Stable and color tunable emission properties based on non-cyclometalated gold(iii) complexes

Abstract

Stable and emission tunable non-cyclometalated gold(III) triaryl complexes of the type [(L)Au(C6F5)3] [L = 2-(2,4-difluorophenylpyridine) (1), 4-phenylpyridine (2), 2-phenylpyridine (3), 2-phenylisoquinoline (4), 2-thienylpyridine (5)] were synthesized starting from a common precursor complex [(THT)Au(C6F5)3] [THT = tetrahydrothiophene] in good to modest yields. Extensive characterization of the complexes by various nuclear magnetic resonance spectroscopy techniques and elemental analysis further corroborated the single-crystal X-ray diffraction studies. The complexes displayed room temperature phosphorescence in the neat solid and in 2-MeTHF at 77 K. Detailed photophysical investigations of the complexes in the neat solid and at 77 K revealed the successful tuning of the emission maxima with modest quantum yields across the visible part of the electromagnetic spectrum depending on the electronic properties of the heterocyclic ligands. DFT (Density Functional Theory) and TDDFT (Time Dependent Density Functional Theory) calculations were performed to discern the composition of the excited state as well as confirm the obtained relative emission energies upon substitution with electronically different ligands. The obtained diverse emissive behavior of the complexes combined with the ease of synthesis illustrate the generality and applicability of the design approach to obtain emissive gold(iii) complexes devoid of cyclometalation.

Tunable and Efficient White Light Phosphorescent Emission Based on Single Component N-Heterocyclic Carbene Platinum(II) Complexes

“…General Procedure. 10b, 16 All manipulations requiring inert atmosphere were carried out using standard Schlenk techniques under N 2 gas. 1 H, 13 C{ 1 H}, and 19 F NMR spectra were performed using Bruker 400 and 500 MHz spectrometers.…”

“…Crystal Structure Determinations. 10b, 16 Single-crystal X-ray diffraction data for 1 were collected at 183(1) K on an Agilent Technologies SuperNova Atlas area-detector diffractometer and for 2 and 3 on an Agilent Technologies Xcalibur Ruby area-detector diffractometer using a single wavelength Enhance X-ray source with Mo Kα radiation (λ = 0.71073 Å) 21 from a microfocus X-ray source and an Oxford Instruments Cryojet XL cooler. The single crystals that were selected carefully were mounted using polybutene oil on a flexible loop fixed on a goniometer head and immediately transferred to the diffractometer.…”

“…Computational Details. 10b, 16 The luminescent properties of compounds 1−4 were evaluated by density functional theory (DFT) calculations using the Gaussian 03 program package. 27 The hybrid functional PBE1PBE 28 together with the Stuttgart/Dresden effective core potentials (SDD) basis set 29 for the Pt center augmented with one f-polarization function (α = 0.993) and the standard 6-31+G(d) basis set 30 for the remaining atoms were used in all calculations.…”