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.

A novel Fe(III) based gel was synthesized via self-assembly of Fe(III) and pyridine 2,6 dicarboxylic acid. The synthesized gel has remarkable mechanical strength as well as self sustainability. The metallogel...

In this contribution we have carried out a systematic magnetostructural investigation to establish a robust one-to-one correlation between quasi-orthogonal bridging mode of pyrazolate ring and ferromagnetism coupling. Generating a...

This contribution deals with the synthesis and utilization of a new pyrazole-based unsymmetrical ligand, 3-(3-carboxyphenyl)-1 H -pyrazole-5-carboxylic acid (H 2 CPCA), for generating multifunctional materials. The reaction with the Co(II) salt in the presence of a co-ligand 2,9-dimethyl phenanthroline (dmphen) results in the formation of the helical compound {[Co 2 (dmphen) 2 (CPCA) 2 ]DMF} n ( 1 ). However, two isostructural monomeric complexes are formed {[M(HCPCA) 2 (H 2 O) 2 ], M = Co(II), ( 2 ) and Mn(II) ( 3 )} when reactions were carried out in the absence of dmphen. Compound 1 shows some highly encouraging single-ion magnetic (SIM) properties. Detailed magnetic studies unveil slow relaxation of magnetization of compound 1 , driven by the higher magnetic anisotropy of the cobalt ion, with the energy barrier of ∼9.2 K and relaxation time of 9.1 × 10 –5 s, suggesting a SIM behavior. Moreover, UV–vis and fluorescence studies confirm the selective dye degradation of compound 1 with methylene blue both in the presence and absence of H 2 O 2 , with the remarkable degradation efficiency of ∼98 and ∼82%, respectively.

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Two newly synthesized Fe(III) based complexes, [Fe 4 L 2 (μ 3 -O) 2 (Cl) 2 (MeOH) 4 (H 2 O) 4 ](ClO 4 ) 2 •4H 2 O•MeOH (1) and [Fe 2 L 3 ]•4DMF (2) were isolated in solid crystalline form using the reaction of iron(III) perchlorate with the ligand H 2 L (H 2 L = 6,6′-((1E,1′E)-hydrazine-1,2-diylidenebis(methanylylidene))bis(2-methoxyphenol). (DMF= N,N-dimethylformamide, MeOH = methanol). Compound 1 was self-assembled in MeOH, but when the solvent was changed to DMF, compound 2 was harvested. Furthermore, compound 1 was converted to compound 2 just by dissolving compound 1 in DMF. Sequential self-assembly and conversion of compound 1 to 2 were monitored by UV−vis spectroscopy and ESI-Mass spectroscopy in solution phase. Single crystal X-ray analysis showed that compound 1 has μ 3 -oxo bridged tetranuclear structure whereas compound 2 has puckered dinuclear structure. Magnetic studies indeed revealed frustrated magnetic spin for compound 1 whereas antiferromagnetic interaction was observed for compound 2. The spectrophotometrical investigation on their phosphatase like activity revealed remarkable hydrolytic efficiency for both the complexes. Michaelis−Menten-derived kinetic parameters suggest the competitiveness of the rate of P−O bond fission employing the phosphomonoester (4-nitrophenyl)phosphate (PNPP) in 97.5% DMF is 1 > 2, and the k cat value lies in the range 28.95−38.43 s −1 at 298 K. Computational calculations have verified the higher catalytic activity of compounds 1 over 2 attributed to the large number of labile groups attached to the metal centers.

The present work reports the design and synthesis of a low molecular weight gelator (LMWG), where1-(3-(pyridin-2-yl)-1H-pyrazole-5-carboylimino) ethyl) phenyl) ethylidene)-3-(pyridin-2-yl)-1H-pyrazole-5-carbohydrazide (H3BPDP). H3BPDP acts as a gelator to encapsulate the toxic heavy...