Covalent Conducting Belts

A new type of covalent organic framework (COF) assumes a belt shape and exhibits luminescence and electrical conductivity, reports a research group led by Donglin Jiang of Japan's Institute for Molecular Science (Angew. Chem. Int. Ed., DOI: 10.1002/anie.200803826). First reported last year as a general class of materials (C&EN, May 28, 2007, page 32), COFs are lightweight porous macromolecules with high surface areas that have been touted for gas storage applications. Jiang and coworkers designed a π-conjugated system of interlocking hexagons made from hydroxytriphenylene molecules (green) that occupy the vertices and pyrenediboronic acid groups that form the edges (blue). Planar sheets of the 3.2-nm-diameter hexagons layer in a perfectly eclipsed fashion, interacting through π-π stacking. The overall belt-shaped structure is 300-nm wide, 100-nm thick, and micrometers long. The authors propose that the material could be used for optoelectronic devices.