Unlocking New Dimensions in Switchable Spin Crossover Systems Through Co-crystallisation
In a pioneering study titled Co-crystallisation as a modular approach to the discovery of spin-crossover materials, published in Chemical Science, Lee Birchall, Giada Truccolo, Lewis Jackson, and Helena Shepherd, all SISC members, have introduced a transformative strategy for discovering new materials in the realm of switchable spin crossover (SCO) systems. This approach focuses on the co-crystallisation technique, which has proven to be a rapid, facile, and highly modular tool, opening up a world of possibilities for creating switchable materials with tailored properties.
Starting with [Fe(3-bpp)2]·2A (where 3-bpp = 2,6-bis(pyrazol-3-yl)pyridine, A = BF4−/PF6−) as a foundation, the team has successfully synthesised a total of 11 new co-crystals using five different dipyridyl coformers. Impressively, eight of these systems exhibit spin-crossover behaviour, each demonstrating markedly different switching properties compared to the parent complex. This diversity highlights the power of co-crystallisation in modifying the SCO behaviour of materials by simply altering the coformer.
To understand the structure-property relationships of these co-crystals, the team employed variable temperature single-crystal X-ray diffraction and SQUID magnetometry. These analyses revealed that the supramolecular architecture of the co-crystals is significantly influenced by the properties of the coformer. Linear, rigid coformer molecules lead to the formation of 1D supramolecular hydrogen-bonded chains, whereas flexible coformers create 2D sheets, and bent coformers result in intricate 3D network structures.
This research not only provides a new pathway for the discovery and design of switchable SCO materials but also opens up broader prospects for developing hybrid multifunctional materials. By harnessing the versatility of co-crystallisation, the team has laid the groundwork for future advancements in materials science, offering a modular approach that promises customization and innovation in the design of next-generation materials.
For more information please read the research article by Helena Shepherd and co-authors, which can be found here.