Crystallization Behavior and Crystallographic Properties of dl-Arabinose and dl-Xylose Diastereomer Sugars

[BMIM][X] Ionic Liquids Supported on a Pillared-Layered Metal-Organic Framework: Synthesis, Characterization, and Adsorption Properties

Combining ionic liquids (ILs) and metal-organic frameworks (MOFs) can be an intriguing opportunity to develop advanced materials with different adsorption capabilities for environmental applications. This study reports the preparation and characterization of a 3D pillared-layered compound, namely, [Zn2(tz)2(bdc)] (CIM91), formed by 1,2,4-triazole (Htz) and 1,4-benzenedicarboxylic acid (H2bdc) ligands. Then, various loadings of the water-stable and hydrophobic IL, 1-n-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]), and the water-soluble 1-n-butyl-3-methylimidazolium chloride ([BMIM][Cl]) were incorporated into CIM91. Detailed characterization by X-ray powder diffraction (XRD), FT-IR spectra, scanning electron microscopy (SEM), Energy dispersive X-ray (EDX) analysis, N2 adsorption measurements, and thermogravimetric analysis confirmed the formation of [BMIM][X]/CIM91 composites and the structural stability of the MOF after the incorporation of the ionic liquids. CO2 adsorption-desorption analysis was experimentally carried out for all the materials at 298 K and 318 K, demonstrating a great enhancement in the CO2 adsorption properties of the sole MOF CIM91, particularly by including [BMIM][PF6] species in its structure with a double isosteric heat of CO2 adsorption. The composites were also tested for the adsorption of methylene blue (MB) dye. The results indicate that the incorporation of [BMIM][X] into CIM91 can substantially modify the adsorption properties of the MOF. The influence of the nature of the [BMIM][X] anions on these properties has also been analyzed.

Polyglycerol polyricinoleate and lecithin stabilized water in oil nanoemulsions for sugaring Beijing roast duck: Preparation, stability mechanisms and color improvement

Traditional Beijing roast duck often suffers from uneven color and high sugar content after roasting. Water-in-oil (W/O) nanoemulsion is a promising alternative to replace high concentration of sugar solution used in sugaring process according to similarity-intermiscibility theory. Herein, 3% of xylose was embedded in the aqueous phase of W/O emulsion to replace 15% maltose solution. W/O emulsions with different ratios of lecithin (LEC) and polyglycerol polyricinoleate (PGPR) were constructed by high-speed homogenization and high-pressure homogenization. Distribution and penetration extent of solutions and emulsions through the duck skin, as well as the color uniformity of Beijing roast duck were analyzed. Emulsions with LEC:PGPR ratios of 1:3 and 2:2 had better stability. Stable interfacial film and spatial structure were important factors influencing emulsion stabilization. The stable W/O emulsions could more uniformly distribute onto the surface of duck skin and longitudinally penetrate through the skin than solutions.

Ultra-sensitive detection and scavenging of arsenic ions and ciprofloxacin using 3D multipurpose hemicellulose based aerogel: Adsorption mechanism and RSM optimization

Trace level detection and efficient removal of arsenite ions (As (III)) and ciprofloxacin (CPR) antibiotic was achieved using hemicellulose based ratiometric fluorescent aerogel. Hemicellulose derived from rice straw was oxidised to dialdehyde hemicellulose followed by crosslinking using chitosan via a Schiff base reaction (C = N) yielding a highly porous 3D fluorescent aerogel (CS@DAHCA). Various factors governing adsorption were analyzed by applying response surface methodology (RSM) approach. CS@DAHCA exhibited ultra-trace level monitoring with the limit of detection of 3.529 pM and 55.2 nM for As (III) and CPR, respectively. The CS@DAHCA showed maximum adsorption capacity of 185 μg g-1 and 454 mg g-1 for As (III) and CPR, respectively. Finally, the feasibility of CS@DAHCA was ascertained for real water samples confirming it as promising candidate for remediation of As (III) and CPR.

Revisiting Homochiral versus Heterochiral Interactions through a Long Detective Story of a Useful Azobis-Nitrile and Puzzling Racemate

This paper documents and reinvestigates the solid-state and crystal structures of 4,4'-azobis-4-cyanopentanoic acid (ACPA), a water-soluble azobis-nitrile of immense utility as a radical initiator in living polymerizations and a labile mechanophore that can be embedded within long polymer chains to undergo selective scission under mechanical activation. Surprisingly, for such applications, both the commercially available reagent and their derivatives are used as "single initiators" when this azonitrile is actually a mixture of stereoisomers. Although the racemate and meso compounds were identified more than half a century ago and their enantiomers were separated by classical resolution, there have been confusing narratives dealing with their characterization, the existence of a conglomeratic phase, and fractional crystallization. Our results report on the X-ray crystal structures of all stereoisomers for the first time, along with further details on enantiodiscrimination and the always intriguing arguments accounting for the stability of homochiral versus heterochiral crystal aggregates. To this end, metadynamic (MTD) simulations on stereoisomer molecular aggregates were performed to capture the incipient nucleation events at the picosecond time scale. This analysis sheds light on the driving homochiral aggregation of ACPA enantiomers.

On the Origin of Sugar Handedness: Facts, Hypotheses and Missing Links-A Review

By paraphrasing one of Kipling's most amazing short stories (How the Leopard Got His Spots), this article could be entitled "How Sugars Became Homochiral". Obviously, we have no answer to this still unsolved mystery, and this perspective simply brings recent models, experiments and hypotheses into the homochiral homogeneity of sugars on earth. We shall revisit the past and current understanding of sugar chirality in the context of prebiotic chemistry, with attention to recent developments and insights. Different scenarios and pathways will be discussed, from the widely known formose-type processes to less familiar ones, often viewed as unorthodox chemical routes. In particular, problems associated with the spontaneous generation of enantiomeric imbalances and the transfer of chirality will be tackled. As carbohydrates are essential components of all cellular systems, astrochemical and terrestrial observations suggest that saccharides originated from environmentally available feedstocks. Such substances would have been capable of sustaining autotrophic and heterotrophic mechanisms integrating nutrients, metabolism and the genome after compartmentalization. Recent findings likewise indicate that sugars' enantiomeric bias may have emerged by a transfer of chirality mechanisms, rather than by deracemization of sugar backbones, yet providing an evolutionary advantage that fueled the cellular machinery.