Photoisomerization of Stilbene Dendrimers: The Need for a Volume-conserving Isomerization Mechanism¶

Abstract
Highly branched stilbene dendrimers were synthesized and their photochemical behavior was studied. Even the stilbene dendrimer with molecular weight over 6500 underwent transcis isomerization in the excited singlet state within the lifetime of 10 ns. The photoisomerization of C=C double bond of stilbene dendrimers in the excited state may proceed by a volume‐conserving novel mechanism such as hula‐twist rather than conventional 180° rotation around the C=C double bond based on fluorescence and isomerization experiments.