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The Reasons for Ligand‐Dependent Quantum Yields and Absorption Spectrum of Four Polypyridylruthenium(II) Complexes with a Tetrazolate‐Based Ligand: TDDFT Study
Author(s) -
Li XiaoNa,
Wu ZhiJian,
Zhang HongJie,
Si ZhenJun,
Zhou Liang,
Liu XiaoJuan
Publication year - 2009
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.200900344
Subject(s) - chemistry , time dependent density functional theory , pyrazine , density functional theory , quantum yield , pyridine , ligand (biochemistry) , phosphorescence , deprotonation , photochemistry , absorption spectroscopy , absorption (acoustics) , computational chemistry , crystallography , stereochemistry , medicinal chemistry , organic chemistry , fluorescence , ion , biochemistry , physics , receptor , quantum mechanics , acoustics
The quantum yield, lifetime, and absorption spectrum of four [Ru(bpy) 2 L] + [where bpy is 2,2′‐bipyridyl; L is represented by the deprotonated form of 2‐(1 H ‐tetrazol‐5‐yl)pyridine (L1) or 2‐(1 H ‐tetrazol‐5‐yl)pyrazine (L2)], as well as their methylated complexes [Ru(bpy) 2 LMe] 2+ (RuL1Me and RuL2Me) are closely ligand dependent. In this paper, density functional theory (DFT) and time‐dependent DFT (TDDFT) were performed to compare the above properties among these complexes. The calculated results reveal that the replacement of pyridine by pyrazine or the attachment of a CH 3 group to the tetrazolate ring greatly increases the π‐accepting ability of the ancillary ligands. The stronger π‐accepting ability of the ancillary ligands in RuL2 results in stronger interaction with polar solvents and a relaxed geometrical structure; these are the main reasons for the lowest quantum yields and the shortest lifetime. The electron‐donating CH 3 group buffers the interaction between RuL2Me and the solvent, and together with the enhanced MLCT participation, these account for the highest quantum yields and the longest lifetime. This theoretical contribution allows the factors determining the efficiency of radiative and nonradiative decay pathways in this series of complexes to be rationalized and also allows design of new ruthenium(II) complexes with higher phosphorescence efficiency. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)