- [Show abstract] [Hide abstract] ABSTRACT: A family of thiophene-based metal–organic frameworks (MOFs), [Zn(L)(BBI)•(H2O)2] (1) (BBI = 1,1'-(1,4-butanediyl)bis(imidazole)) and [Cd(L)(TPOM)0.75]•xS (2) (TPOM = tetrakis(4-pyridyloxy-methylene) methane, S represents noncoordinated solvent molecules) were constructed by employing a new linear thiophene-functionalized dicarboxylic acid (benzo-(1,2;4,5)-bis(thiophene-2'-carboxylic acid, H2L) to assemble with d10 ions in the presence of flexible ancillary ligand under solvothermal conditions, which exhibit diverse structures. Most strikingly, both compounds 1 and 2 could be efficient luminescent sensory materials for highly selective and sensitive to environmental contaminants, especially for Hg(II), Cu(II), Cr(VI) and salicylaldehyde, and yet remain unaffected by other molecules that may coexit. Furthermore, this is the first report on the MOF-based sensors capable of recyclable detection of Hg (II), Cr(VI) and salicylaldehyde so far. The luminescent sensing mechanism was studied in detail as well. In addition, compound 2 is one of the rare examples of high-performance MOFs trapping 2,4-dichlorophenol from the wasted methanol solution.
- [Show abstract] [Hide abstract] ABSTRACT: The reaction of tricarboxytriphenyl amine (H3TCA) with CdII and auxiliary ligand 4,4′-bis(1-imidazolyl)biphenyl (bimb) afforded [Cd3(TCA)2(bimb)·(DMA)6]n (1) containing a two-fold interpenetrating three-dimensional microporous framework. Compound 1 showed remarkable adsorption enthalpies for CO2 and H2 and good H2/N2 selectivity at low temperature. Moreover, activated 1 showed a highly selective adsorption towards CO2 over N2 and CH4 under ambient conditions. Interestingly, compound 1 selectively removed methyl orange (MO) over methylene blue (MB) from contaminated water with good recyclability, and possessed the second highest adsorption capacity for MO among the MOFs reported to date. Remarkably, complex 1 showed strong guest-dependent luminescence behavior.
- [Show abstract] [Hide abstract] ABSTRACT: Fabrication of ZnO/graphene hybrid by homogeneous depositing a continuous and conformable ZnO layer on graphene remains a great challenge and highly desired. In this paper, well-defined flake-like ZnO/graphene hybrid was fabricated by a facile in situ hydrolysis-deposition route using zinc acetate and graphene oxide (GO) as starting materials and ammonia as precipitator and reductant. By rational control the hydrolysis and condensation of Zn precursor, ZnO nanocrystals are homogeneously anchored on graphene due to the strong interaction between ZnO and GO, which was simultaneously reduced to graphene. The photocatalytic activity of the photocatalyst was evaluated using Brilliant Red X-3B (X3B) dye as probe. It was found that the presence of GO enhanced the crystallization of ZnO, and the photocatalytic activity of ZnO/graphene hybrid increases first and then decreases with increasing the amount GO. The hybrid with 3. wt.% of GO shows the highest photocatalytic activity, which is 3 times higher than that of pure ZnO.
- [Show abstract] [Hide abstract] ABSTRACT: Two amino-decorated metal-organic frameworks have been constructed, which are the rare examples of MOF-based fluorescent probes targeting environmentally relevant guest species, such as Hg (II) and Cr (VI) ions in aqueous solution, with high selectivity and sensitivity. The possible sensing mechanism is also discussed.
