title: Synthesis, Characterization, and Biological Studies of a Piperidinyl Appended Dipicolylamine Ligand and Its Rhenium Tricarbonyl Complex as Potential Therapeutic Agents for Human Breast Cancer.
abstract: A novel ligand bearing a central piperidinyl sulfonamide group, N(SO2pip)dpa, and its corresponding Re tricarbonyl complex, [Re(CO)3(N(SO2pip)dpa)]+, have been synthesized in good yield. The methylene CH2signal seen as a singlet (4.54 ppm) in a1H NMR spectrum of the ligand in DMSO-d6appears as two doublets (5.39, 5.01 ppm) in a spectrum of the [Re(CO)3(N(SO2pip)dpa)]+complex and confirms the presence of magnetically nonequivalent protons upon coordination to Re. Structural results revealed that the Re-N bond lengths fall within the normal range establishing coordination of ligand to metal. The presence of intraligandπ→π⁎andn→π⁎transitions is indicated by the absorption peaks around 200-250 nm in UV-visible spectra. Absorption peaks in UV-visible spectra around 300 nm for metal complexes were identified as MLCT transitions. The S-N stretch observed as a strong peak at 923 cm-1for N(SO2pip)dpa appeared at a shorter frequency, at 830 cm-1in an FTIR spectrum of the [Re(CO)3(N(SO2pip)dpa)]+. The intense fluorescence displayed by the N(SO2pip)dpa ligand has quenched upon coordination to Re. Relatively low IC50values given by human breast cancer cells, MCF-7, (N(SO2pip)dpa = 139μM, [Re(CO)3(N(SO2pip)dpa)]+= 360μM) indicate that N(SO2pip)dpa and [Re(CO)3(N(SO2pip)dpa)]+are promising novel compounds that can be further investigated on their usage as potential anticancer agents.
authors.affiliation: Department of Chemistry, University of Sri Jayewardenepura, Nugegoda, Sri Lanka.
authors.forename: Amali
authors.initials: A
authors.lastname: Subasinghe
authors.affiliation: Department of Zoology and Environmental Science, University of Colombo, Colombo, Sri Lanka.
authors.forename: Inoka C
authors.initials: IC
authors.lastname: Perera
authors.affiliation: Department of Chemistry, Louisiana State University, Baton Rouge, LA, USA.
authors.forename: Svetlana
authors.initials: S
authors.lastname: Pakhomova
authors.affiliation: Department of Chemistry, University of Sri Jayewardenepura, Nugegoda, Sri Lanka.
authors.forename: Theshini
authors.identifier: 0000-0002-0624-4984
authors.initials: T
authors.lastname: Perera