Dynamic Water Nanotube Cluster Stabilized in Molecule-Based Hydrophilic Nanoporous Crystal with New Organic Spacers

This study investigated the structure and phase transition behaviour of a dynamic water nanotube cluster (WNT) confined within hydrophilic 1D nanochannels. We demonstrated that the WNT has a three-layered hydrate structure stabilized by hydrogen bonds with carboxylate groups in the outer channel walls. Moreover, it exhibits a pre-melting state that was attributed to the presence of metastable structures. Interestingly, the dynamic WNT structure was maintained even in the melting state because the multi-layered water cluster was stabilized in the hydrophilic nanoporous channel. To our knowledge, such a dynamic three-layered WNT structure is unique and rare because most WNTs are regarded as disordered water clusters. Therefore, we constructed another dynamic WNT using [RuIII(H2bim)3]3+ (H2bim = 2,2′-biimidazole) and a new organic spacer, 1,3,5-triazine-2,4,6-tricarboxylate (TATC3−). The dynamic WNT cluster has been identified for the crystal structure and heat properties.