Proton-Induced Reversible Modulation of the Luminescent Output of Rhenium(I), Iridium(III), and Ruthenium(II) Tetrazolate Complexes

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• 作者：Melissa V. Werrett ; Sara Muzzioli ; Phillip J. Wright ; Antonio Palazzi ; Paolo Raiteri ; Stefano Zacchini ; Massimiliano Massi ; Stefano Stagni
• 刊名：Inorganic Chemistry
• 出版年：2014
• 出版时间：January 6, 2014
• 年：2014
• 卷：53
• 期：1
• 页码：229-243
• 全文大小：824K
• ISSN：1520-510X

文摘

One of the distinct features of metal鈥搕etrazolate complexes is the possibility of performing electrophilic additions onto the imine-type nitrogens of the coordinated five-membered ring. These reactions, in particular, provide a useful tool for varying the main structural and electronic properties of the starting tetrazolate complexes. In this paper, we demonstrate how the use of a simple protonation鈥揹eprotonation protocol enables us to reversibly change, to a significant extent, the light-emission output and performance of a series of Re(I)-tetrazolate-based phosphors of the general formulation fac-[Re(NN)(CO)₃L], where NN denotes diimine-type ligands such as 2,2鈥?bipyridine (bpy) or 1,10-phenanthroline (phen) and L represents a series of different 5-aryl tetrazolates. Indeed, upon addition of triflic acid to these neutral Re(I) complexes, a consistent blue shift (螖位_max ca. 50 nm) of the emission maximum is observed and the protonated species also display increased quantum yield values (4鈥?3 times greater than the starting compounds) and longer decay lifetimes. This alteration can be reversed to the initial condition by further treating the protonated Re(I) complex with a base such as triethylamine. Interestingly, the reversible modulation of luminescent features by the same protonation鈥揹eprotonation mechanism appears as a quite general characteristic of photoactive metal tetrazolate complexes, even for compounds in which the 2-pyridyl tetrazolate ligands coordinate the metal center with a bidentate mode, such as the corresponding Ir(III) cyclometalates [Ir(CN)₂L] and the Ru(II) polypyridyl derivatives [Ru(bpy)₂L]⁺. In these cases, the protonation of the starting materials leads to red-shifted and more intense emissions for the Ir(III) complexes, while almost complete quenching is observed in the case of the Ru(II) analogues.