Synthesis And Characterization Of Polymers, Functionalized With The Mimics Of Diiron Sub-unit Of [FeFe]-Hydrogenase

In this thesis, a series of models of the diiron active site of [FeFe]-hydrogenase was covalently bound at branched polymeric material PEI (polyethyleneimine) and formed polymers PEI-P-Fe2-A,-B,-C,-D,-E respectively. In order to discuss how PEI as secondary coordination sphere effects on polymers’characterizations and catalysis of proton reduction, these polymers were fully characterized by TGA, SEM, FTIR, NMR and cyclic voltammetry. Complex2, a substituted compound of complex1upon PPh3, was considered as a reference. Compared to those models of the diiron active site of [FeFe]-hydrogenase, polymers showed better thermostability and catalytic ability, which shifted to positive direction by ca.220mV compared with complex2. All the experimental observations suggested that the base group (amino) of secondary coordination sphere meliorated both the morphology and property of polymers PEI-P-Fe2.At the same time, to further discuss whether the space structure affects catalytic ability of polymers, we designed polymers PEI-P-Fe2-B’, PEI-P-Fe2-B’-2, PEI-P-Fe2-B-2, PEI-(CH2)11-O-P-Fe2-B, HOOCCH2-PEI-P-Fe2with different molecular weight or functional groups. Results showed that changing molecular weight of PEI didn’t play an important role in catalytic protons reduction process, while polymer PEI-(CH2)11-O-P-Fe2-B performed best catalytic ability in this system. This showed that different functional groups introduced to polymers did actually improve the catalysis of proton reduction via changing space structure.