- [Show abstract] [Hide abstract] ABSTRACT: Three MOFs [M2(D-cam)2(bimb)2]n•3.5nH2O (M = Mn for 1, Co for 2) and [Cd8(D-cam)8(bimb)4]n (3) (D-H2cam = D-camphor acid, bimb = 4,4'-bis(1-imidazolyl)biphenyl) have been solvothermally synthesized, which exhibit structural diversity. The charming aspect of these frameworks is that, compound 3 is the very first MOF-based sensor for quantitative detecting three different types of analytes (metal ions, aromatic molecules and pesticides). And also, both compounds 2 and 3 show rapid uptake and ready regeneration for the methyl orange (MO), as well as can selectively MO over methylene blue (MB) with high MO/MB separation ratio.
- [Show abstract] [Hide abstract] ABSTRACT: Solvothermal reactions of 5-(4-pyridyl)-isophthalic acid (H2pbdc) and transition-metal centers (Ni2+/Co2+/Zn2+) in the presence (or absence) of N-auxiliary 4,4′-bis(1-imidazolyl)biphenyl (bimb) ligand produce [Ni2(pbdc)2(μ2-H2O)(H2O)2·(DMA)2.7]n (DMA = N,N′-dimethylacetamide, 1), [Ni12(pbdc)12(μ2-H2O)6(py)2(H2O)8(DMA)2·(H2O)5·(DMA)9]n (2), [Co2(pbdc)2(bimb)2·(bimb)0.5·(H2O)4·(DMF)0.25]n (3) and [Zn(pbdc)(bimb)·(H2O)]n (4), which exhibit structural diversity. Both compounds 1 and 2 display a uninodal 8-connected 3D tsi net, but feature different crystal systems and space groups from each other. Compound 3 adopts a 2-fold interpenetrating binodal (3,5)-connected 3D hms net and compound 4 features a rare 2-fold interpenetrating binodal (3,4)-connected 3D fsx architecture. In particular, activated 3 shows high-efficiency for the selective sorption of small molecules, including CO2 over N2 and CH4, H2 over N2, as well as alcohols from water. More importantly, 4 represents the first report on a MOF as a promising luminescent probe for detecting pesticides, and also the very first example for detecting both pesticides and solvent molecules simultaneously.
- [Show abstract] [Hide abstract] ABSTRACT: Two three-dimensional microporous compounds, Cu6(BTTC)4(H2O)6·xS (1) and [(CH3)2NH2]3[(Cu4Cl)3(BTTC)8]·yS (2, H3BTTC = benzo-(1,2;3,4;5,6)-tris (thiophene-2′-carboxylic acid), S represents noncoordinated solvent molecules), have been solvothermally synthesized and characterized, both of which are based upon truncated octahedron subunits and contain uniform nanosized cavities but exhibit different topological frameworks. Complex 1 demonstrates high adsorption enthalpies for H2 and CO2 gas molecules, stemming principally from the presence of the exposed metal Cu(II) sites on the pore surface. In particular, activated complex 1 shows high efficiency for the separation of energy-correlated molecules, including CO2 over N2 and CH4 under ambient conditions.
- [Show abstract] [Hide abstract] ABSTRACT: A three-dimensional microporous framework, Zn(ii)-MOF [Zn(HPyImDC)(DMA)]n () (H3PyImDC = 2-(pyridine-4-yl)-1H-4,5-imidazoledicarboxylic, DMA = N,N'-dimethylacetamide), with open metal sites and small-sized pores, exhibits excellent selective capture of CO2 over N2 and CH4 at 273 K, as well as alcohols from water. The excellent CO2 adsorption selectivity of allows its potential use in the capture of CO2 from industrial flue gas or the removal of CO2 from natural gas. More interestingly, compound represents the rare case of porous materials separating propanol isomers, which may be caused by the relative flexibility of the linear n-propanol considering that both n-propanol and i-propanol have similar kinetic diameters.
