Synthesis, structure and photocatalytic degradation of organic dyes of a copper(II) metal-organic framework (Cu-MOF) with a 4-coordinated three-dimensional CdSO4 topology.

Metal-organic frameworks (MOFs) have attracted much interest in the fields of gas separation and storage, catalysis synthesis, nonlinear optics, sensors, luminescence, magnetism, photocatalysis gradation and crystal engineering because of their diverse properties and intriguing topologies. A Cu-MOF, namely poly[[(µ2-succinato-κ2O:O'){µ2-tris[4-(1,2,4-triazol-1-yl)phenyl]amine-κ2N:N'}copper(II)] dihydrate], {[Cu(C4H4O4)(C24H18N10)]·2H2O}n or {[Cu(suc)(ttpa)]·2H2O}n, (I), was synthesized by the hydrothermal method using tris[4-(1,2,4-triazol-1-yl)phenyl]amine (ttpa) and succinate (suc2-), and characterized by IR, powder X-ray diffraction (PXRD), luminescence, optical band gap and valence band X-ray photoelectron spectroscopy (VB XPS). Cu-MOF (I) shows a twofold interpenetrating 4-coordinated three-dimensional CdSO4 topology with point symbol {65·8}. It presents good photocatalytic degradation of methylene blue (MB) and rhodamine B (RhB) under visible-light irradiation. A photocatalytic mechanism was proposed and confirmed.

Construction of (3,8)-connected three-dimensional cobalt(II) and copper(II) coordination polymers with 1,3-bis[(1,2,4-triazol-4-yl)methyl]benzene and benzene-1,3,5-tricarboxylate ligands.

Coordination polymers (CPs) have been widely studied because of their diverse and adjustable topologies and wide-ranging applications in luminescence, chemical sensors, magnetism, photocatalysis, gas adsorption and separation. In the present work, two coordination polymers, namely poly[(µ5-benzene-1,3,5-tricarboxylato-κ6O1:O1':O3:O3:O5,O5'){µ3-1,3-bis[(1,2,4-triazol-4-yl)methyl]benzene-κ3N:N':N''}di-µ3-hydroxido-dicobalt(II)], [Co2(C9H3O6)(OH)(C12H12N6)]n or [Co2(btc)(OH)(mtrb)]n, (1), and poly[[diaquabis(µ3-benzene-1,3,5-tricarboxylato-κ3O1:O3:O5)bis{µ3-1,3-bis[(1,2,4-triazol-4-yl)methyl]benzene-κ3N:N':N''}tetra-µ3-hydroxido-tetracopper(II)] monohydrate], {[Cu4(C9H3O6)2(OH)2(C12H12N6)2(H2O)2]·H2O}n or {[Cu4(btc)2(OH)2(mtrb)2(H2O)2]·H2O}n, (2), were synthesized by the hydrothermal method using 1,3-bis[(1,2,4-triazol-4-yl)methyl]benzene (mtrb) and benzene-1,3,5-tricarboxylate (btc3-). CP (1) exhibits a (3,8)-coordinated three-dimensional (3D) network of the 3,8T38 topological type, with a point symbol of {4,5,6}2{42·56·616·72·82}, based on the tetranuclear hydroxide cobalt(II) cluster [Co4(µ3-OH)2]. CP (2) shows a (3,8)-coordinated tfz-d topology, with a point symbol of {43}2{46·618·84}, based on the tetranuclear hydroxide copper(II) cluster [Cu4(µ3-OH)2]. The different (3,8)-coordinated 3D networks based on tetranuclear hydroxide-metal clusters of (1) and (2) are controlled by the different central metal ions [CoII for (1) and CuII for (2)]. The thermal stabilities and solid-state optical diffuse-reflection spectra were measured. The energy band gaps (Eg) obtained for (1) and (2) were 2.72 and 2.29 eV, respectively. CPs (1) and (2) exhibit good photocatalytic degradation of the organic dyes methylene blue (MB) and rhodamine B (RhB) under visible-light irradiation.

Sonochemical synthesis and characterization of four nanostructural nickel coordination polymers and photocatalytic degradation of methylene blue.

Four nanostructural nickel(II) coordination polymers {[Ni(ttpa)(1,4-ndc)(H2O)2]·2H2O}n (1), {[Ni(ttpa)(1,3-bda)]·2H2O·DMF}n (2·2H2O·DMF), {[Ni(ttpa)(1,4-bdc)]·H2O}n (3) and {[Ni(ttpa)(aip)(H2O)]·3H2O}n (4·3H2O) were synthesized using hydrothermal and sonochemical methods (ttpa = tris(4-(1,2,4-triazol-1-yl)phenyl)amine, 1,4-ndc = 1,4-naphthalenedicarboxylate, 1,3-bda = 1,3-benzenediacetate, 1,4-bdc = 1,4-benzenedicarboxylate, aip = 5-aminoisophthalate), and characterized by elemental analysis, IR spectra, scanning electron microscopy, single-crystal and powder X-ray diffraction analysis, optical band gaps, VB XPS spectra and luminescence. The effects of sonication power, time and frequency on the size and morphology of nano-sized 1-4 have been studied. 1 exhibits an unusual 2D + 2D → 3D inclined polycatenated motif based on the (3,3)-coordinated 63-hcb topology. 2 shows a (3,4)-coordinated 2D network of the bey topology. 3 presents a rare example of the 4-fold interpenetrating array of (3,5)-coordinated 3D network belonging to the 35T1 topology type. 4 displays an unusual 2D → 3D polythreaded network based on 2D sql networks. 1-4 exhibit luminescent emissions at 409, 399, 413 and 402 nm, respectively. 1-4 are semiconducting in nature, with Eg of 2.12 eV (1), 2.34 eV (2), 2.32 eV (3), and 2.47 eV (4). 1-4 are good catalysts for the degradation of MB under visible light irradiation. The effects of the size and morphology of nano-sized 1-4 on the photocatalytic efficiencies were studied. The higher sonication frequency obtains uniform and smaller nano-sized coordination polymers which have higher catalytic efficiencies.

