A series of meso-trifluoromethyl-substituted expanded porphyrins, including N-fused pentaphyrin 3, hexaphyrin 4, heptaphyrin 5, decaphyrin 6, and dodecaphyrin 7, were synthesized by means of an acid-catalyzed one-pot condensation reaction of 2-(2,2,2-trifluoro-1-hydroxyethyl)pyrrole (1) as the first examples bearing meso-alkyl substituents. Besides these products, porphyrin 2 and two calixphyrins 8 and 9 were also obtained. Hexaphyrin 4 was quantitatively oxidized to hexaphyrin 14 with MnO2. These expanded porphyrins have been characterized by mass spectrometry, 1H and 19F NMR spectroscopy, and UV/Vis spectroscopy. The single-crystal structures have been determined for 3, 4, 6, 7, and 14. The N-fused pentaphyrin 3 displays a distorted structure containing a tricyclic fused moiety that is similar to those of mejo-aryl-substituted counterparts, whereas 8 and 9 are indicated to take roughly planar conformations with an inverted pyrrole opposite to the sp3-hybridized meso-carbon atom. Both - and hexaphyrins 4 and 14 have figure-of-eight structures. Solid-state structures of the decaphyrin 6 and dodecaphyrin 7 are remarkable, exhibiting a crescent conformation and an intramolecular two-pitch helical conformation, respectively.
All Science Journal Classification (ASJC) codes
- Organic Chemistry