Modified 1,4-hydroquinone ligands bridging CuII ions – Building blocks for a new class of quantum magnets

A series of low-dimensional quantum-spin systems, including isolated CuII dimers, various coupled CuII-dimer systems and a 1-D uniform S = 1/2 Heisenberg antiferromagnet has been synthesized. All materials are based on hydroquinone-derived linkers connecting CuII ions carrying a spin of S = 1/2. Magnetic measurements covering wide ranges of temperature 0.06 K ≤ T ≤ 300 K and magnetic fields B ≤ 50 T reveal an antiferromagnetic coupling constant J of moderate strength for all systems. Electron-spin resonance measurements over wide frequency ranges have been used to determine the local coordination environment of the CuII centers. The distinct magnetic properties of these materials along with their flexibility against chemical modifications make them excellent model systems for exploring fundamental aspects of quantum magnetism.