Synthesis Of Large Sterically Hindered Iron Porphyrins And Their Oxygen Binding

Blood substitutes are driven due to worldwide blood shortages and the problems of unsafe transfusion.Many artificial oxygen carriers were synthesized through the analysis of the structure and properties of natural oxygen carrier(hemoglobin).So far,the artificial blood substitutes appearing in clinical practice are perfluorocarbons(PFC)blood substitutes,hemoglobin based oxygen carriers(HBOCs)and heme and its polymer complexes.Hemoglobin(heme)has the function of oxygen carrying and oxygen releasing.Based on the structure of hemoglobin,The meso-2,6-dihydroxyphenylporphyrin was synthesized by the reaction of boron tribromide.And then acylation of the hydroxyl group on the benzene ring to obtain a bulk sterically hindered meso 2,6-dipivaloyloxyphenylporphyrin.The synthesized compounds were characterized by UV-Vis spectroscopy,nuclear magnetic resonance spectroscopy,infrared spectroscopy and mass spectroscopy.The synthesis of porphyrins that the yield is low with about 8%and the conditions is harsh.Based on the methods described in the literature,the L9(34)orthogonal test was used to investigate the effects of catalyst dosage,substrate dosage,solvent dosage and reaction time on the yield.Designed to improve yields,mild reaction conditions and better synthetic properties.In this paper,The both-faces-hindered complexes,porphyrinato-iron(II),was formed stable and reversible dioxygen adducts with different steric ligands(such as 1-methyl imidazole,1,2-dimethyl imidazole and other imidazole derivatives)or oxygen in toluene at 25 ?.The equilibrium constants(KB,KBB)and oxygen binding parameters P50 were calculated by UV-Vis spectra data.Compared to those of one-face-hindered porphyrinatoiron complexes,the equilibrium constant(KB,KBB)and oxygen binding constant KBO2 is reduced.This shows that the"double-barrier" structure porphyrin with large steric hindrance can effectively protect the binding of iron ions and oxygen molecules and is expected to become an ideal blood substitute.