Premium
Influence of structure on the kinetics of assembly of cyclic dipeptides into supramolecular tapes
Author(s) -
Luo TzyJiun M.,
Palmore G. Tayhas R.
Publication year - 2000
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/1099-1395(200012)13:12<870::aid-poc324>3.0.co;2-o
Subject(s) - chemistry , supramolecular chemistry , dipeptide , kinetics , molecule , diffusion , crystallography , hydrogen bond , context (archaeology) , crystal structure , stereochemistry , amino acid , organic chemistry , thermodynamics , paleontology , physics , quantum mechanics , biology , biochemistry
Cyclic dipeptides with a variety of substituents assemble into supramolecular tapes, which can function as scaffolds to position co‐crystallized guest molecules. To examine how molecular structure influences the kinetics of crystal growth, we compared the rate at which two cyclic dipeptides assembled into supramolecular tapes using atomic force microscopy as an in situ probe of the kinetics of step advancement in these crystalline solids. Changes in the molecular structure of the substituents from two hydrogen atoms on the cyclic dipeptide of glycine (GLYDKP) to two methyl groups on the cyclic dipeptide of alanine ( R , R ‐ALADKP) reduces the rate at which R , R ‐ALADKP assembles into supramolecular tapes by a factor between four and five relative to that of GLYDKP. These results are discussed in the context of barriers to desolvation, surface diffusion, ledge diffusion and incorporation into kink sites and the energies of adsorption at these different sites on a crystal. We show that the difference in the rate at which these two molecules assemble into tapes corresponds to the difference in the barriers for attachment to a kink site at the temperature and concentrations used. The degree to which these solutes must change conformationally is proposed to be the source of the observed difference in the barriers for incorporation into a kink site. Copyright © 2000 John Wiley & Sons, Ltd.