TTF–PTM dyads: from switched molecular self assembly in solution to radical conductors in solid state

Abstract

Dyads formed by tetrathiafulvalene (TTF) linked to perchlorotriphenylmethyl (PTM) radicals exhibit interesting physical properties such as bistability in solution or conductivity in solid state.

Mixed valence salts based on carbon-centered neutral radical crystals

“…High conductivities over several S cm -1 have been also realized in several single component bis(dithiolene)-type metal complexes [25][26][27] (σ RT = 750 S cm -1 at most 27 , measured for single crystal). Highly conductive single component neutral radicals are also reported on several TTF derivatives having neutral radical units, such as nitronyl nitroxide 28 (σ RT = 9 × 10 -4 S cm -1 , measured for single crystal) and triphenylmethyl [29][30][31] (σ RT = 4 × 10 -1 S cm -1 at most 29 , measured for single crystal under 15.2 GPa).…”

Tetrathiafulvalene–Polychlorotriphenylmethyl Dyads: Influence of Bridge and Open‐Shell Characteristics on Linear and Nonlinear Optical Properties

“…Recently, we have reported different D-π-A systems based on a PTM radical electron-acceptor linked to a TTF electron-donor through conjugated vinylene bridges that exhibit a reversible switching between a neutral and a zwitterionic state in solution through the application of external stimuli [29][30][31][32] or conductivity in solid state. [33][34][35] In order to study the optical properties of this kind of radical dyads and evaluate the influence of the open-shell character and the length of the bridge, we have synthesized and characterized a family of TTF-π-PTM radical derivatives (1a-1c) and their non-radical analogues (2a-2c) (Scheme 1). In this article, we present a detailed study of the intramolecular charge-transfer dependence on the open-shell structure and the bridge length of this family of compounds.…”

Synthesis and Characterization of Ethylenedithio-MPTTF-PTM Radical Dyad as a Potential Neutral Radical Conductor

“…Thus, the bistability of dyad 2 was only observed in the most polar solvent (i.e., DMF), as demonstrated by the presence of the intense band at 512 nm attributed to the anionic form of the PTM unit due to the formation of zwitterionic species. Moreover, solution of dyad 2 in DMF was ESR silent suggesting that the zwitterionic species formed diamagnetic dimers as it has been observed for similar TTF-PTM dyads [12,14,20]. Most of the absorption bands related to the TTF radical cation dimer are overlapped by the intense absorption band related to the PTM anion as it has been previously observed ( Figure S4) [22].…”

“…Subsequently, we evaluate the physical properties in solution of the radical dyad 2 that could be a neutral radical conductor in the solid state. In this direction, we have very recently reported the organic donor-acceptor (D-A) dyad 1 based on the non-planar and spin localized radical perchlorotriphenylmethyl (PTM) radical linked to a monopyrrolo-tetrathiafulvalene (MPTTF) unit that exhibited semiconducting behavior with high conductivity upon application of high pressure [12][13][14][15]. The origin of such conducting behavior was attributed to the increased electronic bandwidth W, thanks to short intermolecular interactions between the MPTTF and PTM subunits, and the decreasing of the Coulomb repulsion energy U due to the charge reorganization occurring at high pressure.…”