120th General Meeting of the KCS

Type Poster Presentation
Area Industrial Chemistry
Room No. Exhibition Hall 2+3
Time 10월 20일 (금요일) 13:00~14:30
Code IND.P-68
Subject Investigation of the Electrochemical, Photochemical, and Spectroelectrochemical Properties of the Ir (III)/Pt (II) and Ir(III)/Ir(III) Bimetal Complex bridged by Dipyridylpyrazine
Authors Bo-Sun Yun, Yang-Jin Cho, So-Yoen Kim, DAE WON CHO, Chul Hoon Kim, Sang Ook Kang, Ho-Jin Son*
Department of Advanced Materials Chemistry, Korea University, Korea
Abstract We investigated the electrochemical and excited-state properties of 2,3-bis(2-pyridyl)pyrazine (dpp)-bridged bimetallic complexes, (L)2Ir-dpp-PtCl (1, L = 2-(4′,6′-difluorophenyl)pyridinato-N,C2 (dfppy); 2, L = 2-phenylpyridinato-N,C2 (ppy)) and [(L)2Ir]2(dpp) (3, L = dfppy; 4, L = ppy) compared to monometallic complexes, (L)2Ir-dpp (5, L = dfppy; 6, L = ppy) and dpp-PtCl (dpp-PtIICl2) (7). The same L (C^N) ligand exhibited close similarities in their electrochemical, photophysical, photochemical, and transient absorption decay behavior. The similarities were: potentials of the dpp0/–, dpp–/2–, and L0/– couples in CV, the absorption spectra with similar spectral shape and absorption coefficients, the emission spectra at 77 K similar in wavelength and lifetime, the complete or extensive quenching of emission at room temperature, and the selective photochemical splitting of the metal-dpp linkages. The lowest-energy absorption and emission is attributed by L(π)-participated MLCT transitions occurring between the (L)2Ir-based orbitals and dpp-localized π* orbital. The low efficiencies of photoluminescence of dpp-bridged Ir-Pt and Ir-Ir bimetallic complexes (1‒4) could be explained by assuming the involvement of crossing to Pt- and Ir-based d-d states from the emissive state. The crossing to such d-d states has been assumed to be thermally accessible as a consequence of the strained planar conformation of dpp that should give impacts on relative energy levels of the relevant d-d states in the bimetallic complex.
E-mail yunbosun@korea.ac.kr