Synthesis And Properties Of Organic And Inorganic-organic Hybrid Discoloration Materials Based On Viologen

In recent years,with more and more studies on the synthesis,structure and properties of complexes based on viologen and its derivatives as ligands,it has been found that the structures of organic and inorganic organic complexes with carboxyl groups as bridging ligands are very interesting.These materials are promising candidates,especially in the detection of toxic gases or volatile organic compounds,heavy metal ions detection,chemical sensors,light-emitting diodes and environmental monitors.The construction of organic and inorganic organic hybrid multi-functional color changing materials has become a hot topic in functional material chemistry.The complexes were characterized by elemental analysis,single crystal X-ray diffraction,UV,IR and thermogravimetric analysis.The main contents in this report can be summarized as follows:（1）A novel multifunctional photochromic Cd（II）three-dimensional Inorganic-organic framework[Cd（bdcbpy）]_n（1）has been synthesized by using a viologen ligand H₄bdcbpy·2Cl=1,1’-bis（3,5-dicarboxylatobenzyl）-（4,4’-bipyridinium）dichlorideand Cd（NO₃）₂·4H₂O,[Cd（bdcbpy）]_nexhibits metal-dependent photochromism and adjustable photosensitivity.[Cd（bdcbpy）]_nis sensitive and reversible to UV light,sunlight,and blue light by ET progress due to the viologen radical formation exhibits interesting reversible photochromic behavior with color changes that are visible to naked eyes.The detection of volatile amines has been confirmed by visual color changing phenomenon and luminescence quenching experiment.Luminescence studies indicate complex 1 has strong fluorescence,it can be used as multi-responsive sensors for selective sensing of Cr₂O₇^2-anions in water via luminescence quenching with fast response.（2）By means of solvothermal synthesis,as 1,1’-bis（3-carboxylic benzyl）-（4,4’-bipyridine）dichloride ligand（H₂bcbpy·2Cl）,Co Cl₂·6H₂O,1,2,4,5-Benzenetetracarboxylic acid（H₄btec）,N,N’-dimethylformamide and water preparation of a novel organic discoloration compound[（bcbpy）₂·9H₂O]_n（2）,and its structure was analyzed by single crystal X-ray diffraction.Crystals of compound 2under 300W Xenon lamp irradiation changed from pale yellow to dark green.And it turns dark green when heated,it shows that the compound 2 has both photochromic and thermochromic properties.The discoloration characteristics of compound 2 has been confirmed by discoloration experiments and photo-controlled fluorescence,the stability was confirmed by thermogravimetric analysis.