Squaraine-derived rotaxanes: sterically protected fluorescent near-IR dyes

J Am Chem Soc. 2005 Mar 16;127(10):3288-9. doi: 10.1021/ja042404n.


A squaraine dye with bulky end groups is employed as the thread component in two Leigh-type amide rotaxanes. The rotaxanes are synthesized in a simple two-step process. X-ray crystal structures of the rotaxanes show that the pyridyl-containing macrocycle is more rigid and wraps more tightly around the cyclobutene core of the squaraine thread compared to the isophthalamide-containing macrocycle. The rotaxanes exhibit photophysical properties that are similar to the precursor squaraine. The encapsulating macrocycle greatly increases the chemical stability of the squaraine thread and inhibits aggregation-induced broadening of its absorption spectrum. It should be possible to prepare squaraine-derived rotaxanes with improved properties for a wide range of photophysical, photochemical, and biomedical applications.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Crystallography, X-Ray
  • Cyclobutanes / chemistry*
  • Cyclodextrins / chemistry
  • Fluorescent Dyes / chemistry*
  • Molecular Structure
  • Phenols / chemistry*
  • Photochemistry
  • Rotaxanes / chemistry*
  • Spectroscopy, Near-Infrared / methods*


  • Cyclobutanes
  • Cyclodextrins
  • Fluorescent Dyes
  • Phenols
  • Rotaxanes
  • squaraine