1D Lanthanide Coordination Polymers Based on 3-(Pyridin-4-yl)benzoic Acid: Syntheses, Structures and Luminescent Properties

ABSTRACT Four novel 1D lanthanide coordination polymers with formula [Ln（3,4-pybz）3（HzO）2. H2O]n （Ln = 1 Sm; 2 Eu; 3 Tb; 4 Dy, 3,4-Hpybz = 3-（pyridin-4-yl）benzoic acid） have been synthesized by hydrothermal reactions of lanthanide oxide and 3-（pyridine-4-yl） benzoic acid. Single-crystal X-ray diffraction shows that the four compounds are isostructural. They all crystallize in a monoelinic system, space group P1^-. They have a doubly carboxylate-bridged infinite-chain structure with alternating Ln-（carboxylate）2-Ln linkages and one chelating carboxylate group on each metal center. The Ln ion also combines to two water molecules to form an eight-coordinate square antiprismatic geometry. The pyridine nitrogen atoms of the ligand do not coordinate to the metal centers but direct the formation of a 3D network through hydrogen bonding with coordinated water molecules. The photoluminescent properties of 2 and 3 have been also studied.

Three Lanthanide Coordination Polymers Based on Novel Rigid Tetracarboxylate Ligand:Syntheses,Crystal Structures,and Luminescence Properties

Three lanthanide coordination polymers [Ln（bcpb）0.5（NO3）（DEF）2] （Ln = Y （1）, Tb （2）, Eu （3）, H4bcpb = 2,5-bis（2,4-dicarboxyphenyl） pyridine and DEF = N,N-diethylformamide）） have been solvothermally synthesized under hydrothermal conditions with a novel Hnbcpb ligand and trivalent lanthanide nitrates. Single-crystal X-ray diffraction analysis reveals that compounds 1-3 are isostructural and crystallize in the monoclinic system, space group P21/n. Crystal data for 1： C20H26N409Y, Mr = 555.36, a = 13.022（9）, b = 17.778（12）, c = 10.861（8） A, β= 100.208（3）°, V = 2475（3） A3, Z = 4; Crystal data for 2： C20H26N4OgTb, Mr = 625.37, a = 13.0476（4）, b = 17.8037（7）, c = 10.9398（3） A, β = 100.008（4）°, V = 2496.4（12） A3, Z = 4; Crystal data for 3： C20H26N409Eu, Mr = 618.41, a = 13.055（4）, b = 17.833（5）, c = 10.893（3）A, β = 100.133（4）°, V= 2496.4（12） A3, Z = 4. The compounds were characterized by thermogravimetric analysis （TGA）, IR spectroscopy, and X-ray single-crystal diffraction. Compounds 1-3 all feature 2D networks with -ABAB- fashions. The luminescent properties of compounds 1-3 and free H4bcpb ligand were investigated at room temperature. The results show that the H4bcpb ligand can efficiently transfer energy to the Tb（III） ions, while the energy is not fully transferred from the H4bcpb ligand to the Eu（III） ions.

Syntheses,Crystal Structures and Luminescent Properties of Two Lanthanide Coordination Polymers Based on Bifunctional Ligand

Two lanthanide coordination polymers, [Eu（HL）（L）（H2O）2]n（1） and [Tb（H0.5L）2]n（2）, based on bifunctional 5-（1H-imidazol-1-yl） isophthalic acid（H2L）, are hydrothermally synthesized and characterized by both single-crystal and powder X-ray diffraction analyses, and FT-IR. In compound 1, the basic inorganic building unit of the coordination network is the dinuclear [Eu2（COO）6] cluster. Each [Eu2（COO）6] cluster connects four HL^- ligands and each HLligand links two [Eu2（COO）6] clusters, resulting in a 2D coordination layer. The adjacent 2 D layers are further connected via neighboring inter-layer hydrogen bonds to give a 3D supramolecular structure. In compound 2, the Tb^3＋ is coordinated to six oxygen atoms. Each Tb^3＋ ion connects six ligands and each ligand links three Tb^3＋ ions, leading to a 3D coordination polymeric network which exhibits remarkably high thermal stability up to 500℃. Furthermore, due to the successful incorporation of Tb^3＋, compound 2 displays characteristic luminescent emission in the solid state at room temperature. The combination of high thermal stability and fluorescent property of compound 2 would make it as a promising light-emitting material.

