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In this work, Pd and Pt electrocatalysts were electrodeposited on three-dimensional carbon paper and carbon nanofoam with the purpose of increasing the catalytic area to improve the glycerol electro-oxidation. SEM and cross-sectional SEM micrographs showed that Pd and Pt particles were well-distributed over the entire three-dimensional electrode surfaces. Commercial Pd/C and Pt/C catalysts deposited by the spray method were used for comparison, showing lower surface area (SA) utilization than those electrodeposited. The electrodeposition effectiveness to cover the electrode surfaces was evaluated by changes in overall SA and through the calculation of electrochemically active surface area (EASA) and specific surface area (SSA). Despite the larger EASA values found for Pd and Pt on nanofoam, Pt on paper showed the highest utilization of the surface area, obtaining an SSA of 58.1 m2 g−1. Moreover, the electrodeposition of Pd and Pt dramatically increased the EASA versus the geometrical area, improving this ratio 16 (Pd on paper), 151 (Pt on paper), 158 (Pd on nanofoam) and 277-fold (Pt on nanofoam). The electrodeposited porous Pt electrodes showed good activity for glycerol oxidation, exhibiting a more negative potential than Pd-based materials. However, for fuel cell applications operated at intermediate temperatures, Pd on carbon paper is the optimal candidate to be used as an anode because of its high current density and excellent poisoning tolerance. [ABSTRACT FROM AUTHOR]

This study presents a pioneering nanohybrid catalyst featuring hierarchically porous dual-functional (acid–base) active sites, which is a versatile catalyst for the crucial bio-glycerol acetalization reaction. The nanohybrid catalyst demonstrated remarkable efficiency in converting bio-diesel derived waste glycerol into excellent green fuel additive 'solketal,' achieving an unprecedented yield of approximately 99%. Insights into the structural properties and the relationship between the structure and properties of the catalyst were obtained through various characterization techniques, including FTIR spectroscopy, XRD, NH3-TPD, CO2-TPD, 27Al-NMR spectroscopy, SEM, TEM, UV-Vis spectroscopy, and X-ray photoelectron spectroscopy. The hybrid catalyst shows several highly desirable properties, including enhanced acidity, a strong affinity for reactants, mesoporosity, stability, and the proximity of potent acidic and basic sites. Simplicity, cost-effectiveness, exceptional recyclability, and resistance to moisture make the synthesized MgAl-oxide/HZSM-5 (MAZ) nanohybrid catalyst an appealing candidate for potential commercial applications in bio-refinery processes. [ABSTRACT FROM AUTHOR]

Mg–Ba mixed oxide catalysts are synthesized using the co-precipitation method by varying the molar compositions of MgO and BaO. The catalysts' surface/structural properties are characterized by N2 physisorption, PXRD, CO2-TPD, FT-IR spectroscopy, X-ray photoelectron spectroscopy, and laser Raman spectroscopy. The characterization results showed that the insertion of Mg2+ into the BaO lattice results in the generation of stable mixed oxide solid solutions. These catalysts are evaluated for continuous glycerol transesterification with dimethyl carbonate to yield glycerol carbonate under solvent free and atmospheric pressure conditions. The activity of catalysts mainly relied on strong basic centres (c-MgO) originating from Mg and Ba of different molar ratios and the catalyst with a 3 : 1 molar ratio exhibited an excellent glycerol carbonate yield of up to 70% with nearly 100% selectivity. The activities of the catalysts are well explained based on their surface-structural integrity. The catalysts exhibited exceptional stability during the time on stream study over a period of 100 h. [ABSTRACT FROM AUTHOR]

In the present investigation, glycerol and dimethyl carbonate were transesterified using a Li/Mg/K modified zeolite beta catalyst to synthesize glycerol carbonate. The various prepared zeolite catalysts were characterized using XRD, FE-SEM, EDS, HR-TEM, XPS, and DLS techniques. Many tests were conducted to optimize the reaction conditions to obtain the highest yield of glycerol carbonate by changing the catalyst concentration (5–20 wt%), glycerol-to-dimethyl carbonate mole ratio (1 : 2–1 : 6), and reaction temperature (65–105 °C). A maximum of 81.48% glycerol carbonate was obtained under optimized reaction conditions (a glycerol : dimethyl carbonate mole ratio of 1 : 5, a Li20β dosage of 10 wt% w.r.t. GLY, a temperature of 95 °C, and a time of 5 h). The experimental data followed second-order reaction kinetics with an activation energy of 34.60 kJ mol−1. [ABSTRACT FROM AUTHOR]

Copper-modified phosphotungstic acid (CuPW) supported on titania materials with various CuPW contents were successfully synthesized by ion exchange followed by an impregnation method. The prepared materials were characterized using XRD, Raman, ammonia TPD, pyridine FT-IR spectroscopy, and BET-surface area measurements. The XRD results revealed that the crystalites of Keggin ions of heteropolyacid were merged with the anatase support. The Raman spectroscopy results of the fresh and regenerated 30 wt% CuPW/TiO2 clearly showed the characteristic peak of Keggin ions being intact with the support. The results from the temperature-programmed desorption (TPD) of ammonia tests revealed that a 30 wt% catalyst possessed a greater number of acidic sites than the other loadings. Pyridine-adsorbed FT-IR spectroscopy suggested that the 30 wt% catalyst calcined at 300 °C had high amount of Lewis and Brønsted acidity. The copper-modified phosphotungstic acid on the titania support significantly altered the Brønsted and Lewis acidity of the catalysts and promoted a remarkable catalytic performance during glycerol carbonylation as well as provided related structural and acidity functionalities to the CuPW/TiO2 catalyst. [ABSTRACT FROM AUTHOR]

Arylamine-based push–pull molecules were successfully grafted onto various chiral diols (isomannide and isosorbide) or glycerol moieties, used as central biosourced cores, for the preparation of multichromophoric materials. Once their optical and electrochemical properties were investigated and rationalized, these new photoactive multimers were evaluated as potential donors in simple, air processed organic solar cells. [ABSTRACT FROM AUTHOR]

