A mixed-valence coordination polymer featuring two-dimensional ferroelectric order: {[Cu(I)4Cu(II)(Et2dtc)2Cl3][Cu(II)(Et2dtc)2]2(FeCl4)}n (Et2dtc- = diethyldithiocarbamate).

The first mixed-valence coordination polymer indicating ferroelectric properties, {[CuI4CuII(Et2dtc)2Cl3][CuII(Et2dtc)2]2(FeCl4)}n (Et2dtc- = diethyldithiocarbamate), has been synthesized and crystallographically characterized. This complex has a two-dimensional infinite square lattice structure, including both Cu(I) and Cu(II) ions, which is confirmed by XPS and SQUID measurements. In addition, the ferroelectric behaviors are revealed by the dielectric measurements with a LCR meter and a ferroelectric tester.

Spin-crossover cobalt(II) compound with banana-shaped structure.

A banana-shaped spin-crossover (SCO) cobalt(II) complex [Co(C16-terpy)2](BPh4)2 (1) with long alkyl chains, based on a terpyridine frame, was synthesized. Compound 1 exhibited very gradual SCO behavior and changes in the dielectric constant. This shows a way in which SCO materials can be used in electronic devices.