Chemical Stimulus-responsive Folding and Unfolding of a Dendrimeric Assembly.

A dendrimeric trimer undergoes folding and unfolding in response to a chemical stimulus. The trimer of interest contains a central dendrimer with a butadiyne-linked zinc porphyrin dimer ((ZnP)2 ) core, in addition to two terminal dendrimers with zinc porphyrin (ZnP) cores. The obtained absorption spectra indicate that the unfolded form is the exclusive conformer in chloroform, while the addition of 1,4-diazabicyclo[2.2.2]octane (DABCO) in chloroform leads to transformation from the unfolded to the folded structure containing two DABCO units per trimer; the folded structure originates from the cross-linking of (ZnP)2 and ZnP with DABCO. Moreover, the addition of excess DABCO promotes the generation of the unfolded structure containing four DABCO units.