquid crystalline compounds. The odd–even effect emerges as a central theme, weaving a captivating narrative of molecular dynamics within this intriguing class of materials. [ABSTRACT FROM AUTHOR]

[Display omitted] • A wide range of dipyrromethenes with alkyl, aryl, and meso -aza substituents was synthesized. • Dipyrromethenes absorb in spectral range from ∼ 420 to ∼ 600 nm due to the structural modification of the ligand backbone. • The most significant red (100 nm) shift are observed when four methyl substituents are replaced by phenyl groups. • Reaction of dipyrromethenes with Zn2+ is accompanied by intense color and spectral responses with form high stable [ZnL 2 ] complexes. • The dipyrromethenes are promising chromophore analytical agents for zinc ions. A wide range of dipyrromethenes (17 objects) with different nature, number, and attachment positions of alkyl, aryl, and meso -aza substituents was synthesized, and the effect of molecular structure features on their spectral properties was analyzed. It is shown that, chromophores absorb in a wide spectral range from ∼ 420 to ∼ 600 nm due to the structural modification of the dipyrromethene ligand backbone. Partially alkylated dipyrromethenes containing 4–5 methyl substituents absorb in the region from 421 to 436 nm. For fully alkylated dipyrromethenes, the band maximum position shifts to the region from 437 to 446 nm for ligands with 4,4′-substituents in the sequence: methyl, ethyl, propyl, butyl, amyl, hexyl, heptyl. The most significant spectral responses in the form of a red shift of 100 nm (in DMF) are observed when four methyl substituents in the 3,3′,5,5′-positions are replaced by phenyl groups. The replacement of the methine meso -spacer by a nitrogen atom leads to an additional red shift by another 70 nm. Particular attention is paid to the comparative analysis of the effect of structural factors on the coloristic and spectral responses of the complexation of dipyrromethene ligands with zinc(II) acetate and the stability of the resulting complexes [ZnL 2 ], for which the lg K o values are varied from 6.4 to 10.9. The auxochromic action of Zn2+ cations shifts the band maxima of electronic absorption spectra to the long wavelength region by 20–76 nm relative to the spectra of the ligands. The highest complexation constant lg K o is 10.9 was obtained for the reaction of Zn(AcO) 2 with hexamethylsubstituted dipyrromethene. Ligands with partially methylated pyrrole nuclei and extended alkyl and benzyl substituents form less stable complexes. The greatest effect of lowering the [ZnL 2 ] stability is produced by the introduction of an electron-withdrawing aryl substituent into the meso -spacer of the dipyrromethene ligand (lg K o is 6.4). [ABSTRACT FROM AUTHOR]

Thiacyanine chromonic liquid crystals reveal nanotubular templates through a polynuclear growth mechanism. [Display omitted] • Thiacyanine chromonic liquid crystals (CLCs) in water exhibit phases like nematic (N), lamellar, columnar rectangular (Col r), and columnar oblique (Col ob), even at a minimal 1% (w/v). • Varied aliphatic and aromatic counter ions, with different spacer lengths in thiacyanine dye, influence CLC formation, indicating a significant relationship between counter ion size and water solubility. • Results suggest the application of cost-effective dyes for large-scale CLCs production, opening avenues for exploring interconnected nanotubular fibers. We synthesized novel thiacyanine chromonic liquid crystals (CLCs) and structurally characterized using NMR and mass spectrometry. The impact of distinct substitution at the para position of aromatic counter anions, aliphatic counter ion chain length, and varied spacer parity of thiacyanine dyes on CLC formation is investigated. Liquid crystal properties of the synthesized dyes are characterized by polarizing optical microscopy (POM) and X-ray diffraction (XRD) studies. Dyes exhibit nematic (N), lamellar (L α), columnar rectangular (Col r), and columnar oblique (Col ob) CLCs at different concentrations in the water. Electronic absorption spectra reveal Scheibe aggregation in all the dyes. Cylicvoltametry studies confirm redox behaviour in TC-1a and TC-5e dyes. Chromonic LCs hybrid nano-materials are synthesized using sol–gel method. Scanning electron microscopy employed to confirm nano tubular fiber structure of the hybrid nanomaterilals.. [ABSTRACT FROM AUTHOR]

