Binary and Ternary Core–Shell Crystals of Polynuclear Coordination Clusters via Epitaxial Growth

For the first time, an abundant series of 12 colorful binary and ternary millimeter-sized core–shell composite crystals, representative of hierarchical crystalline species, were designed and prepared from functional magnetic polynuclear clusters phases using the epitaxial growth method. The synthesis is based on isomorphous (space group C2/c) crystalline phases composed of 15 nuclear clusters {M9[WV(CN)8]6(MeOH)24} (M 9 W 6 ) (M, color = MnII, pale brown; FeII, green; CoII, red; NiII yellow; and an Fe/Co 2:1 mixture, dark brown, respectively) of six-capped body-centered-cubic topology, revealing appealing magnetic properties such as a high spin in the ground state, slow magnetic relaxation, and structural spin-phase transitions. A series of 11 binary core–shell composites and 1 ternary composite have been reproducibly synthetized and carefully characterized from a structural and composition point of view. Phase composition agreement and the size of the interface of ca. 10 μm were assessed using microscopic observations, single-crystal X-ray diffration, and scanning electron microscopyenergy-dispersive spectroscopy. SQUID measurements reveal an active spin transition Fe 6 Co 3 W 6 seed compound enveloped within the paramagnetic Mn 9 W 6 crystalline shell, providing a rare example of a millimeter-sized hierarchical crystalline architecture, Fe 6 Co 3 W 6 @Mn 9 W 6 , with a switchable function.