- Synthesis and characteristics of a nonaggregating tris(tetrathiafulvaleno) dodecadehydro[18]annulene
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A new tris(tetrathiafulvaleno)dodecadehydro[18]annulene with six peripheral n-hexyl substituents was prepared by oxidative Glaser-Hay cyclization of a corresponding diethynylated tetrathiafulvalene (TTF) precursor. The electronic properties of the neutral and oxidized species were studied by both UV/Vis absorption spectroscopy and electrochemistry. From these studies, it transpires that the strongly violet-colored macrocycle does not aggregate in solution to any significant degree, which was confirmed by 1H NMR spectroscopy. This reluctance towards aggregation contrasts that observed for related TTF-annulenes containing other peripheral substitutents. Oxidation of the TTF-annulene occurs in two three-electron steps as inferred from both the peak amplitudes and the spectroelectrochemical study. We find that the tris(TTF)-fused dehydro[18]annulene is more difficult to oxidize (by + 0.20 V) than the silyl-protected diethynylated mono-TTF precursor. In contrast, the first vertical ionization energy calculated at the B3LYP/6-311 + G(2d,p) level for the parent tris(TTF)-fused dehydro[18]annulene devoid of peripheral hexyl substituents is in fact lower (by 0.44 eV). Moreover, the surface morphology of 1d drop-cast on a mica substrate was investigated by atomic force microscopy (AFM). Crystalline domains with slightly different orientations were observed. The thickness of individual layers seen in the crystalline domains and the thickness of a monolayer obtained from a very dilute solution were determined to 1.8-1.9 nm. This thickness corresponds to the diameter of the macrocycle and the layers seen in the film are apparently formed when the molecules stack in the horizontal direction relative to the substrate.
- Andersson, Asbjorn Sune,Kilsa, Kristine,Hassenkam, Tue,Gisselbrecht, Jean-Paul,Boudon, Corinne,Gross, Maurice,Nielsen, Mogens Brondsted,Diederich, Francois
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- Acetylenic tetrathiafulvalene scaffolds - Intramolecular charge-transfer molecules
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Two tetrathiafulvalene-functionalized acetylenic scaffolds were synthesized by Glaser-Hay and Sonogashira coupling reactions; the one scaffold was based on a central dehydroannulene core and the other on a tetraethynylethene core. Peripheral propyl groups on the tetrathiafulvalenes ascertained solubility. The compounds are strong donor-acceptor chromophores and exhibit characteristic charge-transfer absorptions according to UV/VIS absorption spectroscopy. Furthermore, the redox properties were investigated by cyclic and differential-pulse voltammetries. The experiments allow for a direct comparison between the acceptor strengths of the two acetylenic cores, and the conclusions are supported by electron-affinity calculations. Copyright
- Lincke, Kasper,Christensen, Mikkel Andreas,Diederich, Francois,Nielsen, Mogens Brondsted
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- Tetrathiafulvalene- and dithiafulvene-substituted mesitylenes, new π-donor molecules with 3-fold symmetry and the formation of an unprecedented new class of electroactive polymers
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Novel π-donor molecules with 3-fold symmetry are built on the 1,3,5-benzene core, substituted with three identical moieties, i.e. -CH=CH(TTF) (8) (TTF = tetrathiafulvalene), -CH2S((TTF)Me3) (9), 1,4-dithiafulven-6-yl (10a,b), and 6-methyl-1,4-dithiafulven-6-yl (11a,b). Cyclic voltammetry experiments demonstrate that oxidation of 10a,b gives rise to the precipitation of an electroactive polymer on the electrode, while 9 can be reversibly oxidized to 93+ and 96+. Electrocrystallization of 9 in the presence of TBA2(Mo6Cl14) affords crystals of (92+)·Mo6Cl142-, whose magnetic properties are investigated by EPR. 10a crystallizes in the monoclinic system, space group P21/c, with a = 3.986(1) A?, b = 21.312(2) A?, c = 20.473(2) A?, β = 94.24(1)°, and Z = 4. 11a crystallizes in the monoclinic system, space group P21/a, with a = 10.919(4) A?, b = 17.175(2) A?, c = 11.481(1) A?, β = 97.86(2)°, and Z = 4. Columns of planar molecules of 10a are exquisitely interlocked to create a dense (dcalcd = 1.61 g cm-3) solid whereas no stacking pattern is observed in the structure of the nonplanar, puckered molecule 11a (dcalcd = 1.44 g cm-3). MO calculations demonstrate that, because of their meta orientation, the three dithiolyidene fragments in 10a and 11a are nearly independent.
- Fourmigué, Marc,Johannsen, Ib,Boubekeur, Kamal,Nelson, Catherine,Batail, Patrick
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p. 3752 - 3759
(2007/10/02)
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- Highly Conjugated ?-Electron Donors for Organic Metals: Synthesis and Redox Chemistry of New 1,3-Dithiole and 1,3-Selenathiole Derivatives
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The bis(1,3-dithiolium) dication salts 8a-c have been synthesised in three steps (31-51percent overall yields) starting from 1,4-bis(bromomethyl)naphthalene, 9,10-bis(chloromethyl)anthracene and 4,4'-bis(chloromethyl)biphenyl, respectively.The bis(halogenomethyl) compounds 5 were converted into the dipiperidiniumbis(dithiocarboxylate) salts 6, which on alkylation with 3-chlorobutan-2-one yielded bis(dithioesters) 7; cyclisation of 7 occurred on treatment with concentrated sulphuric acid to give dication salts 8.Dimethyl 1,3-dithiol-2-ylphosphonate 20, dimethyl 4,5-dimethyl-1,3-dithiol-2-ylphosphonate 21 and dimethyl 1,3-selenathiol-2-ylphosphonate 22 were treated with butyllithium in the presence of a range of carbonyl compounds and quinones, e.g., cyclopentanone, cyclohexanone, benzophenone, acetophenone, benzaldehyde, thioxanthen-9-one, anthraquinone, bianthrone and naphthacene-5,12-quinone to yield Wittig-Horner products, e.g., alkenes 26-34 and the anthracenediylidene derivatives 35, 36, 40-43 and 53.Unsymmetrical derivatives 37-39 were prepared in two steps as follows: anthrone reacted with 2-methylthio-1,3-dithiolium iodides 45 and 46 in pyridine-acetic acid to yield ketones 48 and 49 which were then treated with the Wittig-Horner reagents 23-25.Cyclic voltammetric data for the new tetrathiafulvalene, selenatrithiafulvalene and diselenadithiafulvalene derivatives 35-43 and 53, show that these systems undergo two-electron redox behaviour which is observed as a single wave.Complexes of these donors with electron acceptors, e.g. 7,7,8,8-tetracyano-p-quinodimethane (TCNQ), have been obtained, some of which are organic semiconductors.
- Moore, Adrian J.,Bryce, Martin R.
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p. 157 - 168
(2007/10/02)
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