Photochromic properties of ruthenium complexes with dithienylethene-ethynylthiophene. (January 2021)

• Record Type: Journal Article
• Authors: Chen, Jinxiang; Wang, Jin-Yun; He, Jinru; Peng, Xiangfang
• Is Part Of: Dyes and pigments. Volume 184(2021)
• Publication Date: 2021-01
• Subjects: Dithienylethene -- Photochromism -- Ruthenium complex -- Multi-switch -- Energy transfer -- Electronic communication; Dyes and dyeing -- Periodicals; Pigments -- Periodicals; 667.2
• DOI: 10.1016/j.dyepig.2020.108750
• Languages: English
• ISSNs: 0143-7208

Abstract

Abstract: In order to extend stepwise photochromism to more metal-coordination systems for multicolors and multistates, a new photochromic dithienylethene-ethynylthiophene (L1o) was synthesized to design head–head coupled symmetric ruthenium(II) complex trans-Ru(dppe)2 (L1o)2 (1oo ) and head-shoulder coupled asymmetric ruthenium(II) complex trans-Ru(dppe)2 (L1o)(L2o) (2oo ). However, upon irradiation under UV light, 1oo only converts to 1co without the observation of dually ring-closed species 1 cc, and only the dually ring-closed species 2 cc is observed without the detection of the mixed ring-open/closed species 2co and 2oc, implying that it is difficult to achieve substantial stepwise photochromic process of 1oo-2oo → 1co-2oc/2co→1cc-2 cc due to the rapid intramolecular energy transfer in 1co and the absence of electronic communication between two dithienylethene units in 2oo . The photochemical processes are well demonstrated and explained by NMR, UV–vis, electrochemical, as well as time-dependent density functional theory (TD-DFT) computational studies. Highlights: A new photochromic dithienylethene-ethynylthiophene L1o with an extended π-system at ethene bridge unit has been successfully synthesized. A head–head coupled symmetric ruthenium(II) complex and a head-shoulder coupled asymmetric ruthenium(II) complex based were first prepared. Only the singly ring-closed species 1co and the fully ring-closed isomer 2cc can be obtained for 1oo and 2oo, attributing to the quenching effect of the first ring-closed dithienylethene moiety and the absence of electronic communication between two DTEs, respectively.