HIGH BINDING AFFINITY OF DABCO WITH PORPHYRIN IN A PORPHYRIN-CIS-STILBENE-PORPHYRIN TRIAD

摘要

Porphyrin-stilbene-porphyrin triad (mZnPst) where a central cis-stilbene unit is connected to zinc-tetraphenylporphyrin (ZnTPP) was synthesized and its binding ability with a selected guest ligand DABCO was investigated. The association constant was evaluated to be 2.47 x 10~8 M~(-1), from the iterative least squares fitting to a 1:1 binding model, which is larger than that of monomer ZnTPP/DABCO complex (3.50 x 10~5 M~(-1)). In addition, when a toluene solution of mZnPst is mixed with 1 equivalent of DABCO, the color of the solution was changed abruptly to light purple from bright reddish, providing further a visual evidence of forming strong complex. Such a high association constant suggests mZnPst/DABCO to be a promising photoresponsive supramolecular system.