An organic molecular acid-base complex has been synthesized from pyridine-substituted biradical 2 in a triplet (S = 1) ground state and a benzoic acid derivative of monoradical 3 with S = 1/2. The two constituent molecules are bound by an OH-N hydrogen bond in a crystalline solid state. The complex has been found to exhibit an antiferromagnetic phase transition at 5 K. The complex is the first example of a hydrogen-bonded heterospin, heteromolecular complex exhibiting a magnetic phase transition in purely organic molecule-based materials.

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Ferroelectric domain structure in triglycine sulfate (TGS) was observed by a system based on a pyroelectric probe technique. A light beam from a laser diode was focused on the surface of a TGS specimen, and the specimen was two-dimensionally scanned by an X-Y pulse stage. Analyzing the pyroelectric signal, we obtained high-resolution domain patterns. The whole system was controlled with a computer. The scanning area was from 0.5×0.5 mm2 to 10×10 mm2. Imaging of an area took about 30 min. Changes of domain structure caused by successive application of pulsed electric field were also examined. Some interesting results concerning the domain dynamics in TGS were obtained.

Magnetic properties and crystal structure of a pyridine-substituted iminonitroxide biradical, 2,6-bis(4,4,5,5,-tetramethyl-4,5-dihydro-1H-imidazol-2-yl-1-oxyl)pyridine (1), were examined. The molecular ground state of 1 was found to be triplet (S = 1) with a singlet–triplet energy gap of 7 K. The ground-state triplet biradical serves as a building block for molecule-based magnets of S > 1/2 based on intermolecular noncovalent bonding architecture.