Abstract
A star-shaped cyclometalated triruthenium complex 2(PF6)n (n = 3 and 4) with a triarylamine core was synthesized, which functions as a molecular switch with five well-separated redox states in both solution and film states. The single-crystal X-ray structure of 2(PF6)3 is presented. This complex displays four consecutive one-electron redox waves at +0.082, +0.31, +0.74, and +1.07 V vs Ag/AgCl. In each redox state, it shows significantly different NIR absorptions with λmax of 1590 nm for 24+, 1400 nm for 25+, 1060 nm for 26+, and 740 nm for 27+, respectively. Complex 24+ shows a single-line EPR signal at g = 2.060, while other redox states are all EPR inactive. The spin density distributions and NIR absorptions in different redox states were rationalized by DFT and TDDFT calculations. A vinyl-substituted triruthenium analogous 3(PF6)4 was prepared, which was successfully polymerized on ITO glass electrode surfaces by reductive electropolymerization. The obtained poly-3n+/ITO film was characterized by FTIR, AFM, and SEM analysis. It shows four well-defined redox couples and reversible multistate NIR electrochromism. In particular, a contrast ratio (ΔT%) up to 63% was achieved at the optic telecommunication wavelength (1550 nm).
Highlights
Recent attention has been focusing on the design of smart and sophisticated switching molecules that can display multiple and consecutive redox processes at low potentials with each redox state being distinguished by specific readout signals[12,13,14]
A cyclometalated diruthenium system bridged by a redox-active amine unit was reported by us[33,34], which showed the presence of four redox states at a low potential region
We present in this contribution the synthesis and study of a star-shaped tris-cyclometalated ruthenium complex with an amine core
Summary
Jian-Hong Tang[1,2], Yan-Qin He1, Jiang-Yang Shao[1], Zhong-Liang Gong1 & Yu-Wu Zhong[1,2]. Recent attention has been focusing on the design of smart and sophisticated switching molecules that can display multiple and consecutive redox processes at low potentials with each redox state being distinguished by specific readout signals[12,13,14] This is important for the application of these materials in information storage because the information density can be significantly increased in the form of multistate memory[15,16]. A cyclometalated diruthenium system bridged by a redox-active amine unit was reported by us[33,34], which showed the presence of four redox states at a low potential region We present in this contribution the synthesis and study of a star-shaped tris-cyclometalated ruthenium complex with an amine core. Electropolymerized films of a vinyl-functionalized derivative were prepared, which were used to examine the redox switching behavior in film state
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