Photoactive Anthracene-9,10-dicarboxylic Acid for Tuning of Photochromism in the Cd/Zn Coordination Polymers

Abstract

Electron transfer photochromic materials with photo-triggered radicals have received huge interest from chemists due to their potentialities in anticounterfeiting, displays, energy conversion, and information storage. However, utilizing the sole carboxylic acid to synthesize novel electron transfer photochromic species is still confronted with huge challenges. Herein, an acentric three-dimensional network Cd2(ADC)2(DMF)2(H2O) (1; ADC = anthracene-9,10-dicarboxylate; DMF = N,N-dimethylformamide) and a two-dimensional layer Zn­(ADC)­(H2O)·DMA·H2O (2; DMA = N,N-dimethylacetamide) were synthesized and characterized via a photoactive H2ADC ligand. Both compounds exhibited electron transfer photochromism with the formation of radical photoproducts at the solid state, which was revealed by IR, UV–Vis absorption, photoluminescence and electron spin resonance spectra, and magnetic susceptibility measurements. Density functional theory calculations for 1 showed that the coloration process is a metal-assisted ligand-to-ligand electron transfer process between adjacent ADC molecules, and photogenerated stable radicals are delocalized over the ADC components. Compared with 1, the shorter distances between ADC components via coordination bonds promoted 2 to exhibit a higher coloration efficiency and larger quantity of photogenerated radicals. Furthermore, both compounds showed unexpected radical-actuated photochromism in aqueous solution. This work showed that the carboxylic acid ligands, without viologen acceptors, could construct the electron transfer photochromic complexes, showing a novel kind of ligand for the design of hybrid photochromic materials.

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

“…The Cd-O bond length is in the range of 2.201(4)-2.472(4) Å (Table S2 †), which corresponds to those of the reported Cd(II)based coordination polymers. 33,34 Owing to the existence of long Hbpdc + pendants, 2D sheets in compound 1 interdigitate with its neighbouring counterparts to form a 3D supramolecular structure (Fig. 2) with the assistance of C-H⋯O and O-H⋯O hydrogen bonding interactions.…”

A Series of 9-Anthracene Carboxylic Acid-Based Lanthanide Binuclear Complexes: Construction, Magnetism, Photoluminescence, and Photochromism

“…As a result, the coordination assembly strategy provides more efficient electron transfer pathways and promotes photochromic behavior. The effect of coordination of photochromic ligands with metal ions on the electron transfer photochromism has been reported in other works. ,, …”

“…To better compare the coloration rates of the four compounds, we measured the photochromic kinetics of these compounds at 500 nm of the UV–vis spectra by the kinetic rate equation of ln­( A 0 – A ∞ )/( A t – A ∞ ) = Kt , where A 0 , A t , and A ∞ represent the absorbance that was observed at the beginning, versus time and the end of the reaction, respectively. The linear fitting curves were performed, and the results showed that the coloration efficiency followed the first-order reaction kinetics. − As shown in Figure , compound 2 shows the fastest color rendering rate. To investigate the differences in the rate of discoloration, we analyzed the structure of the compounds and found that the four complexes exhibited the same number of intermolecular/intramolecular hydrogen bonds, while compound 2 showed the shortest distance in the intramolecular hydrogen bonds, with the C17–H17···O3 distance of 2.8185(2) Å, whereas the other compounds are C34–H34···O5 of 2.8322(1) Å for 1 , C43–H43···O6 of 2.8365(1) Å for 3 , and C42–H42···O5 of 2.8238(2) Å for 4 (Tables S10–S13), respectively.…”

The effect of conjugation degree of aromatic carboxylic acids on electronic and photo-responsive behaviors of naphthalenediimide-based coordination polymers

“…[18][19][20][21] Especially, the photochromic performances in terms of photoresponsive rate, photo-response range and coloration contrast of these hybrids have been optimized by rational selection and masterly integration of EDs and EAs as well as effectively modulating intermolecular electronic behaviors. [22][23][24][25][26][27][28][29][30][31] Intermolecular charge transfer (ICT) and photoinduced intermolecular electron transfer (PIET) are two fundamental electron behaviors, and both interactions exist between EDs and EAs in electron donor-acceptor hybrid systems. ICT is the continuous charge transition and recombination between EDs and EAs, and is related to the initial color states of these hybrids because of their noncharacteristic absorption in the visible light region generally.…”

“…18–21 Especially, the photochromic performances in terms of photo-responsive rate, photo-response range and coloration contrast of these hybrids have been optimized by rational selection and masterly integration of EDs and EAs as well as effectively modulating intermolecular electronic behaviors. 22–31…”