Tuning (Anti)Aromaticity: Variations on the [8]-Circulene Framework.

Autor: Fowler PW; Department of Chemistry, University of Sheffield, Sheffield, United Kingdom., Anstöter CS; School of Chemistry, University of Edinburgh, Edinburgh, Edinburgh, United Kingdom.
Jazyk: angličtina
Zdroj: Chemphyschem : a European journal of chemical physics and physical chemistry [Chemphyschem] 2024 Apr 02; Vol. 25 (7), pp. e202300791. Date of Electronic Publication: 2024 Mar 06.
DOI: 10.1002/cphc.202300791
Abstrakt: Optoelectronic properties of organic molecules are underpinned by delocalisation and delocalisability of π-electrons. These properties are sensitive to small changes in electron count, whether achieved by heteroatom substitution or redox chemistry. One measure of the delocalisability of π-electrons is the current induced by an external magnetic field, which is diagnostic of (anti)aromaticity. The ab initio ipsocentric method is used here to model diverse ring-current patterns in the family of [8]-circulenes based on tetracyclopenta[def,jkl,pqr,vwx]tetraphenylene (TCPTP), in different charge states, with disjoint hetero-atom substitution, and with CC units systematically replaced by BN pairs. Maps calculated at the CHF/CTOCD-DZ2/6-31G** level reveal that these modifications of the TCPTP framework access the full range of possibilities for current from concentric global circulations (typically counter rotating) to full (non-aromatic) localisation. In the ipsocentric approach, induced current density is partitioned into robust orbital contributions that obey selection rules based on orbital symmetry, energy and nodal character. The selection rules are applied here to interpret current-density and exploit insights gained from simpler models to suggest design strategies for fine-tuning of π-delocalisability (aromaticity and antiaromaticity) in macrocyclic frameworks.
(© 2024 The Authors. ChemPhysChem published by Wiley-VCH GmbH.)
Databáze: MEDLINE
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