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

Abstract

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 (H2IPA) and its four 5-substituted derivatives R-H2IPA (R = COOH, OH, tBu, 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.

Multifunctional Properties of a 1D Helical Co(II) Coordination Polymer: Toward Single-Ion Magnetic Behavior and Efficient Dye Degradation

“…In recent years, inorganic polymeric compounds like CPs have been widely used for wastewater treatment. 32 Organic dye sequestration by CPs usually has two different routes: (a) chemical reaction at the surface of the CPs and (b) photocatalytic degradation in the presence of an inorganic catalyst. 33 The later process is particularly suitable for CPs based on metal, which can easily adopt variable oxidation states during the catalytic cycles.…”

R-Substituent-Induced Structural Diversity and Single-Crystal to Single-Crystal Transformation of Coordination Polymers: Synthesis, Luminescence, and Magnetic Behaviors

“…Yield: 5.9 mg (50.9% based on 3-bpdb). Elemental analysis (%): calcd for (C 21 [Co(3-bpdb)(EtO-ip)] n (8). 8 was prepared similar to that of 2 except that Zn(NO 3 ) 2 •6H 2 O (14.9 mg, 0.05 mmol) was replaced with Co(NO 3 ) 2 •6H 2 O (14.6 mg, 0.05 mmol).…”

“…Coordination polymers (CPs) have recently attracted enormous attention not only because of their structural and topologically diversity but also for their important properties and broad application prospects, such as sensing, magnetism, proton conduction, gas adsorption, and catalysis, and so on. During CPs’ evolution, researchers have made great progress in controlling and tuning of the network topology; nevertheless, prediction of the structural network is largely considered to be serendipitous. , This may be attributed to, except for the proper choice of metals and linkers in CPs synthesis, some weak factors, such as the ratio of metal to ligand, reaction time, pH values; more often than not, the substituent groups of carboxylate ligands also have a great and delicate influence on the structures of the resulting CPs. However, research in this respect is still less explored.…”

“…During CPs' evolution, researchers have made great progress in controlling and tuning of the network topology; nevertheless, prediction of the structural network is largely considered to be serendipitous. 7,8 This may be attributed to, except for the proper choice of metals and linkers in CPs synthesis, some weak factors, such as the ratio of metal to ligand, reaction time, pH values; more often than not, the substituent groups of carboxylate ligands also have a great and delicate influence on the structures of the resulting CPs. However, research in this respect is still less explored.…”

Applying the Influence of Conformational Freedom on the Network Topologies Showing Impressive Proton Conductivity

“…Unlike rigid ligands, flexible linkers, depending on the conformational and coordination requirement, can adopt different conformations by bending or rotating when coordinating to the metal center. The advantages of conformational freedom of the spacer have been successfully exploited by many in recent times leading to a surge in intriguing architectures with the use of flexible bridging ligands. − Our recent works on mixed-ligand systems are highly relevant here. − Our earlier studies with the titular flexible ligand, methylenebis­(3,5-dimethylpyrazole) (H 2 MDP) along with various flexible polycarboxylic acids as auxiliary ligands result in several MOFs with free solvent molecules in the cavity as well as the presence of noncoordinating −COOH groups . Interestingly, H 2 MDP is also a bis-pyrazole system.…”