Cyclohexane bis-urea compounds for the gelation of water and aqueous solutions. 2005

Maaike de Loos, and Arianna Friggeri, and Jan van Esch, and Richard M Kellogg, and Ben L Feringa
Department of Organic and Molecular Inorganic Chemistry, Stratingh Institute, University of Groningen, Nijenborgh 4, 9747 AG, Groningen, The Netherlands.

A new class of efficient hydrogelators has been developed by a simple modification of the peripheral substituents of cyclohexane bis-urea organogelators with hydrophilic hydroxy or amino functionalities. These bis-urea hydrogelators were synthesised in two or three steps using an alternative procedure to the common isocyanate method. Gelation was obtained with organic solvents, water and strongly basic aqueous solutions like 25% ammonia. Hydrogelation was found to depend on a delicate balance between the hydrophobicity of the alkyl chains, hydrophilicity of the terminal substituents and the enantiomeric purity of the compound. The hydrogels consisted of a network of fibers, in which all urea groups are involved in intermolecular hydrogen bonding. Most likely, gelation is driven by hydrophobic interactions of the methylene units, whereas hydrogen bond formation between the urea groups provides the necessary anisotropy of the aggregation and the high thermal stability of the gels.

UI MeSH Term Description Entries
D003510 Cyclohexanes Six-carbon alicyclic hydrocarbons.
D005782 Gels Colloids with a solid continuous phase and liquid as the dispersed phase; gels may be unstable when, due to temperature or other cause, the solid phase liquefies; the resulting colloid is called a sol.
D006863 Hydrogen-Ion Concentration The normality of a solution with respect to HYDROGEN ions; H+. It is related to acidity measurements in most cases by pH pH,Concentration, Hydrogen-Ion,Concentrations, Hydrogen-Ion,Hydrogen Ion Concentration,Hydrogen-Ion Concentrations
D012996 Solutions The homogeneous mixtures formed by the mixing of a solid, liquid, or gaseous substance (solute) with a liquid (the solvent), from which the dissolved substances can be recovered by physical processes. (From Grant & Hackh's Chemical Dictionary, 5th ed) Solution
D012997 Solvents Liquids that dissolve other substances (solutes), generally solids, without any change in chemical composition, as, water containing sugar. (Grant & Hackh's Chemical Dictionary, 5th ed) Solvent
D014508 Urea A compound formed in the liver from ammonia produced by the deamination of amino acids. It is the principal end product of protein catabolism and constitutes about one half of the total urinary solids. Basodexan,Carbamide,Carmol
D014867 Water A clear, odorless, tasteless liquid that is essential for most animal and plant life and is an excellent solvent for many substances. The chemical formula is hydrogen oxide (H2O). (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed) Hydrogen Oxide
D017550 Spectroscopy, Fourier Transform Infrared A spectroscopic technique in which a range of wavelengths is presented simultaneously with an interferometer and the spectrum is mathematically derived from the pattern thus obtained. FTIR,Fourier Transform Infrared Spectroscopy,Spectroscopy, Infrared, Fourier Transform
D046529 Microscopy, Electron, Transmission Electron microscopy in which the ELECTRONS or their reaction products that pass down through the specimen are imaged below the plane of the specimen. Electron Diffraction Microscopy,Electron Microscopy, Transmission,Microscopy, Electron Diffraction,Transmission Electron Microscopy,Diffraction Microscopy, Electron,Microscopy, Transmission Electron
D021241 Spectrometry, Mass, Electrospray Ionization A mass spectrometry technique used for analysis of nonvolatile compounds such as proteins and macromolecules. The technique involves preparing electrically charged droplets from analyte molecules dissolved in solvent. The electrically charged droplets enter a vacuum chamber where the solvent is evaporated. Evaporation of solvent reduces the droplet size, thereby increasing the coulombic repulsion within the droplet. As the charged droplets get smaller, the excess charge within them causes them to disintegrate and release analyte molecules. The volatilized analyte molecules are then analyzed by mass spectrometry. ESI Mass Spectrometry,Electrospray Ionization Mass Spectrometry,Mass Spectrometry, ESI,Spectrometry, ESI Mass

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