Organogelators

There ai e noted the most convenient, simple and chip methods, which ensure the high quality of specimens and can be easily combined with different techniques for analytical pre-concentration of impurities. In particulaidy, it is proposed to make specimens in the form of gel, film or glass in the case of XRF analysis of concentrates obtained by low-temperature crystallization of aqueous solutions. One can prepai e film or organogel specimens from organic concentrates obtained by means of extraction of impurities by organic solvent. Techniques for XRF analysis of drinking, natural and wastewater using considered specimens ai e adduced. 

Under comparable conditions, the reaction rates of the octyl decanoate synthesis by chromobacterium viscosum lipase in AOT-based microemulsions or immobihzed in AOT-based organogels were similar [286,287],... 

Percolated microemulsions composed of biocompatible substances, such as some lecithin-based organogels, have been considered interesting vehicles for the delivery of drugs [288],... 

It has also been suggested that solubihzation of enzymes in organogels allows interesting reaction media to be realized since they facilitate enzyme reuse and easy product separation [281],... 

Ishi-i T, Shinkai S (2005) Dye-Based Organogels Stimuli-Responsive Soft Materials Based on One-Dimensional Self-Assembling Aromatic Dyes. 258 119-160... 

Ajayagosh, A. and Praveen, V.K. (2007) rt-Organogels of self-assembled p-phenylenevinylenes soft materials with distinct size, shape, and functions. Accounts of Chemical Research, 2007,40 (8), 644-656. 

S.-i. Kawano, S.-i. Tamaru, N. Fujita, and S. Shinkai, Sol-gel polycondensation of tetraethyl orthosilicate (TEOS) in sugar-based porphyrin organogels Inorganic conversion of a sugar-directed porphyrinic fiber library through sol-gel transcription processes, Chem. Eur. J., 10 (2004) 343-351. 

His research interests deal with the chemistry of cyclopropane derivatives, 1,3-dipolar cycloadditions, synthesis of natural compounds and biologically active analogues. Recently, the research activity is also dedicated to synthetic studies for the production of new materials light-harvesting antenna systems and functionalized organogelators. 

Fig. 5.1 Template (organogelator) synthesis of metal oxide nanotubes.

Nakamura and Matsui [71] prepared silica nanotubes as a spin-off product of sol-gel synthesis wherein tetraethylorthosilicate (TEOS) was hydrolyzed in the presence of ammonia and D, L-tartaric acid. Ono et al. [72] showed that certain cholesterol derivatives can gelate tetraethyl orthosilicate (TEOS) to obtain tubular silica structures. Using cholesterol based gelators nanotubes of transition metal (Ti, V and Ta) oxides can also be prepared. The organogelators used in these processes are chiral diamino... 

Kobayashi S, Hamasaki N, Suzuki M, Kimura N, Shirai H, Hanabusa K (2002) Preparation of helical transition-metal Oxide tubes using organogelators as structure-directing agents. J Am Chem Soc 124 6550-6551... 

Jung JH, Ono Y, Hanabusa K, Shinkai S (2000) Creation of both right-handed and left-handed silica structures by sol-gel transcription of organogel fibers comprised of chiral diaminocyclohexane derivative. J Am Chem Soc 122 5008-5009... 

Yount et al. (2005) reported the formation of organogels using poly(vinylpyridine) (PVP) and ditopic metallopincer cross-linkers. This study provided particularly pertinent information on the dynamic elements of MSPs and elegantly demonstrated how they control the material s properties. PVP dissolved in dimethylsulfoxide (DMSO) is cross-linked with either bis-Pd - (18a) or Pt -pincer compounds (18b, Fig. 7.13 Yount et al. 2005). Addition of 5% 18a -Pd to a PVP solution results in a viscous material (77 = 6.7 Pa s), whereas the corresponding PVP 18b Pd is a gel (77 = 550 Pa s). Changing R from methyl to ethyl does not affect the thermodynamics of the pyridine/Pd interaction however, the rate of exchange decreases by approximately 2 orders of magnitude. Further studies on these materials and their... 

Das AK, Bose PP, Drew MGB, Baneijee A. The role of protecting groups in the formation of organogels through a nano-fibrillar network formed by self-assembling terminally protected tripeptides. Tetrahedron 2007 63 7432-7442. 

Simmons B, Li CS, John VT, McPherson GL, Taylor C, Schwartz DK, Maskos K (2002) Spatial compartmentalization of nanoparticles into strands of a self-assembled organogel. Nano Lett 2 1037-1042... 

Figure 9.14 The simple addition of a minimal amount of water to a hydrocarbon solution of lecithin (or other phospholipids) brings about the formation of an organogel. (Adapted from Scartazzini and Luisi, 1988.)...

Make an organogel with lecithin and entrap an enzyme in the aqueous gel compartment. Can you make in this way a column for enzymatically induced chemical transformations ... 

Luisi, P. L., Scartazzini, R., Haering, G., and Schurtenberger, P. (1990). Organogels from water-in-oil microemulsions. Colloid Polymer ScL, 268, 356-74. 

Willimann, H. and Luisi, P. L. (1991). Lecithin organogels as matrix for the transdermal transport of drugs. Biochem. Biophys. Res. Commun., 177, 897-900. 

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