Abstract
The oxidation pathways and products of a discrete, sulfide-endcapped donor-acceptor-donor (D/A/D) molecule, namely, propylenedioxythiophene-benzothiadiazole-propylenedioxythiophene, are investigated. The electrochemical and chemical oxidations proceed by two distinct routes. Specifically, electrochemical oxidation undergoes a sequential two-step, one-electron (1e - ) oxidation route with a 117 mV difference between consecutive half-wave potentials. In contrast, chemical oxidation by antimony(V) chloride (SbCl 5 ) causes the generation of four different oxidized species: (a) the 1e - oxidation state, (b) a decomposition product, (c) the 2e - oxidation state, and (d) a chloride adduct of the 2e - oxidation state. The decomposition product is generated by the reaction of the 1e - oxidation state with residual water, resulting in nucleophilic aromatic substitution at the sulfide group terminal positions. This reaction leads to the formation of a 2e - oxidized, oxygen atom (ketone) terminated decomposed molecule. The chloride adduct is determined to be produced by electrophilic chloronium ion (2e - ) oxidation by the SbCl 4 + complex, which is a product of SbCl 5 ligand disproportionation. The formation of the 2e - oxidized chlorine adduct shows to be linearly dependent on the molarity of SbCl 5 in dichloromethane, giving new insight into the concentration dependent reactivity of SbCl 5 as a 2e - oxidant. The electronic, optical, and magnetic properties and geometric structures of the 1e - and 2e - oxidized hexachloroantimonate salts are fully characterized by a combination of electrochemistry, X-ray crystallography, UV-vis-NIR, electron paramagnetic resonance, NMR spectroscopies, and density functional theory calculations. The aim of this study is to provide a thorough understanding of the redox pathways of a D/A/D π-conjugated organic molecule for potential application in organic electrochromic devices.
Original language | English |
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Pages (from-to) | 3866-3874 |
Number of pages | 9 |
Journal | Journal of Physical Chemistry B |
Volume | 123 |
Issue number | 17 |
DOIs | |
State | Published - May 2 2019 |
Bibliographical note
Publisher Copyright:© 2019 American Chemical Society.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Surfaces, Coatings and Films
- Materials Chemistry