H6P2W18O62/γ-Al2O3 catalysts were prepared with different methods: (a) supercritical impregnation; (b) conventional wet impregnation. The obtained catalysts were characterized with XRD, SEM, N2 adsorption, NH3-TPD, Pyridine-IR, TG, ICP, and CHNS analyses. The results showed that supercritical CO2 was helpful in enhancing the dispersity of H6P2W18O62 supported on γ-Al2O3 and increased the surface area, pore volume and size, the total acid amount, and the proportion of Brønsted acid, and the formation of coke and the leaching of H6P2W18O62 were retarded. The main reason is because supercritical carbon dioxide has high solubility and diffusivity, which favors H6P2W18O62 dispersion and strengthens the interaction between H6P2W18O62 and hydroxyl on γ-Al2O3. The performances of two catalysts in glycerol dehydration were evaluated. The conversion of glycerol, selectivity and yield of acrolein, and catalytic stability were significantly enhanced on the H6P2W18O62/γ-Al2O3 catalyst prepared by supercritical impregnation because greater total acidity is conducive for improving the conversion of glycerol, while a higher ratio of Brønsted acid sites to total acidity is conducive for enhancing the acrolein selectivity. [ABSTRACT FROM AUTHOR]

The fabrication of a flexible and highly sensitive strain sensor with the incorporation of glycerol, by vapor phase hybridization, improves the physical properties of ternary composite elastomers consisting of thermoplastic polyurethane (TPU), graphene oxide, polyethylene glycol and silica (TPU-GPS). The addition of glycerol to the TPU-GPS composite improves the dispersion of graphene oxide and the mechanical, electrical, thermal, and strain sensing sensitivity properties of the graphene oxide-based strain sensor. A certain amount of glycerol in the composite blend is modified to achieve excellent strain sensor performance. The results revealed 65% strain increase compared to the TPU-GPS strain sensor on its elongation at break. The presence of glycerol in the polymer matrix is confirmed by field-emission scanning electron microscopy (FE-SEM), attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR), X-ray diffraction (XRD) and differential scanning calorimetry (DSC) characterization studies. More impressively, TPU-GPS with 3 wt% of glycerol (TPU-GPS-3GLY) demonstrates outstanding sensitivity (gauge factor = 20) that is two times higher than that of the TPU-GPS pristine composite. Furthermore, the sensor can monitor a small-scale strain up to <1% and respond for up to 20 000 cycles with extraordinary stability and repeatability. Owing to the uniform dispersion of graphene oxide in the polymer matrix as a result of glycerol introduction, the composite represents a useful development in the strain sensor application. [ABSTRACT FROM AUTHOR]

In this paper, we report the study of the free-solvent nucleophilic addition of alcohols and glycerol to acrylic compounds, in the presence of catalytic bases. With acrylates, Michael addition and transesterification are in competition: only the PTC reaction with t-butyl acrylate gave trifunctionalized glycerol. With acrylonitrile, the cyanoethylation of glycerol varies with catalysts, temperature, time of reactions and amounts of acrylonitrile. Mono functionalisation of glycerol can be obtained in 28% yield. The optimization of the free-solvent Michael addition of glycerol to acrylonitrile (3.4 equiv., 4 mol% NaOH, 5 h) leads to TCEG (tricyanoethylglycerol, 88% yield, 99% purity) without HCl neutralisation, chlorinated solvents or purification (chromatography or distillation). TCEG can be used as a prochiral core of G0.5 dendrimers. [ABSTRACT FROM AUTHOR]

In this work, we describe the use of Water Extract of Rice Straw Ash (WERSA) as an efficient sustainable approach for the Knoevenagel reaction and a reaction medium, in combination with glycerol as a co-solvent, without the employment of any additional catalyst, base, ligand, or promoter. The effect of WERSA as an alternative catalytic source increased the reagent solubility provided by glycerol, resulting in several α,β-unsaturated carbonyl compounds with yields between 83 and 98%. The easy isolation of these compounds arising from their low solubility in this medium allowed the WERSA/glycerol mixture to be reused even after five reaction runs while yielding excellent results. The versatility of this system was tested for the multicomponent synthesis of heterocyclic moieties, which are attractive targets for synthesis that have been of great interest due to their biological properties. In this sense, 9-phenyl-3,4,5,6,7,9-hexahydro-1H-xanthene-1,8(2H)-dione (6a) was synthesized with an 83% yield, demonstrating a great opportunity to expand this protocol for the synthesis of valuable compounds in a sustainable approach without the use of any additional catalyst. [ABSTRACT FROM AUTHOR]

The choice of the active site and support matrix decides the activity of a catalyst. Any modifications on these will have a significant impact on the reactivity and selectivity of the catalyst. Here, we have synthesised WO3-loaded boehmite and applied it for the acetalization of a biomass-derived bulk chemical, glycerol. The well-characterized acid catalyst exhibits a selective acetalization of glycerol with good conversions into a five-membered dioxolane product. The cyclability of the catalyst up to six times along with the retention of the catalytic activity ensures the heterogeneity of the material. [ABSTRACT FROM AUTHOR]

Citric acid (CA) modified Ni3P catalysts with small particle sizes were prepared by H2 temperature-programmed reduction (H2-TPR) of the precursors, which were prepared by co-precipitation with Ni(NO3)2·6H2O and (NH4)2HPO4, using citric acid as the chelating agent and calcining under a N2 atmosphere. The catalytic activity of the prepared catalysts was tested in the aqueous phase reforming (APR) and hydrogenolysis of glycerol to 1,2-propanediol (1,2-PDO). The effects of the CA/Ni molar ratio and reaction conditions (temperature, pressure, and time) on APR and hydrogenolysis of glycerol were investigated. The CA(1)–Ni3P catalyst exhibited the best performance at 220 °C, 0.5 MPa N2, and 8 h with 74.6% glycerol conversion and 43.2% selectivity of 1,2-PDO. The prepared CA(x)–Ni3P catalysts were characterized by XRD, N2 adsorption, Raman spectroscopy, CO-chemisorption and TEM. The addition of CA significantly enhanced the dispersion of Ni species in the precursors and enlarged the surface area of the catalyst. The residual carbonaceous species after calcination in N2 prevented the aggregation of Ni3P particles and promoted the reduction of the precursors. Compared with the unmodified Ni3P and CA(x)–Ni3P calcined in air, the CA(x)–Ni3P calcined in N2 with a smaller average particle size exhibited higher catalytic activities. [ABSTRACT FROM AUTHOR]

