Exotic water state in hydrophilic nanospace of porous coordination polymers.

Nanoconfined water exhibits physical properties not seen in the bulk phase due to confinement effects. In this study, using highly designable nanopores of porous coordination polymers, we discovered an exotic water state between solids and liquids. Single-crystal X-ray diffraction found that nanoconfined water has a discrete symmetry like solid ices, but infrared spectroscopy showed the existence of broken hydrogen bonds like liquid water. Because there exist no solid-liquid critical points in the bulk phase diagram, the water state does not correspond to any bulk states. We showed that the theoretically predicted solid-liquid supercritical-like state is realized even at standard ambient conditions in hydrophilic nanospaces.