[Display omitted] • 6-Chloro-2-(4-Aminophenyl)-1H-Benzimidazole was synthesized and performed structural analysis at various solvents. • The compound was characterized experimentally and theoretically by SC-XRD, FT-IR, FT-Raman, UV-Vis and NMR Spectroscopy. • MEP and NBO determine the compound's chemical reactivity and active sites. • Based on the electron localization density and color scale indicator was performed using ELF, LOL and DORI, ED interactions. • Molecular docking and ADMET profiling were carried out. 6-Chloro-2-(4-Aminophenyl)-1H-Benzimidazole compound were synthesized and characterized by SC-XRD, FT-IR, FT-Raman, UV–Vis, 1H NMR, and 13C NMR and analyzed with experimental data. The DFT approach with the B3LYP functional and 6-311++G(d,p) basis set was used to calculate the geometry parameters and wavenumbers of the title compound. Electronic absorption spectra and 1H–13C NMR studies have been computed in gas and solvents (dimethylsulfoxide, chloroform, and H 2 O) by using the TD-DFT and the IEFPCM solvation model. The HOMO-LUMO energy band gap has also been determined. To identify the electron localization density and weak interactions, the Multiwin-3.8 was subjected to a topological analysis and non-covalent interactions, including ELF, LOL, DORI and ED. Studies of donor–acceptor connections were performed using NBO analysis. To calculate contributions to the molecular orbitals, TDOS was determined. Molecular electrostatic potential (MEP) reveals the chemical reactivity sites for the reaction. The antibacterial activity of the compound has been assessed with a zone of inhibition by the well diffusion method using a panel of selected gram-positive Staphylococcus aureus (MTCC-3160), Enterococcus faecalis (MTCC-3159) and gram-negative Pseudomonas aeruginosa (MTCC-4030), Escherichia coli (MTCC-1667) bacterial strains that have shown better activity than the standard drug (Ciprofloxacin). Finally, molecular docking and pharmacokinetics have been agreed upon to understand the binding energy of the ligand–protein interaction. [ABSTRACT FROM AUTHOR]

• Topological analysis has been obtained for the polar and non-polar solvents. • Electronic properties, FT-IR, NMR, and solvent effects were investigated. • Electronic spectrum was compared with the help of TD-DFT. • Reactive regions are identified by MEP, FUKUI, and dual descriptors. • Docking simulations were done using antiviral proteins. A theoretical study of three pyridine carboxamide derivatives in conjunction with the Density Functional Theory (DFT) approach at the 6-311+G(d,p) basis set is presented along with X-ray results. The pyridine carboxamide derivatives were analyzed with the help of FT-IR, UV–Vis, 1H and 13C NMR investigation. The spectral characterizations were made by vibrational energy distribution analysis (VEDA4), which helps to assign vibrational frequencies to specific molecular vibrations. A comparative analysis of computed 1H and 13C NMR chemical shift values with experimental chemical shifts for the pyridine carboxamide compounds by applying the gauge-including atomic orbitals method in chloroform and acetone solvents was carried out. UV–Vis spectroscopy and electronic transitions were conducted on both chloroform and acetone solvents through the assistance of the TD-DFT methodology. Hirshfeld Surface analysis was employed to analyze the intermolecular hydrogen bonds of the type N-H⋯N to the crystal packing. The chemical properties of frontier molecular orbital and global reactivity descriptors were analyzed for the different solvents such as chloroform and acetone. The Fukui functions were used to identify reactive sites in a molecule, including those susceptible to nucleophilic and electrophilic outbreaks. The weak interactions were analyzed using reduced density gradient (RDG) analysis, a computational method used to study noncovalent interactions, including hydrogen bonding. The Absorption, Distribution, Metabolism, and Excretion (ADME) attributes of the studied compounds have been evaluated for drug discovery initiatives. Molecular docking studies with antiviral SARS-CoV-2 Mpro and Omicron variant containing the Q493R mutation proteins of three pyridine carboxamide derivatives (L3–L5) have been performed, and L5 has maximum binding energy values of −7.13 kcal/mol for 6LU7. [ABSTRACT FROM AUTHOR]