Investigation on Optical and Biological Properties of 2-(4-Dimethylaminophenyl)benzothiazole Based Cycloplatinated...

The optical and biological properties of 2-(4-dimethylaminophenyl)benzothiazole cycloplatinated complexes featuring bioactive ligands ([{Pt(Me₂ N-pbt)(C₆ F₅ )}L] [L=Me₂ N-pbtH 1, p-dpbH (4-(diphenylphosphino)benzoic acid) 2, o-dpbH (2-(diphenylphosphino)benzoic acid) 3), [Pt(Me₂ N-pbt)(o-dpb)] 4, [{Pt(Me₂ N-pbt)(C₆ F₅ )}₂ (μ-PR_n P)] [PR₄ P=O(CH₂ CH₂ OC(O)C₆ H₄ PPh₂ )₂ 5, PR₁₂ P=O{(CH₂ CH₂ O)₃ C(O)C₆ H₄ PPh₂ }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 O₂ and the formation of ¹ O₂ , 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 O₂ , which causes a local degassing. Me₂ 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.