Synthesis, crystal structures, magnetic and luminescent properties of nickel(II) and cadmium(II) coordination polymers bearing 5-(2′-carboxylphenyl) nicotate ligands

Abstract

Two coordination polymers, namely [M(cpna)-(phen)(H 2 O)] n (M = Ni, 1; Cd, 2, H 2 cpna = 5-(2 0 -carboxylphenyl) nicotic acid, phen = 1,10-phenanthroline), have been hydrothermally synthesized and characterized by single-crystal X-ray diffraction, magnetic and luminescence measurements. Single-crystal X-ray diffraction studies show that the two complexes are isostructural polymers. They have 1D step-like chain structures, which are further extended into 3D metal-organic supramolecular frameworks by p-p stacking interactions. Magnetic studies for complex 1 show antiferromagnetic coupling between the adjacent Ni(II) centers, with g = 2.10 and J = -4.30 cm -1 . Complex 2 displays strong green fluorescent emission at room temperature.

pH and Auxiliary Ligand Influence on the Structural Variations of 5(2′-Carboxylphenyl) Nicotate Coordination Polymers

“…The distances of Cd–O and Cd–N bonds span the range of 2.221(2)–2.380(2) Å and 2.330(2)–2.379(2) Å. All the Cd–O and Cd–N distances in 1 – 3 are in good with the bond lengths observed in other Cd(II) complexes. ,,,, In 4 , the Co–O bond lengths range from 2.045(3) to 2.171(3) Å, and the Co–N bond distances are 2.155(3)–2.163(3) Å. In 5 , the Mn–O bond lengths range from 2.103(3) to 2.245(3) Å, and the Mn–N bond distances are 2.252(3)–2.302(3) Å.…”

“…(2) To our knowledge, H 2 cpna has not been adequately explored in the construction of coordination polymers. 6 In this work, by using ligand H 2 cpna, changing the reaction pH value and/or using auxiliary ligand, a series of coordination compounds {[Cd (Hcpna) (4), and Mn (5)), [Co(cpna)(phen)(H 2 O)] n (6), [Mn(cpna)-(phen)(H 2 O)] n (7), {[Nd(Hcpna)(cpna)(H 2 O) 2 ]•3H 2 O} n (8), and {[Ln(Hcpna)(cpna)(phen)]•2H 2 O} n (Ln = Pr (9), Nd (10), Eu (11), and Gd (12), 2,2′-bipy = 2,2′-bipyridine, phen = 1,10-phenanthroline) were prepared by the hydrothermal method (Scheme 1). Their structural diversities show that the pH value of the reaction system and auxiliary ligand played a significant role in the structural self-assembled process.…”

“…The carboxylate groups can act not only as hydrogen-bond acceptors but also as hydrogen-bond donors, depending upon the degree of deprotonation, which is beneficial for the construction of coordination polymers. (2) To our knowledge, H 2 cpna has not been adequately explored in the construction of coordination polymers …”

Metal–Organic Architectures Assembled from Multifunctional Polycarboxylates: Hydrothermal Self-Assembly, Structures, and Catalytic Activity in Alkane Oxidation

“…The five-coordinate copper­(II) atom is surrounded by two carboxylate oxygen donors coming from two different μ 3 -cpna 2– moieties, an nitrogen donor from another μ 3 -cpna 2– ligand, and two phen nitrogen donors, thus forming a distorted square-pyramidal {CuN 3 O 2 } environment with the τ parameter of 0.0792 (τ = 0 or 1 for a regular square-pyramidal or trigonal-bipyramidal geometry, respectively) . The Cu–N and Cu–O bonds are in the 2.034(4)–2.382(4) and 1.934(3)–1.965(3) Å ranges, respectively (Figure a); these bond lengths are within the typical values for related copper­(II) compounds ,, and CPs of other metals derived from H 2 cpna . In 1 , cpna 2– acts as a μ 3 -N,O 2 spacer, with the carboxylate groups being monodentate (mode I, Scheme ).…”

“…Coordination polymers (CPs) and related metal–organic architectures are of great interest in modern inorganic and materials chemistry because of their structural features, functional properties, and variety of applications in catalysis, magnetism, sensing, luminescence, and selective sorption. − The generation of CPs can be affected by numerous parameters such as the nature of the metal nodes, organic building blocks, and supporting ligands, stoichiometry, type of solvent, and reaction temperature. − In particular, diverse aromatic multicarboxylic acids are commonly applied for the design of CPs because such building blocks are thermally stable and flexible and can easily satisfy the charge balance of metal nodes, thus leading to a variety of coordination modes. − ,− Carboxylic acids with phenylpyridine or biphenyl cores and a different arrangement of the COOH and pyridine N sites have been of particular interest, − owing to a possible rotation of two aromatic cycles and variable levels of deprotonation of carboxylic acid groups. These characteristics of multifunctional carboxylic acid ligands can lead to the generation of new CPs with distinct structures. − …”