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Bioinorganic Chemistry and Applications
Volume 2016, Article ID 2675937, 10 pages
http://dx.doi.org/10.1155/2016/2675937
Research Article

Synthesis, Characterization, and Biological Studies of a Piperidinyl Appended Dipicolylamine Ligand and Its Rhenium Tricarbonyl Complex as Potential Therapeutic Agents for Human Breast Cancer

1Department of Chemistry, University of Sri Jayewardenepura, Nugegoda, Sri Lanka
2Department of Zoology and Environmental Science, University of Colombo, Colombo, Sri Lanka
3Department of Chemistry, Louisiana State University, Baton Rouge, LA, USA

Received 24 July 2016; Accepted 6 September 2016

Academic Editor: Konstantinos Tsipis

Copyright © 2016 Amali Subasinghe et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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 CH2 signal seen as a singlet (4.54 ppm) in a 1H NMR spectrum of the ligand in DMSO- appears 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 intraligand and 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−1 for N(SO2pip)dpa appeared at a shorter frequency, at 830 cm−1 in 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 IC50 values given by human breast cancer cells, MCF-7, (N(SO2pip)dpa = 139 μM, [Re(CO)3(N(SO2pip)dpa)]+ = 360 μM) 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.