Imidazolium sulfonate zwitterions (ZIs) with unconventional counter-anions were used to fabricate a series of mesoporous silica-gel-immobilized Brønsted acid ionic liquid (SG@BAIL) nanocatalysts. In comparison to traditional heterogeneous catalysts, these immobilised heterogeneous catalysts have the advantage of ionic-liquid acidic sites and the advantage of solid silica gel as a support, increasing their catalytic activities. The catalysts were analysed using a series of physicochemical techniques and their catalytic efficiencies were evaluated during the acetalization of glycerol (G) with benzaldehyde (B). The influence of the counter-anions present in the SG@BAIL catalysts was initially investigated in terms of the percentage conversion vs. the reaction time at a particular temperature. Furthermore, different parametric studies relating to the acetalization reaction were carried out based on the catalyst with the maximum activity. SG-[C3ImC3SO3H][OTf] was observed to have the highest catalytic performance and durability during ecofriendly acetal synthesis, with the highest selectivity for 1,3-dioxane. Parametric studies of the acetalization reaction were carried out, and the catalyst showed noteworthy performance at 90 °C, showing 94% conversion in an equimolar reactant mixture under solvent-free conditions with 0.03 wt% catalyst loading in a short time span of 75 min. In addition, kinetics modelling was performed using reversible second-order kinetics to calculate the forward rate constants at various temperatures. The activation energy of the reaction was determined using the Arrhenius equation, and the overall activation energy was 69.33 kJ mol−1. These investigations have demonstrated the excellent potential of SG@BAIL catalysts for practical application in the glycerol acetalization process. [ABSTRACT FROM AUTHOR]

Selective oxidation of biomass resource glycerol to produce high value-added formic acid, dihydroxyacetone and other fine chemicals is in line with the current development concept of green and sustainable chemistry. A Bi quantum dot and oxygen vacancy modified BiOBr photocatalyst was applied to the selective aerobic oxidation of glycerol. A series of characterization results showed that the introduction of Bi quantum dots and oxygen vacancies can promote the effective transfer of photo-generated electrons and the adsorption of molecular oxygen on the catalyst surface to promote the activation of molecular oxygen, thereby significantly improving the photocatalytic efficiency of BiOBr. BiQDs/BiOBr–Ov can efficiently catalyze the oxidation of glycerol to yield FA and DHA (FA selectivity 46.2%, DHA selectivity 26.9% at 98.4% glycerol conversion) under mild conditions, which is around 2.9 times that of normal BiOBr. In addition, the relevant reaction mechanism and path were systematically studied: two reaction paths to yield FA and DHA independently were found, where photo-generated holes and superoxide radicals played important roles. This work provided an efficient catalyst modification scheme by promoting the activation of molecular oxygen to improve the photocatalytic oxidation efficiency of biomass resources. [ABSTRACT FROM AUTHOR]

Bifunctional Pt/WO3/zirconium phosphate catalyzes the liquid-phase hydrogenolysis of glycerol in an aqueous medium. 1H NMR spectroscopy (solvent suppression pulse program) is employed to monitor this reaction. Propanediols (1,3 + 1,2-PDO) formed as the major product along with propanols (1- and 2-POs) as the minor product. A synergistic enhancement in glycerol conversion and selectivity to 1,3-PDO was observed when both Pt and WO3 were present in the catalyst. A volcano-shape variation of catalytic activity with W content was observed. A catalyst with 8 wt% W and 1 wt% Pt exhibited the highest selective hydrogenolysis performance (glycerol conversion = 92.3% and total PDOs selectivity = 45.9% and 1,3-PDO selectivity = 20.8% at 200 °C). Dispersed Pt in contact with polytungstate-type WO3 species was found to be the active catalytic site. 1H NMR spectroscopy is demonstrated as an attractive technique to quantify the products of a glycerol hydrogenolysis reaction. [ABSTRACT FROM AUTHOR]

This work describes a hydrophilic polymeric gel with satisfactory water absorption (1.4 gH2O g−1gel at pH = 10) and reducing capacity prepared from the reaction of glycerol oleate esters with citric acid. Elemental analysis and FTIR spectroscopy suggest that the oleate portion of the starting material is not present in the final composition of the isolated gel. Nevertheless, it plays a vital role in the reaction while assisting the formation of the crosslinked polymer composed by glycerol and citric acid in a 1 : 1 molar ratio. This gel allows for the simultaneous adsorption/reduction of dark-blue indigo carmine dye in aqueous medium endorsing its dual role in this process. The reducing capacity of the gel was also confirmed through the reactivity towards permanganate (MnO4−) ions, leading to the formation of MnO2, whose crystalline phase was confirmed by PXRD. Citrate present in the structure of the gel matrix is key to justify its reducing behavior. This property opens new avenues to produce gels bearing noble metal nanoparticles, and we demonstrate this approach via adsorption/reduction of Ag+ ions in aqueous solution that yields a gel containing Ag nanoparticles with potential biomedical applications. This hybrid material was fully characterized by UV-Vis, SEM, and PXRD analyses indicating the formation of highly dispersed Ag0 nanoparticles with an average diameter of 20 nm. [ABSTRACT FROM AUTHOR]

This work reports the electrocatalytic activity of the AuCeO2/C and Au/C catalysts toward the oxidation reaction of alcohols: methanol, ethanol, ethylene glycol, and glycerol in an alkaline medium. Gold nanoparticles (AuNPs) were deposited onto the CeO2/C and C (carbon) substrates using the microwave irradiation method. It has been found that deposition of AuNPs onto the CeO2/C substrate results in the enhanced electrocatalytic activity of the AuCeO2/C catalyst toward the oxidation reaction of methanol, ethanol, ethylene glycol, and glycerol compared with that of the AuNPs deposited on the carbon substrate. The AuCeO2/C catalyst showed up to 3 times higher electrocatalytic activity toward the oxidation of the mentioned alcohols compared with that of the Au/C catalyst. [ABSTRACT FROM AUTHOR]

A series of Au catalysts supported on Cu–Al composite oxides were prepared and applied for the selective catalytic oxidation of glycerol to 1,3-dihydroxyacetone (DHA) in base-free conditions. The optimal Au/CuAlO-3 catalyst (the molar ratio of Cu/Al was 5 : 1) exhibited the best performance, and reached the glycerol conditions of 76.7% and DHA selectivity of 97.3% under the optimized reaction conditions. The high catalytic activity of the Au/CuAlO-3 catalyst correlated to the large concentration of surface-active oxygen species, the low reduction temperature of the support, the small size of Au nanoparticles (NPs) and the interactions between Au NPs and the support. This work demonstrates that Cu–Al composite oxides are promising supports for selective catalytic oxidation of glycerol to DHA, and may offer guidelines for designing efficient support for the selective conversion of glycerol to other high value-added products. [ABSTRACT FROM AUTHOR]

