Intramolecular Electron Transfer Mediated by a Tetrathiafulvalene Bridge in a Purely Organic Mixed‐Valence System

Gautier, Nicolas; Dumur, F.; Lloveras, Vega; Vidal-Gancedo, José; Veciana, Jaume; Rovira, Concepció; Hudhomme, Piétrick

doi:10.1002/ange.200250587

Cited by 57 publications

(70 citation statements)

References 39 publications

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“…This localization effect observed for the radical anion 1 ·-is in contrast to other fused A-D-A triads using a TTF as a bridge where the MV compounds have delocalized the unpaired electron at high temperatures. [40][41][42][43][44][45] However, in all these examples the molecules are almost planar and in our case the molecule has several degrees of conformational freedom. Also it is important to mention the influence of the different topologies of the possible isomers on the ease of the electron transfer as it has been previously studied.…”

mentioning

confidence: 66%

Three Redox States of a Diradical Acceptor–Donor–Acceptor Triad: Gating the Magnetic Coupling and the Electron Delocalization

Souto

Lloveras

Vela

et al. 2016

J. Phys. Chem. Lett.

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The diradical acceptor-donor-acceptor triad 1 ·· , based on two polychlorotriphenylmethyl (PTM) radicals connected through a tetrathiafulvalene(TTF)-vinylene bridge, has been synthesized. The generation of the mixed-valence radical anion, 1 ·-, and triradical cation species, 1 ···+ , obtained upon electrochemical reduction and oxidation, respectively, was monitored by optical and ESR spectroscopy. Interestingly, the modification of 2 electron delocalization and magnetic coupling was observed when the charged species were generated and the changes have been rationalized by theoretical calculations. TOC GRAPHICSIn the last few years, there is an increasing interest in the design and synthesis of novel organic materials exhibiting intramolecular electron transfer (IET) phenomena. Challenging are dyadic systems formed by donor (D) and acceptor (A) units connected by conjugated bridges due to their potential applications as molecular wires or switches. [1][2][3][4][5][6][7][8] Organic mixed-valence (MV) compounds containing at least two redox sites with two different oxidation states connected through a conjugated bridge are good examples for this kind of compounds. [9][10][11][12][13][14] On the other hand, research on organic molecules containing several stable radical centres linked through ferromagnetic coupling bridges have also received much attention during the past decades. [15][16][17][18][19][20][21][22] In fact, there are recent examples of diradical compounds that can switch the magnetic interaction between the radical centres by changing the chemical nature of the bridge. 19,20 Thus, switching the magnetic response of organic molecular materials through the application of an external stimulus is an interesting phenomenon since they mimic elemental electronic operations.In our group, we have recently reported an organic radical D-A dyad, based on the electron π-donor tetrathiafulvalene (TTF) connected to the electron acceptor 3 polychlorotriphenylmethyl (PTM) radical, that exhibits bistability in solution through the application of external stimuli such as the polarity of the solvent or temperature. Figure S1). DFT calculations show that E and Z isomers of 4 lie extremely close in energy (ca. 0.1 kcal/mol). In addition the computational analysis suggests that the cis configuration of the vinylene units is ca. 2 kcal/mol disfavoured with respect to the trans one (see Table S4). Finally, subsequent deprotonation of 4 with two equivalents of TBAOH and oxidation of corresponding dicarbanions using silver nitrate yield diradical 1 ·· (E + Z) in 71%, as a brownish powder.5 Scheme 1. Three-step synthesis of 1 ··. TBAOH = tetrabutylammonium hydroxide. showing an intense band at 385 nm, characteristic of PTM radical chromophores. The shoulders around 420 and 540 nm are attributed to the electronic conjugation of the unpaired electron into the π-framework. Regarding the low-energy region, the weak broad band that appears around 900 nm is assigned to the intramolecular charge transfer process from the e...

