The
obtainment of materials featured by high environmental compatibility
is one of the main goals of modern research. On this subject, we herein
report the first example of supramolecular gel in deep eutectic solvents.
In particular, we prepared gels of the L-amino acids isoleucine and
tryptophan in choline chloride/phenylacetic acid 1:2. All gel components
are readily available and nontoxic. Gels have been fully characterized
by standard gelation tests, rheology, X-ray diffraction, morphology
and gelation kinetics. Data collected show that gels properties depend
on the gelator nature. In particular, gel phases exhibit strong colloidal
forces and, this high mechanical resistance, together with their environmental
friendly nature, make them promising candidates for applications in
all those fields requiring good performance and low environmental
impact.
A versatile and DES-compatible bipyridine palladium complex has been developed as a general precatalyst for different cross-coupling reactions (Hiyama, Suzuki-Miyaura, Heck-Mizoroki and Sonogashira) in deep eutectic solvents. Hydrogen bond capacity of the ligand allows to keep the excellent level of results previously obtained in classical organic solvents. Palladium pre-catalyst showed a high catalytic activity for many cross-coupling reactions, demonstrating a great versatility and applicability. Also, this methodology employs sustainable solvents as a reaction medium and highlights the potential of DES as alternative solvents in organometallic catalysis. The catalyst and DES were easily and successfully recycled. The formation of PdNPs in DES has been confirmed by TEM and XPS analysis and their role as catalyst by mercury test. The dynamic coordination of bipyridine-type ligand in the palladium complex formation has been studied via UV/Vis.
Current concerns for sustainability and the environment make low‐impact materials desirable for environmental remediation and, in particular wastewater treatment. We obtained supramolecular gels of l‐amino acids in the deep eutectic solvent formed by choline chloride and phenylacetic acid. After gel characterization, and investigating gel–sol transition temperatures, gelation kinetics, rheological properties, and morphology, the gels were applied as sorbents to remove cationic dyes from aqueous solutions. The effects of the pH, dye nature, volume, and concentration of wastewater were analyzed, and the best result was obtained with a l‐phenylalanine‐based eutectogel. It can be reused for at least 9 times without losing efficiency, also with dye mixtures. Interestingly, this gel can be loaded onto columns to decolorize flowing solutions, achieving 85 % of removal efficiency in only 10 minutes and allowing its reuse for at least 4 cycles. In terms of adsorption capacity, this eutectogel is competitive with efficient gel‐based dye sorbent systems, with a value 1930 mg/g reached at a high concentration of rhodamine B 479 mg/L.
The efficient conversion of biomass into value-added compounds under mild and safer conditions is a cornerstone of present research efforts to meet the needs of the chemical industry with sustainable development. In this work, we studied the dehydration of fructose, glucose, and sucrose into 5-hydroxymethylfurfural (5-HMF), catalyzed by HY zeolite, in three ionic liquid mixtures differing for the cation, aromatic, or aliphatic. We investigated the effect of several operational parameters such as temperature, catalyst loading, zeolite counterion, solvent mixture, and added chloride. In the optimal experimental conditions, we obtained good conversions to 5-HMF especially for fructose and sucrose, 73% and 62%, using the relatively low temperatures of 80 and 120 °C, respectively. Interestingly, in the used experimental conditions, the solvent−catalyst systems can be reused for at least 6 cycles without loss in performance. We also investigated the dehydration of fructose under sonochemical activation, obtaining a conversion to 5-HMF of 71% in 0.5 h, at the remarkably low temperature of 40 °C.
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