Synthesis, structure, spectral characteristic and photocatalytic degradation of organic dyes of a copper metal-organic framework based on tri(triazole) and pimelate.

A copper(II) metal-organic framework {[Cu(ttpa)(pim)]·H2O}n (1) was synthesized and characterized by EA, IR, X-ray powder diffraction, optical band gaps, VB XPS spectra and luminescence (ttpa = tris(4-(1,2,4-triazol-1-yl)phenyl)amine, pim = pimelate). 1 exhibits the 3D pcu topology containing the [Cu2(COO)4] dimer building block. Eg, Ev and Ec of 1 were 2.37, 1.64 and -0.73 eV, respectively. MOF 1 exhibits a highly photocatalytic efficiency for the degradation of methylene blue and rhodamine B by visible light irradiation. The photocatalyst 1 is very stable after photocatalytic experiment and can be reused for at least five times. The photocatalytic mechanism was detailedly assumed and confirmed by the photocatalytic reaction in the presence of the hydroxyl radical scavenger mannitol and trapping agent 1,4-benzenedicarbolic acid.

A bifunctional cationic metal-organic framework based on unprecedented nonanuclear copper(ii) cluster for high dichromate and chromate trapping and highly efficient photocatalytic degradation of organic dyes under visible light irradiation.

A bifunctional cationic metal-organic framework {[Cu9(OH)6Cl2(itp)6(1,4-bdc)3](NO3)2(OH)2·20H2O}n (1-NO3-OH·20H2O) was synthesized and characterized (itp = 1-imidazol-1-yl-3-(1,2,4-triazol-4-yl)propane, 1,4-bdc = 1,4-benzenedicarboxylate). In 1-NO3-OH·20H2O, three [Cu3(µ3-OH)(µ2-OH)] trimeric clusters are bridged by two µ3-Cl and form a [Cu9(µ3-OH)3(µ2-OH)3(µ3-Cl)2] cluster. Such a nonanuclear copper(ii) cluster [Cu9(µ3-OH)3(µ2-OH)3(µ3-Cl)2] has not been reported till now, at least to the best of our knowledge. 1-NO3-OH·20H2O showed a 6-connected 2D 36-hxl net based on a nonanuclear copper(ii) cluster [Cu9(µ3-OH)3(µ2-OH)3(µ3-Cl)2]. 1-NO3-OH·20H2O is also the first 2D 36-hxl net-based nonanuclear cluster. 1-NO3-OH (guest-free phase) showed fast and highly efficient Cr2O72- and CrO42- trapping, and good recyclability for capturing Cr2O72- and CrO42-. The adsorption capacities of 1-NO3-OH to capture Cr2O72- and CrO42- were 1.762 mol mol-1 (154.8 mg g-1) and 1.896 mol mol-1 (89.5 mg g-1), respectively, at a molar ratio of 1 : 2 (1-NO3-OH to 2.5 × 10-3 mol L-1 Cr2O72- or CrO42-). 1-NO3-OH exhibited the selective sorption of Cr2O72- or CrO42- from a solution containing a mixture of Cr2O72- or CrO42- and a ten-fold molar amount of ClO4-, NO3-, Cl-, BF4- or a five-fold molar amount of mol L-1 SO42-. 1-NO3-OH could capture 87.9% dilute Cr2O72- or 91.8% dilute CrO42- at an equimolar 1-NO3-OH to 20 ppm Cr2O72- or CrO42-. 1-NO3-OH·20H2O exhibited a highly efficient photocatalytic degradation of the cationic organic dyes methylene blue (MB) and rhodamine B (RhB) under visible light irradiation, and was shown to be a good photocatalyst for photocatalytic degradation of the cationic organic dyes.

A luminescent zinc(ii) coordination polymer with unusual (3,4,4)-coordinated self-catenated 3D network for selective detection of nitroaromatics and ferric and chromate ions: a versatile luminescent sensor.

A zinc(ii) coordination polymer {[Zn3(mtrb)3(btc)2]·3H2O}n (1) was synthesized and characterized (mtrb = 1,3-bis(1,2,4-triazole-4-ylmethyl)benzene, btc = 1,3,5-benzenetricarboxylate). The polymer 1 shows an unusual (3,4,4)-coordinated self-catenated 3D network with the point symbol of {63}2{62·82·102}{64·82}2. The polymer 1 is the first luminescent sensor for the detection of 2-amino-4-nitrophenol (ANP). The polymer 1 is also a good luminescence sensor for detection of TNP, 2,4-DNP, 4-NP, ANP and 2-NP in MeOH, particularly for TNP. The order of detection efficiency is TNP > 2,4-DNP > 4-NP > ANP > 2-NP. The polymer 1 also exhibits high sensitivity and selectivity as a luminescence sensor for the detection of Fe3+, Cr2O72- and CrO42- in aqueous solution. Our experiments showed that the presence of interfering ions had no significant effect on the sensing of Fe3+, Cr2O72- or CrO42- ions. The detection limits for TNP, ANP, Fe3+, Cr2O72- and CrO42- are 0.22 µM, 4.12 µM, 1.78 µM, 2.83 µM, and 4.52 µM, respectively. The luminescence sensor is stable and can be recycled for detection at least five times. The possible quenching mechanisms are discussed. The polymer 1 is also an effective photocatalyst for degradation of methylene blue (MB) under visible or UV light irradiation.