Environmentally friendly procedure for the aqueous oxidation of benzyl alcohols to aldehydes with dibromodimethylhydantoin (DBDMH) and cyclodextrin: Scope and mechanistic insights

<p>Reported herein is an environmentally friendly procedure for the oxidation of benzyl alcohols to aldehydes using an inexpensive, commercially available reagent, 1,3-dibromo-5,5-dimethylhydantoin (DBDMH), and a variety of cyclodextrin additives under fully aqueous solvent conditions. This reaction proceeds with moderate to good yields for a broad scope of benzyl alcohol substrates, with the cyclodextrin acting to enhance the desired reactivity and limit undesired aromatic bromination side products. The reported experiments provide substantial mechanistic insight that will drive further reaction optimization and have broad-reaching applications.</p

Impact of Nearly Water-Insoluble Additives on the Properties of Vesicular Suspensions

Nearly water-insoluble additives are commonly used in surfactant-based consumer products to enhance their appeal or performance. We used viscosity measurements, time-resolved cryogenic transmission electron microscopy, and NMR spectroscopy to investigate the effect of several additives, linalyl acetate (LA), cyclohexanol, phenol, catechol, guaiacol, and eugenol, that have extremely low water solubility, on the evolution of microstructures in an aqueous multilamellar vesicle suspension of diethylester dimethylammonium chloride (DEEDMAC), a major ingredient in fabric softeners. LA and eugenol are used as fragrances in some detergent-related consumer products. The other additives were chosen to have degrees of aromaticity that are intermediate between LA and eugenol. The viscosity of the DEEDMAC suspension increased only marginally upon addition of LA, while it rose significantly upon addition of eugenol. Cryo-TEM revealed no observable changes to the multilamellar structures in the DEEDMAC suspension when LA was added. The addition of eugenol triggers a transition from multilamellar vesicles to predominantly unilamellar vesicles and bilayer fragments through exfoliation and breakage. By examining NMR results from all the additives, we propose that π electrons in aromatic rings interact strongly with the cationic DEEDMAC head groups. Such interactions are strong in eugenol but not present in LA

Cyclodextrin-Based Pseudorotaxanes: Easily Conjugatable Scaffolds for Synthesizing Hyperpolarized Xenon-129 Magnetic Resonance Imaging Agents

Hyperpolarized (HP) xenon-129 (Xe) magnetic resonance (MR) imaging has the potential to detect biological analytes with high sensitivity and high resolution when coupled with xenon-encapsulating molecular probes. Despite the development of numerous HP Xe probes, one of the challenges that has hampered the translation of these agents from in vitro demonstration to in vivo testing is the difficulty in synthesizing the Xe-encapsulating cage molecule. In this study, we demonstrate that a pseudorotaxane, based on a γ-cyclodextrin macrocycle, is easily synthesized in one step and is detectable using HyperCEST-enhanced ¹²⁹Xe MR spectroscopy