Zero-Dimensional Chiral Copper Halides with Strong Circular Dichroism and Low-Temperature Ferromagnetism

Chiral molecular magnets are attractive for next-generation sensing, information storage, and spintronic technologies. Here, we report the synthesis and characterization of the zero-dimensional enantiomeric copper halides (R/S-PPA)2CuX4 (X = Cl, Br) (PPA = phenylpropylamine), prepared via a slow solvent evaporation crystallization method. These materials consist of isolated [CuX4]2– tetrahedra embedded in chiral organic frameworks and exhibit intense and opposite circular dichroism signals with amplitudes up to ±100 mdeg. Although the inorganic lattice is structurally zero-dimensional with isolated [CuX4]2– units, effective three-dimensional magnetic connectivity is established via supramolecular superexchange pathways. The bromide analogue displays clear low-temperature ferromagnetic ordering, with a saturation magnetization of 8.72 emu g–1 (1.02 ± 0.03 μB/f.u.) and a Curie temperature of 9.7 ± 0.2 K. These lead-free 0D copper halides provide a low-temperature platform for chirality-magnetism and spin-dependent studies, and offer design guidelines toward higher ordering temperatures.