max.,~inin. residual elccti-on density: 0.64, -0 3 2 eA -3 . Crqst;illogr;iphic data (excluding structure factors) for the structure aepoi-ted in this paper have been deposited with the Cambridge Crystallographic Data Centre as supplementary pnhlication no. CCDC-179-63. Cope5 o l tho data can be ohtaincd l'ree of chnrge on application to The Director. CCDC. 12 Union Ro;td.Cambridge CB2 IEZ, U K (fax: Int. code +(1223) 336-1133: e-mail:
Quasi-solid-state dye-sensitized solar cells were fabricated using low-molecular-weight gelators. They showed
comparable photoenergy conversion efficiencies to the liquid cell at high illumination intensity up to AM 1.5
(1 sun). Conductivity measurements of the electrolyte phases revealed that the gelation does not affect the
conductivity of the electrolyte and that the conductivity increased with an increase of iodine in both gel
electrolytes and liquid electrolyte. The formation of polyiodide ions, such as I3
- and I5
-, caused by addition
of iodine was confirmed by Raman spectroscopic measurement. The self-diffusion of iodide species in the
gel electrolyte was found about a quarter of that of I- in acetonitrile. The formation of less-mobile polyiodide
ions in electrolyte increased the conductivity in the mesoporous phase, which should be rationalized as due
to the Grotthuss-type electron exchange mechanism caused by rather packed polyiodide species in the
electrolytes. The optimized quasi-solid-state cell showed the values of 0.67 V for open-circuit voltage, 12.8
mA cm-2 for short-circuit photocurrent density, and 5.91% for photoenergy conversion efficiency under AM
1.5 irradiation with higher durability.
We prepared novel transition-metal (Ti, Ta, V) oxide fibers with chiral, helical, and nanotubular structures. The nanostructured metal oxide materials were provided by the sol-gel polymerization of metal alkoxides using chiral self-assemblies of organogelators as structure-directing agents. The chiral structures of the metal oxide fibers can be created by the formation of chiral self-assemblies constructed by organogelators and the transcription of the organogel superstructure into metal oxides.
Cyclo(l-beta-3,7-dimethyloctylasparaginyl-L-phenylalanyl) (1) and cyclo(L-beta-2-ethylhexylasparaginyl-L-phenylalanyl) (2), prepared from L-asparaginyl-L-phenylalanine methyl ester, have been found to be specialist gelators for ionic liquids. They can gel a wide variety of ionic liquids, including imizazolium, pyridinium, pyrazolidinium, piperidinium, morpholinium, and ammonium salts. The mean minimum gel concentrations (MGCs) necessary to make gels at 25 degrees C were determined for ionic liquids. The gel strength increased at a rate nearly proportional to the concentration of added gelator. The strength of the transparent gel of 1-butylpyridinium tetrafluoroborate ([C(4)py]BF(4)), prepared at a concentration of 60 g L(-1) (gelator 1/[C(4)py]BF(4)), was ca. 1500 g cm(-2). FT-IR spectroscopy indicated that a driving force for gelation was intermolecular hydrogen bonding between amides and that the phase transition from gel to liquid upon heating was brought about by the collapse of hydrogen bonding. The gels formed from ionic liquids were very thermally stable; no melting occurs up to 140 degrees C when the gels were prepared at a concentration of 70 g L(-1) (gelator/ionic liquid). The ionic conductivities of the gels were nearly the same as those of pure ionic liquids. The gelator had electrochemical stability and a wide electrochemical window. When the gels were prepared from ionic liquids containing propylene carbonate, the ionic conductivities of the resulting gels increased to levels rather higher than those of pure ionic liquids. The gelators also gelled ionic liquids containing supporting electrolytes.
trans-(1R,2R)-1,2-Cyclohexanedi(11-aminocarbonylundecylpyridinium) hexafluorophosphate (1) was synthesized. The sol−gel polymerization of Ti[OCH(CH3)2]4 using compound 1 as a self-assembled template afforded fibrous TiO2 materials with a “macaroni”-like structure. The unique structure of TiO2 could be created by the formation of a fibrous self-assembled aggregate and electrostatic interaction between anionic titania species and cationic 1 under basic conditions.
Using N-carbobenzyloxy-L-isoleucylaminooctadecane as a low molecular weight gelator for polar solvents, organogel electrolytes were prepared from supporting electrolyte and a polar solvent such as DMF, DMSO, and PC by physical gelation. The ionic conductivity of the prepared organogel electrolytes decreased very slightly with increasing concentration of gelator, while the gel strength drastically increased with increasing concentration. The organogel prepared from DMF exhibited relatively high ionic conductivity, interpreted due to the high mobility of carrier ions in the low-viscosity DMF. Arrhenius plots of ionic conductivities of organogel electrolytes indicate that the behavior of supporting electrolytes in the organogels is essentially similar to that in the isotropic solution, and the ionic mobility of supporting electrolytes is scarcely affected by the gelator molecules. The optimal concentration of supporting electrolytes in organogel electrolytes to achieve both high conductivity and high gel strength was 0.05-0.2 M. The addition of PEG to organogel electrolytes markedly raised the gel strength without decreasing ionic conductivity.
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