Self-assembled Langmuir monolayers and trilayers at the air-formamide interface

The spontaneous formation of highly crystalline two-dimensional films of uncompressed long chain amide and carboxylic acid amphiphiles spread on formamide has been demonstrated by grazing incidence X-ray diffraction. These results were compared to those found for the same amphiphiles on water. The observed diffraction data of C 29 H 59 CONH 2 over both water and formamide and those of C 29 H 59 CO 2 H over formamide are strikingly similar, while those of C 29 H 59 CO 2 H over water are different. Arachidamide (CH 19 H 39 CONH 2 ) over water subphase forms a unimolecular layer with the molecules tilted by 18 o