Porphyrin‐Geländer–Helical Conjugated Banister Type Porphyrin Dyads

A new "Porphyrin-Geländer" (PoGe) macrocycle rac-PoGe[Zn, Zn] embodying a twisted butadiyne-linked porphyrin dyad as the banister was designed and synthesized according to a previously published successful design principle for Geländer molecules. The C₂-symmetric properties of rac-PoGe[Zn, Zn] were revealed by detailed 2D NMR analysis. Postsynthesis modification consisting of central metal ion exchange in the porphyrin moieties led to PoGe macrocycles rac-PoGe[2H, 2H] and rac-PoGe[Cu, Cu] and was demonstrated to lead to finely tunable absorption and emission spectra, reaching in the near-IR region. CSP-HPLC resolved all rac-PoGe[M, M] into their (P) and (M) enantiomers, which were analyzed by UV-Vis, fluorescence and ECD spectroscopy. The absolute configuration was assigned by the exciton chirality method (ECM) and corroborated by comparing experimental and simulated ECD spectra.