A theoretical analysis of the phosphorescence efficiencies of Cu(i) complexes

Abstract

We herein report a theoretical analysis using density functional theory (DFT) and time-dependent DFT (TDDFT) to study the electronic structures and photophysical properties of mixed-ligand Cu(i) complexes. An evaluation of the non-radiative and radiative decay rate constants (knr and kr) is presented. It is found that large spin-orbit coupling (SOC) matrix elements do not necessarily result in large values of kr. Introducing the POP (bis[2-(diphenylphosphino)phenyl]ether) ligand instead of a pair of PPh3 (triphenylphosphine) ligands, it is found that the ether linkage plays an important role in governing the quantum efficiency of the studied complexes. However, the balance between hole injection and electron acceptance, which leads to the quantum yield of [Cu(dmp)(POP)](+) being close to that of [Cu(dbp)(POP)](+), is another important factor in tuning the quantum efficiency. A thorough understanding of the effect of the coordinating ligand on the photophysical behavior of a transition metal complex is desirable for the rational synthesis of highly phosphorescent materials.

Energy Dependence of the Ruthenium(II)-Bipyridine Metal-to-Ligand-Charge-Transfer Excited State Radiative Lifetimes: Effects of ππ*(bipyridine) Mixing

“…We have attempted to find well behaved Ru-bpy chromophores with emission maxima at 35 values of k RAD appear to be largely the result of mixing between the 3 MLCT and *(bpy) excited states, or based on eq 5 and setting IL = * for these complexes,…”

“…While spin-orbit coupling is likely to be important in promoting such transitions in heavy metal complexes, it will be most important when the spin-orbit coupled electronic state is near in energy to the emitting state and therefore a higher energy excited state. 34,35 The various formulations of the transition moment summarized above assume that no …”

Copper Photosensitizers Containing P^N Ligands and Their Influence on Photoactivity and Stability

“…As a consequence of this large distortion the triplet excited states can be efficiently quenched by solvent molecules . A reduced distortion and a shielding through the diphosphine ligand was found for [(DPEphos)Cu(dmp)] + (DPEphos=bis[2‐(diphenylphosphino)phenyl] ether) with a change from 82.5° (S 0 ) to 69.0° (S 1 ) and 70.2° (T 1 ), resulting in a considerably evolution of H 2 . In contrast, the angles between the planes of 1 and 2 in the excited states were obtained by TDDFT calculation to be 60.6° (59.6° in T 1 ) and 50.9° (55.4° in T 1 ), respectively (see Table SI7 and Figure SI 17).…”

Structures and photophysical properties of copper(i) complexes bearing diphenylphenanthroline and bis(diphenylphosphino)alkane: the effect of phenyl groups on the phenanthroline ligand

“…16,17 One of the most intensively studied types of complexes is the copper(I) species having a 2,9-disubstituted 1,10-phenanthroline ligand and a diphosphine ligand. 18 We previously reported a series of copper complexes (1a, 2a, and 3a shown in Scheme 1) bearing dmp (= 2,9dimethyl-1,10-phenanthlorine) and a diphosphine ligand. 19 Armaroli et al reported that a complex [Cu(dmpp)(DPEphos)] + , where dmpp and DPEphos are 2,9-dimethyl-4,7-diphenyl-1,10phenanthroline and 2,2′-bis(diphenylphosphino)diphenyl ether, respectively, shows high-quantum yield luminescence in solution.…”