Photophysical and electrochemical properties of Ru(ii) complexes containing tridentate bisphosphino-oligothiophene ligands
作者:Angela M. Kuchison、Michael O. Wolf、Brian O. Patrick
DOI:10.1039/c1dt10217f
日期:——
Nine Ru(II) complexes containing the conjugated oligothiophene ligands 3,3′′-bis(diphenylphosphino)-2,2′:5′,2′′-terthiophene (P2T3) and 4′,3′′′-bis(diphenylphosphino)-3,3′′′′-dihexyl- 2,2′:5′,2′′:5′′,2′′′:5′′′,2′′′′-pentathiophene (P2T5) were prepared and characterized. P2T3 and P2T5 bond as tridentate ligands and three of the complexes (1, 2 and 5) form green five-coordinate Ru(II) complexes in solution. Cyclic voltammetry, variable temperature UV-vis spectroscopy and time-resolved transient absorption spectroscopy were used to characterize the electronic properties of the complexes. Increased conjugation in the complexes containing the P2T5 ligand resulted in a lowering of the oxidation potential of the oligothiophene, but electropolymerization was not observed. The electronic spectra were dominated by π–π* transitions. All of the complexes were non-emissive both at room temperature and low temperature, indicating the excited state decays by other, non-radiative pathways. The transient absorption spectrum of complex 7 shows a species with a band at 475 nm and a lifetime of ∼100 ns, assigned to a ligand-based triplet state.
含有共轭低聚噻吩配体 3,3''-双(二苯基膦)-2,2':5',2''-三联噻吩 (P2T3) 和 4',3'''-双(二苯基膦) 的九个 Ru(II) 配合物)-3,3''''-二己基-2,2':5',2'':5'',2''':5''',2''''-五噻吩(P2T5)并进行了表征。 P2T3 和 P2T5 作为三齿配体键合,其中三个配合物(1、2 和 5)在溶液中形成绿色五配位 Ru(II) 配合物。使用循环伏安法、变温紫外可见光谱和时间分辨瞬态吸收光谱来表征配合物的电子性质。含有 P2T5 配体的复合物中的缀合增加导致低聚噻吩的氧化电位降低,但没有观察到电聚合。电子光谱以 π-π* 跃迁为主。所有配合物在室温和低温下均不发光,表明激发态通过其他非辐射途径衰减。配合物 7 的瞬态吸收光谱显示,该物质的谱带位于 475 nm,寿命约为 100 ns,属于基于配体的三重态。