A Study on the Effect of Dianionic Tridentate Ligands on the Radiative and Nonradiative Processes for Gold(III) Alkynyl Systems by a Computational Approach

Gold­(III) alkynyl complexes with dianionic tridentate pincer ligands have received growing attention recently because of their rich luminescence behavior and their potential applications in areas such as optoelectronics and sensors. In this study, density functional theory (DFT) and time-dependent DFT (TDDFT) calculations have been performed to investigate the radiative and nonradiative processes for the gold­(III) alkynyl complexes with different dianionic tridentate ligands, [Au­(C^N^C)­(CCC₆H₅)] (1; C^N^C = 2,6-diphenylpyridine), [Au­(C­(Np)^N^C­(Np))­(CCC₆H₅)] [2; C­(Np)^N^C­(Np) = 2,6-di­(2-naphthyl)­pyridine], [Au­(N^N^N)­(CCC₆H₅)] [3; N^N^N = 2,6-bis­(benzimidazol-2′-yl)­pyridine], and [Au­(C^C^N)­(CCC₆H₅)] [4; C^C^N = 3-(2-pyridyl)­biphenyl]. It has been found that the electronic properties of the tridentate ligand could have a significant impact on the radiative and nonradiative processes. This study provides an in-depth understanding on the effect of the dianionic pincer ligands on the different photophysical behaviors among the gold­(III) alkynyl complexes and crucial information for the future design of gold­(III) complexes in various applications.