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Three new metal-organic frameworks (MOFs), namely, {[Zn 2 (abtc)(bpa)(H 2 O)]·5H 2 O} n (1) , {[Cd 3 (abtc) 2 ]·2H 3 O} n (2) and [Cd 3 (H 2 abtc) 3 (bpp)(μ 2 -OH 2 ) 2 (H 2 O) 3 ] n (3) [bpa = bis(4-pyridyl)amine, bpp = 1,3-bis(4-pyridyl)propane] have been constructed mainly from the ligand of 3,3′,5,5′-azobenzene-tetracarboxylic acid (H 4 abtc) and metal centers of Zn 2+ or Cd 2+ . Single crystal X-ray diffraction analysis reveals that compounds 1 and 2 display 3D frameworks, while compound 3 displays a 2D layered structure consisting of intriguing 1D rhombic chains and bpp ligands. The solid-state luminescent properties of three products are investigated at room temperature. Furthermore, fluorescence measurements indicated that the complex 1 could sensitively sense Fe 3+ ions and nitrobenzene molecules. [ABSTRACT FROM AUTHOR]

A novel metal-organic framework, [Zn(HL)(HO)]·[EMI] ( 1), has been hydro/solvothermally synthesized in the presence of [EMI]Br ionic liquid (IL) (HL = 2,2′,4,4′-quaterphenyl tetracarboxylic acid, EMI = 1-ethyl-3-methylimidazolium). The interesting feature of 1 is that the HL ligands connect Zn(II) ions to afford a fascinating meso-helical chains with left- and right-handed helical loops in one single strand along the c axis, which are further connected by O-H···O hydrogen bonds to generate a 3D supramolecular framework. The free IL [EMI] cations are filled in the voids of the framework. The title complex was characterized by elemental analysis, IR spectra, thermogravimetric analysis, single-crystal X-ray crystallography and powder X-ray diffraction. More interesting, the fluorescence of 1 shows fast and reversible detection of NB vapour, which exhibits its potential as NB sensor. [ABSTRACT FROM AUTHOR]