Bisindole [3]arenes-Indolyl Macrocyclic Arenes Having Significant Iodine Capture Capacity

Abstract

Several novel macrocyclic arenes that are composed of six indole subunits, so-called bisindole [3]arenes (BID[3]s), were conveniently synthesized by the aluminum trichloride-catalyzed one-pot condensation of bisindole derivatives and paraformaldehyde in dichloromethane at room temperature. Their macrocyclic structures were demonstrated by X-ray single-crystal studies, and the presence of the macrocyclic cavities made it possible to accommodate specific small organic molecules. The BID[3]s have exceptionally high iodine adsorption ability due to the strong and synergic interaction of indole units toward iodine, exhibiting significant morphology changes upon adsorption and desorption of iodine. Iodine uptake capacity of up to 5.12 g g-1 was found with MeBID [3], which is the highest value ever reported for macrocyclic arenes.