Naslov
Promjene u feromagnetski spregnutom [Ni4L4] klasteru pod utjecajem otapala
(Solvent-induced transformations in feromagnetically coupled [Ni4L4] cluster)

Autori
Cindrić, Marina

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Skup
Kongres hemičara i tehnologa Bosne i Hercegovine s međunaronim učešćem

Mjesto i datum
Sarajevo, Bosna i Hercegovina, 10.10.2014. - 12.10.2014

Vrsta sudjelovanja
Pozvano predavanje

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
tetranuclear clusters; ferromagnetic materials; solvent induced transformations; Ni-cubans

Sažetak
To date several magnetic systems with SMM-type behaviour based on polynuclear complexes of the Mn, Fe, Ni, V and Co or mixed metals have been described. Their synthesis poses a number of challenges, often related with inability to predict the exact cluster structure due to potentially variable outcomes of self–assembly process. Owing to a wide range of their potential applications, e.g. in data storage, memory devices, switches and sensors, considerable attention has been devoted to the targeted synthesis of such systems. The importance and great influence of the solvent on modulation of the SMM's magnetic features was first described in 1999 by Olivier Khan1, who introduced the concept of a “magnetic sponge” to describe magnetic materials that can reversibly release and reabsorb both coordinated and uncoordinated solvent molecules. Importantly, it was shown that these processes are accompanied by the structural changes related to a cleavage/formation of the coordination bonds which subsequently also affect the magnetic properties. 2, 3 Among different cluster types that can exhibit SMM features, cubane–like magnetic clusters with [Ni4(μ3–O)4] core are especially well–studied class. The cubane–like core of nearly all investigated tetranuclear Ni(II) complexes includes four identical μ3–O bridges originating from –OH or –OR moieties. Previous studies have unveiled that the symmetry of [Ni4O4] core and the differences in the Ni–μ3–O–Ni angles play a crucial role in the intramolecular magnetic interactions. Namely, it was shown that the ferromagnetic interactions are associated with the core angles close to 90°, whereas the antiferromagnetic interactions involve larger angles. This was also corroborated by the latest investigation of [Ni4L4(solv)4] type of complexes which exhibit a switching of the spin ground state from S = 4 to S = 0 at ambient temperature, triggered by the reversible exchange of the coordinated solvent molecules (MeOH vs. H2O).4 Although the structural alterations induced by such solvent exchange were subtle, substantial changes of the physical and chemical properties have been established. Our latest investigations were directed to synthetic procedures, interconversion scenarios of reabsorption and exchanging solvent molecules, structural and magnetic studies of a new family of Ni(II) compounds based on cubane–like clusters. Depending on synthetic conditions different cubane–like clusters [Ni4L4(ROH)4], [Ni4L4(H2O)2], [Ni4L4(ROH)2(R’OH)2] and [Ni4L4(ROH)2] (H2L = tridentate Schiff base ligand, N–(2–hydroxy–5–methylphenyl)salicylideneimine, R = -CH3, -C2H5, -C3H7, -C4H9 i –C5H11) were isolated. The exhibited solvent–induced transformations of the clusters have been studied by SCXRD (at 150 K and at 296 K) and PXRD, TG/DSC, DVS, SQUID magnetometry, Hot–stage microscopy, IR as spectroscopic method and quantum chemical calculations. All experiments are showed possibility to come again to the well–defined initial state exposing clusters to methanol vapours, in turn. mjerenja magnetske susceptibilnosti.

Izvorni jezik
Engleski

Znanstvena područja
Kemija

POVEZANOST RADA