Nalazite se na CroRIS probnoj okolini. Ovdje evidentirani podaci neće biti pohranjeni u Informacijskom sustavu znanosti RH. Ako je ovo greška, CroRIS produkcijskoj okolini moguće je pristupi putem poveznice www.croris.hr
izvor podataka: crosbi

Positionally Isomeric Organic Gelators: Structure-Gelation Study, Racemic versus Enantiomeric Gelators, and Solvation Effects (CROSBI ID 158450)

Prilog u časopisu | izvorni znanstveni rad | međunarodna recenzija

Čaplar, Vesna ; Frkanec, Leo ; Šijaković Vujičić, Nataša ; Žinić, Mladen Positionally Isomeric Organic Gelators: Structure-Gelation Study, Racemic versus Enantiomeric Gelators, and Solvation Effects // Chemistry : a European journal, 16 (2010), 10; 3066-3082. doi: 10.1002/chem.200902342

Podaci o odgovornosti

Čaplar, Vesna ; Frkanec, Leo ; Šijaković Vujičić, Nataša ; Žinić, Mladen

engleski

Positionally Isomeric Organic Gelators: Structure-Gelation Study, Racemic versus Enantiomeric Gelators, and Solvation Effects

Low molecular weight gelator molecules consisting of aliphatic acid, amino acid (phenylglycine), and -aminoaliphatic acid units have been designed. By varying the number of methylene units in the aliphatic and -aminoaliphatic acid chains, as defined by descriptors m and n, respectively, a series of positionally isomeric gelators having different positions of the peptidic hydrogen-bonding unit within the gelator molecule has been obtained. The gelation properties of the positional isomers have been determined in relation to a defined set of twenty solvents of different structure and polarity and analyzed in terms of gelator versatility (Gver) and effectiveness (Geff). The results of gelation tests have shown that simple synthetic optimizations of a lead gelator molecule by variation of m and n, end-group polarity (carboxylic acid versus sodium carboxylate), and stereochemistry (racemate versus optically pure form) allowed the identification of gelators with tremendously improved versatility (Gver) and effectiveness (Geff). Dramatic differences in Geff values of up to 70 times could be observed between pure racemate/enantiomer pairs of some gelators, which were manifested even in the gelation of very similar solvents such as isomeric xylenes. The combined results of spectroscopic (1H NMR, FTIR), electron microscopy (TEM), and X-ray diffraction studies suggest similar organization of the positionally isomeric gelators at the molecular level, comprising parallel -sheet hydrogen-bonded primary assemblies that form inversed bilayers at a higher organizational level. Differential scanning calorimetry (DSC) studies of selected enantiomer/racemate gelator pairs and their o- and p-xylene gels revealed the simultaneous presence of different polymorphs in the racemate gels. The increased gelation effectiveness of the racemate compared to that of the single enantiomer is most likely a consequence of its spontaneous resolution into enantiomeric bilayers and their subsequent organization into polymorphic aggregates of different energy. The latter determine the gel fiber thickness and solvent immobilization capacity of the formed gel network.

enantiomers ; fatty acids ; gelation ; racemates ; self-assembly

nije evidentirano

nije evidentirano

nije evidentirano

nije evidentirano

nije evidentirano

nije evidentirano

Podaci o izdanju

16 (10)

2010.

3066-3082

objavljeno

0947-6539

10.1002/chem.200902342

Povezanost rada

Kemija

Poveznice
Indeksiranost