Pyrazine

The ligands, 2,6-di-(N-methylimidazolium)pyrazine dichloride (1); 2,6-di-(N-methylbenzimidazolium)pyrazine dichloride (2) and their Ru(II)-complexes, bis-[2,6-di-(N-methylimidazol-2-ylidene)pyrazine]ruthenium(II) hexaflurophosphate (3), bis-[2,6-di-(N-methylbenzimidazol-2-ylidene)pyrazine]ruthenium(II) hexaflurophosphate (4) have been synthesized and characterized by NMR (1H,13C), mass spectrometry, microanalysis and single crystal X-ray analysis. Complex 3 and 4, both were formed the nanosphere structure  in aqueous growth medium. This is the first report on the formation of ‘nanoball’ structure of Ru(II)-NHC complexes. Both complexes were studied to determine their pro-apoptotic activity against HCT15 and Hep2 cell lines, and antimicrobial activity against P. aeruginosa, S. epidermidis and C. albicans., whereas complex 3 was more effective than complex 4. The mechanism of action were evaluated and revealed their target was DNA and cell wall. Thus, complex 3 convey a new insight to develop antitumor drug which simultaneously control the secondary infection in immunosuppressed cancer patients.

The design and synthesis of a novel series of 2,6-disubstituted pyrazine derivatives as CK2 kinase inhibitors is described. Structure-guided optimization of a 5-substituted-3-thiophene carboxylic acid screening hit (3a) led to the development of a lead compound (12b), which shows inhibition in both enzymatic and cellular assays. Subsequent design and hybridization efforts also led to the unexpected identification of analogs with potent PIM kinase activity (14f).

The general expressions we recently derived for calculating internal conversion decay rate constants between two adiabatic and between two diabatic displaced-distorted-rotated harmonic potential energy surfaces (including all vibrational modes) are now applied to determine the decay rate constants of 1B(2u)(pi pi*)-->1B(3u)(n pi*), 1B(2u)(pi pi*)-->1A(g), and 1B(3u)(n pi*)-->1A(g) internal conversions in pyrazine molecule. The minimal models with respect to the number and the types of vibrational modes are investigated for these processes. An exact expression for the adiabatic vibrational frequencies of the coupling modes in terms of interstate coupling constants and the parameters determining the diabatic potential energy surfaces are also derived.

Abstract In the study, some new 1,3,4-thiadiazole compounds were synthesized and we have reported identification of the structures by using UV-Vis, FT-IR, 1H NMR, 13C NMR and Mass spectroscopic methods. Antimicrobial activities of the compounds against three microorganisms, namely, Candida albicans ATCC 26555, Staphylococcus aureus ATCC 9144, and Escherichia coli ATCC 25922 were investigated by using disk diffusion method. These thiadiazoles exhibited an antimicrobial activity against Staphylococcus aureus and Candida albicans. The experimental data was supported by the quantum chemical calculations. Density functional theory (DFT) calculations were carried out to obtain the ground state optimized geometries of the molecules using the B3LYP, M06 and PBE1PBE methods with 3–21 g, 4–31 g, 6–311++g(2d,2p), cc-pvtz and cc-pvqz basis sets in the different combinations. Frontier molecular orbitals (FMOs) energies, band gap energies and some chemical reactivity parameters were calculated by using the aforementioned methods and basis sets, and the results were also compared with the experimental UV-Vis data.