Photoisomerization of azobenzene derivatives confined in gold nanoparticle aggregates†
Abstract
Photoisomerization is an important reaction that confers photoresponsive functionality on N stretching character redshift upon irradiation, suggesting that the N
N bond is significantly weakened when Az is in the cis form in the AuNP aggregates. The weakening of the N
N bond is attributed to the interaction of the N
N bond, which is more exposed to the outside in the cis conformation, with the nearby AuNPs that have come closer by the isomerization of adsorbed Az. We find that backisomerization from cis to trans occurs much faster in the AuNP aggregates (k = 1.9 × 10−2 min−1) than in solution (k = 1.3 × 10−3 min−1) because of the reduced N
N bond order of cis-Az in the aggregates.