In this work, Ru-based catalysts with the synthesized and commercial Mg(OH)2 and MgO as supports such as Ru/Mg(OH)2(S) (or Ru/Mg(OH)2(B), Ru/MgO(S), and Ru/MgO(B)), S and B representing "synthesized" and "commercial", respectively, were prepared at room temperature by a simple chemical reduction approach. The Ru/Mg(OH)2(S) catalyst exhibited the best catalytic activity (TOF = 134 h−1) and the highest selectivity to 1,2-propanediol (65%) for glycerol hydrogenolysis. Moreover, this reaction was performed over the as-prepared catalysts without adding any liquid acid (e.g., HCl) or base (e.g., NaOH). Selectivity of 1,2-propanediol increased with an increase in the reaction temperature or time, but that towards ethylene glycol did not show any obvious change. Characterization techniques such as XRD, SEM, XPS, TG, TEM, HRTEM, STEM, STEM-EDX elemental analysis (mapping and line-scanning), and CO2-TPD were used to explore related properties of the as-synthesized catalysts to explain the difference in their catalytic activity and selectivity. The reasons for Ru/Mg(OH)2(S) to exhibit high catalytic activity are as follows: Ru with high dispersion on the support, Mg(OH)2 with a cotton-like morphology, numerous defect sites and strong basic active sites. [ABSTRACT FROM AUTHOR]

The application of magnetic nanoparticles as an adsorbent and a catalyst support in solving the environmental issues has recently received great attention due to their unique physical and chemical properties, such as high surface area, ease of anchoring the functional groups, lower processing cost, high stability and ease of separation under an external magnetic field. In the present study, a magnetic catalyst was prepared by embedding magnetite (Fe3O4) within the silica shell on which sulfate ions were anchored (Fe3O4@SiO2@SO42−). The catalyst was successfully employed for glycerol esterification with acetic acid to obtain 100% selectivity towards triacetin within 45 min of reaction duration at 80 °C. The catalyst was successfully isolated from the reaction medium magnetically and reused for six consecutive reaction cycles while retaining 90% glycerol conversion levels and 50% triacetin selectivity in the reaction cycles. [ABSTRACT FROM AUTHOR]

A bimetallic vanadium and niobium oxide catalyst using alumina as support was developed for the conversion of crude glycerol from biodiesel production into formic acid. The high dispersion of the active oxide phase combined with the presence of acid and redox active centers resulted in a high glycerol conversion (>90% for 25 h) with a good selectivity for formic acid (∼55%). This process is the first example of a heterogeneous liquid-phase process for the conversion of crude glycerol to formic acid, which is an important chemical intermediate currently derived from petroleum feedstock. [ABSTRACT FROM AUTHOR]

Recently, great effort has been made to improve the activity and stability, as well as increase the utilization efficiency of noble metal-based electrocatalysts. Herein, a dealloyed PtPd-based nanoparticle (PtPd-x/C, x = 0, 2, 4, 6, 8, 10), with a small amount of Fe inside, is obtained by etching a high-Fe-content PtPdFe nanoparticle precursor. The final PtPd-x/C having a large amount of PtPd exposed on the surface can effectively increase the utilization efficiency of the mass-based unit precious-metal to facilitate glycerol electrooxidation. Attractively, the optimal PtPd-6/C not only exhibits higher electrochemically active surface area (113.33 cm2 mgPtPd−1), oxidation peak current (0.86 A mgPtPd−1) and stability (0.48 A mgPtPd−1 after 3000 s and 5.8% current decreases after 400 cycles), but also shows excellent CO tolerance compared to others. This work demonstrates that the design of a multi-component noble metal composite is a feasible way to obtain some efficient electrocatalysts. [ABSTRACT FROM AUTHOR]

Copper and chromium supported on ZSM-11 (MEL-type structure) microporous zeolites were investigated as catalysts for glycerol oxidation towards dihydroxyacetone and lactic acid. ZSM-11 was synthesized by hydrothermal crystallization. Subsequently, alkaline treatment of desilication was carried out in order to generate zeolites with micro-mesoporosity. Ion exchange with ammonium chloride was performed to recover acidic sites and then, Cr(III) and Cu(II) species were incorporated onto these materials. Finally, thermal treatment at 500 °C was carried out. These materials were characterized by different techniques and then evaluated in the glycerol oxidation reaction by employing H2O2 as an oxidizing agent. The maximum conversion of glycerol (∼70%) was reached over the Cr–ZSM-11 catalyst with a selectivity of ∼28% towards dihydroxyacetone. Meanwhile, Cu-ZSM-11 offered 50% glycerol conversion with a selectivity of 68% towards lactic acid. In both the cases, the optimal reaction conditions were studied to maximize the selectivity towards the products mentioned above. [ABSTRACT FROM AUTHOR]

Alumina supported copper–cobalt catalysts were made and screened for continuous hydrogenolysis of glycerol to 1,2-propanediol at atmospheric pressure. BET surface area, temperature-programmed reduction, X-ray diffraction, pulse N2O chemisorption, transmission electron microscopy and X-ray photoelectron spectroscopy techniques were used to derive the characteristics of the catalysts. The presence of Co in Cu/alumina significantly increased the reducibility of CuO species and also the metallic Cu surface area. The catalyst with 10%Cu–7%Co on Al2O3 afforded complete glycerol conversion with 77% selectivity to 1,2-propanediol. The catalysts activity was found to be mainly due to the existence of Cu in a highly dispersed state with a high metal surface area and synergistic interactions between the Cu–Co moieties. The influence of the reaction parameters was investigated and the best possible parameters were determined. The most active catalyst showed high stability during the time on stream analysis. [ABSTRACT FROM AUTHOR]

