Photochromism and hydrochromism of three two-dimensional coordination polymers constructed from a carboxybenzyl viologen ligand. (November 2020)

• Record Type: Journal Article
• Authors: Liu, Jinjian; Lu, Yiwei; Lu, Wenbo
• Is Part Of: Dyes and pigments. Volume 182(2020)
• Publication Date: 2020-11
• Subjects: Coordination polymers -- 1, 1′-Bis(4-carboxybenzyl)-4, 4′-bipyridinium dichloride (H2BpybcCl2) -- 1, 4-Benzenedicarboxylic acid -- Photochromism -- Hydrochromism; Dyes and dyeing -- Periodicals; Pigments -- Periodicals; 667.2
• DOI: 10.1016/j.dyepig.2020.108631
• Languages: English
• ISSNs: 0143-7208

Abstract

Abstract: Stimulus-responsive viologen coordination polymers (CPs) have been very popular in the past few years due to the increasing demand for smart materials. In order to obtain such CPs, in this work, a flexible carboxybenzyl viologen ligand 1, 1′-bis(4-carboxybenzyl)-4, 4′-bipyridinium dichloride (H2 BpybcCl2 ), and its self-assembly with transition metal ions in the presence of 1, 4-benzenedicarboxylic acid ( p -H2 BDC) leads to the formation of three novel isostructural CPs {[TM4 (Bpybc)6 (H2 O)12 ]·(OH)2 ·( p -BDC)3 ·22H2 O}n (TM = Co (1 ), Ni (2 ), Mn (3 )). Each Bpybc ligand bridges two metal ions to create an infinite two-dimensional network. Due to the formation of Bpybc radicals, all three compounds are photochromic under UV irradiation. At the same time, the three compounds exhibit unique hydrochromic properties. The reversible color changes are caused by both electron transfer and the modulation of d–d transitions in the ligand field through dehydration and rehydration accompanied by structure transformations. Graphical abstract: Image 1 Highlights: Three new isostructural CPs based on 1, 1′-bis(4-carboxybenzyl)-4, 4′-bipyridinium dichloride have been prepared. They exhibit ET photochromic behaviors. They exhibit unique hydrochromic properties caused by both ET and the modulation of d–d transitions.