Syntheses and Structures of Three Novel 1-D Lanthanide-isonicotinate Coordination Polymers

Three novel lanthanide-IN coordination polymers [Ln（IN）3（H2O）2], （Ln = Sm 1, Dy 2, Eu 3; IN = isonicotinate） have been hydrothermally synthesized and characterized by FT-IR spectra, elemental analysis and TG analysis. Single-crystal X-ray diffraction shows that 1, 2 and 3 are isostructural. Crystal data for 1： monoclinic, space group C 2/c, a = 15.8384（14）, b = 14.2662 （12）, c = 9.5073（7） A, β = 97.705（4）°, V = 2128.8（3） A^3, Z = 4, Dc = 1.724 g/cm^3, F（000） = 1084 , μ = 2.806 mm^-1 and R = 0.0226; Crystal data for 2： monoclinic, space group C 2/c, a = 15.7890（3）, b = 14.1356（6）, c = 9.5152（3） A, β= 97.899（2）°, V = 2103.52（12） A^3, Z = 4, Dc = 1.784 g/cm^3, F（000） = 1100, μ = 3.601 mm^-1 and R = 0.0406; Crystal data for 3： monoclinic, space group C 2/c, a = 15.802（5）, b = 14.242（4）, c = 9.513（3） A, β = 97.695（5）°, V = 2121.8（10） A^3, Z = 4, Dc = 1.735 g/cm^3, F（000） = 1088 ,μ = 3.004 mm^-1 and R = 0.0273. In the three compounds, the Ln（Ⅲ） centers are eight-coordinated with antiprismatic geometry. The Ln（IN）3（H2O）2 unit connects mutually to form a one-dimensional double zigzag chain via isonicotinate oxygen bridging. The infinite chains are further linked by inter-chain hydrogen-bonding to form a three-dimensional supramolecular network.

Recent developments on carbon-carbon cross-coupling reactions using rare-earth metals-derived coordination polymers as efficient and selective Pd catalytic systems

Most recent progress on the Suzuki-Miyaura, Heck and Sonogashira cross-coupling reactions, induced by heterobimetallic Pd-Ln coordination polymers as heterogeneous catalysts has been accurately reviewed. Physical-chemical characterization of the Pd-Ln composite materials by adequate physical methods revealed the distinct structure and configuration of the two- and three-dimensional frameworks. The important contribution of the coordination polymers as catalyst supports to finely modulating the catalytic activity and chemoselectivity has been considered. Published results illustrate the high activity and chemoselectivity of Pd-Ln coordination polymers in cross-coupling reactions, excellent catalyst recoverability and recyclability as well as low catalyst loading or metal leaching, under optimized reaction conditions. The particular effect of the solvent, base, aryl halide or related reagents in governing the main steps of the Pd catalytic cycle has been particularly outlined. In addition, the well-established cooperative effect of the lanthanides with palladium, with emphasis on the synergism between different metals in heterobimetallic catalytic systems, has been highlighted.

Synthesis and crystal structure of a neodymium coordination polymer with 2,6-anthraquinonedisulfonate

The coordination polymer, （Nd（H2O）5）2（2,6-AQDS）3.2H2O where 2,6-AQDS = 2,6- anthraquinonedisulfonate, has been synthesised via a hydrothermal route. Structurally, it consists of layers of monomeric Nd polyhedra which are linked by 2,6-AQDS anions forming a polymeric, three-dimensional network. Each Nd atom is nine coordinate, bonding to five water molecules and to four oxygen atoms from four 2,6-AODS anions which in turn pillar the layers by bridging two Nd atoms in one layer, and coordinating to a single Nd in the other.