Charge Delocalization in an Organic Mixed Valent Bithiophene Is Greater Than in a Structurally Analogous Biselenophene

Jahnke, Ann Christin and Proppe, Jonny and Spulber, Mariana and Palivan, Cornelia G. and Herrmann, C. and Wenger, Oliver S.. (2014) Charge Delocalization in an Organic Mixed Valent Bithiophene Is Greater Than in a Structurally Analogous Biselenophene. Journal of Physical Chemistry A, 118 (47). pp. 11293-11303.

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Official URL: http://edoc.unibas.ch/dok/A6328815

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A series of selenophenes with redox-active amine end-capping groups was synthesized and investigated. A combination of cyclic voltammetry, optical absorption, EPR spectroscopy, and quantum-chemical calculations based on Kohn–Sham density functional theory was used to explore charge delocalization in the monocationic mixed-valence forms of these selenophenes, and the results were compared to those obtained from analogous studies of structurally identical thiophenes. The striking finding is that the comproportionation constant (Kc) for the experimentally investigated biselenophene is more than 2 orders of magnitude lower than for its bithiophene counterpart (in CH3CN with 0.1 M TBAPF6), and the electronic coupling between the two amine end-capping groups in the mixed-valent biselenophene monocation is only roughly half as strong as in the corresponding bithiophene monocation. These are surprisingly large differences given the structural similarity between the respective biselenophene and bithiophene molecules. However, the computationally determined comproportionation constants for biselenophene and bithiophene are almost identical, and the electronic coupling in the monocationic biselenophene is only slightly smaller than that in the monocationic bithiophene. We assume that the external electric field may be responsible for the differences in monocation stabilities between experiment and computation. Our findings indicate that charge delocalization across individual selenophenes tends to be less pronounced than across individual thiophenes, and this may have important implications for long-range charge transfer across selenophene oligomers or polymers.
Faculties and Departments:05 Faculty of Science > Departement Chemie > Chemie > Anorganische Chemie (Wenger)
UniBasel Contributors:Wenger, Oliver and Jahnke, Ann Christin and Spulber, Mariana and Palivan, Cornelia G
Item Type:Article, refereed
Article Subtype:Research Article
Publisher:American Chemical Society
Note:Publication type according to Uni Basel Research Database: Journal article
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Last Modified:06 Jun 2018 13:24
Deposited On:06 Feb 2015 09:58

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