Tungstated metal phosphate (WOx/MP; M = Al, Zr and Ti) solid acid catalysts were examined for vapor phase glycerol dehydration to acrolein and hydroxyacetone. The physico-chemical characteristics of the samples were explored using X-ray diffraction (XRD), N2 sorption, Fourier-transform infrared spectroscopy (FT-IR), UV-visible diffuse reflectance spectroscopy (UV-DRS), and ex situ FT-IR investigation of the adsorbed pyridine and ammonia temperature programmed desorption (NH3-TPD) analysis to gain an understanding of the impact of the structural and acidic nature of the catalysts upon changing the metal component. The catalytic activity and selectivity functionalities were interpreted in terms of the acidity and structural properties of the WOx/MP catalysts. The outcomes demonstrated that WOx/TiP was the most selective and stable catalyst during the catalytic dehydration of glycerol owing to the acceptable amount of surface acidity and the substantial number of pores available on its surface. A detailed study on WOx/TiP was also performed to understand the interaction between the tungsten and the TiP support. [ABSTRACT FROM AUTHOR]

The promoting effect of cobalt oxide on alumina-supported Cu oxide catalysts for the hydrogenolysis of glycerol was investigated. A series of Co(y)Cu/Al2O3 oxide catalysts with a fixed Cu loading of 7 wt% and a variable Co loading from 0 to 1.5 wt% was prepared by successive wet impregnation. The catalysts were characterized by X-ray diffraction (XRD), nitrogen sorption, temperature programmed reduction (TPR), ultraviolet-diffuse reflectance spectroscopy (UV-DRS), temperature programmed desorption of ammonia (TPD-NH3), and X-ray photoelectron spectroscopy (XPS). The catalysts were tested in a batch reactor at 220 °C and 5 MPa of H2. The activity of the catalysts on a per mole of Cu basis increased with Co content up to the plateau, and subsequently decreased at higher Co content. The increase of activity is attributed to the combined effect of the distortion of the octahedral geometry of CuO by the presence of CoO and the increase in the number of surface acid sites. In contrast, the subsequent decrease of activity at higher loading is related to the formation of less reducible, less acidic, and less active aluminates. The selectivity of products did not vary substantially with Co loading, indicative of the existence of active sites of similar characteristics on all the catalysts. Overall, all the catalysts favored the route comprising of C–O hydrogenolysis followed by hydrogenation, at the expense of the pathway involving C–C hydrogenolysis, leading to the predominant formation of 1,2-propanediol (1,2-PDO). This is probably due to the prevalence of metallic active sites over acidic sites on the surface, ensuring that partial removal of oxygen occurred without the loss of carbon atoms. [ABSTRACT FROM AUTHOR]

In this study, different acidic (V2O5, ZrO2, and TiO2) and basic (CaO and MgO) oxide-supported copper–zinc bimetallic catalysts were prepared by a deposition–precipitation method, and they were evaluated for the vapor-phase hydrogenolysis of glycerol to propylene glycol at 0.1 MPa and at 220 °C. The catalysts were thoroughly characterized by different techniques such as BET, XRD, H2-TPR, NH3 and CO2 TPD, N2O adsorptive decomposition, TEM, XPS, FE-SEM and TGA. Among all the supported catalysts, the Cu–Zn/MgO catalyst was found to be the most selective to propylene glycol. High copper-metal dispersion (∼5%), surface area (∼23 m2 g−1), the highest basicity (0.25 mmol CO2 g cat−1) and the availability of partially reduced copper species (Cu2O, CuO and Cu0) were the primary reasons for the higher propylene glycol selectivity. At optimum reaction conditions, i.e., at 220 °C, 0.72 MPa and a weight hourly space velocity (WHSV) of 0.073 h−1, ∼98.5% conversion of glycerol with ∼89% selectivity to propylene glycol was obtained over the Cu–Zn/MgO catalyst. This catalyst was also found to be stable for a long period of time (84 h) without much deactivation and without decrease in the selectivity to propylene glycol. [ABSTRACT FROM AUTHOR]

The development of antioxidants with phenol, hydroxyl, and ketal functional groups provides a creative approach to preventing the degradation of stored petroleum-derived products such as gasoline. The present study proposes a simple and efficient protocol for successful synthesis of improved phenolic derivatives in good yields. The novel antioxidants were characterized via nuclear magnetic resonance (1H NMR, 13C NMR, and DEPT 135°), elemental analysis, thermogravimetry (TG), and derivative thermogravimetry (DTG). TG/DTG curves show that 2,6-di-t-butyl-4-(2-(4-(hydroxymethyl)-2-methyl-1,3-dioxolan-2-yl)ethyl)phenol possesses a higher thermal degradation temperature (298 °C) than 2,6-di-t-butyl-4-methylphenol (BHT). The novel phenolic derivative with the glycerol ketal group was submitted for accelerated oxidation and induction period tests. The synthesized additive gave the best performance at 10 ppm concentration, which increases the induction period to 185 min. In the accelerated oxidation test, the carbonyl and peroxide band areas declined with the addition of 1% antioxidant to gasoline. The results revealed a significant reduction in the formation of oxidation products in gasoline at low concentration of the proposed antioxidants. [ABSTRACT FROM AUTHOR]

We report the efficacy of the pulse electrodeposition technique for the preparation of Ni with two structure directing agents, viz citric acid and tetrabutylammonium bromide. The electrodes were characterized using FESEM, TEM, EDAX, XRD, XPS and AFM for surface morphology, chemical composition, preferred orientation, oxidation states and surface roughness. In the presence of the structure directing agents, the surface morphologies get modified from pine-cone to sponge-like structures and the relative intensities of the (111), (220), (311) and (222) crystal planes get enhanced. The electro-oxidation of glycerol is investigated using cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy. The electrochemical studies indicate that Ni–CA and Ni–TBr exhibit higher catalytic activity with lower onset potentials of 1.32 and 1.33 V vs. RHE and smaller Tafel slopes of 80 and 84 mV dec−1 than bare Ni. An empirical correlation of the experimental peak current density with the work function of the metals has also been deduced. [ABSTRACT FROM AUTHOR]

In this work, we report a selective and straightforward process to synthesize glycerol carbonate from urea and glycerol using a simple but commercially unavailable catalyst (Sn(OH)2). This catalyst was generated in situ from the reaction of Sn(ii) halides and urea during the glycerol carbonatation process. Effects of main reaction parameters (i.e., temperature, molar ratio of urea to glycerol, catalyst concentration) were investigated. Different tin halides were assessed as catalytic precursors, with SnCl2 being the most efficient. We found that Sn(OH)2-catalyzed glycerol carbonation reactions with urea achieved high conversion and selectivity (ca. 87 and 85%, respectively). The samples of Sn(OH)2 generated in situ or previously synthesized were equally active and selective catalysts toward glycerol carbonate were successfully reutilized without loss activity. This is a very attractive route based on two inexpensive and readily available feedstocks in a chemical cycle that, overall, results in the chemical fixation of carbon dioxide and, concomitantly, adds value to glycerol, a biodiesel byproduct. [ABSTRACT FROM AUTHOR]

