Naslov
Impact of dehydration and mechanical amorphization on the magnetic properties of Ni(ii)-MOF-74

Autori
Muratović, Senada ; Karadeniz, Bahar ; Stolar, Tomislav ; Lukin, Stipe ; Halasz, Ivan ; Herak, Mirta ; Mali, Gregor ; Krupskaya, Yulia ; Kataev, Vladislav ; Žilić, Dijana ; Užarević, Krunoslav

Izvornik
Journal of Materials Chemistry C (2050-7526) 8 (2020); 7132-7142

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
MOF-74 ; Ni(II) ; mechanically responsive MOF ; magnetic MOF ; amorphization ; dehydration ; magnetism ; ESR/EPR ; high and low spin Ni(II) ; spin-crossover

Sažetak
Mechanically responsive metal–organic frameworks (MOFs) came very recently into the spotlight of material science for their unique properties and potential new fields of application. We present here a clarification of the magnetic properties of prototypical magnetic MOF-74 material, Ni(II)-MOF-74, using magnetization measurements, X-band electron spin resonance (ESR), multi-frequency high-field ESR (HF-ESR), and theoretical model. It was established that the guests populating the honeycomb channels have little influence on the magnetism of Ni-MOF-74, whereas magnetic properties change significantly upon mechanical amorphization. Amorphous material (am-Ni-MOF-74), which can be readily prepared by the mechanochemical treatment of dehydrated Ni-MOF-74 (deh-Ni-MOF-74), as shown by in situ monitoring methods, displays significantly lower bulk magnetization compared to Ni-MOF-74 and deh-Ni-MOF-74. This decline in magnetization is established to be a consequence of the spin-crossover from high-spin to a low-spin state of nickel(II) ions. The observed spin-crossover was rationalized by an insight into the changes of the nickel coordination sphere during the amorphization, which was provided by solid-state nuclear magnetic resonance (NMR) and infrared (IR) spectroscopy. Additionally, it was found that am-Ni-MOF-74 behaves differently than its zinc analogue when exposed to vapors or liquid-additives in the milling process, indicating that the nature of the metal node plays a substantial role in the mechanical properties of this modular family of MOF materials.

Izvorni jezik
Engleski

Znanstvena područja
Fizika, Kemija, Interdisciplinarne prirodne znanosti

Napomena
Uz financijsku podršku Slovenian Research Agency No. P1-0021 and No. N1-0079

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