- [Show abstract] [Hide abstract] ABSTRACT: A Cd(ii)-MOF [Cd(L)(DMF)] () (H2L = 5-(4-pyridyl)-isophthalic acid) featuring high thermal and chemical stability has been solvothermally synthesized and characterized. Complex is a robust multifunctional three-dimensional (3D) microporous framework possessing an unusual (4,5)-connected topological net. Activated shows high-efficiency for the selective capture of CO2 over N2 and CH4 under ambient conditions, which ranks it among MOFs with the highest selectivity. In addition, desolvated exhibits good separation ratios of H2 over N2 at lower temperature, as well as alcohols from water. In particular, desolvated demonstrates significantly higher adsorption enthalpies for CO2 and CH4 gas molecules, which are in the range of the highest Qst values reported to date. Furthermore, complex displays visible photoluminescence in the solid state under UV irradiation.
- [Show abstract] [Hide abstract] ABSTRACT: Solvothermal reactions of 2,5-thiophenedicarboxylate (H2tdc) and N-auxiliary ligands in the presence of cobalt(ii), zinc(ii) and cadmium(ii) salts have given rise to seven new metal-organic frameworks, namely, [Co2(tdc)2(bpp)2(H2O)·(H2O)]n (bpp = 1,3-bis(4-pyridyl)propane) (), [Cd(tdc)(bpp)(H2O)·(H2O)2]n (), [Zn2(tdc)2(bbi)2·(H2O)2]n (bbi = 1,1'-(1,4-butanediyl)bis(imidazole)) (), [Co4(tdc)3(bimb)4(H2O)5·(tdc)·(DMF)·(H2O)2]n (bimb = 4,4'-bis(1-imidazolyl)biphenyl) (), [Zn4(O)(tdc)3(bimb)4·(H2O)5.25·(CH3OH)]n (), [Cd4(tdc)4(bimb)6·(H2O)2·(CH3OH)2·(DMF)4] () and [Co2(tdc)2(tib)2·(H2tdc)·(DMF)2] (tib = 1,3,5-tris(1-imidazolyl)benzene) (), which exhibit structural diversity. Compounds display 3D 2-fold interpenetrating 8-connected tsi net, 2D 4-connected sql net, and 3D 5-fold interpenetrating 4-connected dia net, respectively; while compound features an extremely rare 3D 7-connected hxg-d cationic net and compound adopts a 3D trinodal (4,4,6)-connected net with a new topology structure. For compounds and , the topology in the structures were determined as 3D 3-fold interpenetrating 5-connected bnn net and 3D 2-fold interpenetrating binodal (3,5)-connected net, respectively. In the solid state, complexes , and exhibit nonlinear optical properties, and complex has also been evaluated as a promising visible-light-driven photocatalyst for degradation of organic pollutants. The magnetic investigation of complexes and shows that there exists spin-canted antiferromagnetism for , whereas strong antiferromagnetic interaction and/or the depopulation of the higher energy Kramers doublets of the Co(ii) centers are dominant in .
- [Show abstract] [Hide abstract] ABSTRACT: Solvothermal reactions of 2-amino-1,4-benzene dicarboxylic acid (NH2bdcH2) and N-auxiliary ligands in the presence of manganese(II), zinc(II) and cobalt(II) salts have given rise to four new metal–organic frameworks, namely, [Mn5(NH2bdc)5(bimb)5·(H2O)0.5]n (bimb = 4,4′-bis(1-imidazolyl)biphenyl) (1), [Zn(NH2bdc)(bix)·(DMF)2]n (bix = 1,4-bis(imidazol-1-ylmethyl)benzene) (2), [Co(NH2bdc)(bix)·(DMF)·(CH3CH2OH)]n (3) and [Co(NH2bdc)(bpp)]n (4) (bpp = 1,3-bis(4-pyridyl)propane). Single-crystal X-ray diffraction analyses revealed that MOF 1 displays 5-fold interpenetrating 4-connected dia 3D net; MOFs 2 and 3 are isomorphic, which possess 3-fold interpenetrating dia 3D nets; MOF 4 exhibits 4-connected sql 2D net. Noncentrosymmetric structures and multifunctionality in 1–3 are established by varying ligands and metal centers. In the solid state, polar MOFs 1–3 exhibit nonlinear-optic (NLO) and MOF 1 demonstrates typical ferroelectric behaviour with a remnant electric polarization (Pr) of 1.2 μC cm−2 and an electric coercive field (Ec) of 0.35 kV cm−1. In addition, MOF 2 could be a potential luminescent probe for detecting nitrobenzene or 2-nitrotoluene via fluorescence enhancement and has been evaluated as a promising visible-light-driven photocatalyst for degradation of organic pollutants.
