| As an emerging hybrid material,metal-organic complexes(MOCs)have potential applications in adsorption,separation,catalysis,magnetism,photoluminescence and other fields.In recent years,crystalline hybrid photochromic materials(CHPMs)based on MOCs have attracted extensive attention due to their structural designability and functional tunability.Hitherto,most CHPMs derives from MOCs based on photoinduced isomeric moieties and photochromic units.It is of great significance to develop new CHPM systems for expanding the synthesis methodology and studying the related photoresponsive properties.In this dissertation,based on the principle of crystal engineering and electron transfer(ET)mechanism,a series of CHPMs based on MOCs have been constructed via the coordination-driven assembly of appropriate electron donor(ED)units(1,2,3-diphenyltricarboxylic acid(H3BTA),(+)-camphoric acid(H2Cam),mellitic acid(H6L),nitrate(NO3-))and electron acceptor(EA)units conjugated dipyridine(4,4'-bipyridine(bipy)and 1,10-phenanthroline(phen)):[Zn2(Cam)2(bipy)](1),[Zn4(BTA)2(HBTA)(bipy)3]·3H2O(2),[Cd2(HBTA)2(bipy)2](3),[Zn(HBTA)(phen)2](4),[Cd(HBTA)(phen)2](5),[Zn2(H2L)(phen)4]·2H2O(6),[Dy(BTA)(phen)2]·2H2O(7),[Pb(NO3)(phen)2]·NO3(8),[Pb(phen)(NO3)2(H2O)](9),[Cd(phen)2(NO3)2](10),[Ln(NO3)3(phen)](11-Gd,Ln=Gd;11-Dy,Ln=Dy)(11).Their structures and properties were characterized by single crystal X-ray diffraction(SCXRD),powder XRD(PXRD),elemental analysis(EA),thermogravimetric analysis(TGA),infrared(IR),fluorescence(FL),solid state UV-Vis and electron spin resonance(ESR)spectroscopy,etc.The main contents are listed as following:The first chapter mainly introduces the research background of this dissertationwith focus on the progress of CHPMs directed by photochromic and non-photochromic units.Then,the research topic and significance of this dissertation is illustrated.The second chapter introduces the experimental principle and synthetic method,together with the starting reactants and solvents.In the third chapter,the construction and photochromic properties of MOCs based on linear EA-unit bipy are introduced.Among them,[Zn2(Cam)2(bipy)](1)has a pillar-layer frame structure.In 1,Cam2-ligand links Zn2+to form hybrid layers,which are further pillared by bipy.In the 3D MOC[Zn4(BTA)2(HBTA)(bipy)3]·3H2O(2),tricarboxylate ligands link Zn2+to form hybrid layers,which are further strengthened by bipy via coordinating with intralayer Zn2+ions.The resulting Zn-tricarboxylate-bipy hybrid layer is further linked by bipy to form the final frame structure.The MOC[Cd2(HBTA)2(bipy)2](3)exhibits pillar-layer structure,in which the tricarboxylate links Cd2+ions to form the metal-carboxylate layers,which are further pillared by bipy via linking interlayer metal ions.Under the irradiation of Xe-lamp(300 W),photochromic performance driven by ligand-to-ligand ET(LLET)(from O-atoms of carboxylate to nitrogen N-atoms of bipy)is observable in MOCs 1-3.In chapter four,the construction and photochromic properties of MOCs based on coplanar EA-unit(phen)are introduced.Among them,MOCs[Zn(HBTA)(phen)2](4)and[Cd(HBTA)(phen)2](5)feature discrete structures.The tricarboxylate ligand and phen unit chelate central metal ions to form metal-organic coordination molecules as monomeric units,which are further connected with each other via forming hydrogen bonds with adjacent units.Under the irradiation of Xe-lamp,phen and tricarboxylate ligands in 4 and 5 act as?-EAs and EDs,respectively.Photochromic properties derived from LLET is observed.Interestingly,although 4 and 5 have the same ED-and EA-unitsand the similar monomeric units and supramolecular chains,they exhibit obvious central metal-dependent photochromic behavior.The MOC[Zn2(H2L)(phen)4]·2H2O(6)with binuclear structure exhibits obvious photochromic behavior under Xe-lamp irradiation.On the basis of the aforementioned work,the MOC[Dy(BTA)(phen)2]·2H2O(7)with chain structure was obtained by assembling the paramagnetic metal ion(Dy3+),ED-unit H3BTA and EA-unit phen,in which the tricarboxylate ligands bridge Dy3+to form hybrid chains,and phen chelate with the intrachain metal ions to further modify the hybrid chain Under the photoactivation of Xe-lamp,the ET between the tricarboxylate and phen gives birth to photogenerated radicals,resulting in photochromism,photomodulated fluorescence,magnetism and second-order nonlinear optical properties.Considering the economic cost of the organic ED-units,the introduction of phen into metal nitrate system generates a series of phen-modified hybrid metal nitrates:[Pb(phen)2(NO3)]·NO3(8)with discrete structure,[Pb(phen)(NO3)2(H2O)](9)with chain structure,[Cd(phen)2(NO3)2](10)and[Ln(phen)(NO3)3](Ln=Gd,Dy)(11)with discrete structure.Under the stimulus of Xe-lamp,all the targeted products exhibit obvious photochromic behavior,in which the ED and EA units are coplanar NO3-and phen respectively.The fifth chapter summarizes the main work of this dissertation and gives the prospect of the future work. |
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