Zhao-Min Hao

One-dimensional channel-structured Eu-MOF for sensing small organic molecules and Cu2+ ion

Two new lanthanide metal–organic frameworks Ln(FBPT)(H2O)(DMF) (FBPT = 2′-fluoro-biphenyl-3,4′,5-tricarboxylate, Ln = Eu and Tb) were prepared under solvothermal conditions. Single crystal X-ray diffraction analyses reveal that the two compounds are isostructurally related with the same one-dimensional channel structure on the basis of FBPT as an organic linker. Herein, the Eu(FBPT)(H2O)(DMF) (EuL) is selected as a representative sample for luminescent measurements. Study of the photoluminescence properties reveals that the EuL exhibits red emission, corresponding to the 5D0 → 7FJ (J = 1–4) transitions of the Eu3+ ion under UV light excitation. Most interestingly, when this compound was immersed in the different organic solvents and metal ion DMF solutions, it shows highly selective and sensitive sensing for small organic molecules and Cu2+ ions. In connection to this, a probable sensing mechanism was also discussed in this paper.

A europium(III) based metal–organic framework: bifunctional properties related to sensing and electronic conductivity

The accessible interspace of [Eu4(BPT)4(DMF)2(H2O)8] (EuL) metal–organic framework (MOF) based host materials can serve as good candidates for loading of a variety of guest molecules. In this regard, two functional properties, sensing and electronic conductivity of EuL MOF were systematically studied in this contribution. The photoluminescent properties reveal that the EuL exhibits characteristic red emission of Eu3+ ion, and presents highly detectable luminescence responses for Cu2+ ions and acetone molecules in DMF solution. For the studies of electrical properties, they were focused on the electronic conductivities of I2-incorporated EuL in anhydrous media and at different temperatures. With the increase of temperature from 25 to 80 °C, the I2-incorporated EuL showed significant changes in conductivities from 8.27 × 10−7 S cm−1 to 2.71 × 10−5 S cm−1. Meanwhile, the activation energy (Ea) was for the first time estimated for iodine-element-incorporated MOF with the help of Arrhenius plots. The successful achievements of the impedance measurements and analyses for I2-incorporated EuL prove for the first time that iodine-element-incorporated MOF can also be used for studies of conductivity under anhydrous conditions and at moderate temperature.

Two high-connected metal–organic frameworks based on d10-metal clusters: syntheses, structural topologies and luminescent properties

The d(10)-metal-oxo clusters connected by the asymmetric tricarboxylate and linear neutral ligands give rise to two novel high-connected MOFs. They feature the highest (3,16)- and (3,8)-connected three-dimensional frameworks based on cube-like octanuclear [Zn8(μ2-OH)4(CO2)12] clusters and butterfly-like tetranuclear [Cd4(μ3-OH)2(CO2)6] clusters as the secondary building units, respectively.

A series of POM/Ag-based hybrids: distinct forms and assembly of [AgxLy] complexes through combinational effects of POM and isomeric ligands

Five POM/Ag-based hybrids were obtained under hydrothermal conditions: (AgLa)2[Ag2La2(SiW12O40)] (1), [(AgLb)2-Ag2Lb2][(SiW12O40)] (2) Na2[AgLa(HLa)]2[Ag5La4(H2O)2][H(P2W18O62)2] ·21.6H2O (3), [Ag5Lb5][K2(OH)P2W18O62]·H2O (4) and [Ag2La2][HPW12O40]·7.5H2O (5) (La = 1,2-bis(imidazol-1-ylmethyl)benzene; Lb = 1,3-bis(imidazol-1-ylmethyl)benzene). It is likely that the forms and assembly of [AgxLy] complexes are crucial to the eventual structures, which are quite dependent on the POM and isomeric ligands in combination. Compound 1 shows a “S”-like chain structure with [(AgLa)2]n2n+ templates, while compound 2 features a unique 2D layer constructed by polypseudo-rotoxane motifs and infinite Ag chains. Compound 3 exhibits a 2D layer consisting of {Dawson-Ag5} double chain and [AgLa2] complexes. Compound 4 possesses a 3D poly-threading framework containing {POM-K} chains and interdigitated metal–organic layers. Compound 5 is a 1D chain, formed by Keggin anions and [Ag2La2] circles. Further, the luminescent and electrochemical properties of 1–5 are also investigated.