A novel photochromic calcium-based metal–organic framework derived from a naphthalene diimide chromophore

Abstract

A novel 3D calcium-based metal-organic framework based on a naphthalene diimide chromophore has been synthesized which displays a unique doubly interpenetrated 7-connected net with total point symbol of {3(6)·4(9)·5(6)}. Excellent thermal stability and reversible photochromic properties have been observed in this compound.

Anion-Controlled Architecture and Photochromism of Naphthalene Diimide-Based Coordination Polymers

“…To confirm the generation of the radicals, the electron spin resonance (ESR) spectra of 1-3 were measured before and after irradiation ( Figure 5). Compounds 1 and 3 exhibit no ESR signal before irradiation, but strong ESR signals at 2.0026 and 2.0019 for compounds 1 and 3 are observed after irradiation, which are similar to those found in NDI-based coordination polymers [29,30,32,40]. This indicates that DPNDI ligand is indeed reduced to generate DPNDI − free radicals after two compounds are irradiated.…”

“…After irradiation, the photochromic products of 1 and 3 show new characteristic bands around 520 nm and 645 nm. These characteristic spectral bands are similar to that observed for NDI radical, suggesting that the color changes of 1 and 3 may arise from the photo-induced generation of radicals in DPNDI molecules [29,30,41].…”

“…645 nm. These characteristic spectral bands are similar to that observed for NDI radical, suggesting that the color changes of 1 and 3 may arise from the photo-induced generation of radicals in DPNDI molecules [29,30,41]. To confirm the generation of the radicals, the electron spin resonance (ESR) spectra of 1-3 were measured before and after irradiation ( Figure 5).…”

“…Naphthalene diimide (NDI) possess π-conjugated planes, high redox activity, and strong π-acidity, which are excellent candidates of organic ligands for the construction of photochromic coordination polymers due to the controllability of the substituent groups on the diimide nitrogens and the reversibility of the electron transfer [25][26][27]. Many groups have been used as NDI derivatives as catalysts through anion-π catalysis, and as organic ligands to construct coordination polymers [26,[28][29][30][31][32][33]. In order to investigate the detailed effect of different anions on the structures and photochromic properties, and as coordination polymers constructed by the neutral ligands have close relationship with the counter anions [34], we chose a neutral ligand N,N-di(4-pyridyl)-1,4,5,8-naphthalene diimide (DPNDI) as an organic ligand.…”

A synthetic and crystal structure study of a collection of coordination polymers based on alkaline aroylhydrazonates

“…The synthesis of new coordination polymers (CPs) or metal organic frameworks (MOFs) has captured researchers' interest owing to the variety of compositions and topologies of the produced compounds [1][2][3][4][5][6][7][8][9] together with their interesting functional properties and applications [10][11][12][13][14][15][16][17][18][19][20]. The properties of such systems are controlled by their chemical composition and structure, which are easily monitored by simply varying the reactants and reaction conditions.…”