Monitoring the formation of TTF dimers by Na+ complexation

Lyskawa, Joël; Sallé, Marc; Balandier, Jean‐Yves; Derf, Franck Le; Levillain, Eric; Allain, Magali; Viel, Pascal; Palacin, Serge

doi:10.1039/b518275a

Cited by 97 publications

(49 citation statements)

References 34 publications

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“…Finally, we attempted chemical oxidation of 4a, using either NOSbF 6 [13] or PhI(OAc) 2 /HBF 4 . [14] While both these oxidizing agents did provide access to the radical cation species as judged from the absorption spectrum, the species decomposed within 10 min in the first case and during light excitation in the second.…”

Section: Resultsmentioning

confidence: 99%

Redox‐Controlled Dihydroazulene‐Vinylheptafulvene Photoswitch Incorporating Tetrathiafulvalene

et al. 2009

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A derivative of dihydroazulene (DHA) incorporating the redox‐active unit tetrathiafulvalene (TTF) was prepared and investigated for its ability to undergo light‐induced conversion to the vinylheptafulvene (VHF) isomer. The absorption properties of the oxidized species were investigated by spectroelectrochemistry. Photoswitching was investigated as a function of the redox‐state of the TTF unit, i.e., as neutral or as radical cation, and it was found that photoswitching occurred more than twice as efficiently for the neutral species as for the radical cation species, while the thermal back reaction was unaffected. In addition, we have found that the TTF–DHA conjugate is readily converted to an azulene–TTF donor–acceptor conjugate upon treatment with strong base.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

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Section: Resultsmentioning

confidence: 99%

Redox‐Controlled Dihydroazulene‐Vinylheptafulvene Photoswitch Incorporating Tetrathiafulvalene

et al. 2009

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“…For example, when two TTF units are incorporated into flexible crown ethers, the high local concentration of TTF units allows the electrochemical generation of both the mixed-valence and radical cation dimers in reasonable quantities [30]. Sallé and co-workers [31] have utilized a calix [4]arene, doubly functionalized with TTF units on opposite sides of its lower face, to encourage the formation of both mixed-valence and radical cation TTF dimers. The flexibility of the calix [4]arene allows the TTF units to adopt the appropriate relative orientations for association in each state.…”

Section: Stabilization Through Covalent Intermediacymentioning

confidence: 99%

Molecular recognition and switching via radical dimerization

Spruell

2010

Pure and Applied Chemistry

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This article highlights the emerging use of the interactions of radical π-dimers to drive both molecular recognition and switching processes within supramolecular systems and mechanically interlocked molecular architectures. The enhanced stability experienced by dimers of radical cation species when encapsulated, as compared to when they are free in solution, is driving their useful incorporation into functional systems. The redox stimulation used in the production of radical cation species provides the ideal trigger for molecular switching events. Moreover, the nature and strength of the radical dimerization events introduces a completely novel recognition motif within supramolecular and mechanically interlocked molecular systems, complementing well-established techniques and enabling new research opportunities to blossom.atom-centered radical dimerization and, thereafter, I will highlight the recent advances that have led to the use of this unusual class of bonding as a practical and fully orthogonal molecular recognition motif. EARLY EXAMPLES OF RADICAL DIMERSThe π-dimerization of planar radical species was first observed in the middle of the last century [1][2][3][4][5][6] in both the solid state and in concentrated solutions at low temperatures. Under these conditions, equilibria are established between two paramagnetic free radical species and a diamagnetic dimer, most often with a particular equilibrium favoring the dissociated, non-dimer state. These types of dimeric associations have been observed for a whole range of different types of planar radical species, varying in both the size of the planar systems and the charges of the dimer components. Both radical anions and cations, as well as neutral free radicals, have been observed to associate with one another in this manner. Some of the most common radical π-dimeric species are illustrated in Fig. 1, including the associated radical anions of singly reduced tetracyanoethylene (TCNE) [7], and the neutral radical pairs of phenalenyl [8], as well as the radical cation π-dimers of singly oxidized tetrathiafulvalene (TTF) [9,10] and singly reduced bipyridium (BIPY 2+ ) units [11,12].The π-association of phenalenyl has received much attention [8,13] as a model for the radical dimerization of large planar π-systems. The persistent (i.e., stable) neutral radical is readily generated during the oxidation of phenylene. Its stability can be attributed to the delocalization of the radical throughout the fused polycyclic structure, its character residing predominately on 6 of the 12 peripheral carbons [14,15]. When substituted with bulky side groups to prevent σ-binding (the radical-radical coupling to form a traditional covalent sigma (σ) bond), π-dimer formation is observed in concentrated deoxygenated solutions. Moreover, this π-dimer is comprised of two perfectly overlapping delocalized singly occupied molecular orbitals (SOMOs) on each phenalenyl unit in such a way that the two formal free radical electrons pair to form what has been described as a two-electron...

