Sonocrystallization as an Efficient Way to Control Size, Morphology and Purity of Coordination Compounds Microcrystallites: Application to Single-Chain Magnets

Size, morphology and purity control of coordination compounds powders is a key stage for their conversion into materials and devices. In particular, surface science techniques require highly pure bulk materials with a narrow crystallite‑size distribution together with straightforward, scalable and reproducible crystallization procedures. In this work we demonstrate how sonocrystallization, i.e. application of ultrasounds during the crystallization process, can afford, very quickly, powders made of crystallites with controlled size, morphology and purity. We show that this process drastically diminishes the crystallite‑size distribution (low Polydispersity Indexes, PDI) and crystallite aspect ratio. By comparing sonicated samples with various silent crystallization conditions, we unambiguously show that the improvement of the crystallite morphologies and size‑distribution is not due to any thermal effect but to the sonication of the crystallizing media. The application of sonocrystallization on crystallization batches of Single‑Chain Magnets (SCM) maintains SCMs chemical integrity together with their original magnetic behavior. Moreover, luminescent measurements show that sonocrystallization induces an efficient micromixing that drastically enhances the purity of the SCMs powders. We thus propose that sonocrystallization, which is already used on organic or MOF compounds, can be applied to (magnetic) coordination compounds to readily afford bulk powders for characterization or shaping techniques that require pure, morphology‑ and crystallite‑size‑controlled powder samples.