Systematic Study of Mutually Inclusive Influences of Temperature and Substitution on the Coordination Geometry of Co(II) in a Series of Coordination Polymers and Their Properties

摘要

In this contribution we have extended our current research goal of designing functional metal-organic frameworks (MOFs) using bispyrazole type ligands. Accordingly, ten new cobalt-based MOFs have been synthesized using a simple bispyrazole ligand, 4,4'-methylene-bispyrazole (H2MBP), and isophthalic acid (H(2)IPA) and its four 5-substituted derivatives R-H(2)IPA (R = COOH, OH; Bu-t, NH2). The major aim of this study was to validate the mutual influence of temperature and substitutions on the final structural self-assembly. Five different isophthalic acid derivatives were used to study the influence of substituents while each reaction was carried out at two different temperatures to assess the temperature effect. A clear correlation was observed between the reaction temperature and the coordination number of the cobalt atoms which consequently changes the self-assembly pattern. We have also shown that the periodical change in coordination number did bring about some systematic changes in the structural network via secondary building unit selectivity. With the presence of a tunable cavity inside the network, high surface area, and unsaturated metal centers, MOFs show highly encouraging photocatalytic degradation of toxic dye molecule with a potential application in wastewater purification. Another fascinating aspect of this work is the construction of magnetic coordination polymers with the occurrence of a not-so-common MCE behavior of cobalt-based MOF.