Synthesis, spectroscopical characterization and the biological activity in vitro of new platinum(II) complexes with imidazo[1,5-a]-1,3,5-triazine derivatives and dimethylsulfoxide

A series of platinum(II) complexes with 6,8-dimethylimidazo[1,5-a]-1,3,5-triazin-4(3H)-one (6,8-DiMe-4-O-IMT) (I) and 6,8-dimethyl-2-thioxo-2,3-dihydroimidazo[1,5-a]-1,3,5-triazin-4(1H)-one (6,8-DiMe-4-O-2-S-IMT) (II) of formula trans-[PtCl2(dmso)(6,8-DiMe-4-O-IMT)] (1a) and trans-[PtCl2(dmso)(6,8-DiMe-4-O-2-S-IMT)] (2a) have been prepared and characterized with 1H, 13C, 15N, 195Pt NMR and IR. Significant 15N NMR upfield coordination shifts (81–96 ppm) of N(7) atom indicate this nitrogen atom as a coordination site. The multinuclear NMR and IR spectra indicate the square planar geometry with N(7) bonded heterocycles, S-bonded dimethylsulfoxide and two trans chloride anions. The platinum(II) complexes were tested for their antiproliferative activity in vitro against the cells of four human cell lines: SW707 rectal adenocarcinoma, A549 non-small cell lung carcinoma, T47D breast cancer and HCV29T bladder cancer. The activity of (1a, 2a) was lower than that of cisplatin.

Graphical abstractA number of platinum(II) complexes containing 6,8-dimethylimidazo-[1,5-a]-1,3,5-triazin-4(3H)-one (6,8-DiMe-4-O-IMT) and 6,8-dimethyl-2-thioxo-2,3-dihydroimidazo-[1,5-a]-1,3,5-triazin-4(1H)-one (6,8-DiMe-4-O-2-S-IMT) of the type [PtCl2(dmso)(L) have been prepared and characterized with 1H, 13C, 15N, 195Pt NMR and IR. The platinum(II) complexation results in a large upfield shift of 15N NMR signals of coordinated nitrogens (81–96 ppm) and proves that coordination of investigated ligands occurs via N(7). The molecular structure of platinum(II) complexes indicates that Pt(II) ion has the square planar geometry with N(7) bonded ligand, S-bonded dimethylsulfoxide and two trans chloride anions.Figure optionsDownload full-size imageDownload as PowerPoint slide