Intrinsic 77 K Phosphorescence Characteristics and Computational Modeling of Ru(II)-(Bidentate Cyclometalated-Aromatic Ligand) Chromophores: Their Relatively Low Nonradiative Rate Constants Originating from Low Spin-Orbit Coupling Driven Vibronic Coupling Amplitudes between Emitting and Ground States

Chi-Wei Yin; Li-Ting Zhuo; Jie Ying Chen; Yu-Hui Lin; Yu-Ting Lin; Hsing-Yin Chen; Ming-Kang Tsai; Yuan Jang Chen

doi:10.1021/acs.inorgchem.4c03390

Intrinsic 77 K Phosphorescence Characteristics and Computational Modeling of Ru(II)-(Bidentate Cyclometalated-Aromatic Ligand) Chromophores: Their Relatively Low Nonradiative Rate Constants Originating from Low Spin-Orbit Coupling Driven Vibronic Coupling Amplitudes between Emitting and Ground States

Inorg Chem. 2024 Nov 7. doi: 10.1021/acs.inorgchem.4c03390. Online ahead of print.

Authors

Chi-Wei Yin¹, Li-Ting Zhuo¹, Jie Ying Chen¹, Yu-Hui Lin¹, Yu-Ting Lin¹, Hsing-Yin Chen², Ming-Kang Tsai^{1

3}, Yuan Jang Chen¹

Affiliations

¹ Department of Chemistry, Fu-Jen Catholic University, New Taipei City 24205, Taiwan, R.O.C.
² Department of Medicinal and Applied Chemistry, Kaohsiung Medical University, Kaohsiung 80708, Taiwan, R.O.C.
³ Department of Chemistry, National Taiwan Normal University, Taipei 11677, Taiwan, R.O.C.

PMID: 39509593
DOI: 10.1021/acs.inorgchem.4c03390

Abstract

We investigated the photoinduced relaxation of Kasha-type emitting ruthenium-(bidentate cyclometalated aromatic ligand), Ru-CM, chromophores of [Ru(pzpy)₂(CM)]⁺ ions (CM = 1-phenylisoquinoline, 2,3-diphenylpyrazine, and 1,4-diazatriphenylene and pzpy = 2-pyrazol-1-yl-pyridine). This is the first report of the phosphorescence behavior of pure Ru-(bidentate CM) chromophores. The 77 K photoinduced relaxation characteristics of phosphorescence chromophores showed emission quantum yields higher than those of reference Ru-bpy (bpy = 2,2'-bipyridine) chromophores in the emission region of 670-900 nm. This phenomenon of the Ru-CM chromophores could be attributed to their unusually low magnitudes for 77 K nonradiative rate constants (k_NRD), although their radiative rate-constants (k_RAD) are not remarkable. In order to examine the 77 K photoinduced behavioral relaxation difference between Ru-CM and Ru-bpy chromophores, we used computational simulation, applying the fundamental formalism of k_RAD and temperature-independent k_NRD equations, which included calculated spin-orbit coupling values.