| Homochiral metal-organic frameworks?HMOFs?endowing with chirality and porosity and as well as uniquely optical,electrical and magnetic properties display potential application prospects in asymmetric catalysis,chiral separation,optical devices,and etc.It is one of the effective ways to construct HMOFs through designing chiral bridge ligands with large skeletons by using cheap,non-toxic and readily available natural amino acids as chiral sources.In this thesis,chiral bridge ligands of aromatic polycarboxylic acids functionalized by amino acids were designed and synthesized,and a series of HMOFs were obtained by assembling them with rare earth metal ions,and their structures and properties were systematically studied.Metallocage complexes have attracted much attention due to their attractive structures and host–guest chemistry.Owing to the particularity of the cage structure,the assembly of metallocage complexes has always been challenging.So far,there are many reports about metallocage complexes with univalent anions as the template,but few cases of metallocage complexes with high hydrophilic anions(such as SO42-and PO43-)as the template have been reported.In this thesis,a series of metallocage complexes containing monovalent and divalent ions were prepared by the assembly of rigid V-shaped bridge ligands with cobalt?II?and nickel?II?ions when the chiral amino acid derivative ligands existed in the reaction systems,and their structures and properties were studied.Further investigation has shown that metallocage complexes can be transformed into two-dimensional coordination polymers.The main research content of this thesis includes the following two parts:?1?TwonovelchiralpolycarboxylicacidligandsH3L1[?S?-5-???1-carboxyethyl?amino?methyl?isophthalicacid]andH3L2[?5-?2-Carboxy-5-oxo-pyrrolidin-1-ylmethyl?-isophthalic acid?]were designed and synthesized through functionalizing 5-benzenedicarboxylate by L-alanine and L-glutamic acid,respectively.With H3L1 or H3L2 as chiral ligand to assemble with lanthanide inos,a series of novel homochiral lanthanide metal–organic frameworks,namely,{[Ln2?HL1?2?H2O?4]·2Cl·5H2O}n[Ln=Sm?1?,Eu?2?,Gd?3?,Tb?4?,Dy?5?,Ho?6?,Er?7?]and{[Ln?L2?]·H2O}n[Ln=Eu?8?,Tb?9?]was successfully synthesized,and fully characterized by single-crystal X-ray analysis,PXRD,IR,TGA,CD spectra and etc.Compounds 1-7 are isostructural and crystallize in P1 chiral space group.They are binodal?3,6?-connected frameworks with kgd net based on binuclear cluster units[Ln2?COO?4]and zwitterionic?HL?2-linkers.Considering the same metal ionic charge,similar radius and the isostructuralism of these Ln-HMOFs,as well as the strong red,blue and green light emitted by complexes 2-4,respectively,a series of single-phase mixed-lanthanide HMOFs materials with fluent changes of light-emitting color were obtained by in situ doping to regulate the luminescent properties of the materials in this thesis.Very interestingly,the bimetallic doped Eu/Tb-HMOFs[(Eux Tb1-x)2?HL?2?H2O?4]·2Cl·5H2O display a barcode-like change in colour from green to yellow to red as adjusted the doping concentration of Eu3+ions into the Tb-HMOF.Based on the principle of trichromatism,crystalline material Eu/Gd/Tb-HMOF,namely,[(Eu0.1388Gd0.6108Tb0.2504)2?HL?2?H2O?4]·2Cl·5H2O was synthesized by in situ doping Eu3+,Gd3+and Tb3+ions.Very important,the trimetallic doped Eu/Gd/Tb-HMOF emits white light upon excitation at 355 nm,whose emission can also switch between different colors when excited with different ultraviolet light.Furthermore,the fluorescence response of compound 4 to various usual metal ions,especially to Fe3+,Cr3+and Al3+ions,was preliminarily investigated.Compounds 8and 9 are isostructural and crystallize in chiral space group P212121.Their three-dimensional?3D?chiral frameworks are formed by ligand?L2?3-bridging helical chain secondary structures[Ln?COO?3]n.Under ultraviolet excitation,complexes 8and 9 emit red and green fluorescences with long life and stong intensity,respectively,and their fluorescent life is 1.35 and 1.31 ms,respectively.?2?Sixnewcomplexes,namely,{[Co6??3-OH?2?HCOO?6?pbim?6?H2O?6]·SO4·?HCOO?2·8H2O}n?10?,{[Ni6??3-OH?2?HCOO?6?pbim?6?H2O?6]·SO4·?HCOO?2·9H2O}n?11?,{Co6??3-OH?2?HCOO?6?pbim?6?H2O?6]·ClO4·?HCOO?3·6H2O}n?12?,{Ni6??3-OH?2?HCOO?6?pbim?6?H2O?6]·ClO4·?HCOO?3·6H2O}n?13?,{[Co?pbim?2?H2O?2]·?HCOO?2}n?14?,and{[Ni4?pbim?2?CH3O?4?C6H5COO?4]·2H2O}n?15?,were synthesized through the assemblies of V-shaped bridge 1,1?-?5-methyl-1,3-phenylene?bis?1H-imidazole?[pbim]with transition metal ions Co2+and Ni2+,respectively.The complexes 10-13 were obtained through the spontaneous evaporation of a clear solution from solvothermal reaction.They all are hexagonal-prismatic metallocage templated by SO42-and ClO4-,respectively,and every metallocage is built up from six V-shaped ligands pbim bridging two equilateral triangle metal cluster subunits[M3??3-OH???-HCOO?3]formed in situ.Very interesting,the chiral amino acid derivative ligands added to the reaction system,although not involved in the construction of these metallocages,are indispensable for the formation of metallocages.More importantly,the SO42-or ClO4-anions encapsulated in the cage acted as the template for the formation of these hexagonal-prismatic cages via cooperative weak C-H???O hydrogen bonds,and as the guest anions they also stabilized these high valent cationic metallocages.Notably,a small amount of the 2D compound 14 with?4,4?grids was also crystallized from the mother liquid forming the Co?II?metallocages.It was found that as the mother liquid forming the Co?II?metallocages was disturbed or metallocages and coordination polymer 14 coexisted in the mother liquid for a long time,which was favorable to the formation of coordination polymer 14,indicating that coordination polymer 14 is a thermodynamically stable species.Compounds 15 was solvothermally synthesized using the corresponding Ni?II?metallocage 11 and benzoic acid in a mixed solvent of DMF and methanol,and it exhibits a 2D network with?4,4?grids constructed by tetranuclear cubical metal cluster subunits[Ni4?CH3O?4]and pbim ligands.Remarkably,the tetranuclear cubical metal cluster subunits[Ni4?CH3O?4]in 15 is formed in situ by the equilateral triangle metal cluster subunits[M3??3-OH???-HCOO?3]in metallocage 11.Moreover,the magnetic properties of 10,11 and 15 have been investigated and the results reveal that they all display antiferromagnetic behaviors. |
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