Syntheses,Structure And Properties Of Function Mental-organic Frameworks Based On Dicarxylates Ligands

Metal�organic frameworks?MOFs?are a flourishing class of hybrid porous materials,which are constructed from metal ions/metal clusters and organic linkers by self-assembly coordination interactions.In recent decades,the design and synthesis of MOFs has attracted ever-increasing interest,due to their unique properties?such as high surface area,controlled porosity and adjustable skeleton structures?and potential specific applications in many fields?fluorescence,catalysis,sensing,gas adsorption and so on?.In this article,using pre-synthesis modification strategy,1-nitrodibenzothiophene dicarboxylic acid?H₂NSBPDC?with functional groups has been synthesized and used as the bridging ligands.Two kinds of coordination polymers?Zn-1 and Zn-3?have been obtained and characterized by reaction H₂NSBPDC with transition metal ions.In addition,using series of ligands modified with functional groups?NO₂,NH₂,OH,OMe?,four compounds UiO-67-R with functional groups have been obtained and characterized.The main contents of the paper are presented as following:1.Two anionic Zn?II?complexes?Zn-1 and Zn-3?with three-dimensional porous structures were synthesized and characterized:Zn-1 contains 4-connected tetrahedral [Zn₄?m₄-O??CO₂?₈]clusters,which are further linked by the bridging ligands,generating a three-fold interpenetrated diamond-like network with ultra-microporous channels.Gas adsorption studies reveal that Zn-1 has good adsorption selectivity for CO₂ over CH₄ and N₂.In addition,Zn-1 can serve as a host to incorporate lanthanide cations via a targeted ion-exchanged process.Zn-3 was constructed from 5-connected hexanuclear [Zn₆?m₃-OH??m₄-O??H₂O?₂?COO^-?₁₀]clusters and a predesigned bridging ligand.Zn-3 possesses non-interpenetrating network with large 3D intersecting channels modified with functional groups.UV-vis spectra studies indicated that Zn-3 exhibits selective adsorption and separation of positively charged dyes including Rhodamine B?RhB⁺?,Methylene Blue?MB⁺?and Crystal Violet?CV⁺?dyes molecular respectively.2.A series of UiO-67 compounds modified with functional groups were synthesized and characterized.Based on the high framework stability and high surface area of UiO-67,four predesigned bridging ligands with functional groups?-NO₂?-NH₂?-OCH₃?-OH?were used to react with ZrCl₄ to obtain four functional UiO-67 compounds.The influence of the synthesis conditions on the morphology and structure of the obtained compounds were studied.Additionally,the adsorption properties of N₂ and CO₂ on the compounds were characterized.3.Selective dye adsorption properties of UiO-67-NO₂ and UiO-67-NH₂ in aqueous solution were studied.Remarkably,dye adsorption behavior of UiO-67-R in aqueous phase is based on surface adsorption,due to the framework instability of UiO-67-R in water.At pH=3,UiO-67-NH₂ can absorb anionic dye molecules quickly and effectively,while the adsorption of neutral dye molecules and cationic dye molecules is relatively slow.The experiment of adsorption capacity suggested that the capacity of adsorption increased gradually and then reached saturation along with the increasing of the concentration of dye.In addition,the capacity of adsorption is also affected by the defects in the skeleton of the complex.