Phenylbenzothiazole-Based Platinum(II) and Diplatinum(II) and (III) Complexes with Pyrazolate Groups: Optical Properties and Photocatalysis.

Based on 2-phenylbenzothiazole (pbt) and 2-(4-dimethylaminophenyl)benzothiazole (MeN-pbt), mononuclear [Pt(pbt)(R'-pzH)]PF (R'-pzH = pzH , 3,5-MepzH , 3,5-PrpzH ) and diplatinum (Pt-Pt) [Pt(pbt)(μ-R'pz)] (R'-pz = pz , 3,5-Mepz , 3,5-Prpz ) and [Pt(MeN-pbt)(μ-pz)] () complexes have been prepared. In the presence of sunlight, and evolve, in CHCl solution, to form the Pt-Pt complexes [Pt(R-pbt)(μ-pz)Cl] (R = H , NMe ). Experimental and computational studies reveal the negligible influence of the pyrazole or pyrazolate ligands on the optical properties of - and ,, which exhibit a typical IL/MLCT emission, whereas in the emission has some MMLCT contribution. displays unusual dual, fluorescence (ILCT or MLCT/LC), and phosphorescence (ILCT) emissions depending on the excitation wavelength. The phosphorescence is lost in aerated solutions due to sensitization of O and formation of O, whose determined quantum yield is also wavelength dependent. The phosphorescence can be reversibly photoinduced (365 nm, ∼ 15 min) in oxygenated THF and DMSO solutions. In and , the lowest electronic transitions (S-S) have mixed characters (LMMCT/LXCT/L'XCT and LMMCT/LXCT/ILCT ) and they are weakly emissive in rigid media. The O generation property of complex is successfully used for the photooxidation of -bromothioanisol showing its potential application toward photocatalysis.