Studies On The SchiffBase Complex Immobilized Onto Chtiosan

AbstfactTo mimic the metal enzyme active by using model compound received much attelltion inthe last years because of their relevance to the understanding of enZymic catalysis and theirimportance in industrial aPplications. Howevef, it is a universal law that the active of thelow-molecule-weight complexes is lower than that of enzyme. Obviously the different activebetween them is made by Macromolecule. So, pay more aneniion to investigate the role ofmacromolecule in playing active is very important. In fact, the interactions betwCen active siteand Macromolecule play a very role in enzyme. The interactions include hydrophobic effect,site and isolation neighboring group participation effect at al.Cobalt(lI ) Schiff base complexes carrying molecular.O2 has been the object of extensiveinvestigations. In the solid state, their ability to chemically absorb dioxygen had encounteredproblems because of gradual damage to its crystalline upon cycling dioxygen-separationprocesses result in loss of caPacity. The experiments indicated that there is a transfer ofelectron for a series of cobalt (II) Schiff base compounds from cobalt center to thecoordinated dioxygen fragment. So, tI1ese complexes have been used as models to mimicoxidases that activate dioxygen in the oxidation of oxygen substrates. TO prevent theformation of p-oxo-dimers, which are inactive fOr the activation of molecular oxygen, hasbecome an important field. Based on the set insolution of polymef, the Co (II) complexes ofSchiff bases immobilized onto chitosan employing convalent bond or coordinate bond toovercome the defect of Schiff base con1plexes have been studied in this thesis.According to the purpose as stated above, the investigations include the following severalaspects;l Prepared and characterized the Schiff base complexes, chitosan and its derivates.Immobilized the Schiff base col11plexes oflto chitosan and its derivates thIough thecoordination bond or conva1ent b()nd. Instrumentally characterizatied the immobilizedcomplexes employing IR, UV-vis. /\nalysis element, XPS, Fluorescence spectroscopy andESR.All the characterized infOrmation demonstrated clearly that the inunobilization of Co (II)Schiff base complexes to chitosan or its derivates may be realized through the interactionbetween the cobaIt of the Schiff base complexes and nitrogen atom of some monomeric tmit' in chitosan or its derevates chain. Tl1c immobilized compIexes can reversibly absorb thedioxygen easily to form the super-dioxygen carrier in solid state. It is the site isolation effectpresenting in the immobilized complexcs to inhibit the formation of p-oxo-dimers and dimers.2 The oxidation of DOPA was used as a model system to test the catalytic activity of theimmobilized complexes, and compi1red with that of smaIl complexes. Based on the resultsmentioned above, the mechanisms of cataloytic reactions have been suggested. Theoxidation of mercaPtoethanol was used as a model system to test the catalytic activity ofthe irnmobilized complexes, and compared with that of the small complexes. Themechanisms of cataloytic reactions have been suggested.Assembling together all the results of the catalytic activity it can be conclude that theimmobilized complexes are more efficient than the corresponding monomeric comPlexes incatalysing the oxidation of DOPA and mercaptoethanol. The proposed reaction mechAnsmindicated that the reason for the difference of catalytic activity betWeen the immobilizedcomPlexes and the monomeric Schiff base complexes may be the immobilized complexes toform the higher catalysing activity of superoxo complexes (l: l (Co:O2)). It is efficient methOdto improve the catalytic activity and carrying oxygen ability of the Schiff base comPlexes thatimmobilized the Schiff base complexes onto the polymer prevents the formation ofp-oxo-dimers and other dimers. It is this reason that the immobilized complexes may possessa higher catalytic ac...