Excited state isomerization in photochromic ruthenium complexes

Photochromic ruthenium polypyridyl complexes whose action is based on an excited state linkage isomerization are discussed. Picosecond transient absoption spectroscopic data indicate that isomerization occurs along the charge-transfer manifold. These studies indicate that rotation about the Ru–S bond is an important vibration along this coordinate. These complexes are of interest in photonic molecular devices, specifically molecular information storage applications.