A novel amino siloxane-functionalized MCM-41 supported Wells–Dawson type H6P2W18O62 (D-HPW) catalyst was synthesized by a two-step method and investigated in the gas phase dehydration of glycerol to acrolein. The amino siloxanes (KH-540, KH-792, and NQ-62) were firstly loaded on MCM-41, and then D-HPW was impregnated. After loading of amino siloxanes, the heteropolyanions interacted with the amine groups, generating strongly distorted heteropolyanions on the surface of the host materials. As a result, these heteropolyanions with a highly deformed structure might render H+ more active, finally showing more Brønsted acid sites. The strong chemical interaction between the amine groups and the D-HPW molecules was strengthened with the increase in the number of amine groups. The results showed that the acrolein selectivity was enhanced after loading of amino siloxanes because of the increased Brønsted acid sites. The catalyst stability was enhanced, because the amount of coke decreased, and the enhancement of the interaction between the –NH2 groups in the amino siloxane and the D-HPW molecules prevented the leaching of D-HPW. Finally, D-HPW/NQ-62-MCM-41 exhibited the highest acrolein selectivity and stability. The reaction pathway for the gas-phase dehydration of glycerol on the amino siloxane-functionalized MCM-41 supported D-HPW catalyst is also proposed. [ABSTRACT FROM AUTHOR]

The acetylation of glycerol was achieved with high conversion and selectivity towards triacetin at low temperatures and short reaction times by using acidic imidazolium salts as catalysts. Moreover, the addition of a nitro group to the imidazolium cation affords a much more competent catalyst, indicating a significant effect provided by the simple electronic change in the imidazolium cation. Theoretical calculations revealed increased polarization of the acidic hydrogen bond on the nitrated salts, which may be related to their superior catalytic behavior when compared to the non-functionalized salts. Combining the preliminary experimental and theoretical results, it is possible to suppose that the catalytic activity of acidic imidazolium salts may be better comprehended by its Brønsted acidities, but other parameters such as hardness, electronegativity, electrophilicity and ion-pair binding energy were also evaluated in order to investigate their effects in the acetylation of glycerol promoted by these acidic imidazolium salts. [ABSTRACT FROM AUTHOR]

A catalyst-free, efficient and green protocol has been developed for the chemoselective N-Boc protection of amines by using glycerol as a solvent at room temperature. A variety of functionalized amines, such as aliphatic, aromatic as well as heteroaromatic were protected using the developed protocol. N-tert-Butyloxycarbonylation derivatives were formed without the formation of isocyanate, urea, N,N-di-t-Boc, or oxazolidinone as side products. The operational simplicity, cleaner reaction, rapid reaction convergence, functional group tolerance, excellent yield, high selectivity, catalyst-free feature and solvent recyclability are the distinct advantages of this protocol. Owing to these merits, this protocol is feasible, economical and environmentally benign. [ABSTRACT FROM AUTHOR]

Hydrogenolysis of glycerol has been a subject of intensive research in recent decades. Great efforts have been made investigating the mechanism of bond cleavage using metal or metallic oxide catalysts. In this work, effects of a series of WCx-based catalysts, including WCx, Cu/WCx, Pt/WCx, Ru/WCx, CuRu/WCx and CuPt/WCx, were studied on hydrogenolysis of glycerol to investigate the role of each active phase. WO3-Based catalysts were employed as a comparison with the WCx-based catalysts. Hydrogenolysis of model compounds (1,2-PDO and EG) of glycerol was also studied using these catalysts, in attempts to determine the mechanism of the whole reaction. The presence of metal elements on WCx or WO3 can significantly improve the conversion of reactant. In addition, the ability of WCx to promote cleavage of C–C was verified. Ru is more beneficial for formation of EG than Pt, whereas Pt is favorable for formation of 1,2-PDO. It had been supposed that hydrogenolysis of glycerol by WCx-based catalysts occurred via two different but overlapping routes: WCx-related reactions caused by C–C cleavage and metal-related reactions caused by C–O cleavage, which happen simultaneously in the reaction. The current study not only demonstrates that the catalytic performance of WCx can be manipulated by varying metal loading, but also offers a possible mechanism for C–C and C–O cleavage in hydrogenolysis of glycerol, which could be beneficial when focusing on the target product. [ABSTRACT FROM AUTHOR]

A new synthesis route for colloidal GdF3 nanocrystals was proposed via a thermolysis of trifluoroacetate salts. Its novelty arises from the application of a commercially available rice oil (being a mixture of natural triglycerides) as the synthesis solvent. Rice oil decomposes at ∼254 °C into glycerol and three fatty acids, being a green source of capping ligands. Rapid nucleation with a low concentration of ligands results in monodisperse nanocrystals, while delayed ligand activation results in well-stabilized nanocrystals in the final stage of the synthesis. The nanocrystals show a synthesis time and temperature dependent size (3–11 nm) and shape (spherical and rhombic). We determined a size range (5.6–9.4 nm) in which the nanocrystals show double morphology (spherical and rhombic), while smaller and bigger NCs exist only in a spherical or a rhombic form, respectively. Detailed analysis of the nanocrystal morphology was followed by spectroscopic investigations of their optical properties. We determined a significant influence of a residual oxygen atom and a high surface to volume ratio on the excitation and emission of Eu3+ ions. The contribution of the oxygen diminishes at high temperature and/or with prolonged synthesis. [ABSTRACT FROM AUTHOR]

