Supramolecular and Redox Chemistry of Tetrathiafulvalene Monocarboxylic Acid with Hydrogen-Bonded Pyridine and Bipyridine Molecules

Although tetrathiafulvalene derivatives (TTFs) have been
used as
the redox-active unit in a lot of ion responsive receptors, only a
few such examples of TTF carboxylic acids have been reported, especially
about the responses to neutral organic molecules. In this work, electrochemical
and spectral properties of dimethylthio-tetrathiafulvalene monocarboxylic
acid (DMT-TTFCOOH) have been studied by both experimental methods
and quantum chemical calculations. A square mechanism of proton transfer
and electron transfer equilibriums was proposed. It is noteworthy
that the process of oxidizing the TTF moiety of DMT-TTFCOOH could
be controlled to obtain TTF•+ radical cation or
TTF2+ dication by choosing suitable oxidizing reagents.
Supramolecular responsive properties of DMT-TTFCOOH to py/bpy were
investigated by cyclic voltammetry and 1H NMR spectra.
The results showed that the compound DMT-TTFCOOH is an electrochemically
sensitive hydrogen bonding donor that can detect a tiny difference
in the hydrogen bonding acceptor molecules. The theoretical calculations
further confirm the results. The hydrogen-bonding structure of DMT-TTFCOOH-bpy
in crystal was solved by X-ray diffraction analysis.