Self‐Assembled Monolayers on Gold Surfaces of Ferrocene‐BODIPY‐Fullerene‐Helical Peptide Conjugates: Studies of Electron Transfer Processes by Ultra‐Fast Electrochemistry
Jad Rabah, Anne Vallée, Hélène Fensterbank, Minh‐Huong Ha‐Thi, Rachel Méallet, Souhir Boujday, Emmanuel Maisonhaute, Karen Wright, Emmanuel AllardABSTRACT
Three complex ferrocene‐BODIPY‐fullerene‐peptide conjugates were synthesized by successive CuAAC reactions between firstly ferrocene‐BODIPY azides, then a lipoyl peptide azide, with a dual‐clickable fullerene platform. These conjugates displayed broad absorption in the visible region due to their extended π‐conjugation and the presence of an intramolecular charge transfer band from ferrocene to BODIPY, particularly in the case of BODIPY derivatives functionalized at the beta and alpha positions with ethynylFc and vinylFc groups, respectively. The terminal lipoyl peptide allowed grafting of the conjugates on gold surfaces, to form self‐assembled monolayers that were characterized by PM‐IRRAS and ultrafast electrochemical techniques. Estimation of the heterogeneous electron transfer rate constants for these monolayers revealed higher values for electron transfer from the BDP or C 60 entities to the metal surface compared with conjugates without ferrocene units. This could be attributed to a reduced distance between the (Fc) 2 ‐BODIPY‐C 60 part and the metal surface, due to folding of the conjugates within the monolayer.