Incorporation of cyclopentene fragments into a skeletono fp arental[ 26]hexaphyrin(1.1.1.1.1.1) afforded extended carbaporphyrinoids:3 1,34-dicarbahexa[26]chlorin and its derivatives:t he first externally substituted by ethoxy and 2,4,6-trimethylbenzylidene groups and the second one formed by selective oxidation of one cyclopentenering. Macrocycles adopt dumbbell-shaped conformationsw ith two meso hydrogen atoms located inside the macrocyclic cavity. Protonation of 31,34-dicarba[26]hexachlorins provided dicationse xisting in dumbbellshaped and rectangularc onformations.
“Jumpy” five‐membered carbocycles in carbaporphyrinoids: Dicarba[26]hexachlorins(1.1.1.1.1.1.) with built‐in cyclopentenyl and cyclopentadienyl moieties can adopt two essential conformations: dumbbell‐shaped and rectangular convoluted respectively with regular and doubly inverted carbocyclic rings. The transformation between conformers has been controlled by an external factor including protonation. A cycle created by six monkeys holding hands, two of which easily rotate similarly as carbocyclic moieties, illustrates the observed conformational rearrangements in dicarbahexachlorins. More information can be found in the Communication by A. Berlicka, L. Latos‐Grażyński, et al. on page 12322.
The incorporation of original carbocyclic motifs as cyclopentene and cyclopentadiene rings into af rame of expanded porphyrins in our opinion seems to be an important step in efforts to create novel organometallic environments, eventually aiming to explore their unusual reactivity.F urthermore, the observed conformational switching between two conformers:d umbbell-type and rectangular accompanied by the inversion of cyclopentenyl and cyclopentadienyl moieties is unprecedented in porphyrinoid chemistry.S ignificantly,t he dicarba[26]hexachlorins conformations have been controlled by protonation status, concentration and nature of acid used. Invited for the cover of this issue is Lechosław Latos-Grażyń ski and co-workers at University of Wrocław.T he image depicts two essential conformationso f3 1,34-dicarba[26]hexachlorins:d umbbell and rectangularw ith regular or doubly inverted carbocyclic rings, respectively.Read the full text of the article at 10.1002/chem.202002603.
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