Synthesis, geometry optimization, spectroscopic investigations (UV/Vis, excited states, FT-IR) and application of new azomethine dyes

Photodegradation of the novel herbicide pyraclonil in aqueous solution: Kinetics, identification of photoproducts, mechanism, and toxicity assessment

Pyraclonil is a new type of pyrazole herbicide, whose photochemical fate in aqueous solution has not been reported yet. In this study, effects on the photolysis rate such as light source, pH, NO3-, Fe3+, fulvic acid (FA) and riboflavin (RF) were investigated. Pyraclonil photodegraded in pure water under both UV and simulated sunlight with half-lives of 32.29 min and 42.52 h, respectively. Under UV, the degradation rate of pyraclonil in pH 4 solution (0.0299 ± 0.0033 min-1) was about twice higher than that in pH 9 (0.0160 ± 0.0063 min-1). Under simulated sunlight, low concentration (0.1-1 mg/L) of FA, NO3-, Fe3+ and RF noticeably promoted the photodegradation of pyraclonil. Then, with the combination of experimental UPLC-Q-TOF/MS and computational calculation of density functional theory (DFT), fourteen transformation products (TPs) of pyraclonil were identified with possible mechanism of C-N bond cleavage, photorearrangement, demethylation, hydroxylation and oxidation. Additionally, acute toxicity assessment was conducted through ECOSAR prediction and laboratory bioassays. The prediction results indicated that toxicity of TP157 to daphnid and green algae was 1.3 and 1.4 times higher than that of the parent, respectively. The bioassay results indicated that toxicities of TP157 and TP263 to C. vulgaris were about 1.6 and 5.9 times higher than that of the parent, respectively. The results provided a reference for elucidating the potential hazards of pyraclonil to non-target organisms and promoting its rational use.

Solvent-Dependent Spectral Properties in Diverse Solvents, Light Harvesting and Antiviral Properties of Mono-Azo Dye (Direct Yellow-27): A Combined Experimental and Theoretical Study

In this paper, we have discussed for the first time a detailed electronic absorption study of the mono-azo dye Direct Yellow 27 [C[Formula: see text]H[Formula: see text]N4Na2O9S3] (DY-27) with five different homogeneous media by applying experimental and theoretical techniques along with some new characteristics of DY-27 in the field of solar cells as well as antiviral activities. A clear absorption band in the UV-visible region was observed, although the absorption maxima lie in the visible region. The electronic absorption transitions observed in our study were fully spin and symmetry allowed transitions with [Formula: see text]–[Formula: see text] character. Time-dependent density functional theory (TD-DFT) analysis has been done for understanding the electronic and the charge transfer performance. Moreover, the impacts of polar protic and polar aprotic solvents in the structural variation of DY-27 have been reported here. Further, applications of the dye in the field of solar cell, as well as antiviral activity, were performed using molecular modeling approaches. The dye exhibited a D–[Formula: see text]–A–A structure with a high light-harvesting efficiency (LHE) and good injection efficiency acts as an effective dye sensitized solar cell (DSSC). Molecular docking studies of the dye DY-27 performed with M-protease of the different corona viruses, MERS, SARS-CoV-1 and SARS-CoV-2 indicated comparable binding energies with the controlled inhibitors and best interactions are observed for the SARS-CoV-1.

Antimicrobial and antiproliferative activity studies of some new quinoline-3-carbaldehyde hydrazone derivatives

In this study, a total of 22 piece quinoline-3-carbaldehyde hydrazone derivative compounds were designed and synthesized, 2 of which were not original, their antimicrobial activities were determined with microdilution method and their in vitro cytotoxic effect was investigated in MCF-7 and A549 cells by MTT assay. When the activity results are examined, although the antimicrobial effects of quinoline derivatives, in general, are weaker than standard drugs; 3q5 and 3q6 against MRSA showed promising activity with MIC:16 µg/ml compared to reference drugs. Compounds generally showed weaker cytotoxic activity on the A549 and MCF-7 cell line. 3q12, 3q17 and 3q22 at 100 µM reduced cell viability to 59.28%, 76.24% and 72.92% on A549 cells, respectively. Compound 3q6, one of the most effective compounds against MRSA, formed a 2.10 Å long hydrogen bond between the quinoline nitrogen and ARG132 in the DNA topoisomerase IV active site (PDB: 3FV5). Theoretical ADME profiles of all compounds comply with Lipinski and other limiting rules. In addition, MEP analysis of 3q6, geometric optimization and molecular reactivity analysis were calculated with the 6-311G (d,p) base set DFT/B3LYP theory, and ΔE = E_LUMO-E_HOMO, which is a measure of the stable structure of the molecule, was calculated as 0.13377 for 3q6 and had the most stable electronic structure among all compounds.

