Persistent Mixed‐Valence [(TTF)₂]^+. Dyad of a Chiral Bis(binaphthol)–tetrathiafulvalene (TTF) Derivative

Abstract

Mixed-valence dyadic [(TTF)(2)](+*) (TTF=tetrathiafulvalene) species--the elementary building blocks of organic conductors--are usually too weakly associated to be observed in solution, unless covalently bound in dimers or physically constrained into a cage structure. We demonstrate here that a novel chiral tetrathiafulvalene functionalised with two 1,1'-binaphthol units (1) is able to associate in solution into persistent mixed-valence [(TTF)(2)](+*) dyadic moieties through a stereospecific recognition pattern. This redox active molecule exhibits different electrochemical and spectroscopic responses, as enantiopure RR, SS or meso isomers, a rare example of a chiral system in which different diastereoisomers do not exhibit the same electrochemical features, with a selective formation of the mixed-valence species in the enantiopure (RR)-1 or (SS)-1 isomers only, whereas the meso form does not show this association ability. A rationale for the selective self-association of the RR and SS enantiomers upon oxidation is provided, based on the different molecular geometries and accessibility of the TTF core toward the formation of the mixed-valence species.

Chiroptical inversion of a planar chiral redox-switchable rotaxane

“…38,[42][43][44][45][46][47][48][49][50] Apart from rotaxanes, TTF derivatives with covalently bound chiral substituents exhibited a chiroptical response to a change of their redox-state. [51][52][53][54][55][56][57] Hence, our switchable rotaxanes display ideal optoelectronic properties since they are air stable in their neutral and oxidised form and show a clear-cut optical output, 37 which is even visible by the naked eye.…”

Organische gemischtvalente Verbindungen: ein Spielplatz für Elektronen und Löcher

“…Diese TTF-Redoxzentren sind hingegen nicht kovalent miteinander verbunden und demzufolge keine MV-Verbindungen im hier verwendeten Sinn. [263,264] Auch wenn die meisten MV-Verbindungen mit schwefelhaltigen Redoxzentren TTF enthalten, gibt es eine Reihe von MV-Verbindungen mit anionischen Pentakis(thiophenyl)benzol-Redoxzentren (196 À -198 À , Schema 66). [265] Der Grad der elektronischen Kommunikation zwischen den Redoxzentren hängt stark von der Art der Brückeneinheit ab.…”

Tetrathiafulvalene‐[2.2]paracyclophanes: Synthesis, crystal structures, and chiroptical properties

“…A particularly useful electroactive unit to be introduced into chiral systems is tetrathiafulvalene (TTF), 14 as it has previously provided chiral conductors in which differences of conductivity have been observed between the enantiopure and racemic forms due either to structural disorder [15][16][17] or different packings. 20 While strategies based on stereogenic centers, [21][22][23][24][25][26] axial chirality, [27][28][29][30] helical [This article is part of the Special Issue: Proceedings 16th International Conference on Chiroptical Spectroscopy, Rennes France 2017. 20 While strategies based on stereogenic centers, [21][22][23][24][25][26] axial chirality, [27][28][29][30] helical [This article is part of the Special Issue: Proceedings 16th International Conference on Chiroptical Spectroscopy, Rennes France 2017.…”