n124882SE Academic Article uri icon

abstract

  • The solid-state shape, size, and intermolecular packing of a fifth-generation dendritic macromolecule were determined by a combination of site-specific stable-isotope-labeling, rotational-echo double-resonance (REDOR) NMR and distance-constrained molecular dynamics simulations. REDOR experiments measured dipolar couplings between 13C atoms located near the chain ends and an 19F label placed at the core of benzyl ether dendrimers (generations 1-5) based on 3,5-dihydroxybenzyl alcohol as the monomeric repeat unit. Intramolecular 13C-19F coupling was distinguished from intermolecular coupling by dilution with nonlabeled dendrimer. The average intramolecular 13C-19F distances for generations 3-5 were each approximately 12 , which indicates inward-folding of chain ends with increasing generation number. The average intermolecular 13C-19F dipolar coupling decreased with increasing generation number, consistent with decreased interpenetration for larger dendrimers. The measured intra- and intermolecular distances for the fifth-generation dendrimer were used as constraints on energy minimizations and molecular dynamics simulations, which resulted in visualizations of the dendrimer packing and an estimate of density in the solid state.

published proceedings

  • Journal of the American Chemical Society

author list (cited authors)

  • Wooley, K. L., Klug, C. A., Tasaki, K., & Schaefer, J.

publication date

  • January 1, 1997 11:11 AM