Conformationally Controlled Electron Delocalization in n-Type Rods: Synthesis, Structure, and Optical, Electrochemical, and Spectroelectrochemical Properties of Dicyanocyclophanes

Vonlanthen, David; Rudnev, Alexander; Mishchenko, Artem; Käslin, Alexander; Rotzler, Jürgen; Neuburger, Markus; Wandlowski, Thomas; Mayor, Marcel (2011). Conformationally Controlled Electron Delocalization in n-Type Rods: Synthesis, Structure, and Optical, Electrochemical, and Spectroelectrochemical Properties of Dicyanocyclophanes. Chemistry - a European journal, 17(26), pp. 7236-7250. Weinheim: Wiley-VCH 10.1002/chem.201003763

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A series of dicyanobiphenyl-cyclophanes 1-6 with various pi-backbone conformations and characteristic n-type semiconductor properties is presented. Their synthesis, optical, structural, electrochemical, spectroelectrochemical, and packing properties are investigated. The X-ray crystal structures of all n-type rods allow the systematic correlation of structural features with physical properties. In addition, the results are supported by quantum mechanical calculations based on density functional theory. A two-step reduction process is observed for all n-type rods, in which the first step is reversible. The potential gap between the reduction processes depends linearly on the cos(2) value of the torsion angle phi between the pi-systems. Similarly, optical absorption spectroscopy shows that the vertical excitation energy of the conjugation band correlates with the cos(2) value of the torsion angle phi. These correlations demonstrate that the fixed intramolecular torsion angle phi is the dominant factor determining the extent of electron delocalization in these model compounds, and that the angle phi measured in the solid-state structure is a good proxy for the molecular conformation in solution. Spectroelectrochemical investigations demonstrate that conformational rigidity is maintained even in the radical anion form. In particular, the absorption bands corresponding to the SOMO-LUMO+i transitions are shifted bathochromically, whereas the absorption bands corresponding to the HOMO-SOMO transition are shifted hypsochromically with increasing torsion angle phi.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Department of Chemistry, Biochemistry and Pharmaceutical Sciences (DCBP)

UniBE Contributor:

Wandlowski, Thomas

ISSN:

0947-6539

Publisher:

Wiley-VCH

Language:

English

Submitter:

Factscience Import

Date Deposited:

04 Oct 2013 14:26

Last Modified:

05 Dec 2022 14:07

Publisher DOI:

10.1002/chem.201003763

Web of Science ID:

000292208900016

URI:

https://boris.unibe.ch/id/eprint/9292 (FactScience: 214989)

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