A Multifunctional Coordination Polymer Constructed by Viologen Derivatives: Photochromism, Chemochromism, and MnO₄^– Sensing

Abstract

A multifunctional Cd-based coordination polymer based on a viologen derivative and a secondary carboxylic ligand, namely, {[Cd2(bcbp)­(pta)2 (H2O)]·2H2O} n (1, H2bcbpCl2 = 1,1′-bis­(4-carboxyphenyl)-(4,4′-bipyridinium) dichloride, H2pta = p-phthalic acid), has been solvothermally synthesized and structurally characterized. Compound 1 is a 3D framework built on {Cd2(pta)2 (H2O)} n net with square channels which intalls bcbp ligands at the diagonal position of the two adjacent square channels. Notably, compound 1 exhibits a reversible photochromic transformation between yellowish gray and dark green under xenon light irradiation, which should be attributed to the formation of free viologen radicals. Furthermore, compound 1 also displays a chemochromic phenomenon from yellowish gray to dark green after exposure to ammonia and hydrazine, which could be ascribed to the generation of viologen radicals and charge-transfer complexes triggered by nucleophilic attack of electron-rich ammonia and hydrazine molecules to the electron-deficient viologen moiety in the bcbp ligand. Moreover, compound 1 is capable of quickly and selectively detecting MnO4 – with a high quenching coefficient and a low limit of detection via a luminescent quenching process caused by the competitive absorption of excitation energy.

A viologen-based Cd(ii) coordination polymer as a multifunctional platform for photochromism, chemochromism and a broad range of fluorescence pH sensing

“…[21][22][23][24][25][26][27] Our lab has been interested in investigating the chromic behavior of viologen-carboxyl based CPs in recent years. [28][29][30][31][32] In this work, a carboxyl containing viologen derivative, namely 1,1′-bis(4-carboxyphenyl)-(4,4′-bipyridinium) dichloride (H 2 bcbpCl 2 ), has been introduced to construct a Cd(II)-based CP in order to further explore the stimuli-responsive chromic behaviors of this kind of smart material.…”

Multi-Stimuli-Responsive Chromic Behaviors of an All–in–One Viologen-Based Cd(II) Complex

“…It was well-known that viologen derivatives were easily reduced to produce viologen radicals after irradiation, accompanied by a significant color change, , and this phenomenon was also observed in compound 1 . As shown in Figure a, when 1 was irradiated with a UV light (365 nm, 10 W) for 3 s in air at room temperature, the color can rapidly change from white to light blue, and it could reach saturation after being continuously irradiated for 10 min and transformed into a dark blue 1P .…”

Three photochromic materials based on POMs and viologens for UV probing, visual detection of metal ions and amine detection

“…Many viologen-based metal–organic complexes have been reported as photochromic materials. 30,31 Thus, the photochromic properties of compounds 1–3 composed of Cbybpy and tBbbpy viologen molecules were studied. When compound 1 was placed under a Xe lamp (300–400 nm) with a filter, its color changed from blue to brown within 1 min (Fig.…”