Synthesis, Structure And Photopolymerization Study Of Visible-light-responsive Metal-organic Frameworks

In recent decades, the study of metal organic frameworks ?MOFs? has became current research focus due to its potential applications in gas adsorption and separation, sensors, catalysis, drug delivery and so on, relying on their unique features of rich structure, multiple functionallites and large surface area etc. To design and synthesize of MOFs with target property and explore their new applications in novel fields are always among the center of MOFs study. Taking advantage of coordination interaction, the realization of target property of MOFs by incorporating functionalized organic ligand is a feasible approach according to the principle of crystal engineering.We present here two new visible light photoactive MOFs materials, compound 1 and 2, constructed from anthracene based tetracarboxylate ligand which serves also as the visible light harvesting group in the resultant MOFs materials. The as-prepared MOFs were investigated by single crystal X-ray diffraction, thermogravimetry, infrared, ultraviolet, steady-state fluorescence, and electron paramagnetic resonance and surface photovoltage studies. We also tried the new application of photoactive MOFs to induce the atom transfer radical polymerization ?ATRP? reaction. The detailed studies are as follows:First, a new 3D microporous indium MOF compound 1, ?MeNH₂?[InL]·3?H₂O?·0.5DMF, was synthesized using a rigid tetracarboxylate ligand ?H₄L?, where the anthracene group was incorporated into the structure promote the visible light harvesting. Study revealed that 1 has broad-band visible light absorption which could be extend to about 700 nm. The in-situ EPR studies suggest the photoinduced charge generation by forming ligand-based radical. And the SPV spectrum indicates that compound 1 is potential photocatalyst. Further we explored the visible-light induced atom transfer radical polymerization by using MOF 1 as photo sensitizer. Results showed that the as-prepared polymers possess narrow molecular weight distributions and high retention of chain-end groups. Moreover this MOF mediated photopolymerization can be easily controlled by light. This work extends the research and opens a new insight to the field of controlled radical polymerization.Second, we prepare novel cadmium MOF 2, ?CdL?₂·3H₂O·2DMF, using the same ligand. Interestingly, compound 2 possess unique 1-D zigzag chain-like structure. Studies reveal that the as-prepared Cd-MOF is a potential MOFs photocatalyst.