Synthesis and Photophysical Properties of Bis-Cyclometallated Iridium(III)-Styryl Complexes and Their Saturated Analogues

摘要

This manuscript reports the synthesis and photophysical investigation of a series of Ir~(III)complexes Ir(C^N)2(O^O)which are functionalized in the para position of the pyridine ring by styryl groups substituted with electron-donor and-acceptor end groups.The saturated derivative Ir(C^N-ppy-4-CH2CH2C6H40Me)2(O^O-acac)(4a-H2)was formed from [Ir(C^N-ppy-4-CH=CHC6H4OMe)2]2(mu-Cl)2(3a)at 140 °C,whereas at 80 °C the parent unsaturated complexes Ir(C^N-ppy-4-CH=CHC6H4R)2(O^O)[O^O = acac,R = OMe(4a),NEt2(4b),H(4c),NO2(4d);O^O = dpm,R = OMe(5a),NEt2(5b)] were isolated.The saturated complex 4a-H2 exhibits in- tense green emission with a 36 % quantum yield at 298 K.The styryl complexes 4a-4d,5a and 5b are very weakly emissive at 298 K,but show intense red luminescence in alcohol glass at 77 K.The amino-and nitro-substituted complexes 4b and 4d give low-energy emission(lambda_(em)= 651 and 647 nm,respectively).The emissive states of these complexes are believed to possess predominant triplet intra-ligand charge-transfer(~3ILCT)and metal-to-ligand charge-transfer(~3MLCT)character,respectively.