- [Show abstract] [Hide abstract] ABSTRACT: Single-walled carbon nanotubes (SWNTs) that are covalently functionalized with benzoic acid (SWNT-PhCOOH) can be integrated with transition-metal ions to form 3D porous inorganic-organic hybrid frameworks (SWNT-Zn). In particular, N(2)-adsorption analysis shows that the BET surface area increases notably from 645.3 to 1209.9 m(2) g(-1) for SWNTs and SWNT-Zn, respectively. This remarkable enhancement in the surface area of SWNT-Zn is presumably due to the microporous motifs from benzoates coordinated to intercalated zinc ions between the functionalized SWNTs; this assignment was also corroborated by NLDFT pore-size distributions. In addition, the excess-H(2)-uptake maximum of SWNT-Zn reaches about 3.1 wt. % (12 bar, 77 K), which is almost three times that of the original SWNTs (1.2 wt. % at 12 bar, 77 K). Owing to its inherent conductivity and pore structure, as well as good dispersibility, SWNT-Zn is an effective candidate as a sensitive electrochemical stripping voltammetric sensor for organophosphate pesticides (OPs): By using solid-phase extraction (SPE) with SWNT-Zn-modified glassy carbon electrode, the detection limit of methyl parathion (MP) is 2.3 ng mL(-1).
- [Show abstract] [Hide abstract] ABSTRACT: Two microporous cadmium(II) metal–organic frameworks, [Cd(cptpy)(Ac)(H2O)·(DMA)(H2O)]n (1) and [Cd(cptpy)2·(DMF)2]n (2) (Hcptpy = 4-(4-carboxyphenyl)-2,2′:4′,4″-terpyridine, DMA = N,N-dimethylacetamide, DMF = dimethylformamide) have been solvothermally synthesized under different reaction conditions. Complex 1 is a double-interpenetrating 3D network, while 2 is a noninterpenetrating (3,5)-connected 2D framework. The dehydrated forms of compounds 1 and 2 exhibit selective adsorption of CO2 over N2 and H2O over CH3OH. In addition, the adsorption value of CO2 for 2 is higher than that of 1. The contents of uncoordinated pyridine nitrogen (Lewis basic sites) per formula unit of 1 and 2 are 2.16 and 4.36%, respectively. Obviously, the grafting of more uncoordinated pyridine nitrogen into compound 2 could enhance adsorption of the acidic CO2 molecule. Notably, both 1 and 2 display strong photoluminescence. The nature of electronic transitions for complex 1 in the photoluminescent process was investigated by means of time-dependent density functional theory (TDDFT) calculations and molecular orbital analyses, which collaborates that the luminescent property is ligand-based.
- [Show abstract] [Hide abstract] ABSTRACT: Five new metal–organic frameworks [M(btec)0.5(bimb)]n (1) (M = Co (1), Ni (2), Cu (3), Zn (4)) and [Cd(btec)0.5(bimb)0.5]n (5), were obtained by reactions of the conjugated 1,2,4,5-benzenetetracarboxylic acid (H4btec) and 4,4′-bis(1-imidazolyl)biphenyl (bimb) with corresponding metal salts under hydrothermal conditions, respectively. MOFs 1-5 show different structures and topologies: compounds 1 and 4 are isomorphic, which possess typical PtS 3D nets; compound 2, 3 and 5 exhibit 2D layer structure, NbO 3D network and (4,6)-connected 3D binodal topology, respectively. Notably, compounds 1, 2, and 5 represent the rare example of MOFs-based visible-light-driven photocatalysts and show good stability toward photocatalysis. Furthermore, compound 5 is photocatalytically more active than 1 and 2 because of the relatively narrower band gap calculated from LMCT transitions. In addition, the formation rate of •OH radicals on compound 5/H2O interface via photocatalytic reactions is much higher than that of 1 and 2, implying that the formation rate of •OH radicals during photocatalysis is in agreement with photocatalytic activity and the formation rate of •OH radicals is an important factor influencing photocatalytic performance.
