Effect of Ligand Chain Length for Tuning of Molecular Dimensionality and Magnetic Relaxation in Redox Active Cobalt(II) EDOT Complexes (EDOT=3,4-Ethylenedioxythiophene)

Ghosh, S and Kamilya, S and Mehta, S and Herchel, R and Kiskin, M and Veber, S and Fedin, M and Mondal, A (2022) Effect of Ligand Chain Length for Tuning of Molecular Dimensionality and Magnetic Relaxation in Redox Active Cobalt(II) EDOT Complexes (EDOT=3,4-Ethylenedioxythiophene). In: Chemistry - An Asian Journal .

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Abstract

Four cobalt(II) complexes, [Co(L1)2(NCX)2(MeOH)2] (X=S (1), Se (2)) and {[Co(L2)2(NCX)2]}n (X=S (3), Se (4)) (L1=2,5-dipyridyl-3,4,–ethylenedioxylthiophene and L2=2,5-diethynylpyridinyl-3,4-ethylenedioxythiophene), were synthesized by incorporating ethylenedioxythiophene based redox-active luminescence ligands. All these complexes have been well characterized using single-crystal X-ray diffraction analyses, spectroscopic and magnetic investigations. Magneto-structural studies showed that 1 and 2 adopt a mononuclear structure with CoN4O2 octahedral coordination geometry while 3 and 4 have a 2D [4×4] rhombic grid coordination networks (CNs) where each cobalt(II) center is in a CoN6 octahedral coordination environment. Static magnetic measurements reveal that all four complexes displayed a high spin (HS) (S=3/2) state between 2 and 280 K which was further confirmed by X-band and Q-band EPR studies. Remarkably, along with the molecular dimensionality (0D and 2D) the modification in the axial coligands lead to a significant difference in the dynamic magnetic properties of the monomers and CNs at low temperatures. All complexes display slow magnetic relaxation behavior under an external dc magnetic field. For the complexes with NCS− as coligand observed higher energy barrier for spin reversal in comparison to the complexes with NCSe− as coligand, while mononuclear complex 1 exhibited a higher energy barrier than that of CN 3. Theoretical calculations at the DFT and CASSCF level of theory have been performed to get more insight into the electronic structure and magnetic properties of all four complexes.

Item Type:	Journal Article
Publication:	Chemistry - An Asian Journal
Publisher:	John Wiley and Sons Ltd
Additional Information:	The copyright for this article belongs to the John Wiley and Sons Ltd.
Keywords:	Cobalt compounds; Complex networks; Electron spin resonance spectroscopy; Electronic structure; Ligands; Magnetic susceptibility; Magnetism; Paramagnetic resonance; Redox reactions; Single crystals; Synthesis (chemical); X ray diffraction analysis, Co-ligands; Coordination networks; Coordination Polymers; Coordination-polymers; Ethylenedioxythiophenes; High-energy barriers; Higher-energy barriers; Redox-active; Redox-active ligand; Single-molecule magnet, Luminescence
Department/Centre:	Division of Chemical Sciences > Solid State & Structural Chemistry Unit
Date Deposited:	28 Jun 2022 09:40
Last Modified:	28 Jun 2022 09:40
URI:	https://eprints.iisc.ac.in/id/eprint/73981

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