Tuning structural modulation and magnetic properties in metal–organic coordination polymers [CH3NH3]CoxNi1−x(HCOO)3

Geers, Madeleine; Fabelo, Oscar; Cliffe, Matthew J.; Cañadillas-Delgado, Laura

Abstract

Three solid solutions of [CH3NH3]CoxNi1− x(HCOO)3, with x = 0.25 (1), x = 0.50 (2) and x = 0.75 (3), were synthesized and their nuclear structures and magnetic properties were characterized using single-crystal neutron diffraction and magnetization measurements. At room temperature, all three compounds crystallize in the Pnma orthorhombic space group, akin to the cobalt and nickel end series members. On cooling, each compound undergoes a distinct series of structural transitions to modulated structures. Compound 1 exhibits a phase transition to a modulated structure analogous to the pure Ni compound [Cañadillas-Delgado, L., Mazzuca, L., Fabelo, O., Rodríguez-Carvajal, J. & Petricek, V. (2020). Inorg. Chem. 59, 17896–17905], whereas compound 3 maintains the behaviour observed in the pure Co compound reported previously [Canadillas-Delgado, L., Mazzuca, L., Fabelo, O., Rodriguez-Velamazan, J. A. & Rodriguez-Carvajal, J. (2019). IUCrJ, 6, 105–115], although in both cases the temperatures at which the phase transitions occur differ slightly from the pure phases. Monochromatic neutron diffraction measurements showed that the structural evolution of 2 diverges from that of either parent compound, with competing hydrogen bond interactions that drive the modulation throughout the series, producing a unique sequence of phases. It involves two modulated phases below 96 (3) and 59 (3) K, with different q vectors, similar to the pure Co compound (with modulated phases below 128 and 96 K); however, it maintains the modulated phase below magnetic order [at 22.5 (7) K], resembling the pure Ni compound (which presents magnetic order below 34 K), resulting in an improper modulated magnetic structure. Despite these large-scale structural changes, magnetometry data reveal that the bulk magnetic properties of these solid solutions form a linear continuum between the end members. Notably, doping of the metal site in these solid solutions allows for tuning of bulk magnetic properties, including magnetic ordering temperature, transition temperatures and the nature of nuclear phase transitions, through adjustment of metal ratios.

Citation

Geers, M., Fabelo, O., Cliffe, M. J., & Cañadillas-Delgado, L. (2024). Tuning structural modulation and magnetic properties in metal–organic coordination polymers [CH3NH3]CoxNi1−x(HCOO)3. IUCrJ, 11(6), 910-920. https://doi.org/10.1107/s2052252524008583

• Journal Article Type: Article
• Acceptance Date: Aug 30, 2024
• Online Publication Date: Sep 24, 2024
• Publication Date: Nov 1, 2024
• Deposit Date: Sep 30, 2024
• Publicly Available Date: Oct 2, 2024
• Journal: IUCrJ
• Electronic ISSN: 2052-2525
• Publisher: International Union of Crystallography
• Peer Reviewed: Peer Reviewed
• Volume: 11
• Issue: 6
• Article Number: lt5069
• Pages: 910-920
• DOI: https://doi.org/10.1107/s2052252524008583
• Keywords: phase transitions, incommensurate structures, solid solutions, formate ligands, aperiodic structures, materials science, magnetic structures, coordination polymers
• Public URL: https://nottingham-repository.worktribe.com/output/40000453
• Publisher URL: https://journals.iucr.org/m/issues/2024/06/00/lt5069/index.html
• Additional Information: Publication: IUCrJ; Content type: research papers; Article metrics: Available; Peer reviewed: Yes; Review process: Single blind; Received: 23 May 2024; Accepted: 30 August 2024; Published online: 24 September 2024; Supplementary materials: This article has supporting information; Copyright: © 2024 Madeleine Geers et al.; Licence: Creative Commons Attribution (CC-BY)