meso-Trifluoromethyl-substituted expanded porphyrins

Area of Science:

• Organic Chemistry
• Supramolecular Chemistry
• Materials Science

Background:

• Expanded porphyrins are macrocyclic compounds with unique electronic and photophysical properties.
• Meso-substituted porphyrins offer tunable characteristics, but trifluoromethyl substitution presents synthetic challenges.

Purpose of the Study:

• To synthesize novel meso-trifluoromethyl-substituted expanded porphyrins.
• To characterize the synthesized compounds and elucidate their structural features.
• To explore the conformational diversity of these new macrocycles.

Main Methods:

• Acid-catalyzed one-pot condensation reaction of 2-(2,2,2-trifluoro-1-hydroxyethyl)pyrrole.
• Oxidation of [28]hexaphyrin to [26]hexaphyrin using manganese dioxide (MnO2).
• Characterization using mass spectrometry, NMR (1H and 19F), UV/Vis spectroscopy, and single-crystal X-ray diffraction.

Main Results:

• Successful synthesis of N-fused [24]pentaphyrin, [28]hexaphyrin, [32]heptaphyrin, [46]decaphyrin, and [56]dodecaphyrin bearing meso-trifluoromethyl groups.
• Structural determination revealed diverse conformations: distorted tricyclic for pentaphyrin, figure-of-eight for hexaphyrins, crescent for decaphyrin, and helical for dodecaphyrin.
• Identification of porphyrin and calix[5]phyrin byproducts.

Conclusions:

• The study presents the first examples of meso-trifluoromethyl-substituted expanded porphyrins with alkyl substituents.
• The synthesized macrocycles exhibit significant structural diversity, including unique helical and crescent conformations.
• These findings expand the scope of expanded porphyrin chemistry and offer new building blocks for advanced materials.