Electronic, structural and spectroscopic properties of Langmuir-Blodgett films of (o-hexadecylthiocarboxy)tetrathiafulvalene (HDTTTF)

Dhindsa, A. S.; Song, Yi Ping; Badyal, J. P. S.; Bryce, Martin R.; Lvov, Y.; Petty, Michael C.; Yarwood, J.

doi:10.1021/cm00021a042

Cited by 30 publications

(19 citation statements)

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“…Within such TTF derivatives, as reported by Bryce [28], an internal charge transfer (ICT) between the TTF and the EWG moieties increases the hydrophilicity of the TTF head groups and facilitates monolayer formation on the water surface for the preparation of Langmuir–Blodgett films. The structural and electronic properties of a series of ester [15], thioester [29–30], tertiary amide and thioamide [12] TTF derivatives have been then rationalized, based on: (i) the sizeable contribution of the mesomeric form B (Scheme 1) and, (ii) an ICT from the TTF-based HOMO to the EWG-based LUMO, also observed in primary and secondary amides [10]. Another consequence of the contribution of the B form is the shortening of the C–S bond opposite to the EWG, experimentally observed in the structures of such molecules.…”

Section: Introductionmentioning

confidence: 99%

Trifluoromethyl-substituted tetrathiafulvalenes

Jeannin¹,

Barrière²,

Fourmigué³

2015

Beilstein J. Org. Chem.

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SummaryA series of tetrathiafulvalenes functionalized with one or two trifluoromethyl electron-withdrawing groups (EWG) is obtained by phosphite coupling involving CF3-substituted 1,3-dithiole-2-one derivatives. The relative effects of the EWG such as CF3, CO2Me and CN on the TTF core were investigated from a combination of structural, electrochemical, spectrochemical and theoretical investigations. Electrochemical data confirm the good correlations between the first oxidation potential of the TTF derivatives and the σmeta Hammet parameter, thus in the order CO2Me < CF3 < CN, indicating that, in any case, the mesomeric effect of the substituents is limited. Besides, crystal structure determinations show that the deformation of the unsymmetrically substituted dithiole rings, when bearing one, or two different EWG, and attributed to the mesomeric effect of ester or nitrile groups, is not notably modified or counter-balanced by the introduction of a neighboring trifluoromethyl group. DFT calculations confirm these observations and also show that the low energy HOMO–LUMO absorption band found in nitrile or ester-substituted TTFs is not found in TTF-CF3, where, as in TTF itself, the low energy absorption band is essentially attributable to a HOMO→LUMO + 1 transition. Despite relatively high oxidation potentials, these donor molecules with CF3 EWG can be involved in charge transfer complexes or cation radical salts, as reported here for the CF3-subsituted EDT-TTF donor molecule. A neutral charge transfer complex with TCNQ, (EDT-TTF-CF3)2(TCNQ) was isolated and characterized through alternated stacks of EDT-TTF-CF3 dimers and TCNQ in the solid state. A radical cation salt of EDT-TTF-CF3 is also obtained upon electrocrystallisation in the presence of the FeCl4 − anion. In this salt, formulated as (EDT-TTF-CF3)(FeCl4), the (EDT-TTF-CF3)+• radical cations are associated two-by-two into centrosymmetric dyads with a strong pairing of the radical species in a singlet state.

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Section: Introductionmentioning

confidence: 99%

Trifluoromethyl-substituted tetrathiafulvalenes

Jeannin¹,

Barrière²,

Fourmigué³

2015

Beilstein J. Org. Chem.

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“…Two different states of iodine can be disclosed by deconvolution of the spectra. The contribution at 618.63 eV may refer to isolated I − iodide ions and the one at 620.43 eV to I 3 − species, as has been reported in previous studies on iodine‐doped TTF species,66, 67 and also different metal iodides are reported to exhibit comparable binding energies 68. Yet in other studies on iodine‐doped polymers (among others a poly(thiophene)—chemically similar to the system presented here) an almost identical peak profile as obtained here for TTFCMP .+ ‐I n − has been assigned to I 3 − (618.83 eV) and I 5 − (620.43 eV) 69.…”

Section: Introductionmentioning

confidence: 64%

A Tetrathiafulvalene (TTF)‐Conjugated Microporous Polymer Network

Bildirir

Paraknowitsch

Thomas

2014

Chemistry A European J

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Conjugated microporous polymer networks have been prepared from the strong electron donor tetrathiafulvalene (TTF) and 1,3,5-triethynylbenzene (TEB) by using the Sonogashira-Hagihara cross-coupling reaction. Optimization of reaction conditions yields polymers with surface areas of up to 434 m(2) g(-1) . The strong electron-donating properties of the network can be proven by iodine exposure. Structural and electronic changes due to formation of the charge-transfer salt from TTFs in the porous network and iodine within the pores are investigated.

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“…Obviously we have to admit that an oxidation process takes place at any step in the LB film preparation, specifically at the air-water interface or at the air-water-substrate interface. It is well known (3,19,(51)(52)(53) that some reactions which do not take place in the bulk aqueous phase may become possible at the air-water or monolayer-subphase interface and this is the case we are now facing. While solutions of LiTCNQ are stable for several weeks and they present a slow rate of degradation several hours are enough to induce an oxidation process at the air-water interface.…”

Section: Discussionmentioning

confidence: 98%