Topological identification of the first uninodal 8-connected lsz MOF built from 2,2'-difluorobiphenyl-4,4'-dicarboxylate pillars and cadmium(II)-triazolate layers.

Using polynuclear metal clusters as nodes, many high-symmetry high-connectivity nets, like 8-connnected bcu and 12-connected fcu, have been attained in metal-organic frameworks (MOFs). However, construction of low-symmetry high-connected MOFs with a novel topology still remains a big challenge. For example, a uninodal 8-connected lsz network, observed in inorganic ZrSiO4, has not been topologically identified in MOFs. Using 2,2'-difluorobiphenyl-4,4'-dicarboxylic acid (H2L) as a new linker and 1,2,4-triazole (Htrz) as a coligand, a novel three-dimensional CdII-MOF, namely poly[tetrakis(µ4-2,2'-difluorobiphenyl-4,4'-dicarboxylato-κ5O1,O1':O1':O4:O4')tetrakis(N,N-dimethylformamide-κO)tetrakis(µ3-1,2,4-triazolato-κ3N1:N2:N4)hexacadmium(II)], [Cd6(C14H6F2O4)4(C2H2N3)4(C3H7NO)4]n, (I), has been prepared. Single-crystal structure analysis indicates that six different CdII ions co-exist in (I) and each CdII ion displays a distorted [CdO4N2] octahedral geometry with four equatorial O atoms and two axial N atoms. Three CdII ions are connected by four carboxylate groups and four trz- ligands to form a linear trinuclear [Cd3(COO)4(trz)4] cluster, as do the other three CdII ions. Two Cd3 clusters are linked by trz- ligands in a µ1,2,4-bridging mode to produce a two-dimensional CdII-triazolate layer with (6,3) topology in the ab plane. These two-dimensional layers are further pillared by the L2- ligands along the c axis to generate a complicated three-dimensional framework. Topologically, regarding the Cd3 cluster as an 8-connected node, the whole architecture of (I) is a uninodal 8-connected lsz framework with the Schläfli symbol (422·66). Complex (I) was further characterized by elemental analysis, IR spectroscopy, powder X-ray diffraction, thermogravimetric analysis and a photoluminescence study. MOF (I) has a high thermal and water stability.

A ferrocene∩europium assembly showing phototriggered anticancer activity and fluorescent modality imaging.

Two macrocyclic ferrocenophanes containing a coumarin fluorophore, Se2N[7]ferrocenophane (fc1), and Se4N2[7,7]ferrocenophane (fc2), construct an assembly of fc1-H+ClO4[Eu(C10H21COO)2(H2O)2(ClO4)] (fc1∩Eu) and fc2-2H+{ClO4[Eu(C10H21COO)2(H2O)2(ClO4)]}2 (fc2∩Eu) via a N-HO hydrogen bond and a coordinate bond between EuIII and ClO4-. In fc1∩Eu, UV light irradiation triggers non-covalent bond cleavage to release a ferrocenium and EuII complex, accompanying chromism and luminescence signals. Investigations through the steady-state UV-vis absorption, fluorescence, time-resolved fluorescence, femtosecond transient absorption spectra and electrochemical characterization elucidate a stepwise mechanism: firstly, an effective electron transfer occurs from a ferrocene unit to the singlet state of a coumarin unit; the following proton-coupled electron transfer (PCET) reduces EuIII and results in a non-covalent interaction cleavage. Further in vitro exploration of fc1∩Eu in HepG2 cells demonstrated phototriggered integrated cell cytotoxicity and fluorescent modality imaging.

Zeolitic imidazolate framework-8 as sorbent of micro-solid-phase extraction to determine estrogens in environmental water samples.

A novel micro-solid-phase extraction (µ-SPE) device coupled with ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS-MS) was established to determine five typical estrogens in aqueous samples. Zeolitic imidazolate framework-8 (ZIF-8) as sorbent was packed in polypropylene membrane to construct the µ-SPE device. Important extraction parameters including extraction time, extraction temperature, desorption solvent, desorption time and sample pH were carefully optimized to improve the extraction efficiency of the µ-SPE device. ZIF-8 sorbent showed an exceptional chemical stability and extraction efficiency for estrogens. In theory, the high extraction efficiencies may be due to the coordination bonding, intermolecular π-π interactions and hydrophobic interactions between ZIF-8 and the estrogens. Under the most favorable extraction conditions, for estrogens in aqueous samples, the proposed method provided low limits of detection (0.05-0.1µg/L), wide linearity range (three orders), excellent correlation coefficients (0.959-0.999) and satisfactory measurement precision (4.9-9.2%). which can meet the demand of determining estrogens at the trace level. Finally, the proposed method was successfully applied to determine the estrogens in real sewage water samples.

[6,13-Bis(2,4-dichloro-benzo-yl)-5,7,12,14-tetra-methyl-dibenzo[b,i][1,4,8,11]tetra-aza-cyclo-tetra-decinato- κ4N]nickel(II) acetone monosolvate.

In the title complex, [Ni(C36H26Cl4N4O2)]·C3H6O, two 2,4-dichloro-benzoyl groups are grafted onto the methine groups of the Ni(II) complex Ni(tmtaa) (H2tmtaa = 5,7,12,14-tetra-methyl-4,11-dihydro-dibenzo[b,i][1,4,8,11]tetra-aza-cyclo-tetra-decine). The complex has the shape of a saddle. The Ni atom is tetra-coordinated by the four N atoms of the macrocycle, forming a slightly tetra-hedrally distorted square-planar geometry. The metal is displaced by 0.0101 (8) Šfrom the N4 mean plane. The aromatic rings of the 2,4-dichloro-benzoyl groups form dihedral angles of 87.1 (2) and 82.1 (2)° with the N4 mean plane.