甲醛分子印迹聚合物的理论设计

Theoretical design of formaldehyde molecularly imprinted polymers

采用量子化学密度泛函理论中的B3LYP/6-31G(d,p)方法,以甲醛(HCHO)为印迹分子,衣康酸(IA)为功能单体,分别以乙二醇二甲基丙烯酸酯(EDMA)、季戊四醇三丙烯酸酯(PETA)和三甲醇基丙烷三甲基丙稀酸酯(TRIM)为交联剂,以水(H_(2)O)、乙腈(ACN)、甲醇(MT)、四氢呋喃(THF)、氯仿(CAS)和甲苯(TL)作为溶剂,计算并讨论了不同物质的量比例HCHO-IA稳定复合物成键作用位点、成键数目与结合能,优化了印迹物质的量比例、交联剂及溶剂,并基于价键理论的化学键电子密度拓扑分析方法对HCHO-IA稳定复合物的电子密度拓扑性质进行了分析研究.理论研究结果表明,HCHO印迹分子中的O原子与2个H原子均通过氢键与IA单体相互作用,在印迹物质的量比例为1∶3,且以TL为溶剂时形成的HCHO-IA有序复合物氢键数目最多,结合最强,HCHO-IA复合物构型最稳定;与EDMA、PETA交联剂相比,TRIM与IA结合最强,更适宜作为HCHO分子印迹聚合物(MIPs)的交联剂.本研究为HCHO-MIPs合成时印迹物质的量比例、交联剂及溶剂的选择提供了理论指导.

In order to design formaldehyde(HCHO)molecularly imprinted polymers(MIPs),the HCHO was chosen as the template molecule,itaconic acid(IA)was used as the functional monomer.The ethylene glycol dimethacrylate(EDMA),pentaerythritol triacrylate(PETA),and trimethylolpropane trimethylacrylate(TRIM)had been used as the cross-linking agents,respectively.And the water(H_(2)O),acetonitrile(ACN),methanol(MT),tetrahydrofuran(THF),chloroform(CAS),and toluene(TL)were used as the solvents.To discuss and simulate the binding sites,the amount of hydrogen bonds,the binding energy of HCHO-IA stable complexes with different molar ratios,and the optimal molar ratio of imprinting were investigated using the B3 LYP/6-31 G(d,p)density functional theory(DFT)method.The molar ratio of imprinting of the MIPs system was optimized.At the same time,the optimal cross-linking agent was determined by calculating the binding energy between cross-linking agent and the HCHO imprinted molecule,the cross-linking agent and the IA functional monomer.The optimal solvent was determined by comparing the length of hydrogen bond and solvation energy of HCHO-IA stable complex in different solvents.The topological properties of electron density of HCHO-IA stabilized complex were analyzed and studied based on the topological analysis method of electron density of chemical bonds in valence bond theory,and the nature of bonding was further discussed.The theoretical research shows that the O atom and two H atoms in the HCHO imprinted molecule interact with the IA monomer through the hydrogen bonds,when the molar ratio of imprinted molecule was 1∶3,the HCHO-IA complex has the largest number of hydrogen bonds,and the binding energy was the lowest,the stability was the strongest.When TL was used as the solvent,the interaction between HCHO and IA was the strongest.Thus,it was concluded that TL was the best solvent that could be expected to synthesize HCHO-MIPs.In comparison with the EDMA and PETA cross-linking agents,TRIM has the weakest binding with IA and the strongest binding with HCHO,therefore,it is more suitable as the cross-linking agent of HCHO molecularly imprinted polymers.According to the molecular graphs and contours of Laplacian of electronic density of HCHO-IA stable complex,we can judge the interaction between HCHO and IA through hydrogen bond.In this simulation study,DFT was used to simulate the design of HCHO-MIPs,which not only shortened the experimental time and improved the efficiency of research and development,but also provided theoretical guidance for the selection of molecularly imprinted molar ratio,cross-linking agent,and solvent during the synthesis of HCHO-MIPs.It also could provide methods and theoretical basis for the research on the nature of molecular imprinting.