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Issue 45, 2018
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Effect of temperature and ligand protonation on the electronic ground state in Cu(II) polymers having unusual secondary interactions: a magnetic and catechol oxidase study

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Abstract

Two new copper(II) polymeric complexes, {[Cu(HPymat)(H2O)](NO3)}n (1) and [Cu2(Pymat)2(H2O)3]n (2), have been synthesized using the Schiff base ligand H2Pymat [H2Pymat = (E)-2-(1-(pyridin-2-yl)-methyleneamino)terephthalic acid]. Complex 1 is a cationic 1D polymer, whereas complex 2 is a two dimensional polymer. Both complexes were crystallographically, spectroscopically and magnetically characterized. Theoretical studies were performed and the catecholase activity of the complexes was also examined. Complex 1 is a ferromagnetically coupled complex with J = 2.8 cm−1 and 2 shows antiferromagnetic coupling with J = −1.6 cm−1. Both complexes show notable features in the EPR study. They show rhombic spectra at 77 K in the solid state, but by varying the temperature or solvents the nature of the spectra can be changed or inverted. This behaviour indicates a change of the ground state from dx2y2 to dz2 orbitals. Theoretical calculations of 1 focus on the evaluation and characterization of interesting anion–π–anion assemblies that are formed in the solid state. In 2 we have analysed the unconventional chelate ring⋯chelate ring π-stacking interactions that govern its solid state architecture. Both complexes act as functional models and show catechol oxidase activity with a kcat value of the order of 103 h−1.

Graphical abstract: Effect of temperature and ligand protonation on the electronic ground state in Cu(ii) polymers having unusual secondary interactions: a magnetic and catechol oxidase study

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Publication details

The article was received on 12 Jun 2018, accepted on 18 Sep 2018 and first published on 18 Sep 2018


Article type: Paper
DOI: 10.1039/C8DT02417K
Citation: Dalton Trans., 2018,47, 16102-16118
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    Effect of temperature and ligand protonation on the electronic ground state in Cu(II) polymers having unusual secondary interactions: a magnetic and catechol oxidase study

    S. Saha, N. Biswas, A. Sasmal, C. J. Gómez-García, E. Garribba, A. Bauza, A. Frontera, G. Pilet, G. M. Rosair, S. Mitra and C. Roy Choudhury, Dalton Trans., 2018, 47, 16102
    DOI: 10.1039/C8DT02417K

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