title: Supramolecular phase-selective gelation by peptides bearing side-chain azobenzenes: effect of ultrasound and potential for dye removal and oil spill remediation.
abstract: Phase selective gelation (PSG) of organic phases from their non-miscible mixtures with water was achieved using tetrapeptides bearing a side-chain azobenzene moiety. The presence of the chromophore allowed PSG at the same concentration as the minimum gelation concentration (MGC) necessary to obtain the gels in pure organic phases. Remarkably, the presence of the water phase during PSG did not impact the thermal, mechanical, and morphological properties of the corresponding organogels. In the case of miscible oil/water mixtures, the entire mixture was gelled, resulting in the formation of quasi-hydrogels. Importantly, PSG could be triggered at room temperature by ultrasound treatment of the mixture or by adding ultrasound-aided concentrated solution of the peptide in an oil-phase to a mixture of the same oil and water. Moreover, the PSG was not affected by the presence of salts or impurities existing in water from natural sources. The process could be scaled-up, and the oil phases (e.g., aromatic solvents, gasoline, diesel fuel) recovered almost quantitatively after a simple distillation process, which also allowed the recovery and reuse of the gelator. Finally, these peptidic gelators could be used to quantitatively remove toxic dyes from aqueous solutions.
authors.affiliation: Institut für Organische Chemie, Universität Regensburg, Universitätsstr. 31, Regensburg 93053, Germany. bachl_j@web.de.
authors.forename: Jürgen
authors.initials: J
authors.lastname: Bachl
authors.affiliation: Institut für Organische Chemie, Universität Regensburg, Universitätsstr. 31, Regensburg 93053, Germany. stefan.oehm@tu-berlin.de.
authors.forename: Stefan
authors.initials: S
authors.lastname: Oehm
authors.affiliation: Institut für Organische Chemie, Universität Regensburg, Universitätsstr. 31, Regensburg 93053, Germany. judith.mayr@chemie.uni-regensburg.de.
authors.forename: Judith
authors.initials: J
authors.lastname: Mayr
authors.affiliation: Instituto de Síntesis Química y Catálisis Homogénea (ISQCH), CSIC-University of Zaragoza, 50009 Zaragoza, Spain. cativiela@unizar.es.
authors.forename: Carlos
authors.initials: C
authors.lastname: Cativiela
authors.affiliation: Departamento de Química Orgánica, IUBO, "Antonio González", Universidad de La Laguna, Astrofísico Francisco Sánchez 2, 38206 La Laguna, Spain. jtellado@ull.es.
authors.forename: José Juan
authors.initials: JJ
authors.lastname: Marrero-Tellado
authors.affiliation: Institut für Organische Chemie, Universität Regensburg, Universitätsstr. 31, Regensburg 93053, Germany. david.diaz@chemie.uni-regensburg.de.|IQAC-CSIC, Jordi Girona 18-26, 08034 Barcelona, Spain. david.diaz@chemie.uni-regensburg.de.
authors.forename: David Díaz
authors.initials: DD
authors.lastname: Díaz
mesh_terms: D001391:Azo Compounds / Q000737:chemistry*; D004396:Coloring Agents / Q000302:isolation & purification*; D052918:Environmental Restoration and Remediation / Q000379:methods; D005782:Gels / Q000737:chemistry*; D010455:Peptides / Q000737:chemistry*; D059392:Petroleum Pollution / Q000032:analysis*; D013010:Sonication / Q000379:methods; D014465:Ultrasonics / Q000379:methods; D014874:Water Pollutants, Chemical / Q000302:isolation & purification*
chemical_list: D001391:Azo Compounds; D004396:Coloring Agents; D005782:Gels; D010455:Peptides; D014874:Water Pollutants, Chemical; C009850:azobenzene
keywords: azobenzene; dye removal; oil spill; organogel; peptide; phase-selective gelation; side-chain functionalization