Investigation on Optical and Biological Properties of 2‐(4‐Dimethylaminophenyl)benzothiazole Based Cycloplatinated Complexes
Rebeca Lara, Gonzalo Millán, M. Teresa Moreno, Elena Lalinde, Elvira Alfaro‐Arnedo, Icíar P. López, Ignacio M. Larráyoz, José G. Pichel
Abstract
Abstract The optical and biological properties of 2‐(4‐dimethylaminophenyl)benzothiazole cycloplatinated complexes featuring bioactive ligands ([{Pt(Me 2 N‐pbt)(C 6 F 5 )}L] [L=Me 2 N‐pbtH 1 , p ‐dpbH (4‐(diphenylphosphino)benzoic acid) 2 , o ‐dpbH (2‐(diphenylphosphino)benzoic acid) 3 ), [Pt(Me 2 N‐pbt)( o ‐dpb)] 4 , [{Pt(Me 2 N‐pbt)(C 6 F 5 )} 2 (μ‐PR n P)] [PR 4 P=O(CH 2 CH 2 OC(O)C 6 H 4 PPh 2 ) 2 5 , PR 12 P=O{(CH 2 CH 2 O) 3 C(O)C 6 H 4 PPh 2 } 2 6 ] are presented. Complexes 1 – 6 display 1 ILCT and metal‐perturbed 3 ILCT dual emissions. The ratio between both bands is excitation dependent, accomplishing warm‐white emissions for 2 , 5 and 6 . The phosphorescent emission is lost in aerated solutions owing to photoinduced electron transfer to 3 O 2 and the formation of 1 O 2 , as confirmed in complexes 2 and 4 . They also exhibit photoinduced phosphorescence enhancement in non‐degassed DMSO due to local oxidation of DMSO by sensitized 1 O 2 , which causes a local degassing. Me 2 N‐pbtH and the complexes specifically accumulate in the Golgi apparatus, although only 2 , 3 and 6 were active against A549 and HeLa cancer cell lines, 6 being highly selective in respect to nontumoral cells. The potential photodynamic property of these complexes was demonstrated with complex 4 .