SYNTHESES AND INTERFACIAL HYDROGEN-BONDED NETWORK OF HEXAALKYL TRIS(MELAMINE) AMPHIPHILES

At the air-water interface N,N'-dialkylmelamine amphiphiles bind barbi turic acid (BA) in the aqueous phase and produce a linearly extended s upramolecular network (sometimes referred as supramolecular strand, ri bbon, or tape) linked through complementary hydrogen bonds. An amphiph ile with more than two hydrogen-bonding sites may produce cross-linked hydrogen-bonded networks on water with the aid of an appropriate aque ous binding counterpart. Thus, we synthesized new amphiphilic molecule s, Delta(m,n), that bear three melamine (2,4,6-triamino-1,3,5-triazine ) rings and six alkyl chains. The lengths of the inside three alkyl ch ains (CmH2m+1) and the outside three alkyl chains (CnH2n+1) were varie d. The influence of alkyl chain length on the monolayer properties and the binding behavior to aqueous BA was examined for Delta(12,10), Del ta(12,12), Delta(12,14), Delta(12,18), and Delta(18,12). From FT-IR an d X-ray photoelectron spectroscopic measurements of Delta(m,n) LB film s, BA was found to bind to one melamine moiety each of Delta(m,n) in a 1:1 ratio through complementary hydrogen bonds. Plausible network mod els were proposed on the basis of binding stoichiometry and conformati onal consideration of the tris(melamine) amphiphile.