TY - JOUR

T1 - Effect of Ligand Chain Length for Tuning of Molecular Dimensionality and Magnetic Relaxation in Redox Active Cobalt(II) EDOT Complexes (EDOT=3,4-Ethylenedioxythiophene)

AU - Ghosh, Subrata

AU - Kamilya, Sujit

AU - Mehta, Sakshi

AU - Herchel, Radovan

AU - Kiskin, Mikhail

AU - Veber, Sergey

AU - Fedin, Matvey

AU - Mondal, Abhishake

N1 - Funding Information: This research work is supported by the Indian Institute of Science (IISc), Bangalore, India and the Department of Science and Technology (DST‐RFBR, Indo‐Russia Joint Research Funding, Project No: INT/RUS/RFBR/373). R. H. acknowledges financial support from institutional sources of the Department of Inorganic Chemistry, Palacký University Olomouc, Czech Republic. S. K. and S. G. thank the Council of Scientific and Industrial Research (CSIR), Govt. of India, and S. M. thanks to IISc for their fellowship, M. K., S. V. and M. F. thank Russian Foundation for Basic Research (Project No: 19‐53‐45009). We thank A. Mohanty and S. Mandal for luminescence and solid‐state electrochemical studies respectively. Publisher Copyright: © 2022 Wiley-VCH GmbH.

PY - 2022/8/15

Y1 - 2022/8/15

N2 - 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.

AB - 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.

KW - cobalt

KW - coordination polymers

KW - luminescence

KW - redox-active ligands

KW - single molecule magnets

UR - http://www.scopus.com/inward/record.url?scp=85131862044&partnerID=8YFLogxK

U2 - 10.1002/asia.202200404

DO - 10.1002/asia.202200404

M3 - Article

C2 - 35617522

AN - SCOPUS:85131862044

VL - 17

JO - Chemistry - An Asian Journal

JF - Chemistry - An Asian Journal

SN - 1861-4728

IS - 16

M1 - e202200404

ER -