Me4N[Fe(py3COH)(NCS)3](H2O) showed an abrupt spin-crossover with thermal hysteresis, and temperature-scan rate dependence was recorded upon heating.

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The spin-crossover phenomenon is a reversible low- and high-spin transition caused by external stimuli such as heat. In the novel iron(II) complex salt tetraphenylphosphonium tris(thiocyanato-κN)[1,1,1-tris(pyridin-2-yl)ethane-κN,N',N'']ferrate(II), (CHP)[Fe(NCS)(CHN)], the Fe-N bond lengths are in the range 2.027 (2)-2.089 (2) Å, indicating that the specimen consists of comparable molar fractions of the low- and high-spin species at 296 K. A magnetic study confirmed that spin-crossover takes place at around 290 K.

A novel dinuclear iron(II) complex [{Fe(py3COH)(NCS)(μ-NCS)}2](PrOH)2 was prepared. Each Fe ion is coordinated with three N atoms from tridentate tris(2-pyridyl)methanol (py3COH) and two N and one S atoms from NCS− coligand. It showed a one-step gradual spin-crossover at T1/2 = 207 K. This compound is the first spin-crossover material having an FeN5S coordination structure.

Confinement in nanoscaled porous materials changes properties of water significantly. We perform molecular dynamics simulations of water in a model of a nanobrush made of carbon nanotubes. Water crystallizes into a novel structure called dtc in the nanobrush when (6,6) nanotubes are located in a triangular arrangement and there is a space that can accommodate two layers of water molecules between the tubes. The mechanism of the solidification is analogous to formation of gas hydrates: hydrophobic molecules promote crystallization when their arrangement matches ordered structures of water. This is supported by a statistical mechanical calculation, which bears resemblance to the theory on the clathrate hydrate stability.