Crystal Engineering with Copper and Melamine

Coordination complex and polymer are central in inorganic and material chemistry as a variety of both metal centers and coordination geometries lead to a diverse range of interesting properties. Here, size and structure control of gems-like quality monocrystals are demonstrated at room temperature. From the same set of precursors, but the copper-to-melamine molar ratio is adjusted to synthesize either a novel coordination complex of dinuclear copper and melamine (Cu2M1) or a barely-studied coordination polymer of zigzag copper-chlorine chains (Cu4M1). Crystals of the former are dark green and squared with the size up to 350 µm across. The latter is light green and octagonal as large as 5 mm across. The magnetic properties of both crystals reflect their low-dimensional arrangements of copper. The magnetic susceptibility of Cu2M1 is well modelled with a spin-1/2 dimer and that of Cu4M1 with a spin-1/2 one-dimensional Ising chain. Controlled synthesis of such quality magnetic crystals is a prerequisite for various magnetic and magneto-optical applications