| Abstrakt: |
Based on 2-phenylbenzothiazole (pbt) and 2-(4-dimethylaminophenyl)benzothiazole (Me2N-pbt), mononuclear [Pt(pbt)(R′2-pzH)2]PF6(R′2-pzH = pzH 1a, 3,5-Me2pzH 1b, 3,5-iPr2pzH 1c) and diplatinum (PtII–PtII) [Pt(pbt)(μ-R′2pz)]2(R′2-pz = pz 2a, 3,5-Me2pz 2b, 3,5-iPr2pz 2c) and [Pt(Me2N-pbt)(μ-pz)]2(3a) complexes have been prepared. In the presence of sunlight, 2aand 3aevolve, in CHCl3solution, to form the PtIII–PtIIIcomplexes [Pt(R-pbt)(μ-pz)Cl]2(R = H 4a, NMe25a). Experimental and computational studies reveal the negligible influence of the pyrazole or pyrazolate ligands on the optical properties of 1a–cand 2a,b, which exhibit a typical 3IL/3MLCT emission, whereas in 2cthe emission has some 3MMLCT contribution. 3adisplays unusual dual, fluorescence (1ILCT or 1MLCT/1LC), and phosphorescence (3ILCT) emissions depending on the excitation wavelength. The phosphorescence is lost in aerated solutions due to sensitization of 3O2and formation of 1O2, 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 4aand 5a, the lowest electronic transitions (S1–S3) have mixed characters (LMMCT/LXCT/L’XCT 4aand LMMCT/LXCT/ILCT 5a) and they are weakly emissive in rigid media. The 1O2generation property of complex 3ais successfully used for the photooxidation of p-bromothioanisol showing its potential application toward photocatalysis. |
