A porphyrin-anthracene supramolecular system assembled via complementary nucleic acid base pairing

Covalently linked porphyrin-adenine (meso-5(4-(9-(2-oxyethyl)adenine)phenyl ) tritolylporphyrin, 1) and anthracene-thymine (1-(9-methylanthracene)thymi ne, 2) conjugates have been synthesized and fully characterized by elementa l analysis, FAB mass, UV-vis, H-1 NMR, fluorescence and cyclic voltammetric methods. Detailed H-1 NMR studies reveal that 1 and 2 self-assemble in CDC l3 solutions at 293 +/- 3 K to form a two-point hydrogen-bonded, bichromoph oric, supramolecular system 3 with a binding constant of 47 +/- 5 M-1 and t hat both Hoogsteen- and Watson-Crick-type A-T assemblies exist in solution under these experimental conditions. Spectral and electrochemical data poin t out the possibility of occurrence of both energy and electron transfer re actions from the singlet excited state of 2 to 1 in the ensemble 3. The sin glet state activity of the ensemble 3 has been probed mainly by the time-re solved fluorescence method and the results have been discussed in the light of those obtained earlier on similar 'non-covalently' or covalently bound bichromophoric systems. (C) 1998 John Wiley & Sons, Ltd.