Infrared reflection-absorption study of ordering and hydrogen bonding within chiral and nonchiral self-assembled monolayers on gold

Ordering processes in chiral and racemic monolayers of three phenylalanyl-s ubstituted omega-thiol alkanoic acids on gold have been investigated with t he use of infrared reflection absorption spectroscopy. For chiral molecules , packing is influenced by both hydrogen-bonding interactions between the e nd groups at the air/monolayer interface and the length of the spacer chain within the monolayer. Results for a mixed monolayer of octadecylmercaptane and phenylalanyl-substituted omega-thiol docosanoic acid indicate that for mation of large islands of either one of the compounds can be excluded. For a racemic monolayer of phenylalanyl-substituted omega-thiol undecanoic aci d, a dense, yet unregular, packing is observed.