A new “Porphyrin-Geländer” (PoGe) macrocycle rac-PoGeZn, 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-PoGeZn, 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-PoGe2H, 2H and rac-PoGeCu, Cu and was demonstrated to lead to finely tunable absorption and emission spectra, reaching in the near-IR region. CSP-HPLC resolved all rac-PoGeM, 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.
Keller et al. (Thu,) studied this question.