Metal (Co, Fe) tribenzotetraazachlorin-fullerene conjugates: Impact of direct __-bonding on the redox behaviour and oxygen reduction reaction

摘要

Novel hexabutylsulphonyltribenzotetraazachlorin-fullerene (C_(60)) complexes of iron (FeHBSTBTAC-C_(60)) and cobalt (CoHBSTBTAC-C_(60)) have been synthesized and their electrochemistry and oxygen reduction reaction (ORR) compared with their octabutylsulphonylphthalocyanine analogues (FeOBSPc and CoO- BSPc). It is proved that electron-withdrawing substituents (-SO_28u and C_(60)) on phthalocyanine macrocy_cle exhibit distinct impact on the solution electrochemistry of these metallophthalocyanine (MPc) complexes. The more electron-withdrawing C_(60) substituent suppressed ORR compared to the -SO_2Bu in alkaline medium. FeOBSPc showed the best ORR activity involving a direct 4-electron mechanism, a rate constant of__1x10~8 cm~3 mol~(-1) s~(-1) and a Tafel slope of-171 mV dec~(-1).