Synthesis, characterization and biological evaluation of dipicolylamine sulfonamide derivatized platinum complexes as potential anticancer agents.

Three new Pt complexes, [PtCl 2 (N(SO 2 (2-nap))dpa)], [PtCl 2 (N(SO 2 (1-nap))dpa)] and [PtCl 2 (N(SO 2 pip)dpa)], containing a rare 8-membered ring were synthesized in good yield and high purity by utilizing the ligands N(SO 2 (2-nap))dpa, N(SO 2 (1-nap))dpa and N(SO 2 pip)dpa, which contain a dipicolylamine moiety. Structural studies of all three complexes confirmed that the ligands are bound in a bidentate mode via Pt-N (pyridyl) bonds forming a rare 8-membered ring. The intense fluorescence displayed by the ligands is quenched upon coordination to Pt. According to time dependent density functional theory (TDDFT) calculations, the key excitations of N(SO 2 (2-nap))dpa and [PtCl 2 (N(SO 2 (1-nap))dpa)] involve the 2-nap-ligand-centered π → π* excitations. While all six compounds have shown antiproliferative activity against human breast cancer cells (MCF-7), the N(SO 2 pip)dpa and N(SO 2 (2-nap))dpa ligands and [PtCl 2 ((NSO 2 pip)dpa)] complex have shown significantly high cytotoxicity, directing them to be further investigated as potential anti-cancer drug leads.