Ligand based pharmacophoric modelling and docking of bioactive pyrazolium 3-nitrophthalate (P3NP) on Bacillus subtilis, Aspergillus fumigatus and Aspergillus niger — Computational and Hirshfeld surface analysis

Observation of Induced Luminescence and Thermochromism in Achiral Hydrogen Bonded Liquid Crystal Complexes

A novel hydrogen bonded liquid crystal (HBLC) complexes are obtained from the non-mesogenic (benzylmalonic acid) and mesogenic (p-n-alkyloxybenzoic acid, where n = 6, 7 and 8) compound via intermolecular hydrogen bonds (H-bond). H-bonds are experimentally confirmed by the Fourier transform infrared spectroscopic (FT-IR) studies and the same is validated using density functional theory (DFT). Induced thermochromism is observed by the polarizing optical microscope (POM) and its possible applications are reported. Phase transition temperature and their analogous enthalpy values, stability factor and span width are determined by the differential scanning calorimetry (DSC) studies. Band gap energy is calculated using UV-visible and photoluminescence spectrum. Hyper conjugative stabilization energy and atomic charge distribution is studied by the natural bond orbital (NBO) studies. Mulliken analysis clearly reveals the intermolecular interaction and steric effect of the HBLC complexes. An interesting phenomenon is that the observation of luminescence and thermochromism in the highly fluidity nematic phase. This peculiar behavior is attributed due to the intermolecular H-bonding interaction between the BMA and nOBA compounds and the effect of rotatory motion of the molecules in nematic phase. Luminescence increases when the spacer moiety decreases in the present complexes is also reported. In nematic phase, the molecules are in different degrees of the excited state which is correlated with the hyper conjugative energy through NBO studies.

Functional insights of a molecular complex pyrazolium 3,5-dinitrobenzoate:3,5-dinitrobenzoic acid on infectious agents and ctDNA - A comparative biological screening and complementary theoretical calculations

Systematic identification and quantification of active radical sites in a small molecule, pyrazolium 3,5-dinitrobenzoate:3,5-dinitrobenzoic acid as well as in the stable free radical (DPPH^•) were carried out by Fukui functions calculation using DFT functional with B3LYP/6-311++G(d,p) level of basis set. Bioactive Lewis acid-base compound, pyrazolium 3,5-dinitrobenzoate:3,5-dinitrobenzoic acid (PDNB:DNBA) has been synthesized and crystallized by slow evaporation - solution method at 30 °C. Various functional groups and the structural arrangements were ascertained from spectral and XRD analyses, respectively. UV-vis spectral analysis was used to find out the stability of the anticipated drug for about 60 min using methanol as a solvent. Stabilization of the compound was linked to the presence of enormous N-H…O, O-H…O and C-H…O hydrogen bonding interactions identified through Hirshfeld surface analysis. Chemical stability and reactivity of the drug were validated from theoretical optimization and HOMO-LUMO analysis. Active nucleophilic, electrophilic and radical sites of PDNB:DNBA were also identified from molecular electrostatic potential analysis. Inhibition of growth of pathogens in screening experiments by the proposed drug attests its suitability in biological applications. Antioxidant activity of the compound, PDNB:DNBA, endorses its aptness for scavenging reactive radicals. Fluorimetry experiments confirm hyperchromism in DNA binding analysis proving groove mode of binding. Molecular docking explored the various modes of intermolecular interactions of the drug with microbes as well as DNA.

Bioactivity of a radical scavenger bis(pyrazolium p-toluenesulphonate) on ctDNA and certain microbes: a combined experimental and theoretical analysis

A small organic molecule, bis(pyrazolium p-toluenesulphonate) (BPPTS), was crystallized, characterized and used to scavenge free radicals in biological systems. SXRD and spectroscopic analyses were used to confirm the structure of BPPTS. Methanolic and ethanolic solutions of BPPTS were used to assess the stability of the proposed drug using the UV-vis spectrophotometric technique. Optimization of the molecular structure was carried out by DFT with B3LYP/6-311++G(d,p) level of basis set. MEP and Fukui functions that elaborate theoretically the predominant electrophilic, nucleophilic and radical sites in BPPTS were correlated with experimental biological screening. BPPTS exhibits strong activity against Bacillus subtilis and Escherichia coli, comparable with all other analyzed pathogens. The free radical scavenging activity of BPPTS was assessed by both experimental studies and theoretical calculations. The binding sites of DPPH, which can bind to BPPTS, were also predicted by Fukui functions. DNA binding of BPPTS in UV-vis studies revealed the groove mode of binding due to the occurrence of hyperchromism. The phenomenon of hyperchromism was established by the Hirshfeld surface analysis of BPPTS, which confirmed the presence of π···π interactions (2.4%). Molecular docking established a positive correlation between experimental bio-screening reports and simulated data. ADMET properties were also calculated.

Hydrogen bonded charge transfer molecular salt (4-chloro anilinium-3-nitrophthalate) for photophysical and pharmacological applications

Radical scavenging activity against DPPH radical and binding properties of a hydrogen bonded charge transfer molecular salt 4-chloro anilinium-3-nitrophthalate(CANP) with calf thymus DNA has been studied by electronic absorption and emission spectroscopy. The molecular structure and crystallinity of the CANP salt have been established by carried out powder and single crystal X-ray diffraction analysis which indicated that cation and anion are linked through strong N⁺H^…O^- type of hydrogen bond. FTIR spectroscopic study was carried out to know the various functional groups present in the crystal. ¹H and ¹³C NMR spectra were recorded to further confirm the molecular structure of the salt crystal. The thermal stability of the title salt was established by TG/DTA analyses simultaneously on the powdered sample of the title crystal. Further, the CANP salt was examined against various bacteria and fungi strains which showed a remarkable antimicrobial activity compared to that of the standards Ciproflaxin and Clotrimazole. The results showed that the CANP salt could interact with CT-DNA through intercalation. Antioxidant studies of the substrates alone and synthesized CANP salt showed that the latter has been better radical scavenging activity than that of the former against DPPH radical. The third order nonlinear susceptibility of the CANP salt was established by the Z-scan study.