Since 2,3-bis(n-decyloxy)anthracene (DDOA) is a good gelling agent for a large number of solvents including propylene carbonate (PC), the electrochemical properties of organogel electrolytes based on DDOA have been investigated. The presence of tetraalkylammonium salts in DDOA/PC gels is shown to preserve the three-dimensional network of DDOA fibers. In addition, at a given temperature, the conductivity is practically the same in the gel as in the corresponding solution with or without DDOA. The gelation temperature, T gel, is slightly affected by the presence and nature of the salt. Thus, at 1M salt concentration, T gel is increased by 9 °C with Et4NBF4 and decreased by 7 °C with Bu4NBF4, presumably because of a surfactant effect of the Bu4N+ cation. The electrochemical stability window of the liquid electrolyte is limited by the stability of DDOA, which displays the typical redox behavior of anthracene. However, in the gel state, DDOA is apparently protected within the fibers and the electrochemical stability extends up to 3 V. The performances of a DDOA gel electrolyte have been tested in a carbon double-layer capacitor.

The UV absorption spectra of 2,3-didecyloxyanthracene (DDOA) recorded in methanol, ethanol, 1-propanol, acetonitrile and methylcyclohexane reveal interesting features: they show a striking contrast between the isotropic solution and the gel state where, at ambient temperature, a fine structure appears with an apparent bathochromic shift (Dn % À700 cm À1 ), as observed in the solid state. Such an effect was mimicked by 2,3-dioxydi-(and -tri-) methyleneanthracenes in which the conformational mobility of the two juxtanuclear oxygen atoms is reduced in a manner similar to that assumed in the gel state. The fluorescence emission of DDOA (10 À5 M) at very low temperature exhibits a loss of fine structure and a bathochromic shift, for the gel state, in agreement with the presence of aggregates; the excitation spectra were found to be superimposable upon the absorption spectra of the isotropic and gel phases, respectively. Solvent screening for DDOA gelling ability has shown that the most efficient solvents are CH 3 OH and CH 3 CN. From the phase transition diagram (temperatures of gel setting, T gel , and gel melting, T m , versus concentration), thermodynamic parameters were derived: DH 0 gel /kJ mol À1 ¼ À70 (CH 3 OH), À66 (CH 3 CN); DS 0 gel /(J K À1 mol À1 ¼ À147 (CH 3 OH), À140 (CH 3 CN) and DG 0 gel /kJ mol À1 (at 300 K) % À26 (CH 3 OH), À24 (CH 3 CN). These parameters attest to the good stability of these gel systems. Finally, the influence of the chain length (n ¼ C 7 H 15 to C 12 H 25 ) on the efficiency of gel formation (or melting) was investigated in methanol, ethanol, acetonitrile and heptane. It emerges that, to form gels, n-decyl and n-undecyl were found to be the most suitable chains and methanol and ethanol the most efficient solvents. It should be noted that the ability to form gels in methanol at a concentration of 0.6 mM at ambient temperature qualifies DDOA as a supergelator.

No abstract