Three distinct conformational structures of carbaoctaphyrins were prepared by incorporating bis-4,4'-biphenyl units in the macrocyclic core. The free-base form adopts a figure-eight conformation, whereas the protonation triggers a conformational change with a pyrrole ring inversion and acquires an open-framework structure. The insertion of bis-RhI metal ion in the macrocyclic core affords a singly twisted conformational structure. Furthermore, the local aromaticity in the bis-4,4'-biphenyl ring dominates the overall macrocyclic aromaticity in all three forms, and thus adopts nonaromatic characteristics. These results are supported by spectral as well as theoretical studies, and they are unambiguously confirmed by X-ray crystal analyses.
|Number of pages||5|
|Journal||Chemistry - A European Journal|
|Publication status||Published - 2019 Oct 8|
Bibliographical noteFunding Information:
Dr. A.S. thanks NISER, Department of Atomic Energy and SERB (EMR/2017/2932) for financial support. S.C. and M.D. thank NISER for their fellowships.
© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
All Science Journal Classification (ASJC) codes
- Organic Chemistry