A series of lanthanide (III) coordination polymers derived via in situ hydrothermal decarboxylation of quinoline-2,3-dicarboxylic acid

Two novel metal-organic frameworks functionalised with pentamethylcyclopentadienyl iridium(III) chloride for catalytic conversion of carbon dioxide to formate

Hydrogenation of CO₂ to formate is a vital reaction, because formate is an excellent hydrogen carrier, which yields blue hydrogen. Blue hydrogen is comparatively cheaper and attractive as the world envisions the hydrogen economy. In this work, two isostructural lanthanide-based MOFs (JMS-6 and JMS-7 [Ln(bpdc)_3/2(dmf)₂(H₂O)₂]_n) were prepared and used as support materials for molecular catalysts. The bipyridyl MOF backbone were functionalised using pentamethylcyclopentadienyl iridium(III) chloride to give Ir(III)@JMS-6a and Ir(III)@JMS-7a. XPS of the functionalised MOFs show downfield shifts in the N 1s binding energy indicating successful grafting of the complex to the MOF. Hydrogenation experiments in the presence of an organic base showed that the functionalised MOFs were active towards converting CO₂ to formate. Ir(III)@JMS-6a and Ir(III)@JMS-7a exhibited the highest turnover numbers of 813 and 621 respectively. ICP-OES indicated insignificant leaching during catalysis. TEM images and XPS data of the recovered catalyst ruled out the presence of Ir(0), confirming that the activity observed was attributed to the molecular Iridium(III) centres.

An asymmetric mononuclear cobalt(II) compound derived from 3-bromo-pyridine-2,6-dicarboxylic acid involving in-situ hydrothermal decarboxylation: structure, magnetic property and Hirshfeld surface analysis

A new cobalt(II) compound with the formula [Co(5-Br-pyc)(2,2′-bipy)(H2O)(Cl)]·2H2O (1·H2O) (5-Br-Hpyc = 5-bromo-pyridine-2-carboxylic acid, 2,2′-bipy = 2,2′-bipyridine) has been hydrothermally synthesized and well characterized. The X-ray single-crystal diffraction analysis showed that 1⋅2H2O has crystallizes in the monoclinic system, space group P21/c (no. 14). The Co(II) center was octahedrally bonded by one bidentate chelate 5-Br-pyc anion and one 2,2′-bipy, one water molecule as well as one chloride anion to form the mononuclear structure of 1⋅2H2O. Complex 1⋅2H2O forms a 3D network through abundant O–H⋅⋅⋅O hydrogen bonds and π⋅⋅⋅π stacking interactions. Notably, the 5-Br-Hpyc ligand was in situ generated by decarboxylation of the 3-bromo-pyridine-2,6-dicarboxylic acid (3-Br-H2pydc) precursor selectively on 2-position under hydrothermal conditions. The magnetic properties, the Hirshfeld surface structure and the synthetic process for 1⋅2H2O have been carefully described and discussed.

Two 2D Co(II)/Mn(II) coordination polymers based on the quinoline-2,3-dicarboxylate ligand: synthesis, crystal structure, and fluorescence properties

A pair of two-dimensional (2D) isostructural coordination polymers (CPs), {[Co(2,3-qldc)(H2O)]} n (1) and {[Mn(2,3-qldc)(H2O)]} n (2), where 2,3-H2qldc = quinoline-2,3-dicarboxylic acid, were hydrothermally synthesized and characterized through IR spectroscopy, elemental and thermal analysis, power X-ray diffraction, and single-crystal X-ray diffraction. The results have revealed that the fully deprotonated 2,3-H2qldc ligand connects the Co(II)/Mn(II) atoms with a μ 3-bridge to form a square-wave 2D network, which is further extended into 3D stacks through O–H···O, C–H···O hydrogen bonds and π···π stacking interactions. Topologically, 1 or 2 can be simplified as a 4-connected sql type with a Schläfli symbol {44·62} and a Shubnikov tetragonal plane net, or as a 3-connected fes type with a Schläfli symbol {4·82} and a Shubnikov plane net. The thermal stability and the solid state fluorescence properties of 1 and 2 were investigated.

