2012 Volume 70 Issue 12 Pages 1255-1266
Two-dimensional (2D) architectures, particularly porous molecular networks, on solid surfaces formed via self-assembly have received a great deal of interest because of the prospective applications in optoelectronics and tailor-made catalysis. We found that porous 2D molecular networks were formed at liquid-solid interfaces, typically an organic solvent/graphite or Au(111), by triangle-shaped phenylene-ethynylene macrocycles, dehydrobenzo[12]annulenes (DBAs), via their self-assembly by van der Waals interactions between the interdigitated alkyl chains attached to the periphery of the macrocyclic core. Factors that led to the preferential formation of porous, honeycomb-shaped networks were elucidated including the size of the π-conjugated cores, alkyl chain length, solvent, concentration, temperature, and solid substrates. Not only homochiral molecular networks were achieved by self-assembly of DBAs with chiral side chains, but also network homochirality was induced by addition of a small amount of a chiral DBA into an achiral DBA as a chirality inducer. Co-adsorption of guest molecules in the pores occurred through recognition of the size and shape, leading to selective inclusion of homo-molecular as well as hetero-molecular clusters into the nanowells. Moreover, the interior of the pores was functionalized for tailored molecular recognition toward advanced use of 2D molecular networks on surfaces.
