[40]π Fused and Nonfused Core-Modified Nonaphyrins: Syntheses and Structural Diversity

Arindam Ghosh; A Srinivasan; Cherumuttathu H Suresh; Tavarekere K Chandrashekar

doi:10.1002/chem.201602245

[40]π Fused and Nonfused Core-Modified Nonaphyrins: Syntheses and Structural Diversity

Chemistry. 2016 Aug 1;22(32):11152-5. doi: 10.1002/chem.201602245. Epub 2016 Jul 6.

Authors

Arindam Ghosh¹, A Srinivasan¹, Cherumuttathu H Suresh², Tavarekere K Chandrashekar³

Affiliations

¹ School of Chemical Sciences, National Institute of Science Education and Research (NISER), Bhubaneswar -, 751005, Odisha, India.
² Inorganic & Theoretical Chemistry Section, Chemical Sciences and Technology Division, CSIR-National Institute for Interdisciplinary Science and Technology, Trivandrum -, 695019, Kerala, India.
³ School of Chemical Sciences, National Institute of Science Education and Research (NISER), Bhubaneswar -, 751005, Odisha, India. tkc@niser.ac.in.

PMID: 27272458
DOI: 10.1002/chem.201602245

Abstract

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°.

Keywords: Hückel aromaticity; antiaromaticity; core modification; expanded porphyrins; nonaphyrins.