Synthesis, Characterization, and Photophysical Properties of Luminescent Gallium and Indium Complexes Constructed using Tridentate 6-Azolyl-2,2′-bipyridine Chelates

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• 作者：Yi-Hwa Song ; Yuan-Chieh Chiu ; Yun Chi ; Pi-Tai Chou ; Yi-Ming Cheng ; Chun-Wei Lin ; Gene-Hsiang Lee ; Arthur J. Carty
• 刊名：Organometallics
• 出版年：2008
• 出版时间：January 14, 2008
• 年：2008
• 卷：27
• 期：1
• 页码：80 - 87
• 全文大小：518K
• 年卷期：v.27,no.1(January 14, 2008)
• ISSN：1520-6041

文摘

Three systematically functionalized 6-azolyl-2,2′-bipyridine ligands were prepared from reactions initiated by 6-cyano-2,2′-bipyridine. These ligands readily reacted with the metal alkyl reagents GaMe₃ and InMe₃ to afford the pentacoordinate complexes [(fpzbpy)MMe₂] (1a, M = Ga; 1b, M = In), [(ftzbpy)MMe₂] (2a, M = Ga; 2b, M = In), and [(N4bpy)MMe₂] (3a, M = Ga; 3b, M = In), in which (fpzbpy)H, (ftzbpy)H, and (N4bpy)H denote 6-pyrazolyl-, 6-triazolyl-, and 6-tetrazolyl-substituted 2,2′-bipyridine, respectively. These complexes exhibited moderate blue-green emission ranging from 412 to 493 nm. On the other hand, treatment of the bidentate 2-pyridyl tetrazole ligand (pyN4)H with InMe₃ afforded the bridged dimer [Me₂In(pyN4)]₂ (4). Calculation based on time-dependent density function theory (TDDFT) showed that the S₁ state of complexes 1−3 is mainly attributed to an allowed intraligand π → π* electronic transition located at tridentate chelating moieties, together with a small contribution (<10%) of gallium (or indium) → π* (ligand) charge transfer transition. Accordingly, the corresponding emission properties of 1a−3a (or 1b−3b) can be rationalized using the correlation between the substituent effect of azolyl groups and the relative HOMO/LUMO energy level.