Cryptand-like Porphyrinoid Assembled with Three Dipyrrylpyridine Chains: Synthesis, Structure, and Homotropic Positive Allosteric Binding of Carboxylic Acids
作者:Jun-ichiro Setsune、Keigo Watanabe
DOI:10.1021/ja710424n
日期:2008.2.1
Cryptand-like porphyrinoid assembled with three 2,6-dipyrrlpyridine chains binds alcohol at each molecular crevice in the C(3h) symmetric conformation through three hydrogen bondings. This receptor binds dichloroacetic add at each crevice in the D(3) symmetric conformation, where strong positive allosteric effect was observed on the basis of the Hill plot with a Hill coefficient (n = 2.7 +/- 0.2), and the association constant (log K = 13.6 +/- 1.8). Ligand binding at the first crevice enhances polarization of the pi-conjugated chain to make pyrrole more acidic at the second crevice and pyridine more basic at the third crevice.