A general synthetic approach to azobenzenophanes and other cyclic azobenzenes

Abstract

Azobenzenophanes in which two azobenzene units are linked together in a circular manner have been used to correlate the degree of steric distortion with the photochemical and/or thermal E/Z isomerization behavior of azo bond, in light of their utility in the development of nonlinear optics, optical storage media, chemosensors and photochemical switches. We have devised a new effective synthetic route to azobenzenophanes, utilizing the sequential reactions comprised of Cu and/or Pd-catalyzed coupling reaction and oxidation. Application to the synthesis of azobenzenes strapped with polyethers is also included.