CC BY-NC-ND 4.0 · Organic Materials 2022; 4(03): 102-126
DOI: 10.1055/a-1926-6340
Supramolecular Chemistry
Original Article

2,5-Diaryl 6-hydroxyphenalenones for Single-Molecule Junctions

a   Department of Chemistry, University of Basel, St. Johanns-Ring 19, CH-4056 Basel, Switzerland
,
b   Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, The Netherlands
,
a   Department of Chemistry, University of Basel, St. Johanns-Ring 19, CH-4056 Basel, Switzerland
,
a   Department of Chemistry, University of Basel, St. Johanns-Ring 19, CH-4056 Basel, Switzerland
,
b   Kavli Institute of Nanoscience, Delft University of Technology, Lorentzweg 1, 2628 CJ Delft, The Netherlands
,
a   Department of Chemistry, University of Basel, St. Johanns-Ring 19, CH-4056 Basel, Switzerland
c   Institute for Nanotechnology (INT), Karlsruhe Institute of Technology (KIT), P. O. Box 3640, 76021 Karlsruhe, Germany
d   Lehn Institute of Functional Materials, School of Chemistry, Sun Yat-Sen University, Guangzhou 510274, P. R. of China
› Author Affiliations


Abstract

A modular access to 2,5-diaryl 6-hydroxyphenalenone derivatives is developed and demonstrated by a small series of 5 molecules. Within this series, the structures 1 and 2 expose terminal methylsulfanyl anchor groups, enabling their integration in a single-molecule junction. The modular synthesis is based on Suzuki cross-coupling of the aryl substituents as boronic acid precursors with 5,8-dibromo-2-(tert-butyl)-4,9-dimethoxy-2,3-dihydro-1H-phenalen-1-one, and the subsequent transformation of the product to the desired 2,5-diaryl 6-hydroxyphenalenone in a reduction/deprotection sequence. The new structures are fully characterized and their optical and electrochemical properties are analysed. For the derivatives 1 and 2 suitable for single-molecule junctions, the corresponding oxophenalenoxyl radicals 1R and 2R were obtained by oxidation and analysed by electron paramagnetic resonance spectroscopy. Preliminary mechanical break junction experiments with 1 display the structureʼs ability to form transient single-molecule junctions. The intention behind the molecular design is to profit from the various redox states of the structure (including the neutral radical) as a molecular switch in an electrochemically triggered single-molecule transport experiment.



Publication History

Received: 30 June 2022

Accepted after revision: 12 August 2022

Accepted Manuscript online:
17 August 2022

Article published online:
20 September 2022

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