Iridium Cyclometalated Complexes with Axial Symmetry.Synthesis and Photophysical Properties of a trans-Biscyclometalated Complex Containing the Terdentate Ligand 2,6-Diphenylpyridine

摘要

The first example of an iridium biscyclometalated complex with a C^N^C 2,6-diphenylpyridine(dppy)-type ligand,[(4'-(4"bromophenyl)-2:2',6':2"-terpyridine)lr(2,6-diphenyl-4-(4-tolyl)pyridine)](N0_3)(1),has been synthesized and characterized by various techniques such as X-ray crystallography,mass spectrometry,approx 1H and approx 13C NMR,cyclic voltammetry,and both steady-state and time-resolved emission and absorption studies.Preliminary density functional theory calculations have also been conducted.1 crystallizes in the monoclinic space group P2_1.The crystallographic data are as follows:C_45H_31BrN_4lr0_3 centre dot 2H_20,a=17.4308(4) A,b=9.0312(2) A,c=26.7601(7) A,beta=104.496-(1)deg,V=4078.5(2) A~3,Z=4.The relatively long Ir-C distances(2.122 and 2.094 A)reflect the strong mutual trans effect of the cyclometalating carbons.The complex exhibits strong visible absorption and long-lived(1.7 mus) emission(lambda_max,690 nm)in room temperature solution.The inherent asymmetry of the coordination environment offers a unique directional character to the emitting excited state,which is predominately ligand-to-ligand charge transfer(dppy-2,2':6',2"-terpyridine)in nature.