Near‐Infrared Electrochromism of Multilayer Films of an N C N‐Pincer Tri‐Ruthenium(II) Complex

• Published in: European journal of inorganic chemistry 2020-08, Vol.2020 (30), p.2882-2888
• Main Authors: Li, Zhi‐Juan, Tang, Jian‐Hong, Shao, Jiang‐Yang, Zhong, Yu‐Wu
• Format: Article
• Language: English
• Subjects: Electrochromism; Metal oxides; Multilayer films; Pincer complexes; Ruthenium
• ISSN: 1434-1948; 1099-0682
• DOI: 10.1002/ejic.202000400

A star‐shaped N C N‐pincer tri‐RuII complex 3 with a triarylamine core, capped with three 2,2':6',2''‐terpyridine‐4,4',4''‐tricarboxylic acid terminal ligands, has been synthesized. The single‐crystal X‐ray structure of a precursor ester complex 7 is presented. By using the Zr‐mediated layer‐by‐layer assembly, multilayer films FTO/SnO2:Sb/(3)n(Zr)n‐1 (n = 1–4) have been prepared on Sb‐doped SnO2 nanocrystalline substrates. These films have been characterized by XPS and SEM analysis. The electrochromism of these films in the near‐infrared region were examined by oxidative spectroelectrochemical measurements and douple‐potential‐step chronoamperometry. The two‐layered film displays the best overall performance with a contrast ratio (ΔT%) of 36 % at 1550 nm and response time of shorter than 2 s. After 1000 switching cycles, around 11 % loss of the contrast ratio is observed, suggesting good cyclic stability of these films. In addition, a comparison of the electrochromic performance of these multilayer films with respect to the previously reported electropolymerized films of a related tri‐RuII complex and monolayer films of two mono‐RuII complexes on SnO2:Sb is presented. A star‐shaped N C N‐pincer tri‐ruthenium(II) complex with a triarylamine core, capped with three 2,2':6',2''‐terpyridine‐4,4',4''‐tricarboxylic acid terminal ligands, was synthesized. Multilayer films of this complex were prepared by the Zr‐mediated layer‐by‐layer assembly on Sb‐doped SnO2 nanocrystalline substrates. Among them, the bilayer film displays electrochromism at 1550 nm with a contrast ratio of 36 % and response time shorter than 2 s.