Simple Cu(I) Complexes with Unprecedented Excited-State Lifetimes

This report describes new, readily accessible copper(I) complexes that can exhibit unusually long-lived, high quantum yield emissions in fluid solution. The complexes are of the form [Cu(NN)(POP)]+ where NN denotes 1,10-phenanthroline (phen), 2,9-dimethyl-1,10-phenanthroline (dmp) or 2,9-di-n-butyl-1,10-phenanthroline (dbp) and POP denotes bis[2-(diphenylphosphino)phenyl] ether. Modes of characterization include X-ray crystallography and cyclic voltammetry. The complexes each have a pseudotetrahedral coordination geometry and a Cu(II)/Cu(I) potential upward of +1.2 V vs Ag/AgCl. In room-temperature dichloromethane solution, charge-transfer excited states of the dmp and dbp derivatives exhibit respective emission quantum yields of 0.15 and 0.16 and corresponding excited-state lifetimes of 14.3 and 16.1 μs, respectively. Despite the fact that coordinating solvents usually quench charge-transfer emission from copper systems, the photoexcited dmp (dbp) complex retains a lifetime of 2.4 μs (5.4 μs) in methanol.

本报告介绍了一类全新且易于制备的铜(I)配合物，此类配合物在流体溶液中可展现出超长寿命、高量子产率的发光特性。该类配合物的通式为[Cu(NN)(POP)]⁺，其中NN代表1,10-邻菲啰啉（1,10-phenanthroline，简写phen）、2,9-二甲基-1,10-邻菲啰啉（2,9-dimethyl-1,10-phenanthroline，简写dmp）或2,9-二正丁基-1,10-邻菲啰啉（2,9-di-n-butyl-1,10-phenanthroline，简写dbp），POP则代表双[2-(二苯基膦基)苯基]醚（bis[2-(diphenylphosphino)phenyl] ether）。该系列配合物的表征手段包括X射线晶体学与循环伏安法。所有配合物均具有假四面体配位几何构型，且相对于Ag/AgCl参比电极的Cu(II)/Cu(I)氧化还原电位不低于+1.2 V。在室温二氯甲烷溶液中，dmp与dbp衍生物的电荷转移激发态分别展现出0.15和0.16的发射量子产率，对应激发态寿命分别为14.3 μs与16.1 μs。尽管配位溶剂通常会猝灭铜系配合物的电荷转移发光，但光激发后的dmp（dbp）配合物在甲醇溶剂中仍分别保留2.4 μs（5.4 μs）的激发态寿命。