title: A lanthanum chelate possessing an open-channel framework with water nanotubes: properties and desalination.
abstract: A new type of thermally stable chelate {La(H2O)4[La(1,3-pdta)(H2O)]3}n · 12nH2O (1) [1,3-H4pdtaCH2[CH2N(CH2CO2H)2]2] with an open-channel shows significant and unusual solvent transport properties and demonstrates a use for low-pressure desalination, which is constructed by cheap and available lanthanum salt and 1,3-propanediaminetetraacetate. The chelate could be converted reversibly to its trihydrate {La(H2O)4[La(1,3-pdta)(H2O)]3}n · 3nH2O (1a), dehydrated product {La(H2O)4[La(1,3-pdta)(H2O)]3}n (1b) and ethanol adduct {La(H2O)4[La(1,3-pdta)(H2O)]3}n · 3nH2O · 3nEtOH (1c). The latter nano-confined ethanol shows a remarkable downfield shift (Δδ = 6.0 ppm) for the methylene group in the solid 13C NMR spectrum compared with that of the free EtOH. Crystal 1 with a regular hexagonal appearance can be used directly for saline water desalination on a small-scale at an ambient temperature, demonstrating a low energy consumption and environmentally friendly method. This is attributed to the 10.0 Å hydrophobic open-channel containing water nanotubes (WNTs, Φ = 4.2 Å). The nano-confined WNTs can be removed at a low temperature (45 °C).
authors.affiliation: State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005, China. zhzhou@xmu.edu.cn.
authors.forename: Mao-Long
authors.initials: ML
authors.lastname: Chen
authors.forename: Yi-Chao
authors.initials: YC
authors.lastname: Guo
authors.forename: Fang
authors.initials: F
authors.lastname: Yang
authors.forename: Jin-Xia
authors.initials: JX
authors.lastname: Liang
authors.forename: Ze-Xing
authors.initials: ZX
authors.lastname: Cao
authors.forename: Zhao-Hui
authors.initials: ZH
authors.lastname: Zhou