In the field of chemical biology, molecular recognition has served as a basic concept to understand the construction of biological assemblies and the biological functions. Among the model systems available to investigate 'lock and key' interactions, the interfacial molecular recognition at the air-water interface is an appropriate system because it mimics one of the two coupled monolayers that can be viewed in a biological membrane. Amphiphilic derivatives bearing hydrophobic (C10-C26) and hydrophilic moieties can form a two-dimensional layer called a Langmuir monolayer. The binding of a non-surface active substance dissolved in the aqueous subphase underneath the Langmuir monolayer can be realized through the molecular recognition process.