Reverse Micellar Encapsulation of D- and L-Enantiomers of Some Aromatic alpha-Amino Acids and Nucleobases by Glucose-Derived Non-ionic Gemini Surfactants in Neat n-Hexane

摘要

Novel carbohydrate-based non-ionic gemini surfactants consisting of two sugar head groups, two hydrophobic tails having chain lengths of C12, C14, and C16 and a flexible -(CH2)(6)- spacer were synthesized and investigated for their reverse micellar encapsulation properties. The head groups of the geminis comprise glucose entities (with reducing function blocked in a cyclic acetal group) connected through C-6 to tertiary amines. These surfactants were explored for reverse micellar encapsulation of d- and l-enantiomers of aromatic alpha-amino acids viz. histidine (His), phenylalanine (Phe), tyrosine (Tyr) and tryptophan (Trp) in neat n-hexane. Similar studies were carried out for encapsulation of nucleobases viz. adenine (Ade), guanine (Gua), thymine (Thy), cytosine (Cyt) and Uracil (Ura). Reverse micellar studies revealed that aromatic alpha-amino acids were encapsulated in the sequence His > Tyr > Phe > Trp. In most cases, a difference in the degree of encapsulation of d- and l-enantiomers of aromatic amino acids in reverse micellar phases of gemini amphiphiles in neat n-hexane, was revealed. For Tyr, l-enantiomer was better encapsulated than its antipode, i.e., d-enantiomer but for Trp, d-enantiomer was better encapsulated then l-enantiomer. In the case of nucleobases, Ura was found selectively encapsulated by reverse micelles formed by these new amphiphiles.