Metal based drugs have shown great promise as anticancer chemotherapeutic agents over the past five decades. Due to the lack of specificity and detrimental side effects of platinum drugs which are heavily used in the chemotherapeutic regimens, however, scientists are striving to find alternatives. On that topic, Ru-based drugs have emerged as a potential alternative to Pt therapy due to fewer side effects as well as more activity towards Pt drug resistant cells. Ruthenium complexes have reactive excited states, such that selective activation of Ru drugs by means of visible light, an approach known as Photodynamic Therapy (PDT), is a promising strategy for endoscopically accessible tumors.1 One issue however is that PDT therapy relies on singlet oxygen (1O2) generation and a problem arises with many malignant tumors which are often hypoxic and thus new strategies are in order. In this vein, our group has developed a series of solvated dinuclear Ru(II) compounds, [Ru2(μ-BL)(NCCH3)8](PF6)4 [(μ-BL) = dpq (2,3-di(pyridin-2-yl)quinoxaline) (1); dpb (2,3-di(pyridin-2-yl)benzo[g]quinoxaline) (2)] and [Ru2(μ-tppz)(NCCH3)6](PF6)4 [(μ-tppz)= (2,3,5,6-tetra(pyridin-2-yl)pyrazine) (3)]. By using highly electron withdrawing ligands we can red-shift the 1MLCT transition closer to the therapeutic window (600 nm- 850nm) for PDT. Irradiation of the compound with a suitable wavelength of light can photorealease “caged” acetonitrile molecules inside the cell and the resulting coordinatively unsaturated compound can bind to DNA in a manner akin to cisplatin.2 NMR techniques, electronic absorption spectroscopy, electrochemical measurements, elemental analysis and X-ray diffraction were used to characterize the compounds. The crystal structures of (1) and (3) were further employed to interpret our results based on computational analyses. The photochemical studies were performed with compound (3) using NMR techniques and electronic absorption spectroscopy which revealed release of acetonitrile with visible light (λ ≥ 610 nm) irradiation.3 Compounds (1) and (2) are also under investigation and recent results will be presented. 1 Dolmans, D. E. J. G. J.; Fukumura, D.; Jain, R. K. Nat. Rev. Cancer 2003, 3, 380-387. 2 Sgambellone, M. A.; David, A.; Garner, R. N.; Dunbar, K. R.; Turro, C. J. Am. Chem. Soc. 2013, 135, 11274-11282. 3 Liu, Y.; Turner, D.; Singh, T.; Angeles-Boza, A.; Chouai, A.; Dunbar, K.; Turro, C. J. Am. Chem. Soc., 2009, 131, 26-27.

Synthesis, characterization, and photochemical studies of solvated dinuclear Ru(II) compounds with quinoxaline and pyrazine based bridging ligands

249th National Meeting (2015)

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