A novel red aggregation-induced emission enhancement (AIEE) chromophore named BCPA–BODIPY was synthesized based on the construction units 4-N,N-bis[4-(3,6-di-tert-butylcarbazol-9-yl)phenyl]amino-benzaldehyde (BCPA) and fluorogen dipyrromethene boron difluoride (BODIPY). BCPA exhibits bright blue fluorescence (λem = 485 nm) in the solid state while BCPA–BODIPY emits bright red fluorescence in the solid state with a maximum emission wavelength at 633 nm. An obvious bathochromic shift from 485 nm to 633 nm was observed by modification of the BODIPY moiety on BCPA. Its fluorescence spectrum indicates that BCPA–BODIPY is a bimodal structure centred at 520 nm and 656 nm in THF solution; there was almost no fluorescence in pure THF. However, the intensities (＞600 nm) increased obviously with much higher water fractions, demonstrating typical red fluorescence enhancement. Meanwhile, BCPA–BODIPY became a strong emitter in DMF and high viscosity glycerol mixtures which indicates that the intramolecular vibration and rotation of BCPA–BODIPY is considerably restricted in nanoaggregates formed in glycerol, thus leading to significant fluorescence enhancement. Besides, dye-loaded nanoparticles encapsulating BCPA–BODIPY maintain and further reinforce the AIEE effect and achieve higher water solubility. The pure dye was applied in cell imaging and showed a good uptake by MCF-7 cells which suggests it to be promising in biosensor applications. [ABSTRACT FROM AUTHOR]

Nickel catalysed Suzuki reactions of phenyl boronic acids with aryl diazonium salts in glycerol as a reaction medium are reported. Various aryl diazonium salts were efficiently reacted with aryl boronic acids under optimized conditions to give the respective diaryl compounds in good to excellent yields. The base free conditions and use of glycerol as a solvent, which can be recycled successfully for up to five consecutive cycles, make the present protocol environmentally benign in nature. [ABSTRACT FROM AUTHOR]

Selective conversion of glycerol to lactic acid requires the synergistic activation of C–H, C–O, and O–H. Herein, we report an inexpensive Fe–Cr/TiO2 catalyst that achieves lactic acid formation with a high selectivity of 60.5%. By changing the Fe/Cr ratios and reduction temperatures, the structures of Vő and Vő-OH were altered, which determined the overall oxidation–dehydration–isomerization process. The in situ ATR-IR experiments confirmed the activation of glycerol by adsorbing the primary −OH, and a series of control experiments verified that Fe was responsible for the cleavage of C–H and O–H, while CrOx catalyzed the activation of C–O and C–H. This work designs a hydrothermal catalyst with multifunctional ability, which may guide the rational catalyst design for the selective oxidation of glycerol to lactic acid. [ABSTRACT FROM AUTHOR]

Selective hydrogenolysis of glycerol to 1,2-propanediol is one of the options for the chemical utilization of glycerol. In this work, we synthesized sulfate-functionalized metal–organic frameworks loading palladium nanoparticles, MOF-808-SO4-Pd, as effective glycerol hydrogenolysis catalysts. The sulfate groups are responsible for the dehydration of glycerol. Subsequently, palladium nanoparticles hydrogenate the intermediates to 1,2-propanediol. The synergistic reaction between acid sites and Pd gave 93.9% selectivity of 1,2-propanediol with a reaction rate of 22.4 mmol gPd−1 h−1. Our work highlights new opportunities in using acid-functionalized MOFs as novel supports for metal nanoparticle catalysts for dual site catalysis. [ABSTRACT FROM AUTHOR]

This work studied platinum and indium supported on alumina and silica as monometallic and bimetallic catalysts for the aqueous phase hydrogenolysis of glycerol towards 1,2-propanediol (1,2-PDO). The prepared catalysts were characterized by N2 physisorption, XRD, TPR, pyridine adsorption DRIFTS, TPD-H2, TPD-CO, H2 and CO chemisorption, and TEM. For alumina-supported catalysts, there was a conversion of 39% when using Pt/Al2O3 and 33% when using Pt–In/Al2O3. The In/Al2O3 catalyst did not perform well, showing a conversion of 2%. Turnover frequencies for Pt/Al2O3 and Pt–In/Al2O3 showed values of 1.8 × 10−1 s−1 and 3.0 × 10−1 s−1, respectively, considering H2 chemisorption for active site measurements. From the characterization of the catalysts, it can be inferred that In dilutes Pt in bimetallic particles, creating more selective Pt–In sites for the APH of glycerol. The influence of the catalyst structure, bimetallic Pt–In particles and different supports is discussed. [ABSTRACT FROM AUTHOR]

Liquid phase dehydration of glycerol to acrolein commonly suffers from a low acrolein yield because of severe side reactions of chemically active acrolein with itself or glycerol in the reaction system. Rapid separation of acrolein from the reaction system is one of the effective strategies to increase the yield of acrolein. Herein, a renewable water-in-oil Pickering emulsion with silica nanoparticle cages as microreactors was designed for liquid phase glycerol dehydration to acrolein. The influences of the oil phase types on the droplet size of the Pickering emulsion and the yield of acrolein were investigated in a microreactor. The smaller Pickering emulsion droplet showed a superior ability to intensify the separation of chemically unstable acrolein molecules from the nanoparticle cages and thus improved the yield of acrolein. A droplet size of about 11 μm was obtained with peony seed oil as the oil phase, in which 84.6% of acrolein yield was achieved. [ABSTRACT FROM AUTHOR]

Synthesis of a highly ordered mesoporous acid- as well as metal-functionalized carbon (–SO3H/C–Si–Zr) material is achieved for the first time from a simple single-pot template-free carbonization of low-value bio-derived glycerol. Addition of TEOS to glycerol right before the carbonization was observed to facilitate molecular-level interactions between them to establish C–Si bonding, which eventually leads to the formation of a high surface area mesoporous –SO3H/C–Si composite material. Unlike this, the addition of ZrO(NO3)2·xH2O to glycerol could not have such an effect, but when Zr is used in the presence of TEOS the mixture could successfully produce the –SO3H/C–Si–Zr composite possessing mesoporosity and uniform acidity suitable for bulky tri-acetin production useful for fuel applications. Here TEOS is observed to play two roles, (1) as a surface area and porosity improver of graphitic carbon by its C–Si interaction and (2) as a mediator to involve Zr in the carbon composite structure through its Si–OH group. Thus, the combined inclusion of Zr and Si sources in the glycerol-derived carbon structure could successfully introduce the positive aspects of porosity improvement (by Si) and acidity improvement (by zirconia) in the mixed composite –SO3H/C–Si–Zr to produce the highest ever selectivity of tri-acetin (∼94 wt%) from the same low-value bio-derived glycerol by an acetylation reaction. The sustainability of the process lies in the utilization of waste glycerol as a source of the carbon composite, which in turn catalyzes selective low-value glycerol conversion to industrially important fuel additives. [ABSTRACT FROM AUTHOR]

