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

The optical and biological properties of 2-(4-dimethylaminophenyl)benzothiazole cycloplatinated complexes featuring bioactive ligands ([{Pt(Me2N-pbt)(C6F5)}L] [L=Me2N-pbtH 1, p-dpbH (4-(diphenylphosphino)benzoic acid) 2, o-dpbH (2-(diphenylphosphino)benzoic acid) 3), [Pt(Me2N-pbt)(o-dpb)] 4, [{Pt(Me2N-pbt)(C6F5)}(2)(mu-PRnP)] [PR4P=O(CH2CH2OC(O)C6H4PPh2)(2) 5, PR12P=O{(CH2CH2O)(3)C(O)C6H4PPh2}(2) 6] are presented. Complexes 1-6 display (ILCT)-I-1 and metal-perturbed (ILCT)-I-3 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 O-3(2) and the formation of O-1(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 O-1(2), which causes a local degassing. Me2N-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.

Automated summary

The optical and biological properties of cycloplatinated complexes with bioactive ligands 2-(4-dimethylaminophenyl)benzothiazole were studied. These complexes displayed dual emissions, with warm-white emissions achieved for certain compositions. They showed potential in cancer cell targeting, with one complex exhibiting high selectivity towards non-tumoral cells.