| Using solvothermal and hydrothermal methods,fourteen kinds of polymers were designed and synthesized by Ln IIIions and transition metal(Cr III,Zn IIand Ag I)ions as the center metal ions.Multidentate ligands,such as o-phthalic acid and N-containing carboxylic acid were selected as main ligands,at the same time oxalic acid and 2,2'-bipyridine as the auxiliary ligand.Their chemical formulas were listed as following:(1){[Pr4Cr4(?4-O)4(?3-OH)4(o-C8H4O4)6(H2O)6]·4H2O}n(2){[Nd4Cr4(?4-O)4(?3-OH)4(o-C8H4O4)6(H2O)7]·5H2O}n(3){[Sm4Cr4(?4-O)4(?3-OH)4(o-C8H4O4)6(H2O)7]·5H2O}n(4){[Eu4Cr4(?4-O)4(?3-OH)4(o-C8H4O4)6(H2O)7]·5H2O}n(5){[Gd4Cr4(?4-O)4(?3-OH)4(o-C8H4O4)6(H2O)7]·5H2O}n(6){[Tb4Cr4(?4-O)4(?3-OH)4(o-C8H4O4)6(H2O)6]·4H2O}n(7){[Dy4Cr4(?4-O)4(?3-OH)4(o-C8H4O4)6(H2O)6]·4H2O}n(8){[Ho4Cr4(?4-O)4(?3-OH)4(o-C8H4O4)6(H2O)6]·4H2O}n(9){[Sm Zn(imdc)(ox)1.5H2O]·H3O·H2O}n(10){Er Zn2(imdc)2(ox)0.5(H2O)4}n(11){Pr Zn(2-Amic)2.5(2,2'-bipy)}n(12){Gd Ag(3,5-PDA)2(ox)0.5(H2O)2}n(13){[Pr(Himdc)(ox)0.5(H2O)2]·H2O}n(14){[Nd(Himdc)(ox)0.5(H2O)2]·H2O}npolymers(1)-(8)are Cr-Ln coordination polymers with similar asymmetric unit structures but they possess two kinds of crystal structure,that is,(1)is bridged into the 3D infinite network by o-phthalic acid(o-C8H4O42-)in two coordination modes,while(2)-(5)are joined into the 1D double chain structures by o-C8H4O42-.In polymers(9)and(10),imidazole-4,5-carboxylate(imdc3-)and oxalate(ox2-)act as bridging ligands to form 3D infinite network structures.Polymer(11)is a 3D Zn-Ln polymer by 2-amino terephthalate(2-Amic2-)and 2,2'-bipyridine(2,2'-bipy).The polymer(12)is a 3D Ag-Ln polymer composed of pyridine-3,5-carboxylate(3,5-PDA2-)and ox2-.Polymers(13)-(14)are Ln-Ln polymers with 2D structures and formed by Himdc2-and ox2-as bridging ligands,and are further connected to form a 3D hydrogen bonding network structure by hydrogen bond.At the room temperature,IR,UV-Vis-NIR and emission spectra in Vis-and NIR-regions of polymers were determinded and assigned.Except for polymers(5)and(12),the characteristic luminescence of Ln IIIions was shown,and their emission peaks in the NIR region appeared shifted,widened or cleaved compared with the corresponding theoretical values.This may be due to the influenced by crystal field and the transition metal ion d orbitals,the system internal energy level is tuned,and this can be corroborated with their UV-Vis-NIR absorption spectra. |
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