Synthesis, Characterization And Photocatalysis Of Visible-light-active Pillared-layer MOFs

Metal organic frameworks (MOFs), as a new type of multifunctional molecular based material, have been favored by many researchers. MOFs with unique features including regular pore structure, adjustive pore size, large specific surface area and functional organic ligands or metal center, have shown diverse applications in different fields such as gas-sorption, separation, luminescence, magnetic and catalytic. In recent years, the development of visible light responsive MOFs materials and the application of these optically active MOFs for artificial photosynthesis has become hot research topics.By application of the pillared-layer approach, we present here two new visible light photoactive MOFs materials - NNU-35(Zn/Cd), constructed from anthracene derived bipyridine ligand. The as-prepared MOFs are studied by single crystal X-ray diffraction, thermal, infrared, ultraviolet, steady-state fluorescence and electron paramagnetic resonance, etc. It is confirmed that the as-prepared MOFs materials are visible light active by forming organic free radicals from bipyridine pillars under visible light excitation.In our study, we have tried the new application of photoactive NNU-35(Zn) to induce the atom transfer radical polymerization (ATRP) reaction. Besides, we also investigate the photodegradation of dyes by the as-prepared NNU-35(Cd). The detailed studies are as follows:1. The regid planner anthracene-based bipyridine ligand of 9,10-bis(4'-pyridylethynyl)anthracene (L1) was first synthesized by cross-coupling reaction. Then the MOF compound, denoted as NNU-35(Zn), was synthesized using pillared-layer strategy with the recation of Zn(?), terephthalic acid and L1. The molecular NNU-35(Zn) crystallizes in the monoclinic space group C2/c with a formula of{Zn(bdc)(Li)}2·DMF. It is featured by the pillared-layer structure in which the layers are constructed from zinc ions bridged by the terephthalate ligand and these layers are pillared by the anthracene bipyridine. The promising photocatalytic reaction of atom transfer radical polymerization (ATRP) for methacrylates monomers was performed upon the utilization of NNU-35(Zn) as photosensitizer where in situ generation of activator Cu(?) complex by reducing deactivator of Cu(?) complex. It has been demonstrated that the reaction shows characteristics of controlled radical polymerization and the prepared polymers are of narrow molecular weight distributions and high retention of chain-end activities. Moreover, the photopolymerization can be easily manipulated by light switching.2. An isostructural material of Cd-MOF NNU-35(Cd) with a formula of {Cd(bdc)(L1)}2·DMA was prepared in the different reaction by the same pillared-layer strategy. We investigated the use of NNU-35(Cd) as photocatalyst for the degradation of organic dyes of methylene blue and rhodamine B under visible light irradiation. Accroding to the results, NNU-35(Cd) showed good photocatalytic activity. Besides it can be reused in the photocatalytic system.