AMPHIPHILIC CUP-SHAPED [(4-ALKYLPHENYL)AZO]-SUBSTITUTED CALIXARENES -SELF-ASSEMBLY AND HOST-GUEST CHEMISTRY AT THE AIR-WATER-INTERFACE

Chromophoric, amphiphilic [(4-alkylphenyl)azo]-substituted calixarenes 1-4 form stable monolayers at the air-water interface of a Langmuir t rough. Monolayer limiting areas and collapse pressures are controlled with changes in pH and electrolyte concentration of the subphase. At p H = 8.2 or higher, deprotonation of the hydroxyls of the calixarene pr oduces more polar headgroups, which result in larger mean molecular ar eas and increases in film collapse pressures. Similar effects result f rom increasing the concentration of electrolyte in the subphase. Effec ts of potential guests on monolayer assembly of [(4-alkylphenyl)-azo]- substituted calixarenes at the air-water interface were investigated. The limiting area of tetrakis-[(4-octylphenyl)azo]calix[4] arene decre ases in the presence of N,N,N-trimethylanilinium iodide while no chang e is detected for tetramethylammonium iodide or N,N,N-trimethyl-N-(2-n aphthyl)ammonium iodide. Interactions of the amphiphilic calixarenes a nd potential ammonium guests are discussed.