Ultrafast Proton Transfer in Polymer Blends Triggered by Shock Waves

Pore Geometry and Surface Engineering of Covalent Organic Frameworks for Anhydrous Proton Conduction

Developing new materials for anhydrous proton conduction under high-temperature conditions is significant and challenging. Herein, we create a series of highly crystalline covalent organic frameworks (COFs) via a pore engineering approach. We simultaneously engineer the pore geometry (generating concave dodecagonal nanopores) and pore surface (installing multiple functional groups such as -C=N-, -OH, -N=N- and -CF₃ ) to improve the utilization efficiency and host-guest interaction of proton carriers, hence benefiting the enhancement of anhydrous proton conduction. Upon loading with H₃ PO₄ , COFs can realize a proton conductivity of 2.33×10^-2  S cm^-1 under anhydrous conditions, among the highest values of all COF materials. These materials demonstrate good stability and maintain high proton conductivity over a wide temperature range (80-160 °C). This work paves a new way for designing COFs for anhydrous proton conduction applications, which shows great potential as high-temperature proton exchange membranes.

Hydrogen bond network dynamics of heavy water resolved by alcohol hydration under an intense laser

Despite a great deal of effort spanning for decades, it remains yet puzzling concerning how alcohol molecules functionalize the hydrogen bond (H-bond) networks of water. We employed an isotopic substitution method (using alcohol-heavy water system) to avoid spectral overlap between the alcohol hydroxyl groups and water hydrogen bonds. We showed spectrometrically that under the strong pulse laser, the low mixing ratio (V_A < 20%) of alcohol can strengthen the H-bond network structure of D₂O through :ÖC₂H₆↔ D₂Ö: compression. But when V_A > 20%, H-bond network of D₂O will deform via the self-association between alcohol molecules. Our experiments not only reveal the H-bond kinetics of heavy water-alcohol interactions but also provide important reference for understanding the distinctive properties of H-bond in water-organic system.

Ionic surfactants as assembly crosslinkers triggered supramolecular membrane with 2D↔3D conversion under multiple stimulus

HYPOTHESIS

General strategies leading to 2D assemblies promise a significant step forward in the development of supramolecular materials with diversity and superiority. Considering molecular packing parameter indicates a connection between molecular geometry and aggregate morphology, we predict the introduction of ionic surfactants as assembly crosslinker would be endowed to develop a methodology of 2D supramolecular assembles.

EXPERIMENTS

In this work, by introducing ionic surfactants such as sodium dodecylsulfate (SDS), the molecular packing parameter P in bolaamphiphile (A2G) system was increased, which successfully manipulated the transformation of the 3D vesicles into 2D membranes. This 2D membranes further showed excellent light and enzyme response, and thus 2D to 3D morphological conversion can be rationally controlled via UV/Vis light irradiation and alternate addition of β-CD and α-amylase. Significantly, the 2D feature revealed not only a remarkable fluorescence enhancement to luminescent molecules but also the ability to effectively remove pollutants from water through filtration.

FINDINGS

We report a general and facile strategy for the construction of 2D supramolecular membranes, initiated by introducing ionic surfactants as assembly crosslinker to increase P. In the existence of stimulus response factors, 2D↔3D morphological conversion can be further controlled in a flexible manner, which opens up a new paradigm leading to interconvertible supramolecular materials.

Mechanical Force for the Transformation of Aziridine into Imine

Force-selective mechanochemical reactions may be important for applications in polymer mechanochemistry, yet it is difficult to achieve such reactions. This paper reports that cis-N-phthalimidoaziridine incorporated into a macromolecular backbone undergoes migration of N-phthalimido group to afford imine under mechanochemical condition and not thermal one. The imine is further hydrolyzed by water bifurcating into amine and aldehyde. These structural transformations are confirmed by ¹ H NMR and FT-IR spectroscopic analyses. Computational simulations are conducted for the aziridine mechanophore to propose the mechanism of reaction and define the substrate scope of reaction.

Mechanical Force Induces Ylide-Free Cycloaddition of Nonscissible Aziridines

The application of aziridines as nonvulnerable mechanophores is reported. Upon exposure to a mechanical force, stereochemically pure nonactivated aziridines incorporated into the backbone of a macromolecule do not undergo cis-trans isomerization, thus suggesting retention of the ring structure under force. Nonetheless, aziridines react with a dipolarophile and seem not to obey conventional reaction pathways that involve C-C or C-N bond cleavage prior to the cycloaddition. Our work demonstrates that a nonvulnerable chemical structure can be a mechanophore.

Spontaneous proton transfer in a series of amphoteric molecules under hydrostatic pressure

Hydrostatic pressure has induced intermolecular proton transfer in the crystals of a series of amphoteric molecules, which results in significant color changes.

Proton in a Confined Space: Structural Studies of H+ ⊂Crypt-111 Iodide and Some Halogen-Bonded Derivatives

Experimental observations and modeling data are reported on the solid-state structural features of crypt- 111⋅HI (1) and the three-component co-crystals that 1 forms with α,ω-diiodoperfluoroalkanes 2 a-d. X-ray analyses indicate that, in all five systems and at low temperature, the caged proton is covalently bonded to a single nitrogen atom and is involved in a network of intramolecular hydrogen bonds. In contrast, room-temperature, solid-state ¹⁵ N NMR spectroscopy suggests magnetic equivalency of the two N atoms of crypt-111 in both 1 and co-crystals of 1 with diiodoperfluoroalkanes. Computational modelling confirms that the acidic hydrogen inside the cavity preferentially sits along the internitrogen axis and is covalently bonded to one nitrogen. The computed energy barriers suggest that the hopping of the encapsulated proton between the two N atoms of the cage can occur in the halogen-bonded co-crystals of 1⋅2, but it is hardly possible in the pure H⁺ ⊂crypt-111 iodide 1. These different pictures of the proton position and dynamics obtained by using different techniques and conditions confirm the unique characteristics of the confined space within the cavity of crypr-111 and the distinctive features of processes occurring therein.