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

Abstract

The investigation and elaboration of the Spin-Crossover (SCO) phenomenon in Two – Dimensional (2D) Hofmann-type nanosized SCO materials and the size-reduction effect on cooperativity and thermodynamic properties of the nanoparticle...

The Influence of the Substrate on the Functionality of Spin Crossover Molecular Materials

“…An uncontrolled SCO film thickness results in dramatic changes in thickness and cooperativity between molecules and consequently, the SCO properties may be altered. Precise control of the thickness is crucial as changes in the thickness can influence the functionality of the deposited SCO complex, especially for fabricating 2D SCO film complexes [144][145][146][147].…”

Two-Dimensional Coordination Polymer Showing Spin-Crossover Behavior with a 64 K Wide Hysteresis Loop

“…In the third cycle, compound 1·4CHCl 3 remained in the HS state between 250 and 160 K, completing one-step abrupt spin transition as the temperature decreased and reaching the fully populated LS state at 60 K, thus a clear occurrence of temperature-induced one-step complete SCO from HS to LS − with T 1/2 ↓ equal to 143 K is concluded. When the temperature rises, compound 1·4CHCl 3 remains in the LS state until 200 K, then there is an abrupt rise in the curve to the HS state before 225 K with T 1/2 ↑ being 207 K. The resulting W hys value is 64 K, unexpected among the largest values for 2D SCO compounds. − The hysteretic transition is further confirmed by the differential scanning calorimetry (DSC) data (Figure S2). The exothermic and endothermic peaks for compound 1·4CHCl 3 roughly locate at 141 and 199 K, respectively, which result in a lower W hys value (approximately 58 K) than that obtained from magnetic measurements.…”

“…The second method has been well documented in Fe­(II)-1,2,4-triazole SCO CPs − and Hofmann-type SCO materials. , In addition, we notice that 2D SCO CPs formed with rigid bis-monodentate ligands have the potential to show relatively large W hys values in a unconventional way . For example, [Fe­(NCS) 2 (4,4′-bis-1,2,4-triazole) 2 ]·H 2 O showed SCO behavior with a W hys value of 21 K, which had been attributed to the rotation of the triazole plane. , However, to our knowledge, all 2D SCO Fe­(II) CPs exhibited W hys values that were up to date less than 50 K, no matter how to achieve by means of temperature variation, solvent induction, light irradiation, pressure, and downsizing, etc. − In this paper, we report a 2D CP that shows one-step complete SCO behavior with unexpectedly large W hys value of 64 K, and additionally this CP also shows temperature-induced excited spin-state trapping effect (TIESST) with the T TIESST value equal to 91 K.…”

Spin-crossover tuning of the luminescence in 2D Hofmann-type compounds in bulk and exfoliated flakes

“…20 Since 2D Hofmannlike compounds display a layered structure with strong intralayer covalent bonding and weaker van der Waals interactions between the layers, an interesting possibility is the exfoliation into individual nanosheets that have found in other 2D materials a great variety of applications in electronics, gas storage or separation, catalysis or high-performance sensing. 21,22 Previous attempts to exfoliate 2D Hofmann-like compounds by mechanical or solvent-mediated exfoliation methods led to low-quality nanosheets with a thickness of a few nm in the case of the liquid exfoliation method 23,24 or to larger but thicker flakes (more than 300 nm thick) in that of mechanical exfoliation. 25 In this work, we have explored the miniaturization by a mechanical exfoliation of luminescent SCO 2D Hofmann-like compounds.…”