title: Metal-Organic Frameworks Containing Missing-Linker Defects Leading to High Hydroxide-Ion Conductivity.
abstract: The ionic conductivity properties of the face-centered cubic [Ni8 (OH)4 (H2O)2 (BDP_X)6] (H2 BDP_X=1,4-bis(pyrazol-4-yl)benzene-4-X with X=H (1), OH (2), NH2 (3)) metal-organic framework (MOF) systems as well as their post-synthetically modified materials K[Ni8 (OH)5 (EtO)(BDP_X)5.5] (1@KOH, 3@KOH) and K3 [Ni8 (OH)3 (EtO)(BDP_O)5] (2@KOH), which contain missing-linker defects, have been studied by variable temperature AC impedance spectroscopy. It should be noted that these modified materials exhibit up to four orders of magnitude increase in conductivity (-) values in comparison to pristine 1-3 systems. As an example, the conductivity value of 5.86 × 10(-9) S cm(-1) (activation energy Ea of 0.60 eV) for 2 at 313 K and 22% relative humidity (RH) increases up to 2.75 × 10(-5) S cm(-1) (Ea of 0.40 eV) for 2@KOH. Moreover, a further increase of conductivity values up to 1.16 × 10(-2) S cm(-1) and diminution of Ea down to 0.20 eV is achieved at 100% RH for 2@KOH. The increased porosity, basicity and hydrophilicity of the 1@KOH-3@KOH materials compared to the pristine 1-3 systems should explain the better performance of the KOH-modified materials.
authors.affiliation: Departamento de Química Inorgánica, Universidad de Granada, 18071, Granada, Spain), Fax: (+34) 958 248526.
authors.forename: Carmen
authors.initials: C
authors.lastname: Montoro
authors.affiliation: Departamento de Química Física Aplicada, Universidad Autónoma de Madrid, C/ Tomás y Valiente 7, 28049, Madrid, Spain.
authors.forename: Pilar
authors.initials: P
authors.lastname: Ocón
authors.affiliation: Departamento de Química Inorgánica, Universidad Autónoma de Madrid, C/ Tomás y Valiente 7, 28049, Madrid, Spain.
authors.forename: Félix
authors.initials: F
authors.lastname: Zamora
authors.affiliation: Departamento de Química Inorgánica, Universidad de Granada, 18071, Granada, Spain), Fax: (+34) 958 248526. jarn@ugr.es.
authors.forename: Jorge A R
authors.initials: JA
authors.lastname: Navarro
keywords: defects; impedance spectroscopy; ion conductivity; metal-organic frameworks; nickel