The syntheses, structures, and magnetic properties of two mononuclear manganese(II) complexes involving in situ hydrothermal decarboxylation

Two new mononuclear compounds [Mn(3-Br-pydc)(H2O)3] (1) and {[Mn(5-Br-pyc)(bipy)(H2O)(Cl)]·2H2O (2) (3-Br-H2pydc = 3-Br-pyridine-2,6-dicarboxylic acid, 5-Br-Hpyc = 5-Br-pyridine-2-carboxylic acid, bipy = 2,2′-bipyridine) have been synthesized by traditional solution reaction and hydrothermal reaction, respectively. In both compounds, the MnII center is six-coordinated in a distorted octahedral geometry, formed by one tridentate chelate 3-Br-pydc dianion and three water molecules in 1, while the coordination sphere consists of one bidentate chelate 5-Br-pyc anion, one bipy, one water molecule, and one chloride anion in 2 (MnNO5 for 1 and MnN3O2Cl for 2). O–H⋯O hydrogen bonds, Br⋯O halogen bonds, and/or π-π stacking assist in the construction of the three-dimensional (3D) network structures of 1 and 2. Notably, the 5-Br-Hpyc ligand was generated in situ by decarboxylation of the 3-Br-H2pydc precursor under hydrothermal conditions. Variable-temperature magnetic susceptibility data in the 2–300 K temperature range indicate weak antiferromagnetic coupling in both 1 and 2.

Preparation, characterization, and properties of PMMA-doped polymer film materials: a study on the effect of terbium ions on luminescence and lifetime enhancement

Poly(methylmethacrylate) (PMMA) doped with Tb-based imidazole derivative coordination polymer {[Tb(3)(L)(μ(3)-OH)(7)]·H(2)O}(n) (1) (L = N,N'-bis(acetoxy)biimidazole) was synthesized and its photophysical properties were studied. The L'(L' = N,N'-bis(ethylacetate)biimidazole) ligand was synthesized by an N-alkylation reaction process followed by ester hydrolysis to produce ligand L. Polymer 1 and ligand L' have been characterized by (1)H NMR and IR spectroscopy, elemental analysis, PXRD and X-ray single-crystal diffraction. Coordination polymer 1 is the first observation of a CdCl(2) structure constructed with hydroxy groups and decorated by ligand L in lanthanide N-heterocyclic coordination polymers. In the 2D layered structure of 1, each Tb3 metal center is connected with three Tb1 and three Tb2 metal centers by seven hydroxyl groups in different directions, resulting in a six-membered ring. After doping, not only the luminescence intensity and lifetime enhanced, but also their thermal stability was increased in comparison with 1. When 1 was doped into poly(methylmethacrylate) (1@PMMA), polymer film materials were formed with the PMMA polymer matrix (w/w = 2.5%-12.5%) acting as a co-sensitizer for Tb(3+) ions. The luminescence intensity of the Tb(3+) emission at 544 nm increases when the content of Tb(3+) was 10%. The lifetime of 1@PMMA (914.88 μs) is more than four times longer than that of 1 (196.24 μs). All τ values for the doped polymer systems are higher than coordination polymer 1, indicating that radiative processes are operative in all the doped polymer films. This is because PMMA coupling with the O-H oscillators from {[Tb(3)(L)(μ(3)-OH)(7)]·H(2)O}(n) can suppress multiphonon relaxation. According to the variable-temperature luminescence (VT-luminescence) investigation, 1@PMMA was confirmed to be a stable green luminescent polymer film material.

Luminescent properties of Ag(i)/Cu(i) coordination polymers: crystal structures and high intensity luminescence of a PMMA-doped hybrid material based on a quinoline-2,3-dicarboxylic acid ligand

Preparation, characterization, crystal structure and different luminescent properties of Ag(i)/Cu(i) coordination polymers: stable blue emission, thermochromism and PMMA-doped hybrid material.

Structure variations of a series of lanthanide complexes constructed from quinoline carboxylate ligands: photoluminescent properties and PMMA matrix doping

A series of lanthanide complexes constructed from H₂qldc are synthesized and the luminescence properties discussed.

Multifunctional Zn(ii)/Cd(ii) metal complexes for tunable luminescence properties and highly efficient dye-sensitized solar cells

Complexes Zn1 and Cd1 exhibit tunable luminescence properties and they can serve as co-sensitizers to enhance the power-conversion efficiency.