Superprotonic Conductivity of UiO-66 with Missing-Linker Defects in Aqua-Ammonia Vapor.

The design and preparation of proton-conducting metal-organic frameworks (MOFs) with superconductivity are of significance for the proton-exchange membrane fuel cell (PEMFC). Introducing functional structural defects to enhance proton conductivity is a good approach. Here, we synthesized a series of UiO-66 (first synthesized in the University of Oslo) with missing-linker defects and investigated the effect of defect numbers on the proton conductivity of the samples. Among them, 60-UiO-66-1.8 (60 represents the synthesis temperature and 1.8 the number of defects) prepared with 3-mercaptopropionic acid as a modulator has the best proton conductivity, which is 3 × 10-2 S cm-1 at 100 °C and under 98% relative humidity (RH). The acidic sites induced by missing-linker defects further promote the chemisorption of ammonia molecules, resulting in the formation of a richer hydrogen-bond network and hence boosting the proton conductivity to 1.04 × 10-1 S cm-1 at 80 °C, which is one of the highest values among the reported MOF-based proton conductor. Therefore, this work provides a new strategy for enhancing proton conduction in MOF-based materials.

Potassium ditin(IV) tris-[phosphate(V)], KSn(2)(PO(4))(3).

The title compound, KSn(2)(PO(4))(3), belongs to the NASICON-type family of phosphates with the space group R[Formula: see text]. Its structure is constructed by very regular [with P-O distances ranging from 1.513 (6) to 1.522 (6) Å] PO(4) tetra-hedra and SnO(6) octa-hedra on the 3. axis, which are linked by O atoms, forming an [Sn(2)(PO(4))(3)] framework. The K atoms occupy the [Formula: see text]. axis sites and are located in the voids of this arrangement. The crystal studied was a merohedral twin with twin law (010 100 00[Formula: see text]) and a component ratio of 0.580 (7):0.420 (7).

Poly[[tetra-aqua-tris-(µ(3)-hexane-1,6-di-carboxyl-ato)diterbium(III)] 0.25-hydrate].

In the title terbium coordination polymer, {[Tb(2)(C(6)H(8)O(4))(3)(H(2)O)(4)]·0.25H(2)O}(n), the Tb(III) atom is nine-coordinated, forming a TbO(9) polyhedra. Furthermore, two symmetric TbO(9) polyhedra share their edges, forming Tb(2)O(16) dimers, which are linked by adipate bridges into a layered structure. Inter-molecular O-H⋯O hydrogen bonds link these layers into a three-dimensional network. One of the C atoms of the adipate ligand is disordered over two positions with site-occupancy factors of 0.622 (9) and 0.378 (9). The structure also contains a disordered mol-ecule of water of hydration, lying close to a special position, with partial occupancy.

Redetermination of Fe(2)[BP(3)O(12)].

Explorations of phases in the quaternary Fe(III)-B(III)-P(V)-O system prepared by the high temperature solution growth (HTSG) method led to single-crystal growth of anhydrous diiron(III) borotriphosphate, Fe(2)[BP(3)O(12)]. This phase has been synthesized previously as a microcrystalline material and its structure refined in space group P3 from powder X-ray diffraction data using the Rietveld method [Chen et al. (2004 ▶). J. Inorg. Mater.19, 429-432]. In the current single-crystal study, it was shown that the correct space group is P6(3)/m. The three-dimensional structure of the title compound is built up from FeO(6) octa-hedra (3.. symmetry), trigonal-planar BO(3) groups ( symmetry) and PO(4) tetra-hedra (m.. symmetry). Two FeO(6) octa-hedra form Fe(2)O(9) dimers via face-sharing, while the anionic BO(3) and PO(4) groups are connected via corner-sharing to build up the [BP(3)O(12)](6-) anion. Both units are inter-connected via corner-sharing.

Dual-Functional Proton-Conducting and pH-Sensing Polymer Membrane Benefiting from a Eu-MOF.

Porous metal-organic frameworks (MOFs) have demonstrated a great potential in proton conduction and luminescence sensing due to functionalized nodes, ligands and channels, or pores. Herein, we prepared a hydrothermally stable Eu-MOF that also resisted acid and base using a bifunctional organic ligand containing carboxylic acid groups, which are easily coordinated to Eu ions, and Eu-phobic tetrazolyl groups as potential proton-hopping sites. The hydrogen bond network, which was constructed by the uncoordinated anionic tetrazolium and the coordinated and free water molecules, endowed this Eu-MOF with the highest proton conductivity of 4.45 × 10-2 S/cm at 373 K and 93% relative humidity. The proton conductivity of the Nafion membrane containing this Eu-MOF increased 1.74 times. More interestingly, the hybrid membrane displayed luminescence pH sensing because the changeable protonation levels of uncoordinated tetrazolium groups along with the pH tuned the emission of embedded Eu-MOFs. Such a dual-functional MOF-based hybrid membrane including proton conduction and pH sensing is reported for the first time, which could open an avenue to the more practical application for functional MOFs.