Hybrid photochromic materials (HPMs) with specific photoresponsive functionality have applications in many fields. The photoinduced electron-transfer (ET) strategy has been proved to be effective in the synthesis of HPMs with diverse photomodulated properties. The exploitation of new electron acceptors (EAs) is meaningful for promoting the development of HPMs. In this work, we introduced a rigid tetraimidazole derivative, 3,3,5,5-tetra­(imidazol-1-yl)-1,1-biphenyl (TIBP) as a potential EA, into a metal-diphosphonate (1-hydroxyethylidene-1,1-diphosphonic acid, H4-HEDP) system to explore HPMs and finally obtained a hybrid metal phosphonate (H4-TIBP)0.5·[Dy­(H-HEDP) (H2-HEDP)]·H2O (1). 1 features anionic chains composed of diphosphonate and Dy3+ ions. The extra charge is balanced by protonated TIBP cations, which exist in the void of adjacent chains and form H-bonds with Ophosphonate (N–H···O). Upon photostimulation with a Xe lamp (300 W), the crystalline sample 1 exhibited coloration by changing from colorless to pale yellow because of the presence of photoinduced radicals that originated from the ET from Ophosphonate to NTIBP. Along with the coloration, photomodulated fluorescence, magnetism, and proton conductivity were also detected in the photoactivated samples. Different from the reported HPMs based on polypyridine derivatives and photoactive species such as pyridinium and naphthalimide derivatives as EAs, our study provides a new category of EA units to yield HPMs with fascinating photoresponsive functionality via the assembly of polyimidazole derivatives and phosphonate-based supramolecular building blocks.

Photochromic metal–organic complexes (PMOCs) have received huge attention of chemists, thanks to their diverse structural characteristic and various available photo-modulate physicochemical functionalities. The organic ligand plays a crucial role in the quest of PMOCs with specific photo-responsive functionalities. The multiple coordination modes of polydentate ligands also provide possibilities for forming isomeric MOCs, which may open a new perspective on the research of PMOCs. The exploration of suitable PMOC systems is significant for the yield of isomeric PMOCs. Taking into account extant PMOCs based on polypyridines and carboxylate as electron acceptors (EAs) and donors (EDs), the covalent fusion of suitable pyridyl and carboxyl species may produce single functionalized ligands bearing ED and EA moieties for the building of novel PMOCs. In this study, the coordination assembly of bipyridinedicarboxylate (2,2′-bipyridine-4,4′-dicarboxylic acid, H2bpdc) and Pb2+ ions generate two isomeric MOCs, [Pb(bpdc)]·H2O (1 and 2), which have the same chemical compositions with main discrepancies in the coordination mode of bpdc2– ligands. As expected, supramolecular isomers 1 and 2 exhibited different photochromic performance, thanks to the distinct microscopic functional structural units. A schematic encryption and anti-counterfeiting device based on complexes 1 and 2 has also been studied. Compared with the extensively studied PMOCs supported by photoactive ligands like pyridinium and naphthalimide-derivatives and PMOCs derived from mixed electron-accepting polydentate N-ligands and electron-donating ligands, our work provides a new idea for building PMOCs based on pyridinecarboxylic acid ligands.

We provide a general method for modulating the structure and photochromic performance of hybrid metal chlorides with 1,10-phenanthroline and its substituted derivative under the synergy of electron transfer and coordination assembly strategies.

Hybrid photochromic materials (HPMs) have potential application in many fields like display, protection, information storage. The generation of HPMs with tunable photochromic performance is meaningful for the availability of smart...

Hybrid photochromic materials (HPMs) can produce novel photoresponsive properties, thanks to the synergistic effect of each component. One of the widely explored ways toward a novel HPM system is the utilization of the phototriggered electron transfer (ET) mechanism. In this work, the photochromic functionality of pyridinedicarboxylic acid with the chemical formula of H 5), has been first proved via the ligand tailoring and functional group fusion strategy. The photogenerated radicals derived from ET were experimentally characterized. Different from the previously investigated HPMs based on electron-deficient pyridiniums and rigid polydentate N-ligands as electron acceptors (EAs), this work exploits a new category of ligands for developing HPMs and investigating the underlying photoresponsive functionalities. Considering the large varieties of carboxylate and pyridine moieties, this study offers a general strategy for developing new HPMs and exploring the potential photoresponsive functionality via integrating the carboxylic groups as electron donors (EDs) and pyridyl groups as EAs in the single ligand.