A new 1,2,3-triazole and its rhodamine B derivatives as a fluorescence probe for mercury ions

A newly synthesized compound, 5-methyl-1-phenyl-1H-1,2,3-triazole-4- carboxylic acid (MPC) was analyzed for its quantum chemical parameters and theoretical spectrum by computational chemistry. The calculated spectrum was in accord with the experimental measurements in a great degree. Then MPC was successfully designed and synthesized to a novel rhodamine B derivative RMPC. The RMPC exhibited about a 4000-fold increase in fluorescence intensity in the presence of Hg²⁺ ions over most other competitive metal ions. The triazole appended colorless chemodosimeter RMPC turns to pink upon the complex formation only with Hg²⁺ ions as a 1: 2 M ratio and enables naked-eye detection. The coordination mechanism of turning on/off fluorescence for Hg²⁺ ions were well proposed by explaining Hg²⁺ inducing the ring-opened rhodamine B moiety. The fluorescence imaging experiments of Hg²⁺ in HeLa cell demonstrated that the probe was labeled and it could be used in biological systems.

Design, synthesis, molecular docking, density functional theory and antimicrobial studies of some novel benzoxazole derivatives as structural bioisosteres of nucleotides

A series of some novel 2-(p-tert-butylphenyl)-5-(3-substituted-propionamido)benzoxazole derivatives have been designed, synthesized, evaluated for antimicrobial activity and have performed molecular docking studies against penicillin-binding protein 4 (PBP4) and active and allosteric site of PBP2a; were calculated some theoretical quantum parameters and absorption, distribution, metabolism and excretion (ADME) descriptors. B9 acted at minimum inhibitory concentration (MIC) = 8 µg/mL against S. aureus, E. faecalis and their drug-resistant isolates and also formed with GLU145 (1.74 Å) and ILE144 (1.89 Å) two hydrogen bonds at allosteric site of PBP2a with Glide emodel score: -42.168. ΔE of compound B9 had moderate value of all compounds with 0.14742.[Formula: see text]Communicated by Ramaswamy H. Sarma.

1H-Benzimidazole-5-carboxamidine derivatives: design, synthesis, molecular docking, DFT and antimicrobial studies

15 new 1H-benzimidazole-5-carboxamidine derivatives were synthesized, their antimicrobial effects were evaluated, and molecular docking and DFT studies were performed.

Molecular Investigations of the Newly Synthesized Azomethines as Antioxidants: Theoretical and Experimental Studies

BACKGROUND

In this study, the antioxidant property of new synthesized azomethins has been investigated as theoretical and experimental.

METHODS AND RESULTS

Density functional theory (DFT) was employed to investigate the Bond Dissociation Enthalpy (BDE), Mulliken Charges, NBO analysis, Ionization Potential (IP), Electron Affinities (EA), HOMO and LUMO energies, Hardness (η), Softness (S), Electronegativity (µ), Electrophilic Index (ω), Electron Donating Power (ω-), Electron Accepting Power (ω+) and Energy Gap (Eg) in order to deduce scavenging action of the two new synthesized azomethines (FD-1 and FD-2). Spin density calculations and NBO analysis were also carried out to understand the antioxidant activity mechanism. Comparison of BDE of FD-1 and FD-2 indicate the weal antioxidant potential of these structures.

CONCLUSION

FD-1 and FD-2 have very high antioxidant potential due to the planarity and formation of intramolecular hydrogen bonds.

The computational and experimental studies on a 1, 2, 3-triazole compound and its special binding to three kinds of blood proteins

A newly synthesized compound, ethyl 5-phenyl-2-(p-tolyl)-2H-1, 2, 3-triazole-4-carboxylate (EPPC) may be considered as a drug candidate and was exploited to study the structural and spectral properties by using quantum chemical calculation and multiple spectroscopic techniques. The results on theoretical spectrum of EPPC were consistent with experimental spectrum in great degree. In addition, EPPC has been as a special probe and investigated on the interactions with three kinds of blood proteins including human serum albumin (HSA), human immunoglobulin (HIgG) and bovine hemoglobin (BHb) by using UV-Vis, fluorescence spectroscopy and molecular modeling, respectively. Changes in various fluorescence and UV-Vis spectra were observed upon ligand binding along with a remarkable degree of fluorescence enhancement on complex formation under physiological condition with binding constant about 10⁵ order of magnitudes, which caused the variations of conformation and microenvironment of these proteins in aqueous solution. The obtained results from the thermodynamic parameters calculated according to the van't Hoff equation indicated that the entropy change ΔS° and enthalpy change ΔH° were found to be 0.168 KJ/mol K and 22.154 KJ/mol for EPPC-HSA system, 0.284 KJ/mol K and 54.408 KJ/mol for EPPC-HIgG system, and 0.228 KJ/mol K and 37.548 KJ/mol for EPPC-BHb system, respectively, which demonstrated that the primary binding pattern is determined by hydrophobic interaction. The results of docking and molecular dynamics simulation using three proteins crystal models revealed that EPPC could bind to three proteins well into hydrophobic cavity, which showed good consistence with the spectroscopic measurements.Communicated by Ramaswamy H. Sarma.