title: Luminescent and Proton Conducting Lanthanide Coordination Networks Based On a Zwitterionic Tripodal Triphosphonate.
abstract: The synthesis, structural characterization, luminescence properties, and proton conduction performance of a new family of isostructural cationic 2D layered compounds are reported. These have the general formula [Ln(H4NMP)(H2O)2]Cl·2H2O [Ln = La(3+), Pr(3+), Sm(3+), Eu(3+), Gd(3+), Tb(3+), Dy(3+), Ho(3+), H6NMP = nitrilotris(methylphosphonic acid)], and contain Cl(-) as the counterion. In the case of Ce(3+), a 1D derivative, [Ce2(H3NMP)2(H2O)4]·4.5H2O, isostructural with the known lanthanum compound has been isolated by simply crystallization at room temperature. The octa-coordinated environment of Ln(3+) in 2D compounds is composed by six oxygen atoms from three different ligands and two oxygens from each bound water. Two of the three phosphonate groups act as both chelating and bridging linkers, while the third phosphonate group acts solely as a bridging moiety. The materials are stable at low relative humidity at less at 170 °C. However, at high relative humidity transform to other chloride-free phases, including the 1D structure. The proton conductivity of the 1D materials varies in a wide range, the highest values corresponding to the La derivative (σ ≈ 2 × 10(-3) S·cm(-1) at RH 95% and 80 °C). A lower proton conductivity, 3 × 10(-4) S·cm(-1), was measured for [Gd(H4NMP)(H2O)2]Cl·2H2O at 80 °C, which remains stable under the work conditions used. Absorption and luminescence spectra were recorded for selected [Ln(H4NMP)(H2O)2]Cl·2H2O compounds. In all of them, the observed transitions are attributed solely to f-f transitions of the lanthanide ions present, as the H4NMP(2-) organic group has no measurable absorption or luminescence properties.
authors.affiliation: Departamento de Química Inorgánica, Universidad de Málaga , Campus Teatinos s/n, 29071 Málaga, Spain.
authors.forename: Montse
authors.initials: M
authors.lastname: Bazaga-García
authors.affiliation: Crystal Engineering, Growth and Design Laboratory, Department of Chemistry, University of Crete , Voutes Campus, Crete GR-71003, Greece.
authors.forename: Giasemi K
authors.initials: GK
authors.lastname: Angeli
authors.affiliation: Crystal Engineering, Growth and Design Laboratory, Department of Chemistry, University of Crete , Voutes Campus, Crete GR-71003, Greece.
authors.forename: Konstantinos E
authors.initials: KE
authors.lastname: Papathanasiou
authors.affiliation: Departamento de Química Inorgánica, Universidad de Málaga , Campus Teatinos s/n, 29071 Málaga, Spain.
authors.forename: Inés R
authors.initials: IR
authors.lastname: Salcedo
authors.affiliation: Departamento de Química Inorgánica, Universidad de Málaga , Campus Teatinos s/n, 29071 Málaga, Spain.
authors.forename: Pascual
authors.initials: P
authors.lastname: Olivera-Pastor
authors.affiliation: Departamento de Química Inorgánica, Universidad de Málaga , Campus Teatinos s/n, 29071 Málaga, Spain.
authors.forename: Enrique R
authors.initials: ER
authors.lastname: Losilla
authors.affiliation: Laboratorio de Estudios Crystalográficos, IACT-CSIC , Granada, Spain.
authors.forename: Duane
authors.initials: D
authors.lastname: Choquesillo-Lazarte
authors.affiliation: School of Science and Technology, Nottingham Trent University , Clifton Lane, Nottingham NG118NS, United Kingdom.
authors.forename: Gary B
authors.initials: GB
authors.lastname: Hix
authors.affiliation: Departamento de Química Inorgánica, Universidad de Málaga , Campus Teatinos s/n, 29071 Málaga, Spain.
authors.forename: Aurelio
authors.initials: A
authors.lastname: Cabeza
authors.affiliation: Crystal Engineering, Growth and Design Laboratory, Department of Chemistry, University of Crete , Voutes Campus, Crete GR-71003, Greece.
authors.forename: Konstantinos D
authors.initials: KD
authors.lastname: Demadis