CHIRALITY AND MOLECULAR RECOGNITION IN MONOLAYERS AT THE AIR-WATER-INTERFACE

This chapter focuses on the stereochemistry of intra- and inter-molecular interactions in a special kind of highly oriented system-monolayers. The chapter presents the study of chiral monolayers, a classic example of how the purposeful interaction of two fields that were separated by their traditional identifications with organic and physical chemistry can help to illuminate both areas. The chapter investigates the effects of chirality on the properties of monolayer films spread at the air–water interface. Twenty compounds of varied head-group and chain length have been examined carrying one and two chiral centers. In every case, all of the optical isomers-enantiomers and diastereomers-were made and their properties measured both as pure compounds and as mixed monolayers, in order to compare phase changes in the films with mixed melting points of the crystals. The most important series of compounds used for examining the effects of stereo-chemical variation in the head-group is the long-chain (mostly stearoyl) amino acid methyl esters. These were chosen because of the commercial availability of both enantiomers, their relevance to biochemistry, and the compounds produce good monolayer films. For a number of systems, comparisons were made between the effects of enantiomeric composition in the monolayer and corresponding melting-point-composition curves for the crystals. All of the latter gave clear evidence of racemic compound formation in the crystals and this type of pattern was repeated in the monolayer properties. © 1993, Academic Press Limited.