| Metal-organic frameworks are new kind of materials with great prospect of practical application, and draw much attention on the interdisciplinary of energy, materials, environment and life science. In this paper, considering the functionality of the metal-organic materials, several novel compounds have been synthesized based on triazolates ligands and copper salts. These complexes were characterized by IR spectroscopy, elemental analyses, 1H NMR, thermogravimetric analyses, powder X-ray diffraction and X-ray single-crystal diffraction. Meanwhile, we further explored the characters of {[Ag8(3,5-Ph2-1,2,4-tz)6]?2NO3?6H2O}n(6-NO3) which is synthesized in our previous work. The two organic ligands and their abbreviations are as follows: 3,5-diphenly-1,2,4-triazole(L1) 3,5-diisoproply-1,2,4-triazole(L2) The five complexes and their abbreviations are as follows: {[Cu8(L1)6]?2HSO4?6H2O}n(1) {Cu4(L2)2(CN)2}n(2) {Cu4(L2)3I}n(3) {[Cu8(L2)6]?SO4?10H2O}n(4) {[Cu25(L1)18]?2SO4?3OH}n(5) {[Ag8(3,5-Ph2-1,2,4-tz)6(N3)2]?3H2O}n 6-N3 The structures of these six complexes are summerized as following:1. In complex 1-5, the deprotonated triazolato ligand all adopts μ3-N1,N2,N4 bridging mode. And these five complexes are all three dimensional structures.2. Complex 1 and 4, three-diamonal, porous structures, are constructed by [Cu5tz6]? connected by two-coordinate linear Cu-centers(tz? = 3,5-i Pr2-1,2,4-triazole, 3,5-Ph2-1,2,4-triazole).3. Complex 2 is a layered structure, and adjacent layers are pillared by Cu-Cu bonds to generate an interesting 3-D coordination polymer. The cyanide groups are all in situ generated from C-C cleavage reaction of acetonitrile. And then the cyanide group acts as bridge groups in 2.4. Complex 3 prepared by Cu I dissolved in acetonitrile and 3,5-i Pr2-1,2,4-triazole dissoved in water at room temperature, resulting a 3D network with pcu topology. The iodide ions adopt tetrahedrally coordination pattern, exhibiting a special umbrella-like μ4-mode geometries.5. Complex 5 consists of [Cu5tz6]?-cluster and six nuclear Cu6tz6-cluster, further linked by two-coordinate linear Cu-centers, resulting a 3-D, porous MOF. We further investigate these complexes, and draw several conclusions:1. The reactions of copper(II) salts with 3,5-diphenyl-1,2,4-triazole result in a three-dimensional, porous, cationic metal–organic frameworks {Cu8(3,5-Ph2-tz)6(HSO4)2(H2O)6}n(1). We further investigate its optical properties:(1) Complex 1 behaves as a semiconductor upon UV light excitation, showing exciton absorption at low temperature.(2) 1 serves as highly sensitive luminescent probes to methanol. By immersing in methanol solvent, 1 shows instant luminescent response, which can be easily identified by the naked eye under the illumination of the UV lamp.(3) 1 has been successfully applied to hydrogen peroxide detection. The fluorescence of 1 can be quenched quantitatively by adding H2O2, and the limit of detection is as low as 10-4mol/L.(4) The florescence quenching occurs by the oxidised copper(I) during heating, following the process of single-crystal to single-crystal transformation. And the florescence intensity recover to 50% of origin, resulting from the transformation between Cu(I) and Cu(II) is reversible.2. 6-NO3 is a three-dimensional, porous and cationic metal-organic framework. In this paper, we explore its anion exchange property and its application for Cr(VI) removal.(1) 6-NO3 exhibits anion exchange with some anions, such as N3?, Mn O4?, Cl O4? and so on. The result shows that the anion exchange pattern of 6-NO3 conforms to the Hofmeister order, which has been explained based on the hydrophobic structure of 6-NO3. 6-NO3 exhibited an interesting sing-crystal-to-single-crystal(SC-SC) transformation with structural variations when exchanged with azide ions(N3–), resulting from the coordination between Ag(I) and azide.(2) We were tempted to use 6-NO3 as an anion-exchanger to remove Cr(VI) species from water. The results shows that: it took 4 h to reach adsorption equilibrium and 5 h for releasing, which showed high efficiency in removal of Cr(VI), the adsorption capacity for Cr(VI) is as high as 37 mg/g at solution p H 6;6-NO3 can serve as a recyclable adsorbent; 6-NO3 showed great preference for Cr(VI) compared to other anions such as Cl?, SO42? and NO3?; according to the fitting results, the Langmuir model is more suitable to describe the anion-exchange equilibrium performed on 6-NO3 at constant temperature. |
PDF Full Text Request