Noncovalent Control for Bottom-Up Assembly of Functional Supramolecular Wires

Abstract

Noncovalent bonds have been used to assemble stacks of pi-electron-rich moieties at a surface, generating a pathway for charge transport. The system is comprised of a tetrathiafulvalene (TTF) derivative incorporating two amide groups which fasten the relative orientations of the electroactive moieties in the supramolecular polymer that is formed at the surface of graphite in octanoic acid. Scanning tunneling microscopy (STM) combined with molecular mechanics calculations has been used to prove the structure of the wires, and theory, corroborated with STS experiments, predicts that they are promising superstructures for charge transport.

Electrochemistry and time dependent DFT study of a (vinylenedithio)-TTF derivative in different oxidation states

“…The compound can be immobilised on Pt surfaces but surface coverage values suggest that sparse monolayers are formed. From these data alone it is not possible to determine if the monolayer is formed on Pt via the nitrogen atom of the pyridine ring, monolayers of which have been reported by Forster et al [39], or whether the molecules stack parallel to the surface for example through -stacking, as has been shown for graphene and graphite surfaces [35]. TD-DFT calculations reveal a HOMO that is predominantly located on the TTF core and that the addition of pyridine rings does not affect the attractive oxidative properties of the TTF unit.…”

“…Non-covalent binding of TTF derivatives on graphite has also been reported where the molecule's core TTF unit has a strong interaction with the -system of the graphite surface; this allows the molecule to orientate parallel to the graphite surface through -interactions [35,36]. However, the addition of amide groups on the TTF core results in this unit orientating orthogonally to the graphite surface as opposed to in plane [35].…”

“…Stable redox chemistry in self-assembled monolayers of TTF derivatives have been reported by several groups including those of Bryce, Ward, Cooke, Sallé, Echegoyen and Stoddart, where the core TTF moiety is anchored to the surface using a surface active functional group such as an alkyl chain with a thiol end group on Au [13,14,[27][28][29][30], thioctic acid disulfide linkers on Au [31][32][33] and oxide-free hydrogen-terminated Si(1 0 0) surfaces [34]. Non-covalent binding of TTF derivatives on graphite has also been reported where the molecule's core TTF unit has a strong interaction with the -system of the graphite surface; this allows the molecule to orientate parallel to the graphite surface through -interactions [35,36]. However, the addition of amide groups on the TTF core results in this unit orientating orthogonally to the graphite surface as opposed to in plane [35].…”

Sub-50 nm positioning of organic compounds onto silicon oxide patterns fabricated by local oxidation nanolithography

“…Tetrathiafulvalene (TTF) derivatives are in turn, remarkable semiconductors for preparing devices as Field Effect Transistors [18][19][20][21][22] and the obtained results already point out the high potential of these materials, which can be easily procesed [23] and tailored synthesized. [24] Even though nanostructuration of TTF derivatives in different surfaces has been demonstrated, [25][26][27][28] potential applications of TTFs as component in circuitry do still require methods for precise nanoscale controlled position and/or manipulation of those molecules.…”

Charge Transport in Organic Semiconductors: A Multiscale Modeling

“…In this context, the work reported here addresses the impact of intermolecular vibrations in single crystals of anthracene (ANT) and perfluoropentacene on the electronic couplings and mobility values [62,63]. In the previous case, the force field calculations were exploited to depict the lattice dynamics; however, they also proved useful in modeling the packing of organic semiconductors into organized nanostructures, as illustrated in Section 1.3 focusing on the molecular packing of tetrathiafulvalene (TTF) derivatives and the resulting charge transport properties [64]. Since it is highly desirable to validate the structures provided by force field calculations, we introduce in Section 1.4 an original approach where X-ray diffraction spectra are generated on the basis of the calculated structures to be compared to corresponding experimental spectra; this is illustrated here for polythiophene chains incorporating thienothiophene units in order to discuss their hole transport properties [65].…”