Synthesis, Characterization and Biological Application of Pyrazolo[1,5-a]pyrimidine Based Organometallic Re(I) Complexes.

The neutral rhenium(I) complexes (I-VI) of type [ReCl(CO)3Ln-] where L1 = 7-phenyl-5-(pyridin-2-yl)pyrazolo[1,5-a]pyrimidine, L2 = 7-(4-bromophenyl)-5-(pyridin-2-yl)pyrazolo[1,5-a]pyrimi- dine, L3 = 7-(4-chlorophenyl)-5-(pyridin-2-yl)pyrazolo[1,5-a]pyrimidine, L4 = 7-(2-chlorophenyl) -5-(pyridin-2-yl)pyrazolo[1,5-a]pyrimidine, L5 = 7-(4-methoxyphenyl)-5-(pyridin-2-yl)pyrazolo [1,5-a]pyrimidine, L6 = 5-(pyridin-2-yl)-7-(p-tolyl)pyrazolo[1,5-a]pyrimidine were synthesized and characterized by 13C-APT, 1H-NMR, IR, electronic spectra, magnetic moment and conductance measurement. The anti-proliferative activity on HCT116 cells by MTT assay suggests potent cytotoxic nature of complexes, even some complexes have better activity than standard drug cisplatin, oxaliplatin, and carboplatin. The complexes found to have better antimicrobial activity compare to pyrazolo pyrimidine ligands. The theoretical study of compounds-DNA interactions was examined by molecular docking as a supportive tool to the experimental data, which suggests the groove mode of binding. The values of docking energy for compounds-DNA interaction were found in the range of -230.31 to -288.34 kJ/mol. The intrinsic binding constant values of complexes (1.1-3.5×105 M-1) were found higher than the ligands (0.32-1.8×105 M-1).