Angewandte Chemie International Edition
© WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
The cover picture shows a schematic representation of a supramolecular rod composed of meso–meso-coupled porphyrins. The AgI-promoted meso–meso coupling of ZnII 5,15-diarylporphyrins enabled regularly arranged arrays with 2–128 porphyrins to be assembled. An examination of the absorption spectra of these rods show that they all exhibit split Soret bands as a result of exciton coupling. As the number of porphyrins increases the low-energy Soret band is shifted to longer wavelength while the high-energy Soret band stays at nearly the same wavelength, which results in a progressive increase in the splitting energy. A study of the fluorescence spectra of the arrays shows the S1 states are delocalized over 6–8 porphyrin units. The 128mer at 0.1-μm long is the longest monodisperse, rodlike molecule so far known, and should, together with the smaller arrays, have the potential for application as light-harvesting wires. Further details are reported by A. Osuka et al. on p. 1458 ff.