title: pH-Tunable hydrogelators for water purification: structural optimisation and evaluation.
abstract: A focused library of potential hydrogelators each containing two substituted aromatic residues separated by a urea or thiourea linkage have been synthesised and characterized. Six of these novel compounds are highly efficient hydrogelators, forming gels in aqueous solution at low concentrations (0.03-0.60 wt%). Gels were formed through a pH switching methodology, by acidification of a basic solution (pH 14 to ≈ 4) either by addition of HCl or via the slow hydrolysis of glucono-δ-lactone. Frequently, gelation was accompanied by a dramatic switch in the absorption spectra of the gelators, resulting in a significant change in colour, typically from a vibrant orange to pale yellow. Each of the gels was capable of sequestering significant quantities of the aromatic cationic dye, methylene blue, from aqueous solution (up to 1.02 g of dye per gram of dry gelator). Cryo-transmission electron microscopy of two of the gels revealed an extensive network of high aspect ratio fibers. The structure of the fibers altered dramatically upon addition of 20 wt% of the dye, resulting in aggregation and significant shortening of the fibrils. This study demonstrates the feasibility for these novel gels finding application as inexpensive and effective water purification platforms.
authors.affiliation: Department of Chemistry, University of Reading, Whiteknights, Reading, RG6 6AD, United Kingdom.
authors.forename: Daniel M
authors.initials: DM
authors.lastname: Wood
authors.forename: Barnaby W
authors.initials: BW
authors.lastname: Greenland
authors.forename: Aaron L
authors.initials: AL
authors.lastname: Acton
authors.forename: Francisco
authors.initials: F
authors.lastname: Rodríguez-Llansola
authors.forename: Claire A
authors.initials: CA
authors.lastname: Murray
authors.forename: Christine J
authors.initials: CJ
authors.lastname: Cardin
authors.forename: Juan F
authors.initials: JF
authors.lastname: Miravet
authors.forename: Beatriu
authors.initials: B
authors.lastname: Escuder
authors.forename: Ian W
authors.initials: IW
authors.lastname: Hamley
authors.forename: Wayne
authors.initials: W
authors.lastname: Hayes