Tetrathiafulvalene: A Paradigmatic Electron Donor Molecule

Abstract

Tetrathiafulvalene (TTF) and its derivatives are exceptional building blocks in many areas of organic, supramolecular, and materials chemistry. Since the discovery ca. 30 years ago of the first “organic metal” tetrathiafulvalene-tetracyano-p-quinodimethane (TTF-TCNQ), a huge number of TTF derivatives have been synthetized.

Although initial efforts were directed to enhance the electron-donating ability of TTF analogues to improve the conductivities of salts and charge-transfer (CT) complexes derived from them, the developments in synthetic TTF chemistry have made it possible to incorporate TTF into more sophisticated structures such as materials exhibiting intramolecular charge-transfer and nonlinear optical properties, sensors, molecular shuttles and devices.

Compounds in which TTF and electron-accepting molecules, especially C ₆₀ , are covalently tethered exhibit outstanding photophysical properties leading, upon photoexcitation, to charge-separated (CS) states showing remarkable lifetimes. In these systems, the gain of aromaticity upon oxidation of the TTF moiety has been used as a new concept for improving the stability of the charge-separated state, and, therefore, are of interest for the preparation of artificial photosynthetic systems as well as photovoltaic devices.