Highly strained, radially π-conjugated porphyrinylene nanohoops
Xu, Youzhi (University of Ulm. Institute of Organic Chemistry)
Gsänger, Sebastian (Friedrich-Alexander-Universität Erlangen-Nürnberg. Interdisciplinary Center for Molecular Materials)
Minameyer, Martin B. (Friedrich-Alexander University Erlangen-Nürnberg. Department of Chemistry and Pharmacy)
Imaz, Inhar (Institut Català de Nanociència i Nanotecnologia)
Maspoch Comamala, Daniel (Institut Català de Nanociència i Nanotecnologia)
Shyshov, Oleksandr (University of Ulm. Institute of Organic Chemistry)
Schwer, Fabian (University of Ulm. Institute of Organic Chemistry)
Ribas, Xavi (Universitat de Girona. Departament de Química)
Drewello, Thomas (Friedrich-Alexander University Erlangen-Nürnberg. Department of Chemistry and Pharmacy)
Meyer, Bernd (Friedrich-Alexander-Universität Erlangen-Nürnberg. Interdisciplinary Center for Molecular Materials)
Von Delius, M. (University of Ulm. Institute of Organic Chemistry)

Date:	2019
Abstract:	Small π-conjugated nanohoops are difficult to prepare, but offer an excellent platform for studying the interplay between strain and optoelectronic properties, and, increasingly, these shape-persistent macrocycles find uses in host-guest chemistry and self-assembly. We report the synthesis of a new family of radially π-conjugated porphyrinylene/phenylene nanohoops. The strain energy in the smallest nanohoop [2]CPT is approximately 54 kcal mol⁻¹, which results in a narrowed HOMO-LUMO gap and a red shift in the visible part of the absorption spectrum. Because of its high degree of preorganization and a diameter of ca. 13 Å, [2]CPT was found to accommodate C₆₀ with a binding affinity exceeding 10⁸ M⁻¹ despite the fullerene not fully entering the cavity of the host (X-ray crystallography). Moreover, the ?-extended nanohoops [2]CPTN, [3]CPTN, and [3]CPTA (N for 1,4-naphthyl; A for 9,10-anthracenyl) have been prepared using the same strategy, and [2]CPTN has been shown to bind C₇₀ 5 times more strongly than [2]CPT. Our failed synthesis of [2]CPTA highlights a limitation of the experimental approach most commonly used to prepare strained nanohoops, because in this particular case the sum of aromatization energies no longer outweighs the buildup of ring strain in the final reaction step (DFT calculations). These results indicate that forcing ring strain onto organic semiconductors is a viable strategy to fundamentally influence both optoelectronic and supramolecular properties.
Grants:	Ministerio de Economía y Competitividad SEV-2017-0706
Rights:	Tots els drets reservats.
Language:	Anglès
Document:	Article ; recerca ; Versió acceptada per publicar
Subject:	Aromatization energy ; Binding affinities ; Experimental approaches ; Highly strained ; Hostguest chemistry ; Optoelectronic properties ; Shape-persistent macrocycles ; Supramolecular properties
Published in:	Journal of the American Chemical Society, Vol. 141, issue 46 (Nov. 2019) , p. 18500-18507, ISSN 1520-5126

DOI: 10.1021/jacs.9b08584

Postprint 9 p, 1.4 MB

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Research literature > UAB research groups literature > Research Centres and Groups (research output) > Experimental sciences > Catalan Institute of Nanoscience and Nanotechnology (ICN2)
Articles > Research articles
Articles > Published articles