Dicopper(I) Paddle-Wheel Complexes with Thermally Activated Delayed Fluorescence Adjusted by Ancillary Ligands
Alexander V. Artem’ev, Maria P. Davydova, Alexey S. Berezin, Maxim R. Ryzhikov, Denis G. Samsonenko⧫
Abstract
A suite of paddle-wheel shaped [Cu 2 (PymPPh 2 ) 3 (L an ) n ](PF 6 ) 2 complexes showing efficient thermally activated delayed fluorescence (TADF) has been synthesized. In these complexes, Cu(I) ions are P, N -bridged by three diphenyl(2-pyrimidyl)phosphine (PymPPh 2, L) ligands in a “head-to-tail” fashion, and one or both metals are also capped by the ancillary ligand (L an = MeOH, Me 2 CO, MeCN, PhCN). At ambient temperature, the solid complexes emit TADF with the quantum yield of up to 85% and the lifetimes of from 9.6 to 27 μs. The ancillary ligands, whose orbitals negligibly contribute to the radiative 1 (M + L + L an )LCT state, remarkably adjust emission energies and Δ E (S 1 –T 1 ) energy splitting magnitudes of the emitters obtained. Thus, depending on structure and/or number of the L an molecules, the emission maxima vary from 500 to 563 nm, and the Δ E (S 1 –T 1 ) gaps range 550–1100 cm –1 . Such tunable TADF characteristics coupled with the excellent solubility and air-stability make the complexes presented to be promising TADF materials.