Syntheses, Structures And Properties Of Rare Earth Coordination Polymers Templated By Nitrogen Heterocyclic Compounds

In this dissertation,21rare earth coordination polymers in different structures havebeen synthesized via hydrothermal method and using nitrogen heterocyclic compounds astemplates. Their single-crystal structures have been determinated and analyzed, and theyhave been characterized by using elemental analyses, infrared spectra and thermogravimetric（TG） analyses. The absorption spectra and luminescence spectra of some of the compoundshave also been studied. The details are summarized as following:1. A series of novel rare earth coordination polymers {（bpy）[Re（ip）1.5（H₂O）4]}n（Re=Pr（1）, Nd（2）, Sm（3）, Eu（4） and Gd（5）, bpy=4,4′-bipyridine, ip=isophthalate） have beensynthesized by using4,4′-bipyridine molecules as templates. This series of compounds areisostructural. Their three-dimensional （3D） networks are formed by one-dimensional （1D）ladder-shaped chains through hydrogen bonds. The channel regions of the networks are hostto4,4′-bipyridine molecules which serve as guest-templates. These4,4′-bipyridine moleculesshow hydrogen bond participation with metal-bound water molecules. The emission spectrashow that4emits intense sharp red light when it is excited by different wavelengthultraviolet light.2. A series of novel rare earth coordination polymers {（Him）[Re（ip）₂（H₂O）]}_n（Re=Sm（6）, Eu（7）, Gd（8） and Tb（9）, Him=imdazole cation, ip=isophthalate） and{[Re₂（ip）₃（H₂O）₂]·H₂O}n（Re=Er（10）, ip=isophthalate） have been synthesized by usingimdazole cations as templates. The compounds6,7and9are isostructural. The structure ofcompound8is similar to the structures of compounds6,7and9. In the compounds6-9, theisophthalate ligands link the metal ions to form three-dimensional （3D） honeycomb-likeframeworks. The channel regions of the frameworks are host to imdazole cations whichserve as guest-templates. These imdazole cations show hydrogen bond participation with theisophthalate ligands. The three-dimensional （3D） network of the compound10is formed bytwo-dimensional （2D） layers through hydrogen bonds. There are left-and right-handeddouble helical chains in the layers of the compound10. The emission spectra show that7emits intense sharp red light and9emits intense sharp green light when they are excited bydifferent wavelength ultraviolet light. 3. A series of novel rare earth coordination polymers {（bpy）[Re（ip）（Hip）（bpy）]}n（Re=Eu（11）, Ho（13）, Er（14） and Yb（15）, bpy=2,2′-bipyridine, ip=isophthalic acid dianion,Hip=isophthalic acid monoanion） and {（bpy）0.5[Re（ip）（Hip）（bpy）]}n（Re=Tb（12）,bpy=2,2′-bipyridine, ip=isophthalic acid dianion, Hip=isophthalic acid monoanion） havebeen synthesized by using2,2′-bipyridine molecules as auxiliary ligands and templates. Inthe compound11, the isophthalate ligands link the metal ions to form two-dimensional （2D）layer structures. A part of2,2′-bipyridine molecules serve as auxiliary ligands while theother serve as guest-templates which located between the layers. There are π-π stackinginteractions between coordinated2,2′-bipyridine molecules and guest-template2,2′-bipyridine molecules. The three-dimensional （3D） network of the compound11isformed by two-dimensional （2D） layers through π-π stacking interactions. The structure ofcompound12is similar to the structure of compounds11. In the compound13-15, theisophthalate ligands link the metal ions to form one-dimensional （1D） double chains. A partof2,2′-bipyridine molecules serve as auxiliary ligands while the other serve asguest-templates which located around the double chains. There are π-π stacking interactionsbetween guest-template2,2′-bipyridine molecules and isophthalate ligands. Thethree-dimensional （3D） networks of the compound13-15are formed by one-dimensional（1D） double chains through π-π stacking interactions. This is the first time to synthesize rareearth coordination polymers in which2,2′-bipyridine molecules serve as auxiliary ligandsand templates. The emission spectra show that11emits intense sharp red light and12emitsintense sharp green light when they are excited by different wavelength ultraviolet light.4. A novel rare earth coordination polymer {（bpy）0.5[Re3（ip）4（phen）4（H₂O）]·2H₂O}n（Re=Dy（16）, bpy=2,2′-bipyridine, ip=isophthalate, phen=1,10-phenanthroline） have beensynthesized by using1,10-phenanthroline molecules as auxiliary ligands and2,2′-bipyridinemolecules formed in situ reaction as templates. In the compound16, the isophthalate ligandslink the metal ions to form two-dimensional （2D） layer structures. The2,2′-bipyridinemolecules serve as guest-templates which located between the layers.1,10-phenanthrolinemolecules chelate metal ions. There are π-π stacking interactions between guest-template2,2′-bipyridine molecules and1,10-phenanthroline molecules. The three-dimensional （3D）network of the compound16is formed by two-dimensional （2D） layers through π-π stacking interactions. This is the first time to synthesize mixed-valence rare earth coordinationpolymer, and the first time to find1,10-phenanthroline can be transformed into2,2′-bipyridine under hydrothermal conditions in the presence of metal ions. The emissionspectra show that16emits blue light when it is excited by different wavelength ultravioletlight.5. A series of novel rare earth coordination polymers [Re2（ip）2（pic）2]n（Re=Pr（17）,Nd（18）, Eu（19）, Tb（20） and Ho（21）, ip=isophthalate, pic=picolinate） have been synthesizedby using isophthalate ligands and picolinate ligands as mixed ligands, and2,2′-bipyridinemolecules or imdazole cations as templates. This series of compounds are isostructural. Theisophthalate ligands link the metal ions to form one-dimensional （1D） single chains anddouble chains, respectively. The picolinate ligands link these single chains and double chainsto form two kinds of layer structures, respectively. Two kinds of layer structures are furtherlinked by sharing metal ions to form the three-dimensional （3D） net structure. The emissionspectra show that19emits intense sharp red light and20emits intense sharp green lightwhen they are excited by different wavelength ultraviolet light.We have successfully used templates to synthesize coordination polymers withisophthalate ligands in this dissertation. We believe this dissertation has an importantguiding function for the syntheses of novel coordination polymers with other ligands,especially for the syntheses of isomers of coordination polymers.