Recently, the invention of synthetic routes to very large π-conjugated macrocycles has sparked a renaissance in this field, driven by the quest to understand energy transfer, charge delocalization, and nonlinear optical phenomena in these nanostructures.[ 2 – 15 ] Template-directed synthesis makes it possible to create large, fully π-conjugated macrocycles in a size-range that could not have been reached without programmed self-assembly.[ 7, 9, 10 ] The classical template effect translates information from the size and shape of a template to direct the construction of a complementary macrocycle.[ 16 ] We have used this approach to prepare nanorings consisting of 6 and 8 porphyrin units, using hexadentate and octadentate templates.[ 9a – c ] This classical approach is not convenient for the synthesis of larger nanorings because of the inaccessibility of suitable templates.
Source: wiktionary