Control of dihedral angle of meso-meso linked diporphyrins by introducing dioxymethylene straps of various length

[GRAPHICS] Meso-meso linked strapped diporphyrins S-n (n = 10, 8, 6, 4, 3, 2, and 1) were synthesized by intramolecular Ag(I)-promoted coupling of dioxymethylene-bridged diporphyrins B-n. With decrease of strap length, the absorption and fluorescence spectra and the one electron oxidation potentials of S-n changed in a systematic manner, suggesting a progressive increase in electronic communication of two porphyrins.