- [Show abstract] [Hide abstract] ABSTRACT: Six new metal-organic frameworks [Cu(obba)(bimb)·(obbaH(2))](n) (1), [Cu(obba)(bimb)](n) (2), [Zn(2)(obba)(2)(bimb)(2)(DMF)(2)(H(2)O)(3.5)](n) (3), [Ni(3)(2,2',4,4'-bptcH)(2)(bimb)(2)(H(2)O)(2)·(H(2)O)(2)](n) (4), [Ni(2)(bimb)(3)(H(2)O)(6)·(aobtc)·(DMF)(2)·(H(2)O)(2)](n) (5) and [Cd(3,3',4,4'-bptcH(2))(H(2)O)·(bimb)](n) (6), were obtained by reactions of 4,4'-bis(1-imidazolyl)biphenyl (bimb) and multi-carboxylic acids of 4,4'-oxybis(benzoic acid) (obbaH(2)), 2,2',4,4'-biphenyltetracarboxylate acid (2,2',4,4'-bptcH(4)), azoxybenzene-3,3',5,5'-tetracarboxylic acid (aobtcH(4)), and 3,3',4,4'-biphenyltetracarboxylate acid (3,3',4,4'-bptcH(4)) with corresponding metal salts under hydro/solvothermal conditions, respectively. Complexes 1-3 have entangled structures with different topologies: 1 is a 3-fold interpenetrating NbO three-dimensional (3D) network; 2 is a 3-fold interpenetrating dmp 3D net; 3 is a 6-fold interpenetrating dia 3D chiral net containing rare 1D helical chains with the same handedness. Complex 4 is an uninodal 6-connected network with a Schäfli symbol of (4(8)6(4)8(3)) based on the trinuclear Ni(II) subunits, while complexes 5 and 6 are 1D chains. Interestingly, compound 6 represents the rare example of MOFs that exhibit high photocatalytic activity for dye degradation under visible light and shows good stability towards photocatalysis. Complexes 3 and 6 exhibit intense blue emissions in the solid state at room temperature whereas 3 appears to be a good candidate of novel hybrid inorganic-organic NLO material.
- [Show abstract] [Hide abstract] ABSTRACT: The treatment of Ln(NO3)3·6H2O (Ln = La, Ce, Eu, Gd, Dy) with 1,3,5-benzenetricarboxylic acid (H3BTC) in a water–ethanol solution facilely yields crystal nanorods of rare earth metal–organic frameworks (MOFs) at room temperature. Electron micrographs show that the nanorods are 50–200 nm in width, 50–100 nm in thickness and 1–2 μm in length. All the crystal nanorods have the same Ln(BTC)(H2O)6 structure as identified by power X-ray diffraction, elemental analysis, thermogravimetric and Fourier transform infrared analysis. The optical properties of all the compounds are recorded; and, the nanoscale MOFs (NMOFs) with Eu3+ and Dy3+ show excellent photoluminescence.
