Tetracoordinate Co(ii) complexes with semi-coordination as stable single-ion magnets for deposition on graphene

0578593 - ÚFM 2024 RIV GB eng J - Journal Article
Giraldo, J. N. - Hrubý, J. - Vavrečková, Š. - Fellner, O. F. - Havlíček, Lubomír - Henry, D. - de Silva, S. - Herchel, R. - Bartoš, M. - Šalitroš, I. - Santana, V. T. - Barbara, P. - Němec, I. - Neugebauer, P.
Tetracoordinate Co(ii) complexes with semi-coordination as stable single-ion magnets for deposition on graphene.
Physical Chemistry Chemical Physics. Roč. 25, č. 43 (2023), s. 29516-29530. ISSN 1463-9076. E-ISSN 1463-9084
Institutional support: RVO:68081723
Keywords : total - energy calculations * molecule magnet * zero-field * basic-sets * electron-localization
OECD category: Physical chemistry
Impact factor: 3.3, year: 2022
Method of publishing: Open access
https://pubs.rsc.org/en/content/articlelanding/2023/CP/D3CP01426F

We present a theoretical and experimental study of two tetracoordinate Co(ii)-based complexes with semi-coordination interactions, i.e., non-covalent interactions involving the central atom. We argue that such interactions enhance the thermal and structural stability of the compounds, making them appropriate for deposition on substrates, as demonstrated by their successful deposition on graphene. DC magnetometry and high-frequency electron spin resonance (HF-ESR) experiments revealed an axial magnetic anisotropy and weak intermolecular antiferromagnetic coupling in both compounds, supported by theoretical predictions from complete active space self-consistent field calculations complemented by N-electron valence state second-order perturbation theory (CASSCF-NEVPT2), and broken-symmetry density functional theory (BS-DFT). AC magnetometry demonstrated that the compounds are field-induced single-ion magnets (SIMs) at applied static magnetic fields, with slow relaxation of magnetization governed by a combination of quantum tunneling, Orbach, and direct relaxation mechanisms. The structural stability under ambient conditions and after deposition was confirmed by X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. Theoretical modeling by DFT of different configurations of these systems on graphene revealed n-type doping of graphene originating from electron transfer from the deposited molecules, confirmed by electrical transport measurements and Raman spectroscopy.
Permanent Link: https://hdl.handle.net/11104/0347567