In an investigation into the proton conductivity of crystallized water clusters confined within low-dimensional nanoporous materials, we have found that water-stable nanoporous crystals are formed by complementary hydrogen bonding between [Co(III) (H2 bim)3 ](3+) (H2 bim: 2,2'-biimidazole) and TATC(3-) (1,3,5- tricarboxyl-2,4,6-triazinate); the O atoms in the -COO(-) groups of TATC(3-) in the porous outer wall are strongly hydrogen bonded with H2 O, forming two types of WMCs (water molecular clusters): a spirocyclic tetramer chain (SCTC) that forms infinite open 1D channels, and an isolated cyclic tetramer (ICT) present in the void space. The ICT is constructed from four H2 O molecules as a novel C2 -type WMC, which are hydrogen bonded with four-, three-, and two-coordination spheres, respectively. The largest structural fluctuation is observed at elevated temperatures from the two-coordinated H2 O molecules, which begin to rapidly and isotropically fluctuate on heating. This behavior can be rationalized by a simple model for the elucidation of pre-melting phenomena, similar to those in ice surfaces as the temperature increases. Moreover, high proton conductivity of SCTCs (ca. 10(-5) S cm(-1) at 300 K with an activation energy of 0.30 eV) through a proton-hole mechanism was observed for pellet samples using the alternating impedance method. The proton conductivity exhibits a slight enhancement of about 0.1×10(-5) S cm(-1) at 274 K due to a structural transition upon approaching this temperature that elongates the unit cell along the b-axis. The proton-transfer route can be predicted in WMCs, as O(4) of an H2 O molecule at the center of an SCTC shows a motion that rotates the dipole in the b-axis direction, but not the c-axis; the thermal ellipsoids of O(4) based on anisotropic temperature factors obtained by X-ray crystallography reflect a structural fluctuation along the b-axis direction induced by [Co(III) (H2 bim)3 ](3+) .

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Tungsten trioxides and their alkali-metal-intercalated products MzWO3 + show potential for application in electrodes, as ion exchangers, catalysts and the treatment of radioactive waste. Hexagonal tungsten bronze (HTB) features hexagonal channels, of diameter ~0.54 nm, that may be useful for selective and reversible binding of metal ions. In particular doping of HTB with molybdenum (Mo-HTB) has been reported to enhance the uptake of Cs + and Sr 2+ . We have conducted a powder diffraction study, using both x-rays and neutrons on a series of MzHTB (M = Na + , Mn 2+ , Ba 2+ , Ce 3+ , Pb 2+ ), including some doped with molybdenum (Mo-HTB) synthesized using hydrothermal methods. Rietveld refinement of the diffraction patterns show that doping with Mo rapidly degrades the crystallinity of HTB by creating a high degree of disorder in the a-b planes, suggesting that the presence of Mo retards the hydrothermal crystallization process. The refinements confirm previous reports of an exchangeable metal ion binding site that displays varying degrees of affinity for the various metal ions studied. The solution binding affinity behaviour of the Mo-HTB's was also investigated for selected ions (M = Co 2+ , Gd 3+ , Ce 3+ , Ce 4+ Tl + , Pb 2+ doped with respective radiotracer) in a range of concentrations of acid and electrolytes solutions. These results show that the optimum condition for metal ion binding depends not only on the Mo doping level, but also the charge and redox chemistry of the exchange cation. In combination, the structure information and the solution chemistry indicate that the loading capacity of the each metal ion is also dependent on the microstructure of the HTB. Moving water molecules in a limited space within a nanometerscale region, different from the molecular motion of bulk water, have imposed a remarkable nature affected by strong interfacial interactions with a surrounded outer wall. For examples, it has been theoretically predicted that water molecules impacted on a hydrophobic interface inside carbon nanotube lead to osmotic water transport with a one-dimensional chain hydrate in its internal space instantly, have a critical point of the water-ice phase transition depending on the tube widths, and freeze at a novel ice polymorph with a multi-layered helix structure. Experimentally, it is demonstrated that melting point of each confined tube-like water clusters constructed from 5-to 8-membered rings, which is not supported to decrease melting points in inverse proportion to the pore sizes by theoretical expectation, increases as the widths of singlewalled carbon nanotubes. A tube-like three-layered water cluster, called a water nanotube (WNT), forms into each internal channel space and regulates by hydrogen bonds (H-bonds) with the outer wall. In this study, the structure of WNT confined to the channel pores has been investigated by a neutron structure analysis, and revealed to stabilize by an anchor effect of the structural water. Furthermore, by the neutron scattering, a few water molecules around...