Preparation And Chromic Properties Of Hybrid Marerials Based On 1,4,5,8-Naphthelene Diimide

Organic-inorganic hybrid materials composed of electron accepting-donating units not only possess diverse compositions,structures but also exhibit the charge-transfer and electron transfer?ET?between electron accepting-donating units gives unique functional advantages of such hybrid materials,especially it is the chromic performance under external stimulus,such as temperature,light,electricity,magnetism and solvent,which provides the possibility to develop and study the process visualization functional materials.The latest researches indicate that effective regulation for the relative positional relationship of donor-acceptor and energy band structure matching is an important strategy to optimize the electronic behavior and stimuli-responsive performance of materials.From traditional viologen acceptor to various aromatic receptors,from chlorosilicate donors to various halometalates,from hybrid systems to coordination frameworks,modulation of composition and structure enriches the structure type of the chromic material,reveals the chromic mechanism,and optimizes the photochromic behavior.Although some important breakthroughs have been made in improving the stimulation-responsive performance of functional materials,however,many problems including the relatively single external-stimuli response,slow stimuli-responsive rate,low coloration contrast,and poor reversibility,should be addressed for their commercial application of such materials.Based on crystal engineering and energy band engineering,this dissertation combine the dipyridyl-1,4,5,8-naphthalene diimide?DPNDI?possessing position isomerism property with halometalate as electron donors through different methods of coordination and electrostatic interaction.A series of organic-inorganic hybrid materials with excellent photochromic properties have been constructed to reveal the intrinsic relationship of composition-structure-chromic properties.The specific research results are as follows:1.Four organic-inorganic hybrids,[Zn?3-DPNDI??Cl₂]?2H₂O?1?,[Zn?4-DPNDI??Cl₂]?DMA?2?,[3-H₂DPNDI][ZnCl₄]?H₂O?3?,[4-H₂DPNDI][ZnCl₄]?H₂O}?4?were obtained,by combining two positional isomers of electron-deficient acceptors(N,N'-di-?3-pyridyl?-1,4,5,8-naphthalene diimide?3-DPNDI?and N,N'-di-?4-Pyridyl?-1,4,5,8-naphthalene diimide?4-DPNDI?with zinc chloride through coordination assemble and protonated with chlorozinate through electrostatic interaction hybrid.Compounds 1-4were characterized by the single-crystal X-ray diffraction,PXRD,FTIR,TGA,UV-Vis and EPR.The results show that the change of symmetry of DPNDI significantly affects the crystal packing mode and the obvious complicated donor-acceptor system,which directly affects the photochromic performance of the hybrid.Specifically,compared to compound 2,compound 1 possess a relatively closer packing manner and exist relatively stronger weak interactions.Therefore,compound 1 exhibits excellent photochromic behaviors with faster chromic rate and obvious coloration contrast.Compounds 3 and 4are composed of the same building units of[ZnCl₄]^2-/[DPNDI]²⁺,while different packing modes and weak interactions between electron donor and acceptor,give rise to different photoresponsive behaviors for two compounds?photochromism for 3 vs optical inertness for 4?.2.Two organic-inorganic hybrid lead halide coordination polymers,[PbBr₂?3-DPNDI??DMF?]?5?and[PbI₂?3-DPNDI?_2.5]?DMF?6?through the combination of electron-deficient acceptor of 3-DPNDI and lead halide via coordination interaction.Structural analysis indicates that the introduction of different halogens leads to different stacking patterns of lead bromide hybrids and lead iodide hybrids,resulting in different ways of solvent molecules in the crystal lattice?coordinating solvent molecules for 5 and free solvent molecules for 6?.The performance analysis shows that both compounds 5and 6 can exhibit photoinduced ET behaviors and long-lived charge-separated states.However,two compounds exhibit completely different color change phenomenon,which is largely attributed to the different intermolecular charge transfer?CT?behavior between electron donor/acceptor units,implying the subtle modulating effect of CT on photochromic properties.