Study On Molecularly Imprinted Polymeric Microspheres With Dimethyl Methylphosphonate As Template Molecule

The molecular imprinting polymer, which is called as “molecular key” to open themanual lock is according to the artificial simulation of antibody/receptor. Thetechnology is a novel method for synthesis of molecular materials with molecularrecognition capability. Molecular imprinting polymer has many applications in theanalysis of organophosphorus pesticides, such as the solid phase extraction or in thechromatographic stationary phases. The core of the molecular imprinting polymer is toselect the specific functional monomer which can bind to the template molecule.Byusing precursors bearing functional groups required or modifying a porphyrins toconstruct a three-dimensional binding site on a porphyrins plane,in which a guestmolecule is bound via coordination by a porphyrins metal center or hydrogen bondingby modifiers linked with the porphyrin,which has a very important significance for themolecular imprinting polymerFirstly, the single hydroxyl porphyrins MHTPP was synthesized by the Alderapproach, then the final functional monomer alkenyl porphyrins ZnMOTPP, GdMOTPPand MOTPP were synthesized In the process of synthesis, the conditions wereoptimizated, at the same time, the structures of intermediates and final porphyrins werecharacterized.Secondly, the coordination between the three porphyrins and DMMP was studiedby UV-visible and fluorescence spectroscopy, the result showed that the coordinationinteraction only exist between the metal porphyrins and DMMP, which wouled led tothe change of UV and fluorescence spectra. The ruslts laid a preliminary theorecticalfoundation for the synthesis of molecular imprinted microspheres.Finally, MIPs based on porphyrins were prepared when DMMP was as the templewhile MAA as monomer, including MIPMs-Zn+MAA, MIPMs-Gd+MAA andMIP-MAA. MIPs were characterized by scanning electron microscopy (SEM). TheSEM datas showed that the diameters were between50-100μm.The surfaces of MIPswere rough and contained massive imprinted cavities compared with NMIPMs. TheMIPs containing metal porphyrins were rough. The adsorption capacity ofMIPMs-Zn+MAA, MIPMs-Gd+MAA were much greater than MIPMs-MAA, while theadosorption capacity of MIPMs-nonmetal+MAA was almost same with MIPMs-MAA.This could be due to coordination between the metal porphyrins and DMMP. At different concentrations of DMMP, the MIPMs absorbed more substrates than NMIPMs.By Scatchard analysis, the data of equilibrium adsorption experiment displayed that theMIPMs-DMMP only had one affinity binding site. The dissociation constants ofMIPMs-Zn+MAA, MIPMs-Gd+MAA, MIPMs-MAAA were0.167mmol/L,0.179mmol/L and0.338mmol/L and the maximum absorption quantities were148μmol/g,78.9μmol/g and13.57μmol/g respectively. MIPMs also showed better selectivity forDMMP through the isotherm binding test of two different substrates which werediomethoate and phorate.