Dicarba[26]hexaporphyrinoids(1.1.1.1.1.1) with an Embedded Cyclopentene Moiety-Conformational Switching.

Incorporation of cyclopentene fragments into a skeleton of parental [26]hexaphyrin(1.1.1.1.1.1) afforded extended carbaporphyrinoids: 31,34-dicarbahexa[26]chlorin and its derivatives: the first externally substituted by ethoxy and 2,4,6-trimethylbenzylidene groups and the second one formed by selective oxidation of one cyclopentene ring. Macrocycles adopt dumbbell-shaped conformations with two meso hydrogen atoms located inside the macrocyclic cavity. Protonation of 31,34-dicarba[26]hexachlorins provided dications existing in dumbbell-shaped and rectangular conformations.