Formation of Perfluoroalkyl Fullerene Alkylphosphonic Acid Self-Assembled Monolayers on Aluminum Oxide

The possibility of fabricating self-assembled monolayers (SAMs) from alkylphosphonic acids functionalized with trifluoromethyl derivatives of C-60 on a metal oxide surface has been demonstrated in this work. Using several trifluoromethylfullerenes (TMFs) of different compositions and isomeric structures, we explored their relative reactivities in the Bingel-Hirsch cycloaddition reactions with 11-(diethoxyphosphoryl)undecyl methyl malonate for the first time. Only two isomers of C-60(CF3)(10) showed fairly selective monoadduct formation, whereas compounds with lower CF3 content showed no selectivity. Converting the phosphoric ester into a phosphoric acid moiety enabled the successful formation of self-assembled monolayers of the TMF-alkylphosphonic acid on aluminum oxide surfaces. Comparison with analogous SAMs made with underivatized C-60 showed that TMFs form more hydrophobic surfaces. (C) The Author(s) 2017. Published by ECS.