meso‐Aryl‐Substituted [26]Hexaphyrin(1.1.0.1.1.0) and [38]Nonaphyrin(1.1.0.1.1.0.1.1.0) from Oxidative Coupling of a Tripyrrane

Acid-specific conformational changes: Protonation of meso-aryl-substituted rubyrin 1 with HCl or CF3CO2H causes different conformational changes, as revealed by specific shifts in the UV/Vis absorption bands relative to those of the free-base form (Cl−: blue shift; CF3CO2−: red shift). The distinct counteranion-dependent color changes upon addition of the acids to the “anion sensor” 1 are easily detected.