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

New coordination polymers of cobalt(II), namely, [Co(μ 4 -cpna)(H 2 O) 2 ] n (1), [Co(μ 3 -cpna)(phen)(H 2 O)] n ·nH 2 O (2), [Co 3 (μ 4 -dppa) 2 (H 2 O) 6 ] n ·2nH 2 O (3), and [Co 3 (μ 5 -dppa) 2 (μ-4,4-bipy)(H 2 O) 2 ] n ·4nH 2 O (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). © 2019 American Chemical Society.

Gu J.1 , Wen M.1 , Cai Y.1 , Shi Z.1 , Nesterov D.S.2 , Kirillova M.V.2 , Kirillov A.M. 2, 3
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  • 1 State Key Laboratory of Applied Organic Chemistry, Key Laboratory of Nonferrous Metal Chemistry and Resources Utilization of Gansu Province, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou, 730000, China
  • 2 Centro de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, Lisbon, 1049-001, Portugal
  • 3 Peoples' Friendship University of Russia, RUDN University, 6 Miklukho-Maklaya st., Moscow, 117198, Russian Federation
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