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“…Tetrathiafulvalene (TTF)‐based charge transfer complexes have been widely known to form crystals consisting of segregated stacks of TTF and acceptors,1–11 and a variety of TTF derivatives can be used as a building block for constructing self‐assembling structures 12–18. TTF radical cation can work as an acceptor, and the mixture of neutral TTF and TTF radical cation can form conductive nanofibers containing the mixed‐valence state 19–38. The casting films composed of the random network of the TTF nanofibers prepared from the mixture solutions of neutral TTF and TTF radical cation with organic acid anions can show electrical conductivity as a semiconductor (<10 –2 S/cm), and they have attracted interests as a candidate for nanostructured conducting materials or molecular machines 22–30.…”

Section: Introductionmentioning

confidence: 99%

Pilot clinical trial of localized concurrent chemoradiation therapy for locally advanced hepatocellular carcinoma with portal vein thrombosis

Han

Seong

Kim

et al. 2008

Cancer

144

168

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BACKGROUND.Patients with advanced hepatocellular carcinoma (HCC) with portal vein thrombosis (PVT) have a particularly grave prognosis. In the current study, an attempt was made to localize chemoradiation therapy (CCRT) followed by hepatic arterial infusion chemotherapy (HAIC) in patients with locally advanced HCC with PVT and good reserve liver function. The objective of the current study was to evaluate the therapeutic effect of localized CCRT followed by HAIC as a new treatment modality for these patients.METHODS.Between January 1998 and December 2003, 40 patients were recruited. Concurrent regional chemotherapy using an intra‐arterial implanted port plus localized external beam radiotherapy was performed with a total of 45 gray (Gy) over 5 weeks with conventional fractionation and hepatic arterial infusion of 5‐fluorouracil (5‐FU), which was administered during the first and fifth weeks of radiotherapy. One month after localized CCRT, HAIC with 5‐FU and cisplatin was administered every 4 weeks.RESULTS.One month after localized CCRT, an objective response was observed on the intention‐to‐treat analysis in 18 of 40 patients (45%). The actuarial 3‐year overall survival rate was 24.1% and the median survival time was 13.1 months from the start of radiation treatment. Responders after localized CCRT demonstrated significantly better survival (P = .033) than nonresponders.CONCLUSIONS.The substantial response rate as well as median survival time noted in the current study encourages the use of this new approach in patients with locally advanced HCC with PVT. Cancer 2008. © 2008 American Cancer Society.

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Monitoring the formation of TTF dimers by Na+ complexation

Abstract: The formation of the two dimeric species [(TTF)2]+* and (TTF+*)2 can be monitored by complexation of Na+ on a calix[4]arene-TTF assembly.

Cited by 97 publications

References 34 publications

Redox‐Controlled Dihydroazulene‐Vinylheptafulvene Photoswitch Incorporating Tetrathiafulvalene

Redox‐Controlled Dihydroazulene‐Vinylheptafulvene Photoswitch Incorporating Tetrathiafulvalene

Molecular recognition and switching via radical dimerization

Pilot clinical trial of localized concurrent chemoradiation therapy for locally advanced hepatocellular carcinoma with portal vein thrombosis

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