Dipyrrin‐Bis(N‐Confused Porphyrin) Conjugate: Synthesis, Synergetic Ligation and Chirality Sensing

A fully conjugated system 4 consisting of two 2‐aza‐21‐carbaporphyrin (NCP) subunits bridged by dipyrrin was synthesized by a highly selective condensation of 3‐pyrrole‐NCP 2 with aryl aldehydes. The free base 4 as well as its silver(III) complex 5 exhibited flexibility of the bridge allowing synergetic binding of AgI, thus leading to a mixed‐valence tetraporphyrinic assembly consisting of eight silver atoms which was characterized both in the solid state and in solution. Binding of chiral acid by 4 and 5 was shown by observation of an induced optical activity of the adducts. Being somewhat confused: A fully conjugated dipyrrin‐bridged N‐confused porphyrin dimer was obtained by highly selective acid‐catalyzed condensation. The free‐base and bis(silver(III)) complex of the dimer displayed an optical activity induced by chiral acid and formed mixed‐valence assembly comprising eight silver ions.