| Metal-organic frameworks(MOFs),which are also known as porous coordination polymers or porous coordination networks,represent a class of porous materials assembled through the coordination between metal nodes(metal ions or clusters)and organic ligands.In recent years,MOFs have been widely concerned by chemists due to their super high porosity and specific surface area as well as the tunability of pore channels.The modified MOFs can be used as electrocatalysts instead of precious metals,which shows positive significance to solve the problem of energy shortage.So far,although many new MOFs with interesting structures have been synthesized,the design and synthesis of functional MOFs remains a challenge.Compared with MOFs constructed by single ligand,the mixed ligand strategy not only achieves structural diversity,but also can introduce multiple functional groups,which expand the application field of the MOFs materials.Chosing 4,4'-biphenylate(H2PBDC)as the main ligand and nitrogen heterocyclic with different configurations as the auxiliary ligand,compounds 1-3 have been synthesized by adjusting the central metal ions and optimized reaction conditions.In order to study the structural diversity of MOFs,we used 4-pyridine benzoic acid ligand(pyben H)instead of H2PBDC ligand to construct compound 4 together with acetate liagnd.According to the structural characteristics,we explored the potential applications of these compounds in the field of fluorescence detection and electrocatalysis.The main contents of this paper are as follows:(1)Based on the mixed ligand strategy,compound[Co(PBDC)(2,2'-bpy)]·DMF·H2O(1)has been successfully synthesized by using 4,4'-biphenyl acid(H2PBDC)as main ligand and2,2'-bipyridine(2,2'-bpy)as auxiliary ligand,which exhibits a zigzag-like chain structure.When the bidentate nitrogen heterocyclic ligand 2,2'-bpy was replaced by multidentate nitrogen heterocyclic ligand 6-(pyridine-4-yl)-1,3,5-triazine-2,4-diamine(PTD),by optimizing the reaction conditions,we have successfully synthesized[Co3(PBDC)3/2(PTD)1/2(DMF)]·2DMF·H2O(2)and[Zn(PBDC)2(PTD)2]·DMF·2H2O(3)with 3D interpenetrating framework.Significantly,compound 3 shows excellent luminescence property,which could selectively detect Fe3+and Cr2O72-.Compound 3 shows high sensitivity and low detection limit for Fe3+and Cr2O72-(2.0621×10-6 M for Fe3+and 4.3095×10-6 M for Cr2O72-),which can be reused to detect Fe3+and Cr2O72-for four times by simple regeneration.(2)In order to further expand the structure and application of MOFs,chosing pyben H as the main ligand and acetate as the auxiliary ligand,compound [Co2(pyben)2(CH3COO)2]·DMF(4)was synthesized by Co(NO3)2 under solvothermal conditions.In compound 4,the secondary building units of the paddle-wheel binuclear Co2+are connected by pyben-ligand to form a 2D layered structure.Using the mixed metal salt(Fe/Ni or Co/Fe)instead of Co(NO3)2,the mixed metal nanocrystals were obtained.After annealing treatment,a series of mixed metal carbon-based electrocatalysts with stratified structure were successfully prepared.The Ni Fe(3:1)@CN showed excellent electrocatalytic activity for oxygen evolution reaction(overpotential:290 m V)in alkaline solution,which was better than the commercial RuO2. |
PDF Full Text Request