N-(4-vinyl)benzylimidazole and its copolymer with octyl methacrylate(PBIOM)were synthesized and characterized

and oxygen—binding properties of cabaltporphyrin(CoP)complexes with imdazole ligands were studied．The weight—average molecular weight and imidazole content of PBIOM were determined to be 3．4×105 and 57 mol ％ by GPC and elemental analysis

respectively．PBIOM or benzylimidazole(BIm)and CoP in chloroform solution were mixed to complex the imidazolyl residue of the ligands with the fifth coordination site of CoP under nitrogen atmosphere to get CoP complexes．CoP complex displayed a reversible change in the UV-visible absorption spectrum from the deoxy form to the oxygen-binding one with an isosbestic point

in response to the partial oxygen pressure of the atmosphere．The oxygen-binding equilibrium curves of CoP complexes obeyed a Langmuir isotherm

to give the oxygen-binding affinity P50(oxygen partial pressure at which half of the CoP binds with oxygen)．At the same partial oxygen pressure

the oxygen—binding ratio of CoP-BIm complex was a little larger than that of CoP-PBIOM complex．The oxygen—binding affinity of CoP-PBIOM complex in the solid membrane state was larger than that in chloroform solution．The half lifetime of CoP-PBIOM membrane at 60 ℃ was 40．7 h．while that of CoP-BIm membrane(poly(octyl methacrylate) as matrix)was 8．8 h

indicating that polymer ligand significantly prolonged the lifetime of CoP complex．