Due to the concern on residue toxic metal in biodegradable polycarbonate

environmental friendly aluminum complexes

i.e

bifunctional aluminum porphyrin complexes were prepared by anchoring quaternary ammonium salts to the porphyrin ligand framework.The structures of all the complexes were confirmed by 1H-NMR

13C-NMR and MALDI-TOF analysis.These catalysts exhibited enhanced activity and selectivity for the copolymerization of CO2 and propylene oxide (PO) compared with the aluminum porphyrin/quaternary ammonium salt binary catalyst system.Using complex 1b as catalyst

the influence of reaction conditions such as CO2 pressure

reaction temperature and [PO]/[cat.] ratio etc

on copolymerization behavior was investigated.The TOF (turnover frequency of epoxide to products) of catalyst 1b can reach 1152 h-1 in 5 h at 90℃ under 3.0 MPa

while the resultant copolymer showed a carbonate linkage of 98% and number average molecular weight (Mn) of 42 103

though the PPC selectivity was 68%.When the copolymerization of CO2 and cyclohexene oxide (CHO) was conducted by using catalyst 1b at the same reaction condition

a TOF as high as 621 h-1 was reached

the carbonate linkage of the obtained copolymer was 81% and the number average molecular weight was 8.0 103

while the polymer selectivity was 100%.Additionally

our work also indicates that variation of the quaternary ammonium anion and the axial ligand had dramatic effects on the catalytic activity of resultant complex.