Perhalophenyl Three-Coordinate Gold(I) Complexes as TADF Emitters: A Photophysical Study from Experimental and Computational Viewpoints

Abstract

We report the synthesis of novel perhalophenyl three-coordinated gold(I) complexes using 1,2-bis-(diphenylphosphino)benzene (dppBz) as the chelating ligand and [AuR(tht)] (R = C 6 F 5 , C 6 Cl 2 F 3 , C 6 Cl 5 ) as the perhalophenyl− gold(I) source, leading to [AuR(dppBz)] (R = C 6 F 5 (1), C 6 Cl 2 F 3 (2), C 6 Cl 5 (3)) complexes. The solid-state structures of compounds 2 and 3 consist of discrete three-coordinated Au(I) complexes, which show a distorted trigonal planar geometry for the gold center with dissimilar Au−P distances. The distorted structural arrangement is closely related to its photophysical properties. The studied complexes display very intense emissions at room temperature (RT) and at 77 K in the solid state. Studies of the emissive properties of the complexes at different temperatures suggest that the emissions are phosphorescent at 77 K and exhibit thermally activated delayed fluorescence (TADF) at RT. Firstprinciple calculations of the photophysical processes yielded rate constants for intersystem crossing and reverse intersystem crossing that are in excellent agreement with experimental data.

Versatile Emissive Three‐Coordinated Gold(I) Systems‐Properties and Perspectives

“…Thus, for these [Au(N^N)(PPh TADF emission of complexes [Au(dppbz)R] (R = (C 6 F 5 , C 6 Cl 2 F 3, C 6 Cl 5 , Figure 19) has been studied, through the analysis of lifetimes at different temperatures, and estimated values for ΔE(S 1 -T 1 ) range from 656 to 1165 cm À 1 (Table 2). These values, although a bit higher, fit well with those calculated from the difference in the wavelengths of the peak maxima at 300 and 77 K. [56] Complexes [Au(dppnc)(NHC)] [NHC = N-heterocyclic carbene] (Figure 2) and [Au(dppbz)(NHC)]OTf [OTf = SO 3 CF 3 À , NHC = IPr, SIPr, IMes, SIMes] (Figure 20) are emissive in the bluegreen region, with quantum yields from 30 up to near 100 % in the solid state. The emissions of complexes with dppbz have also been studied in dichloromethane and batochromic shifts are observed when changing from solid to dichloromethane solutions.…”

Crystalline Metal‐Organic Materials with Thermally Activated Delayed Fluorescence

“…In 2020, Rodríguez-Castillo's group reported three Au(I) complexes with TADF property, namely AuR(dppBz) (R are different perhalophenyl: C 6 F 5 , C 6 Cl 2 F 3 , C 6 Cl 5 ; dppBz = 1,2-bis-(diphenylphosphino)benzene) (Figure 29a). [100] All Au(I) complexes in solid state were emissive with yellow luminescence centered at 560 nm (QY = 29%; τ = 10.3 µs) for AuC 6 F 5 (dppBz), 545 nm (QY = 16%; τ = 20.8 µs) for AuC 6 Cl 2 F 3 (dppBz), and 555 nm (QY = 11%; τ = 19.9 µs) for AuC 6 Cl 5 (dppBz) at room temperature. And obvious redshifts of emission bands and increase of lifetimes simultaneously took place for these complexes upon lowering the temperature, indicating the existence of a possible TADF process (Figure 29b).…”

“…Reproduced with permission. [100] Copyright 2020, American Chemical Society. ligand (HL) with ZnCl 2 (Figure 33a,b), which simultaneously displayed ESIPT, excitation-wavelength-dependent emission, and TADF properties.…”

“…The red solid line represents the fit of the experimental data based on Equation (1). Reproduced with permission [100]. Copyright 2020, American Chemical Society.…”

Influence of perhalophenyl groups in the TADF mechanism of diphosphino gold(i) complexes

“…We recently reported a new class of TADF emitters consisting of perhalophenyl three-coordinate 1,2-bis(diphenylphosphino)benzene (dppBz) gold( i ) complexes. 6 Despite the rigorous TADF demands, a very simple design strategy gives rise to metal complexes with the desired properties.…”