Aromaticity Reversal in the Lowest Excited Triplet State of Archetypical Möbius Heteroannulenic Systems. (15th April 2016)

• Record Type: Journal Article
• Authors: Oh, Juwon; Sung, Young Mo; Kim, Woojae; Mori, Shigeki; Osuka, Atsuhiro; Kim, Dongho
• Is Part Of: Angewandte Chemie. Volume 128:Number 22(2016)
• Page Start: 6597
• Page End: 6601
• Publication Date: 2016-04-15
• Subjects: Antiaromatizität -- Aromatizität -- Bairdsche Regel -- Elektronische Struktur -- Porphyrinoide; Chemistry -- Periodicals; 540
• DOI: 10.1002/ange.201602083
• Languages: English
• ISSNs: 0044-8249

Abstract

Abstract: The aromaticity reversal in the lowest triplet state (T1 ) of a comparable set of Hückel/Möbius aromatic metalated expanded porphyrins was explored by optical spectroscopy and quantum calculations. In the absorption spectra, the T1 states of the Möbius aromatic species showed broad, weak, and ill‐defined spectral features with small extinction coefficients, which is in line with typical antiaromatic expanded porphyrins. In combination with quantum calculations, these results indicate that the Möbius aromatic nature of the S0 state is reversed to Möbius antiaromaticity in the T1 state. This is the first experimental observation of aromaticity reversal in the T1 state of Möbius aromatic molecules.