- [Show abstract] [Hide abstract] ABSTRACT: A new metal-organic framework, [Zn5(trencba)2(OH)2Cl2·4H2O] (1) [H3trencba=N,N,N′,N′,N′′,N′′-tris[(4-carboxylate-2-yl)methyl]-tris(2-aminoethyl)amine], constructed from a flexible tripodal ligand based on C3 symmetric tris(2-aminoethyl)amine, has been synthesized hydrothermally and characterized by elemental analysis, IR, TG, XRD and single-crystal X-ray diffraction analysis. Compound 1 contains an unprecedented linear penta-nuclear zinc cluster fragment. Each ligand links four penta-nuclear fragments, and every fragment links eight ligands to generate a three-dimensional non-interpenetrated porous framework. The uncoordinated water molecules were observed trapped in the void pores. Compound 1 represents the first example of (6,8)-connected 3D bi-nodal framework based on a single kind of organic ligand. The photoluminescence measurements showed that complex 1 exhibits relatively stronger blue emissions at room temperature than that of the ligand.
- [Show abstract] [Hide abstract] ABSTRACT: Glycoluril-based molecular clip L bearing two N,N'-chelating sites and a rigid cavity has been prepared. With L, one metallomacrocycle and three metal-organic frameworks, (Cu(L)(OAc)2(H2O) ·2H2O)n (1), (Co(L)2(NO3)2(H2O)2 ·4H2O)n (2), (Zn(L)2(NO3)2(H2O)2 ·7H2O)n (3), and (Cu(L)(I) ·DMF)n (4) were crystallized, which display three different structure types. In 1, two ligands are arranged in a face-to-face conformation to coordinate two Cu(II) ions from opposite directions through axial positions, generating a pesudo-rectangular metallomacrocycle. Polymer 2 is an 1D double ribbons. Interestingly, each double ribbons is connected by hydrogen bond with the result that the channels are formed and run parallel to the ab diagonal, and the water chains with the symbol C4 are located within the channels. Polymer 3 exhibits the same topological morphology as polymer 2. However, each double ribbons in 3 is connected by a different type of hydrogen bond with the result that the channels are formed along the b axis. Polymer 4 is a two-dimensional (2D) tubular sheet constructed by an unprecedented (CuI)∞ column and clip ligand L. The type of the (CuI)∞ column can be described as a zigzag chain and has been rarely reported. The DMF solvent molecules are located within the channels.
- [Show abstract] [Hide abstract] ABSTRACT: The X-ray crystal structures of (NH4)2(15-crown-5)3[Cu(mnt)2] (1) and (NH4)2(benzo-15-crown-5)4-[Cu(mnt)2]·0.5H2O (2) were determined. Two single crystals are composed of distinct structures of ammonium-crown ether supramolecular cation and [Cu(mnt)2]2− anion. The triple-decker dication in complex 1 and a sandwich dimmer in complex 2 were observed. X-Band EPR studies on the single crystals of both complex 1 and complex 2 have been carried out at room temperature, which revealed that complex 2 showed a perfect hyperfine structure of Cu whereas that of complex 1 could not be observed. The principal values and direction cosines of the principal axes of the g and A tensors were computed by a least-squares fitting procedure. The spin density of Cu(II) was estimated according to the principal values of the A tensors and compared well with the results calculated based on DFT method.
- [Show abstract] [Hide abstract] ABSTRACT: Two new metal−organic frameworks (MOFs), [Zn(p-BDC)(m-bix)0.5][Zn(p-BDC)(m-bix)]·H2O (1) and [Zn(p-BDC)(m-bix)] (2) (p-BDC = terephthalate, m-bix =1,3-bis(imidazol-1-ylmethyl)benzene), were synthesized and characterized structurally. Both of the MOFs feature the interpenetrated two-dimensional (2D) → three-dimensional (3D) network motifs. In particular, complex 1 represents the second example of intertwining of different 2D coordination motifs, and complex 2 shows a 3-fold parallel interpenetrated framework. In addition, the spectroscopic, thermal, and fluorescence properties of complexes 1 and 2 are investigated.
Huazhong (Central China) Normal University
Wu-han-shih, Hubei, China
- College of Chemistry
Nan-ching, Jiangsu Sheng, China
- • Department of Chemical Engineering
- • State Key Laboratory of Coordination Chemistry
- • Department of Chemistry