Syntheses and Photophysical Properties of Luminescent Mono-cyclometalated Gold(III) cis-Dialkynyl Complexes

Abstract

A series of novel luminescent neutral cyclometalated gold(III) complexes of the type cis-[(N^C)Au(C≡CR)(2)] (R = aryl, silyl groups) having different cyclometalating cores (N^C) have been synthesized by CuI promoted halide to alkynyl metathesis with NEt(3) as in situ deprotonating agent. Along with spectroscopic characterizations (nuclear magnetic resonance and infrared spectroscopies and electrospray ionization mass spectrometry) and elemental analysis, the molecular structures of some of the complexes have been established by single-crystal X-ray diffraction studies. Photophysical studies reveal that the complexes exhibit room-temperature phosphorescence (RTP). Experimental observations and density functional theory calculations qualitatively suggest limited participation of the metal and alkynyl ligands in the lowest energy emitting state. The nature of the emission is mainly governed by metal-perturbed (3)IL(π-π*) transitions originating from the cyclometalate part of the molecule, and its variation readily leads to the tuning of the emission wavelengths. Cyclic voltammetry measurements of selected complexes showed irreversible redox behavior with near-equivalent cathodic peak potential (E(p,c)) assigned to the C^N core.

Structural and spectroscopic studies of Au(III) and Pd(II) chloride complexes and organometallics with 2-benzylpyridine

“…In DMSO-d 6 , their average deshielding is similar to that for [Au(2ppy à )Cl 2 ] (mean D Hð3ÞÀHð6Þ coord : 0.63 ppm vs 0.55 ppm [22]), and the same concerns H(6) (D Hð6Þ coord : 0.69 ppm vs 0.86-0.87 ppm [19,22,47,48]). In CDCl 3 , H(6) is much more deshielded that in [Au(2bzpy)Cl 3 ] (D Hð6Þ coord : 0.79 ppm vs 0.14 ppm), such D Hð3Þ coord;½AuðLL à ÞCl2 ) D Hð6Þ coord;½AuðLLÞCl3 relation being also noted for [Au(2ppy à )Cl 2 ] vs [Au(2ppy)Cl 3 ] (0.86-0.87 ppm ) 0.15 ppm [19,21,22,47,48]), and for (R)/(S)-[Au(2-(1-methylbenzyl)pyridine à )Cl 2 ] vs [Au(2-(1-methylbenzyl)pyridine)Cl 3 ] (0.72/ 0.82 ppm ) 0.08 ppm [1]);Table S3.Similarly high D Hð6Þ coord values were reported for some other [Au(LL à )Cl 2 ] organometallics with derivatives of 2ppy (LL = 2-(4-methylphenyl)pyridine, 4-(n-propyl)-2-phenylpyridine, 2-(2,4-difluorophenyl)pyridine: D Hð6Þ coord = 0.86-1.13 ppm[4,48,51]) or 2bzpy (LL = 3-methyl-2-benzylpyridine, 4-methyl-2-benzylpyridine, 5-methyl-2-benzylpyridine, 2-(6-methylbenzyl)pyridine, 2-(5-methylbenzyl) pyridine, 2-(4-methylbenzyl)pyridine, 2-(4-phenylbenzyl)pyridine, 2-(4-chlorobenzyl)pyridine, 2-(1,1-dimethylbenzyl)pyridine, 2-(1-phenylbenzyl)pyridine: D Hð6Þ coord = 0.45-0.82 ppm[1,7]);…”

Water‐Soluble Luminescent Cyclometalated Gold(III) Complexes with cis‐Chelating Bis(N‐Heterocyclic Carbene) Ligands: Synthesis and Photophysical Properties

“…20, 31 The AuC and AuN distances of the [Au(C^N)] moiety are 2.056 and 2.081 Å, respectively. Similar values are observed in other cyclometalated [Au(C^N)] complexes 26. 27, 32 The molecules of 8 b are arranged in a head‐to‐tail fashion with π–π stacking interactions between adjacent C^N moieties.…”

“…The HC^N ligands were either purchased from chemical suppliers or synthesized by Suzuki coupling reactions that involved the use of aryl boronic acids/boronic esters and aryl halides/triflates. [Au(C^N)Cl 2 ] precursor complexes ( 1 ,25 2 26 and 7 27) were synthesized by following the reported procedures. Other precursor complexes were prepared by following literature methods.…”

(Benzimidazolin‐2‐ylidene)–AuI–Alkynyl Complexes: Syntheses, Structure, and Photophysical Properties

“…On the basis of the optimized geometries, time-dependent DFT (TD-DFT) calculations [21] combined with the conductive polarizable continuum model (CPCM) [22] were used to Table 8. As already observed in a previous study, [23] the PBE1PBE/SDD 6-31+G(d) calculations systematically provide underestimated absorption maxima by only approximately 20 nm. produce the molecular orbital energy levels and compositions, the absorption spectra, and the ten lowest singletsinglet and singlet-triplet vertical excitations (in solution in dichloromethane) with the corresponding energies, transition coefficients, and oscillator strengths.…”