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confidence: 66%

Three Redox States of a Diradical Acceptor–Donor–Acceptor Triad: Gating the Magnetic Coupling and the Electron Delocalization

Souto

Lloveras

Vela

et al. 2016

J. Phys. Chem. Lett.

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“…Further, ⌬G ‡ and in Fig. 58 Thus ͑Q-TTF-Q͒ − is a class II compound in the Robin-Day classification, 59 which means that the coupling between the two charge-localized states Q − -TTF-Q and Q-TTF-Q − is not very strong. 11 The particular compound Q-TTF-Q is designed to study the electron conduction through TTF, an important unit in organic electronics.…”

Section: B Tetrathiafulvalene Diquinone "Q-ttf-q…mentioning

confidence: 98%

“…18 For a symmetric mixed-valence system, the driving force is zero. 58 Experiments show that on the electron spin resonance ͑ESR͒ time scale, the odd electron in the anion of Q-TTF-Q is localized on one particular Q group and undergoes intervalence ET. 1 are simply related by ⌬G ‡ = /4 when both diabatic curves are parabolas with the same curvature.…”

Section: B Tetrathiafulvalene Diquinone "Q-ttf-q…mentioning

confidence: 99%

Extracting electron transfer coupling elements from constrained density functional theory

Wu¹,

Voorhis²

2006

The Journal of Chemical Physics

302

396

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Constrained density functional theory (DFT) is a useful tool for studying electron transfer (ET) reactions. It can straightforwardly construct the charge-localized diabatic states and give a direct measure of the inner-sphere reorganization energy. In this work, a method is presented for calculating the electronic coupling matrix element (Hab) based on constrained DFT. This method completely avoids the use of ground-state DFT energies because they are known to irrationally predict fractional electron transfer in many cases. Instead it makes use of the constrained DFT energies and the Kohn-Sham wave functions for the diabatic states in a careful way. Test calculations on the Zn2+ and the benzene-Cl atom systems show that the new prescription yields reasonable agreement with the standard generalized Mulliken-Hush method. We then proceed to produce the diabatic and adiabatic potential energy curves along the reaction pathway for intervalence ET in the tetrathiafulvalene-diquinone (Q-TTF-Q) anion. While the unconstrained DFT curve has no reaction barrier and gives Hab approximately 17 kcal/mol, which qualitatively disagrees with experimental results, the Hab calculated from constrained DFT is about 3 kcalmol and the generated ground state has a barrier height of 1.70 kcal/mol, successfully predicting (Q-TTF-Q)- to be a class II mixed-valence compound.

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“…The acid-catalyzed condensation of 2 and the 2-thioxo-1,3-dithiole [16] gave molecular clip 3 in 83 % yield. The reaction of molecular clip 3 and the oligo(ethylene glycol) monomethyl ether tosylates 4 a-c under basic conditions afforded the molecular clips 5 a-c with tri-, di-, and mono(ethylene glycol) chains, respectively.…”

Section: Resultsmentioning

confidence: 98%

A Macrocycle/Molecular‐Clip Complex that Functions as a Quadruply Controllable Molecular Switch

Chiang

Cheng

Lin

et al. 2006

Chemistry A European J

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Herein, we report the synthesis of a molecular clip with TTF side-walls and its binding behavior towards electron-deficient guests, namely the formation of macrocycle/molecular-clip supramolecular complexes in solution. Four different sets of external stimuli--the K(+)/[2.2.2]cryptand, NH(4) (+)/Et(3)N and (p-BrPh)(3)NSbCl(6)/Zn pairs, and heating/cooling cycles-control the movement of this molecular switch between its threaded and unthreaded states and provide color changes that are observable by the naked eye. This macrocycle/molecular-clip complex system can be considered not only as a quadruple-use molecular switch, but can also be operated by three of these stimuli as a three-input molecular NOR-functioning logic gate that may be monitored by UV-visible spectroscopy.

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Intramolecular Electron Transfer Mediated by a Tetrathiafulvalene Bridge in a Purely Organic Mixed‐Valence System

Cited by 57 publications

References 39 publications

Three Redox States of a Diradical Acceptor–Donor–Acceptor Triad: Gating the Magnetic Coupling and the Electron Delocalization

Three Redox States of a Diradical Acceptor–Donor–Acceptor Triad: Gating the Magnetic Coupling and the Electron Delocalization

Extracting electron transfer coupling elements from constrained density functional theory

A Macrocycle/Molecular‐Clip Complex that Functions as a Quadruply Controllable Molecular Switch

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