Review: Downsizing effect on 2-D and 3-D spin crossover metal-organic frameworks

Electrical conductivity and magnetic bistability in metal–organic frameworks and coordination polymers: charge transport and spin crossover at the nanoscale

“…Processing SCO materials at the nanometric scale has proven to have very significant effects on all aspects of the SCO phenomena. 29,[406][407][408][409][410] These include: i) the stabilization of one of the spin states, which affects the transition temperature; ii) the cooperativity between the SCO centers, which affects the abruptness of the transition and the width of its hysteresis and iii) the presence of defects, which affects the completeness of the transition. These properties can be altered by changes in the film thickness, sizes and shapes of crystallites; film orientation; substrate coverage and interactions with other SCO particles or non-SCO substrates or matrixes.…”

“…Regarding SCO CPs and MOFs, again most studies has been done with the 1D CP [Fe(Htrz)2(trz)] + and Fe II -HCPs, for which there is an extensive amount of reports about nanostructuration effects on NPs, which have been already covered by various reviews. 406,29,[407][408][409][410] Nonetheless, the study of NPs adds other variables to the problem that are difficult to control such as size polydispersity, chemical composition changes or surface defects. The main consequence of nanostructuration is the size reduction effect.…”

2-D spin crossover materials at the nanometric scale: the effects of the size-reduction on the magnetic properties

“…1 Important discoveries intensify the interest for SCO materials, in particular: (i) the coexistence of SCO with hysteresis loop providing the possibility of the memory effect; 7 (ii) SCO transition at room temperature; 8 (iii) the triggering of the spin state using a plethora of external stimuli; [9][10][11] and (iv) the existence of bistable characteristics in SCO nanoparticles (NPs). [12][13][14][15][16] However, the interconnection of physical properties and spin state, especially at the nanoscale, remains to be explored and thoroughly studied, since SCO phenomena are greatly affected by cooperativity issues among the SCO centres influencing directly the abruptness of the SCO transition and eventually the width of the hysteresis. 1,[12][13][14][15][16] Therefore, experimental and theoretical research is focused on the correlation of the size effect and the first-order phase transition of SCO systems and how the characteristics of the hysteresis are expected to be influenced by the number of molecules forming the nanoparticle.…”

“…[12][13][14][15][16] However, the interconnection of physical properties and spin state, especially at the nanoscale, remains to be explored and thoroughly studied, since SCO phenomena are greatly affected by cooperativity issues among the SCO centres influencing directly the abruptness of the SCO transition and eventually the width of the hysteresis. 1,[12][13][14][15][16] Therefore, experimental and theoretical research is focused on the correlation of the size effect and the first-order phase transition of SCO systems and how the characteristics of the hysteresis are expected to be influenced by the number of molecules forming the nanoparticle. A crucial requirement for successful fabrication of devices is the preservation of the bistability and the cooperativity between the SCO centers during the downsizing experimental protocol.…”

Extreme downsizing of spin crossover nanoparticles towards stable colloids in water: a detailed nano-topographic study

“…The elaboration of the SCO behavior of the latter category has been extensively discussed especially for 3D Hofmann-type coordination polymers. [32][33][34][35][36][37][38][39][40] In our recent article, 41 we review the various synthetic approaches for the preparation of nanoparticles with formula {Fe(pz)[M(CN) 4 ]} (M = Ni, Pd, Pt) and their magnetic behavior upon size reduction which is different than those in the bulk form. Boldog et al 19 and Volatron et al 18 used reverse micelle technique for preparing w/o microemulsions with anionic surfactant sodium bis-(2ethylhexyl)sulfosuccinate (NaAOT) as stabilizer and octane as organic phase.…”