Synthesis and organogelating behaviour of amino acid-functionalised triphenylenes.

Four novel amino acid-functionalised triphenylenes have been prepared with glycine, l-alanine, l-phenylalanine and l-tryptophan ethyl ester side-chains. The glycine derivative is a good gelator of chloroform, the alanine derivative gels ethanol and toluene, and the phenylalanine derivative gels benzene and toluene. The tryptophan derivative does not gel any of the solvents tested, most probably due to its more bulky structure, but forms microspheres by evaporation-induced self-assembly.

On the interactions of alkyl 2-hydroxycarboxylic acids with alkoxysilanes 2. Complexation and esterification of di- and tricarboxylic acids.

The selective esterifications of L-malic, L-tartaric and citric acids with tetramethoxysilane Si(OMe)4, in methanol (MeOH) have been demonstrated for the first time. The interactions between these acids and Si(OMe)4, and also between oxalic acid and Si(OMe)4, were investigated using 1H, 13C and 29Si solution phase NMR, and electrospray mass spectrometry (ES-MS). Si(OMe)4 acts as a catalyst/reagent in the selective esterification of simple 2-hydroxycarboxylic acids (2HOAs), but with the di- and tri-carboxylic acids more complex selectivities are observed: the esterification of oxalic acid proceeds slower than in MeOH alone, L-malic acid is selectively esterified approximately 1000 times faster at the 2-hydroxy acid, L-tartaric acid is esterified approximately 1000 times faster to the mono- and diester, while citric acid is selectively methylated at the terminal (3-hydroxycarboxyl) groups approximately 1000 times faster than in the absence of Si(OMe)4.

On the interactions of alkyl 2-hydroxycarboxylic acids with alkoxysilanes: selective esterification of simple 2-hydroxycarboxylic acids.

The interactions of a range of monocarboxylic acids with tetramethoxysilane Si(OMe)(4) (TMOS), in methanol (MeOH), have been investigated by using (1)H, (13)C and (29)Si solution-phase NMR spectroscopy and electrospray mass spectrometry (ESMS). Si(OMe)(4) acts as a catalyst/reagent in the selective methylation of 2-hydroxycarboxylic acids (2HOAs) in MeOH at room temperature: glycolic acid, lactic acid and 2-hydroxybutyric acid are esterified more than a hundred times faster in MeOH and Si(OMe)(4) than in MeOH alone. No acceleration of methylation is observed for carboxylic acids lacking the 2-hydroxy group.