ISBN: 978-83-60043-10-3 - eurobic9

Eurobic9, 2-6 September, 2008, Wrocław, Poland
P172. New Photoactivable Ruthenium Complexes
L. Salassa a , A.M. Pizarro a , P.J. Sadler a , C. Garino b , R. Gobetto b
a Department of Chemistry, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, United Kingdom
b Dipartimento di Chimica IFM, Università di Torino, via P. Giuria 7, 10125, Torino, Italy
Metal complexes able to dissociate coordinated ligands when irradiated by light of appropriate wavelength have
stimulated much recent research. Such attention is motivated by the possibility of phototriggering specific and
desired interactions between the metal complexes and biological targets, like DNA,[1] but also by the
opportunity to deliver biologically-active small molecules.[2]
We have studied photoactivable ruthenium complexes of formula [Ru(N�N)(4AP)4] 2+ , where N�N = bpy (1), phen
(2), 4-methyl-phen (3) and dppz (4) and 4AP = 4-aminopyridine. Complexes 1�4 are stable in the dark, but
undergo double ligand substitution when irradiated with visible light. The case of complex 1 is discussed in
detail. 1 shows two photoreactions leading to the formation of the photoproducts mer-[Ru(bpy)(4AP)3(H2O)] 2+
and trans-(4AP)-[Ru(bpy)(4AP)2(H2O)2] 2+ . The photodissociation yields are ϕ1 = (6.1±1.0) 10 �3 and
ϕ2 = (1.7±0.1) 10 �4 , respectively. Insights on the ligand photodissociation mechanism were obtained by
combining a mixed experimental and theoretical approach. DFT and TDDFT were used to characterize the
photophysical properties of the complex as well as to determine the relevant singlet and triplet excited states for
the dissociation mechanism.[3] Finally, in vitro cytotoxicity to cancer cells of complexes 1�4 will be discussed
with the aim of designing new photoactivable anticancer agents.
References:
[1] F. S. Mackay, J. A. Woods, P. Heringová, J. Kašpárková, A. M. Pizarro, S. A. Moggach, S. Parsons, V.
Brabec, P. J. Sadler, PNAS, 104, 20743 (2007).
[2] L. Zayat, C. Calero, P. Albores, L. Baraldo, R. Etchenique, J. Am. Chem. Soc., 125, 882 (2003).
[3] L. Salassa, C. Garino, G. Salassa, R. Gobetto, C. Nervi, J. Am. Chem. Soc., In Press (2008).
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