Search

Six functional metal-organic frameworks constructed from semi-flexible 4,4′-bis(imidazolyl)diphenyl ether (bidpe), namely: [Zn(bidpe)(mpa)]n (1), [Cu(bidpe)(mpa)(H2O)]n (2), [Cd(bidpe)(mpa)]n (3), [Zn1.5(bidpe)2(smpa)(H2O)]n (4), [Cu1.5(bidpe)2(smpa)(H2O)]n (5), [Cd(bidpe)(hmpa)]n (6) (H2mpa = m-Phthalic acid, H2smpa = 5-sulfonatobenzene-1,3-dicarboxylate, H2hmpa = 5-Hydroxyisophthalic acid), have been synthesized under solvothermal conditions. Single-crystal X-ray diffraction analysis reveals that complexes 1–4 and 6 show 2D→3D supramolecular structure with a Schlafli symbol of (44·62), (4·65), (44·62), (42·6) and (63) topology, respectively. Complex 5 possesses an unprecedented (3, 4, 6)-connected 3D framework with a Schlafli symbol of (4·64·8)2(42·64·89)(62·8)2. Meanwhile, complexes 1, 3, 4 and 6 have excellent fluorescence properties and can be used as potential luminescent sensors for sensing Cr(VI) anions, Fe(III) ions and nitrobenzene (NB) with high selectivity and sensitivity. The photocatalytic studies indicate that 1 has good photocatalytic capability in degradation of methylene blue (MB), 1 and 6 have good photocatalytic capability in degradation of methyl violet (MV). Furthermore, the possible sensing mechanism and photocatalytic mechanism have been discussed.

Three novel Mn(II)/Co(II)-based 3D metal-organic frameworks (MOFs), namely {[Mn2(L)(tib)(H2O)]·3DMA·4H2O}n (1), {[Co2(L)(bipd)2]·3H2O}n (2) and {[Co(L)0.5(bimb)]·3H2O·0.5O2}n (3) (H4L ​= ​5,5'-(1,4-xylylenediamino) diisophthalic acid, tib ​= ​1,3,5-tris(1-imidazolyl)benzene, bipd ​= ​3,5-bis(1-imidazoly)pyridine, and bimb ​= ​1,4-bis(lmidazol)-butane), have been successfully synthesized using the mixed-ligand as functionalized organic linker. The structural characterization revealed that both MOFs 1 and 2 exhibited an unprecedented 4-nodal 3D framework that enriching crystal engineering, while MOF 3 featured a 2-nodal three-interpenetrating bbf topology framework with a Schlafli symbol of (64·82)(66)2. The title MOFs have been exploited as photocatalysts for degradation of methylene blue (MB), methyl violet (MV) and malachite green (MG). The photocatalytic results demonstrated that MOFs 2 and 3 exhibited efficient photocatalytic abilities to degrade the three aromatic dyes under UV irradiation. The possible catalytic mechanism was also explored and discussed in detail. Moreover, the variable-temperature magnetic analyses indicated that MOFs 1–3 exhibited weak antiferromagnetic behavior between Mn(II)/Co(II) ions.

Three new Zn metal organic frameworks (Zn-MOFs), {[Zn2(L)[H (1,4-bmib)]]·1.5(H2O)}n (1), {[Zn2(HL) (3,5-bip)2]·(H2O)}n (2), and {[Zn2(HL) (4,4′-bbibp)2]·4(H2O)}n (3), have been first synthesized based on a flexible H5L ligand with ether functional group (C–O–C) and successfully characterized (semi-flexible H5L ​= ​3,5-bis(3,5-dicarboxylphenoxy)benzoic acid, flexible 1,4-bmib ​= ​1,4-bis(2-methylimidazol-1-yl)butane, rigid 3,5-bip ​= ​3,5-bis(1-imidazolyl)pyridine, and rigid 4,4′-bbibp ​= ​4,4′-bis(benzoimidazo-1-ly)biphenyl). Zn-MOFs 1–3 are unique topological networks. As multi-responsive fluorescent sensing materials of 1 and 3, they show excellent response and sensitivity for Fe3+, CrO42− and Cr2O72−, and tetracycline (TC) in aqueous system. The quenching mechanism is also investigated in detail.

