Synthesis and characteristics of poly(fluoropentyl methacrylate-co-vinylimidazole) (FIm)

and oxygen-binding properties of its complex with meso-α

α

α

α-tetrakis(o-pivalamidophenyl)porphyrinato cobalt(Ⅱ) (CoP) were studied．FIm was prepared by radical copolymerization of octafluoropentyl methacrylate with 1-vinylimdazole using azobis(isobutyronitrile) as the initiator．The vinylimidazole content and molecular weight of the FIm copolymer were determined to be 25 mol％ and 5.0×104 by elemental analysis and GPC

respectively．FIm and CoP in solution were mixed to complex the imidazulyl residue of the copolymer with the fifth coordination site of CoP under nitrogen atmosphere to yield both art active and homogenous dispersed CoP for oxygen-binding．Oxygen-binding to the CoP-FIm complex was measured spectroscopically with a UV spectrophotometer．The CoP-FIm complex displayed areversible change in the visible absorption spectrum from the deoxy form to the oxy or oxygen-binding one with an isosbestic point

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

to give the oxygen-binding affinity P50 (oxygen partial pressure at which half of the CoP binds with oxygen)．Solvent has great effect on the oxygen-binding properties of the complex．The oxygen-binding affinity of the CoP-FIm complex in tetrabydrofuran was larger than that in N

N-dimethyl formamide solution．It is assumed that a N

N-dimethyl formamide molecule weakly coordinated to the sixth site (oxygen-binding site) of CoP to reduce the oxygen-binding affinity．On the other hand

the oxygen-binding site of the CoP complex could be maintained vacant in tetrabydrofuran before the oxygen-binding．The binding and dissociation rate constants of oxygen to and from the CoP (kon and koff

respectively) for the CoP-Flm solution were large

which indicates a very rapid and reversible oxygen-binding by CoP．