6267-14-7Relevant academic research and scientific papers
Linearly extended tetrathiafulvalene analogues with fused thiophene units as π-conjugated spacers
Leriche, Philippe,Raimundo, Jean-Manuel,Turbiez, Mathieu,Monroche, Vincent,Allain, Magali,Sauvage, Francois-Xavier,Roncali, Jean,Frere, Pierre,Skabara, Peter J.
, p. 1324 - 1332 (2007/10/03)
A new series of linearly extended tetrathiafulvalene analogues with thienothiophene and dithienothiophene π-conjugating spacers has been synthesized. Electronic absorption spectra present a vibronic fine structure typical for rigid conjugated systems. Investigation of the electrochemical behaviour of the new donors by cyclic voltammetry reveals the successive generation of stable radical cation and dication species. The crystallographic structure of a single crystal of a dication salt of TT-TTF(ClO4)2 has been analysed by X-ray diffraction. The dication presents a syn conformation stabilised by S...S intramolecular interactions. The quinoid structure expected for the spacer for the +2 oxidation state is clearly revealed by the bond lengths.
Electrophilic Aromatic Substitution. Part 31. Partial Rate Factors for Detritiation of Thienothiophen and Thienothiophen: Weak Hydrogen Bonding to Sulphur in Trifluoroacetic Acid
Archer, William J.,Roger, Taylor
, p. 295 - 300 (2007/10/02)
Thienothiophen (I) and thienothiophen (II), specifically labelled with tritium in each position have been prepared, and their rates of protiodetritiation measured along with that for thiophen in either pure trifluoroacetic acid, or mixtures of trifluoroacetic acid and acetic acid, all at 70 deg C.The dependence of exchange rate coefficients upon acid composition indicates that the ring sulphur is hydrogen bonded, and to an extent which depends upon the number of sulphur atoms in the heterocycle.Partial rate factors for detritiation of the non-hydrogen-bonded compounds are calculated as follows (position and compound in parentheses): 7.18E8 ; 6.83E8 ; 9.75E7 (2-thiophen); 7.59E5 ; 5.54E5 ; 7.84E4 (3-thiophen), the corresponding ?+-values being -1.012, -1.010, -0.913, -0.672, -0.656, and -0.560.The results, taken along with those for acylation and chlorination show that (II) is more polarisable than (I), so that these compounds, like all other ?-excessive heterocycles previously examined, are unsuitable for rigorous application of the Extended Selectivity Relationship.Annelation of thiophen by thiophen produces a comparable change in reactivities of the α- and β-positions in contrast to annelation by benzene, where the high resonance energy of benzene plays a crucial role in raising the reactivity of the β-position, relative to that of the α-position.
