Spray-Drying to Get Spin-Crossover Materials

Abstract

Spin-crossover (SCO) triazole-based coordination polymers can be synthesized by micelle techniques, which almost always lead to rod-shaped nanoparticles. In order to notably reach new morphologies, we explore here the potentiality of the spray-drying (SD) method to get SCO materials. Three SCO coordination polymers and a mononuclear complex are investigated. In all cases, the SD method obtains particles definitely showing SCO. The features of the latter are yet always different from those of the referenced materials, in the sense that SCO is more gradual and incomplete, in adequacy with the poor crystallinity of the powders obtained by SD. In the case of coordination polymers, the particles are preferentially spherical. Indications of possible polymorphism and/or new materials induced by the use of the SD method are evidenced. In the case of the mononuclear complex, the SD method has allowed reproducing, in a quick and easy way, the well-known bulk compound. This exploratory work demonstrates the relevance of the concept and opens the way to a systematic scrutiny of all the experimental parameters to tune the size, morphology, and properties of the SD-synthesized SCO particles.

Rational direct synthesis of [Fe(Htrz)2(trz)](BF4) polymorphs: temperature and concentration effects

“…However, this is a surfactantfree synthesis that can be of importance in the integration into composites 3,19,20 and hybrid nanomaterials [21][22][23] , deserving then an in-depth investigation. Very recently, new approaches have been proposed for the direct synthesis of such triazole-based compounds, starting from metallic iron 24 or using mechanochemistry 25 as well as surfactant-free synthesis like spraydrying 26 or flow chemistry coupled to supercritical fluids treatment 27,28 . The aim of this paper is to investigate the direct synthesis conditions to obtain NPs of the [Fe(Htrz)2(trz)](BF4) in the appropriate phase.…”

Spray-Drying Synthesis of MOFs, COFs, and Related Composites

“…Similarly, our group and others have since used this strategy to produce a wide range of MOFs with different characteristics, such as dimensionality, metal ions and/or clusters, and organic linkers, and coordination compounds with other functionalities such as thermochromism or spin crossover, revealing the broad scope of this method (Table ). − …”

Optimized Local Synthetic Conditions Induce Size Reduction and Phase Purification in {[Fe(Htrz)2(trz)](BF4)}n Spin Crossover Particles

“…It is generally achieved in classical syntheses starting from separate solutions of reactants and controlling their mixing via magnetic stirring , but not only. Indeed, spray drying, flow chemistry coupled to supercritical CO 2 , and microfluidic methods have also been used in recent years. The extent to which one can control the crystallite size with these methods depends a lot on the compound under study and its bulk crystal structure.…”