Cobalt(II) Coordination Polymers Assembled from Unexplored Pyridine-Carboxylic Acids: Structural Diversity and Catalytic Oxidation of Alcohols

Abstract

New coordination polymers of cobalt(II), namely, [Co(μ 4 -cpna)- 4), have been generated under hydrothermal conditions from CoCl 2 •6H 2 O, two different multifunctional pyridine-carboxylic acids {H 2 cpna: 5-(4-carboxyphenoxy)nicotinic acid; H 3 dppa: 5-(3,4-dicarboxylphenyl)picolinic acid}, and optional N,N-supporting ligands {phen: 1,10-phenanthroline; 4,4′-bipy: 4,4′-bipyridine} acting as mediators of crystallization. These Co(II) coordination polymers (CPs) have been obtained as stable crystalline materials and characterized by conventional solid-state techniques, including X-ray crystallography. The obtained products are 3D metal−organic frameworks (MOFs 1 and 4) or 2D coordination polymers (CPs 2 and 3). Analysis of the topologies of simplified nets has revealed the sra (1), fes (2), and 3,4L13 (3) networks, in addition to a very complex topologically unique framework in 4. An observed diversity of structures is driven by types of carboxylate building blocks and crystallization mediators. Thermal stability and magnetic and catalytic properties of 1−4 have also been studied. In fact, the Co(II) compounds act as heterogeneous catalysts for the oxidation of alcohols with tBuOOH (tert-butylhydroperoxide) under mild conditions. Compound 2 features a good catalytic activity (up to 45% yield) in the oxidation of 1-indanol to 1-indanone. Finally, products 1−4 broaden a still very small number of CPs or MOFs driven by the present type of multifunctional pyridine-carboxylic acids (H 2 cpna, H 2 dppa).

Bringing a New Flexible Mercaptoacetic Acid Linker to the Design of Coordination Polymers

“…By reporting the unique examples of coordination polymers derived from p -xylylene-bis(2-mercaptoacetic) acid, the present work also contributes to widening the family of multifunctional building blocks [ 34 , 35 , 36 , 37 , 38 ] in the assembly of new polymeric metal-organic architectures. We believe that the present study will motivate further research in exploring this and related types of flexible building blocks for the synthesis of coordination polymers with a diversity of topologies, functional properties, and applications [ 39 , 40 ].…”

Crystal structure of a novel one-dimensional zigzag chain-like cobalt(II) coordination polymer constructed from 4,4′-bipyridine and 2-hydroxybenzoate ligands

“…This is because 4,4 0 -bpy is a rigid molecule that can link the metal centers to form a network with well-defined structures and also support the stability of the structures through aromaticand C-HÁ Á Á interactions (Kaes et al, 2000). Furthermore, many researchers incorporate carboxylatebased ligands for the construction of CPs, giving rise to frameworks with a variety of dimensions and topologies (Gu et al, 2019;Horike et al, 2020). Benzoate and its derivatives have been widely used to construct the CPs because of the variety of their coordination modes, resulting in a variety of coordination geometries for the metal centers and interesting properties and applications of their CPs (Tong et al, 2000;Busskamp et al, 2007;Zhang et al, 2007;Song et al, 2009).…”

Metal-directed supramolecular architectures based on the bifunctional ligand 2,5-bis(1H-1,2,4-triazol-1-yl)terephthalic acid

“…Coordination polymers (CPs) have attracted significant interest because of their extensive applications in luminescence (Uchida et al, 2019;Xu et al, 2018;Chen & Zhang, 2019b), magnetism (Li et al, 2019;Liu et al, 2019), gas-storage properties (Hua et al, 2017;Yang & Xu, 2017;Chen & Zhang, 2019a), catalysis (Liu et al, 2014;Gu et al, 2019), and so on (Wang et al, 2015a;Hao et al, 2018;Chen & Zhang, 2019c). In order to promote the functionality of CPs, different synthetic strategies have been employed, and numerous CPs with various architectures and crystal packing structures have been obtained (Rosa et al, 2016;Robin & Fromm, 2006;Stock & Biswas, 2012).…”