Helical Structure of Nucleation in a Solution of a Chiral Trifluoroacetylated Amino Alcohol

Abstract

The occurrence of a nanoscale disperse phase in the homochiral solutions of N-trifluoroacetylated α-amino alcohols (TFAAAs) was found experimentally by the observation of the Tyndall effect and dynamic light scattering (DLS) measurements. The nanoscale fraction was observed at concentrations lower than the critical concentration of gelation and string formation (c*). Direct optical microscopy showed that, as a rule, strings with a helical structure resulted from the homogeneous nucleations. Chirooptical measurements revealed some signs of helicity below the concentration threshold (c*). The molecular dynamics simulation of the condensation of a homochiral TFAAA in heptane showed that TFAAA molecular aggregates 2–3 nm in diameter were formed already after 100 ns. These aggregates have some signs of the homogeneous nucleations with a helical structure, and they can be considered as the nuclei of helical strings.