We discovered a metal-organic nanotube (MON) that possesses a molecular selectivity for water molecules within its 1-D channel (Fig. 1). It was determined via X-ray diffraction that these water molecules arrange themselves in an ordered array, closely mimicking the structure of Ice-II. Due to potential advanced applications in water purification and treatment, we subjected the MON to extensive physical characterization. It was discovered that the MON possesses isotopic selectivity to light water (H2O) over its deuterated analog (D2O). This phenomenon was explored by introducing heavy water to the dehydrated MON and characterizing the water sorption behavior and structural features of the confined water molecules. We also determined that the confined water molecules impart zero thermal expansion behavior upon the entire material in the range -20-7 °C as they undergo a phase change while still confined in the MON channel. We were able to confirm this phenomenon by its absence in the dehydrated MON material.

Behavior of water under confinement in a metal-organic nanotube

255th National Meeting (2018)

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