Organogelation and hydrogelation of low-molecular-weight amphiphilic dipeptides : pH responsiveness in phase-selective gelation and dye removal

The search for efficient low-molecular-weight gelators (LMWGs) with possible structure-activity correlation is on the rise. The present work reports a novel set of amphiphilic dipeptide-based carboxylic acids capable of efficiently gelating organic solvents. More interestingly, their sodium salts sh...

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Veröffentlicht in:Langmuir : the ACS journal of surfaces and colloids. - 1992. - 25(2009), 15 vom: 04. Aug., Seite 8639-48
1. Verfasser: Kar, Tanmoy (VerfasserIn)
Weitere Verfasser: Debnath, Sisir, Das, Dibyendu, Shome, Anshupriya, Das, Prasanta Kumar
Format: Online-Aufsatz
Sprache:English
Veröffentlicht: 2009
Zugriff auf das übergeordnete Werk:Langmuir : the ACS journal of surfaces and colloids
Schlagworte:Journal Article Research Support, Non-U.S. Gov't Carboxylic Acids Coloring Agents Gels Oils Water 059QF0KO0R
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245 1 0 |a Organogelation and hydrogelation of low-molecular-weight amphiphilic dipeptides  |b pH responsiveness in phase-selective gelation and dye removal 
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520 |a The search for efficient low-molecular-weight gelators (LMWGs) with possible structure-activity correlation is on the rise. The present work reports a novel set of amphiphilic dipeptide-based carboxylic acids capable of efficiently gelating organic solvents. More interestingly, their sodium salts showed enhanced efficiency in organogelation with the additional ability to gelate water. Electrostatic interactions present in the aggregation of the sodium carboxylates of amphiphilic dipeptides seem to be important because some of the nongelator carboxylic acids turned out to be excellent gelators upon salt formation. The combinations and sequence of the amino acids in the dipeptide moiety were systematically altered to understand the collective importance of the nonpolar aliphatic/aromatic substitution in amino acids in the self-assembling behavior of amphiphiles. Almost a 20-fold enhancement in the gelation ability was observed on reversing the sequence of the amino acid residues, and in some cases, nongelators were transformed to efficient gelators. Spectroscopic and microscopic studies of these thermoreversible organo/hydrogels revealed that balanced participation of the noncovalent interactions including hydrogen bonding and van der Waals interactions are crucial for organo/hydrogelation. These dipeptides selectively gelate organic solvents from their mixtures with water, and the xerogels prepared from these organogels showed time-dependent adsorption of dyes such as crystal violet. The most remarkable feature of these gelators is the pH responsiveness, which was aptly utilized for the pH-dependent phase-selective gelation of either solvent in a biphasic mixture of oil and water. The dissimilar gelation ability of the acid and its salt originating from the pH responsiveness of the amphiphilic dipeptide was employed in the instant removal of large amounts of dyes for wastewater treatment 
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650 7 |a Coloring Agents  |2 NLM 
650 7 |a Gels  |2 NLM 
650 7 |a Oils  |2 NLM 
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700 1 |a Debnath, Sisir  |e verfasserin  |4 aut 
700 1 |a Das, Dibyendu  |e verfasserin  |4 aut 
700 1 |a Shome, Anshupriya  |e verfasserin  |4 aut 
700 1 |a Das, Prasanta Kumar  |e verfasserin  |4 aut 
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