Herein, a 3D flower-like CoNi2S4 and leaf-like polyaniline (CoNi2S4/PANI) hybrid was designed and prepared using a hydrothermal method and physical grinding method for the electrocatalytic oxidation of glycerol. The as-prepared materials were first screened and optimized, and then, a series of characterizations and electrochemical measurements of modified electrodes towards glycerol were performed. The characterization results showed that the 3D flower-like CoNi2S4 displayed distinct mesoporous structures and large specific surface area. Moreover, based on the X-ray photoelectron spectroscopy results, its nickel and cobalt species mainly contain Ni2+ and Ni3+ and Co2+ and Co3+, respectively. When the mass ratio of CoNi2S4 : PANI was 1 : 1, the material exhibited highest catalytic activity towards the oxidation of glycerol in 1.0 mol L−1 NaOH containing a 1.0 mol L−1 C3H8O3 solution. The electrochemical impedance spectroscopy test shows that the CoNi2S4/PANI (1 : 1) composite presents lower Rct value and larger slope value, indicating that the composite has excellent electrochemical activity. The lower Tafel slope for the CoNi2S4/PANI (1 : 1) composite most likely indicates the increased glycerol oxidation; chronoamperometry has proved that the CoNi2S4/PANI (1 : 1) composite possesses higher stability and better poison resistance as compared to commercial Pt/C (20 wt%); the possible mechanism for the enhanced performance of CoNi2S4/PANI (1 : 1) is attributed to its unique structure with larger specific area, including 3D flower-like CoNi2S4, highly conductive PANI with a leaf shape, and a stable 3D architecture of CoNi2S4/PANI. This pioneering study should be conducive to improving the electro-oxidation of glycerol in the field of direct alcohol fuel cells. [ABSTRACT FROM AUTHOR]

The support effects of graphene oxide (GO) and KIT-6 on alumina loading as a catalyst to convert glycerol into value added products via the acetylation reaction were studied. The catalyst alumina loaded on the different supports of GO and KIT-6 was synthesized via modified Hummers’ and hydrothermal methods, respectively. Different weight percentages of alumina, such as 1, 3, 5, 7 and 9%, loaded on GO and KIT-6 were obtained via a wet impregnation method. The synthesized materials, with different GO and KIT-6 supports and metal oxide loadings, were characterized using the techniques of X-ray diffraction, Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, thermogravimetric analysis (TGA), ammonia temperature programmed desorption (NH3-TPD), scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS) and high resolution transmission electron microscopy (HR-TEM) to obtain the physicochemical characteristics of the materials. Elemental analysis of the catalysts was done via inductively coupled plasma optical emission spectrometry (ICP-OES) analysis to obtain the aluminium content in the supports. The catalytic activities of the catalysts were examined for the acetylation of glycerol with glacial acetic acid. The activities of the catalysts were optimized through studying different parameters, like the alumina loading on the support, temperature, time, and molar ratio of glycerol to glacial acetic acid. The catalysts showed potential to be used as a recycled material for the acetylation reaction. [ABSTRACT FROM AUTHOR]

A novel route for the synthesis of 3-picoline from glycerol via liquid phase reaction under mild condition, using microwave irradiation, had been well established. The heating mode had a profound effect on the yield of 3-picoline. The formation of 3-picoline could be promoted significantly by microwave heating, however, only very little amount of 3-picoline was generated by conventional heating under the reaction conditions employed in this study. Influencing factors were systemically investigated on the basis of a HAc-catalyzed under microwave irradiation. Additionally, a lot of heterogeneous catalysts were screened. It was found that as high as a 71% yield of 3-picoline was obtained with the mass ratio of pure glycerol/ammonium acetate/acetic acid/TiO2 = 1/3/10/0.2 at 373 K, after only 20 min of microwave irradiation. A catalyst pair (HAc and TiO2) exhibited better catalytic performance relative to other catalysts in this work. Accordingly, microwave assistance together with the catalysts achieved effective transformation of glycerol to 3-picoline under mild conditions. The related plausible reaction mechanisms were also proposed. [ABSTRACT FROM AUTHOR]

In this study, N-doped carbon dots (NCDs) could be prepared by using glycerol as the carbon source and ethylenediamine as a nitrogen doped molecule through a one-step microwave irradiation method. The resulting NCD probes could exhibit linear fluorescence response to Pb2+ at a detection limit as low as 15.0 nM, which could be applied for trace levels of direct pb2+ recognition. [ABSTRACT FROM AUTHOR]

Oxidation multi-walled carbon nanotubes (O-MWCNTs)–glycerol nanofluids were prepared, either with or without any polyvinyl alcohol (PVA), and their thermal conductivity (TC), stability, fluidity, and rheological properties were investigated. The results demonstrated that the TC enhancements of the nanofluids were almost linear with the nanotube concentration but showed little dependence on temperature. The largest TC enhancement was up to 21.0% when the volume concentration was only 1.4 vol%. The nanofluids exhibited high stability for more than 2 months and a very interesting gel–sol transition phenomenon induced by a low amount of PVA (about 0.06 wt%), which can be observed by an inverted and side tube method and supported by the rheological data. As the fluidity loss of carbon nanotube-based nanofluids has long been one of the major obstacles for their potential applications in energy transfer technologies, the novel gel–sol transition phenomenon introducing the fluidity recovery has great significance in both academic research and practical application fields of the nanofluids. Furthermore, a reasonably stable and disperse mechanism was also proposed to explain this phenomenon. [ABSTRACT FROM AUTHOR]

In this article, we describe the synthesis of a perfluoro-tagged polyglycerol dendron and its aggregation behavior in the presence of polyglycerol dendrimers with perfluorinated shells in water. The perfluoro-alkyl–perfluoro-alkyl interactions between the perfluorinated shells of the dendrimers and the perfluorinated tags of the dendrons lead to highly stable supramolecular architectures, due to self-assembly of the perfluorinated moieties. Furthermore, we show that the size of the resulting supramolecular complexes can be tuned by simple variation of the dendrimer–dendron ratio. Complexes at various ratios are characterized by optical microscopy, DLS, and TEM. In general, the results presented herein demonstrate that perfluoro-alkyl–perfluoro-alkyl interactions are applicable for the formation of stable supramolecular structures in water and thus provide a new tool for the design of supramolecular architectures in addition to traditional non-covalent interactions. [ABSTRACT FROM AUTHOR]