The role of crystal polarity in alpha-amino acid crystals for induced nucleation of ice.
The hydrophobic faces of single crystals of a series of pairs of racemic and chiral-resolved hydrophobic alpha-amino acids were used as a substrate, onto which water vapor has been cooled to freezing. The morphologies and molecular packing arrangements within each crystal pair are similar but only one of each pair exhibits a polar axis, parallel to the hydrophobic face exposed to water. Those crystals that have a polar axis induce a freezing point higher by 4 degrees to 5 degrees C than the corresponding crystals that do not have a polar axis. The results are interpreted in terms of an electric field mechanism that helps align the water molecules into ice-like clusters en route to crystallization.
Gavish
M
M
Department of Materials and Inferfaces, Weizmann Institute of Science, Rehovot, Israel.
Wang
J L
JL
Eisenstein
M
M
Lahav
M
M
Leiserowitz
L
L
D000596:Amino Acids / Q000737:chemistry*; D000818:Animals; D003460:Crystallization; D007053:Ice; D007536:Isomerism; D008958:Models, Molecular
D000596:Amino Acids; D007053:Ice