[40]π Fused and Nonfused Core-Modified Nonaphyrins: Syntheses and Structural Diversity.
The synthesis of fused and nonfused core-modified 40π nonaphyrins are reported. Spectroscopic and X-ray structural studies reveal a twisted figure-eight conformation in the freebase form that is nonaromatic. Structural changes occur, from figure-eight to open extended conformation, upon protonation, thereby adopting 4nπ Hückel antiaromatic character, which is reflected in spectroscopic and theoretical studies. Such a structural change also induces ring inversions of specific heterocyclic rings by 180°.
School of Chemical Sciences, National Institute of Science Education and Research (NISER), Bhubaneswar -, 751005, Odisha, India.
Arindam
A
Ghosh
School of Chemical Sciences, National Institute of Science Education and Research (NISER), Bhubaneswar -, 751005, Odisha, India.
A
A
Srinivasan
Inorganic & Theoretical Chemistry Section, Chemical Sciences and Technology Division, CSIR-National Institute for Interdisciplinary Science and Technology, Trivandrum -, 695019, Kerala, India.
Cherumuttathu H
CH
Suresh
School of Chemical Sciences, National Institute of Science Education and Research (NISER), Bhubaneswar -, 751005, Odisha, India. tkc@niser.ac.in.
Tavarekere K
TK
Chandrashekar
Hückel aromaticity; antiaromaticity; core modification; expanded porphyrins; nonaphyrins