engleski

Stereoisomeric bis(phenylglycinol)malonamide gelators: rare examples of gelling meso-compounds

Gelation of malonamides was investigated for the first time. Bis(phenylglycinol)malonamide 1, and methyl-, dimethyl-, ethyl-, diethyl- and isopropylmalonamides 2, 3, 4, 5 and 6, respectively, exhibited profoundly different gelling properties. Monoalkyl malonamides are efficient organogelators, and their gelling properties strongly depend on their stereochemistry. In contrast, symmetrically substituted dialkymalonamides, that is, (R, R)-dimethylmalonamide 3 and (R, R)-diethylmalonamide 5 as well as the unsubstituted 1 lack any gelation ability. Methyl derivative (R, R)-2 is an excellent, and its ethyl analogue (R, R)-4 a moderate gelator of toluene, p-xylene and tetralin while the isopropyl derivative (R, R)-6 shows only very weak gelation of tetralin and some more polar solvents. Meso diastereoisomers (R, r, S)-2 and (R, s, S)-2, as well as (R, r, S)-4 and (R, s, S)-4), each possessing a pseudoasymmetric centre represent very rare examples of gelling meso-compounds. The racemate 4 (rac-4) showed more efficient gelation of some solvents than the pure enantiomer (R, R)-4, while rac-2 failed to gel any of the solvents which were efficiently gelled by (R, R)-2.

stereoisomeric gelators ; malonamide ; meso-compounds

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