TY - JOUR

T1 - Synthesis and Properties of Fluorenone-Containing Cycloparaphenylenes and Their Late-Stage Transformation

AU - Bliksted Roug Pedersen, Viktor

AU - Price, Tavis W.

AU - Kofod, Nicolaj

AU - Zakharov, Lev N.

AU - Laursen, Bo W.

AU - Jasti, Ramesh

AU - Brøndsted Nielsen, Mogens

N1 - Funding Information: The Novo Nordisk Foundation (NNF20OC0061574) is acknowledged for financial support. T.W.P. and R.J. were supported by the U.S. National Science Foundation (CHE‐2102567). Publisher Copyright: © 2023 The Authors. Chemistry - A European Journal published by Wiley-VCH GmbH.

PY - 2024

Y1 - 2024

N2 - Cycloparaphenylenes (CPPs) are the smallest possible armchair carbon nanotubes, the properties of which strongly depend on their ring size. They can be further tuned by either peripheral functionalization or by replacing phenylene rings for other aromatic units. Here we show how four novel donor–acceptor chromophores were obtained by incorporating fluorenone or 2-(9H-fluoren-9-ylidene)malononitrile into the loops of two differently sized CPPs. Synthetically, we managed to perform late-stage functionalization of the fluorenone-based rings by high-yielding Knoevenagel condensations. The structures were confirmed by X-ray crystallographic analyses, which revealed that replacing a phenylene for a fused-ring-system acceptor introduces additional strain. The donor–acceptor characters of the CPPs were supported by absorption and fluorescence spectroscopic studies, electrochemical studies (displaying the CPPs as multi-redox systems undergoing reversible or quasi-reversible redox events), as well as by computations. The oligophenylene parts were found to comprise the electron donor units of the macrocycles and the fluorenone parts the acceptor units.

AB - Cycloparaphenylenes (CPPs) are the smallest possible armchair carbon nanotubes, the properties of which strongly depend on their ring size. They can be further tuned by either peripheral functionalization or by replacing phenylene rings for other aromatic units. Here we show how four novel donor–acceptor chromophores were obtained by incorporating fluorenone or 2-(9H-fluoren-9-ylidene)malononitrile into the loops of two differently sized CPPs. Synthetically, we managed to perform late-stage functionalization of the fluorenone-based rings by high-yielding Knoevenagel condensations. The structures were confirmed by X-ray crystallographic analyses, which revealed that replacing a phenylene for a fused-ring-system acceptor introduces additional strain. The donor–acceptor characters of the CPPs were supported by absorption and fluorescence spectroscopic studies, electrochemical studies (displaying the CPPs as multi-redox systems undergoing reversible or quasi-reversible redox events), as well as by computations. The oligophenylene parts were found to comprise the electron donor units of the macrocycles and the fluorenone parts the acceptor units.

KW - chromophores

KW - cross-coupling

KW - donor–acceptor systems

KW - macrocycles

KW - strained molecules

U2 - 10.1002/chem.202303490

DO - 10.1002/chem.202303490

M3 - Journal article

C2 - 37930279

AN - SCOPUS:85178470213

VL - 30

JO - Chemistry: A European Journal

JF - Chemistry: A European Journal

SN - 0947-6539

IS - 5

M1 - e202303490

ER -