In this study, we have synthesized six new coordination polymers (CPs), namely {[Cu6(3,5-bip)6(H2O)12(SO4)6]·3H2O}n (1), [Co(3,5-bip) (H2O)3(SO4)]n (2), {[Cu(1,3-bit)2(H2O)2]·2(NO3)}n (3), {[Cu2(1,3-bit)2 (1,3-bcbb)2]·4(H2O)}n (4), [Cu(4,4′-bibp) (H2O) (NO3)2]n (5), [Cu(4,4′-bibp) (4,4′-Hsbdc)]n (6) via solvothermal methods. The structures of these new CPs have been characterized by elemental analysis, FTIR, TG analysis, PXRD and single crystal X-ray diffraction techniques. Meanwhile, the title CPs are explored for adsorption of organic dyes, i.e., anionic dyes (congo red (CR), and methyl orange (MO)) and cationic dye (methylene blue (MB)) considered extensively as water colorants pollutants. Worth noting, complex 3 can adsorb anionic dyes (CR and MO) quickly; complex 6 shows great performance in CR adsorption. Kinetic study reveals that the adsorption process is performed via pseudo-second-order reaction. The dye removal investigations of complexes 3 and 6 support that ions exchange and H-bonding interactions between CPs and target organic dyes are significant factors, heavily affecting dye adsorption. They have excellent potential in wastewater treatment.

Five novel coordination polymers based on the 2,6-pyridinedicarboxylic acid (H2pdca), namely [Co(pdca)(bibp)0.5H2O)2]n (1), [Ni(pdca)(bibp)0.5(H2O)2]n (2), [Co(pdca)(bbibp)1.5]n (3), [Ni(pdca)(bbibp)1.5]n (4) and Zn(pdca)(bbibp)0.5]n (5) (bibp ​= ​4,4′-bis(imidazole) biphenyl, bbibp ​= ​4,4′-bis(benzoimidazo-l-yl)biphenyl and DMF ​= ​N, N’dimethylformamide) have been synthesized under solvothermal conditions. Single crystal X-ray diffraction analysis reveals that all the complexes have 3D framework structures. In addition, the properties of the complexes for photo-catalytic degradation of organic dyes were discussed. Moreover, luminescence studies reveal that complex 5 shows strong luminescent property and could be a fluorescence sensor for the detection of Cr2O72−ion and antibiotics chloramphenicol. The Ksv values of 5 for Cr2O72− ion and chloramphenicol are 8.05 ​× ​103 ​M−1 and 6.69 ​× ​103 ​M−1, respectively. Meanwhile, the possible mechanism for the luminescence quenching of 5 has been discussed.

Three novel Zn(II)-based coordination polymers (Zn-CPs), namely {[Zn(1,3,5-tib)2(H2O)2]·2(NO3)}n (1), [Zn(1,3,5-tib)(4,4′-saba)]n (2), and {[Zn(1,3-bit)(4,4′-cpmb)]·0.5(1,3-bit)}n (3), have been hydrothermally synthesized and successfully characterized by single crystal X-ray diffraction (1,3,5-tib ​= ​1,3,5-tris(1-imidazolyl)benzene), 4,4′-Hsaba ​= ​4-(4-sulfoacid)-benzoic acid, 1,3-bit ​= ​1,3-bis(l-imidazoly)toluene, and 4,4′-H2cpmb ​= ​4-(4-carboxylphenylmethylthio)benzoic acid). Structural analysis reveals that complex 1 manifests a 2D planar structure with an unprecedented (2,4)-c topological network. Complex 2 and complex 3 display a 3-c fes and 6-fold classical Ia interpenetrated dia framework with 4-c (66) sqc6 topology framework, respectively. Among the three complexes, CPs 1 and 2 demonstrate excellent performance for Azo organic dyes’ adsorption, for which the selectivity and kinetics have been comprehensively studied. CPs 3 shows great luminescent intensity in aqueous solution. It is further applied as a fluorescence sensor to detect Fe3+ cation, Cr2O72− anion, and tetracycline antibiotic.