Chiral Supramolecular Polymers Assembled by Amphiphilic Oligopeptide-Perylene Diimides and High Electrochemical Sensing

Applications of Nanozymes in Chiral-Molecule Recognition through Electrochemical and Ultraviolet-Visible Analysis

Chiral molecules have similar physicochemical properties, which are different in terms of physiological activities and toxicities, rendering their differentiation and recognition highly significant. Nanozymes, which are nanomaterials with inherent enzyme-like activities, have garnered significant interest owing to their high cost-effectiveness, enhanced stability, and straightforward synthesis. However, constructing nanozymes with high activity and enantioselectivity remains a significant challenge. This review briefly introduces the synthesis methods of chiral nanozymes and systematically summarizes the latest research progress in enantioselective recognition of chiral molecules based on electrochemical methods and ultraviolet-visible absorption spectroscopy. Moreover, the challenges and development trends in developing enantioselective nanozymes are discussed. It is expected that this review will provide new ideas for the design of multifunctional chiral nanozymes and broaden the application field of nanozymes.

Chiral Supramolecular Self-Assembly Catalysts with Enhanced Metal Ion Interaction for Higher Enantioselectivity

Understanding the interaction between metal ions as catalytic centers and supramolecular scaffolds as chiral substrates plays an important role in developing chiral supramolecular catalysts with high enantioselectivity. Herein, we found that compared with l-norleucine chiral amphiphile (l-NorC16), l-methionine chiral amphiphile (l-MetC16) with the only heteroatom of S site difference in the hydrophilic group can form a similar supramolecular chiral nanoribbon (NR) with the bilayer structure through the self-assembly approach; yet, the interaction between the Cu(II) ion catalytic centers and supramolecular scaffolds is reinforced, favoring the chirality transfer and therefore enhancing their catalytic enantioselectivity of Diels-Alder reaction from 23% [l-NorC16-NR-Cu(II)] to 78% [l-MetC16-NR-Cu(II)]. Our work demonstrates a new strategy from the perspective of strengthening the metal ion-supramolecular scaffold interaction for the preparation of chiral supramolecular catalysts with good catalytic enantioselectivity.

Phenylglycine amphiphile-metal ion chiral supramolecular nanozymes for enantioselective catalysis

L/D-Phenylglycine amphiphiles and metal ions with peroxidase-like activity self-assembled into chiral nanoribbons, which act as efficient chiral supramolecular nanozymes for catalyzing the 3,4-dihydroxy-L/D-phenylalanine (L/D-DOPA) oxidation reactions. The catalytic efficiency and enantioselectivity are dominated by the chirality transfer and the synergistic effect between the metal ions and chiral nanoribbons.

Molecularly Selective Polymer Interfaces for Electrochemical Separations

The molecular design of polymer interfaces has been key for advancing electrochemical separation processes. Precise control of molecular interactions at electrochemical interfaces has enabled the removal or recovery of charged species with enhanced selectivity, capacity, and stability. In this Perspective, we provide an overview of recent developments in polymer interfaces applied to liquid-phase electrochemical separations, with a focus on their role as electrosorbents as well as membranes in electrodialysis systems. In particular, we delve into both the single-site and macromolecular design of redox polymers and their use in heterogeneous electrochemical separation platforms. We highlight the significance of incorporating both redox-active and non-redox-active moieties to tune binding toward ever more challenging separations, including structurally similar species and even isomers. Furthermore, we discuss recent advances in the development of selective ion-exchange membranes for electrodialysis and the critical need to control the physicochemical properties of the polymer. Finally, we share perspectives on the challenges and opportunities in electrochemical separations, ranging from the need for a comprehensive understanding of binding mechanisms to the continued innovation of electrochemical architectures for polymer electrodes.

Evolution of π-Peptide Self-Assembly: From Understanding to Prediction and Control

Supramolecular materials derived from the self-assembly of engineered molecules continue to garner tremendous scientific and technological interest. Recent innovations include the realization of nano- and mesoscale particles (0D), rods and fibrils (1D), sheets (2D), and even extended lattices (3D). Our research groups have focused attention over the past 15 years on one particular class of supramolecular materials derived from oligopeptides with embedded π-electron units, where the oligopeptides can be viewed as substituents or side chains to direct the assembly of the central π-electron cores. Upon assembly, the π-systems are driven into close cofacial architectures that facilitate a variety of energy migration processes within the nanomaterial volume, including exciton transport, voltage transmission, and photoinduced electron transfer. Like many practitioners of supramolecular materials science, many of our initial molecular designs were designed with substantial inspiration from biologically occurring self-assembly coupled with input from chemical intuition and molecular modeling and simulation. In this feature article, we summarize our current understanding of the π-peptide self-assembly process as documented through our body of publications in this area. We address fundamental spectroscopic and computational tools used to extract information regarding the internal structures and energetics of the π-peptide assemblies, and we address the current state of the art in terms of recent applications of data science tools in conjunction with high-throughput computational screening and experimental assays to guide the efficient traversal of the π-peptide molecular design space. The abstract image details our integrated program of chemical synthesis, spectroscopic and functional characterization, multiscale simulation, and machine learning which has advanced the understanding and control of the assembly of synthetic π-conjugated peptides into supramolecular nanostructures with energy and biomedical applications.

One-Dimensional Helical Nanostructures from the Hierarchical Self-Assembly of an Achiral "Rod-Coil" Alternating Copolymer

The self-assembly of alternating copolymers (ACPs) has attracted considerable interest due to their unique alternating nature. However, compared with block copolymers, their self-assembly behavior has remained much less explored and their reported self-assembled structures are limited. Here, we report the formation of supramolecular helical structures by the self-assembly of an achiral rod-coil alternating copolymer, poly(quarter(3-hexylthiophene)-alt-poly(ethylene glycol)) (P(Q3HT-alt-PEG)). The copolymer exhibited an interesting hierarchical self-assembly process, driven by the π-π stacking of the Q3HT segments and the solvophobic interaction of the alkyl chains in tetrahydrofuran (THF)-isopropanol (iPrOH) mixed solvents. The copolymer first self-assembled into thin nanobelts with a uniform size, then grew to helical nanoribbons and eventually twisted into helical nanowires with an average diameter of 25 ± 9 nm and a mean pitch of 80 ± 10 nm. Dissipative particle dynamics (DPD) simulation supported the formation course of the helical nanowires. Furthermore, the addition of (S)-ethyl lactate and (R)-ethyl lactate in the self-assembly of P(Q3HT-alt-PEG) resulted in the formation of left-handed and right-handed chiral nanowires, respectively, demonstrating the tunability of the chirality of the helical wires. This study expands the library of ordered self-assembled structures of ACPs, and also brings a new strategy and mechanism to construct helical supramolecular structures. This article is protected by copyright. All rights reserved.

Cucurbit[7]uril-Modulated H/D Exchange of α-Carbonyl Hydrogen: Deceleration in Alkali and Acceleration in Acid Conditions

Supramolecular catalysis based on host-guest interactions has aroused much attention in past decades. Among the various strategies, modulation of the reactivity of key intermediates is an effective strategy to achieve high-efficiency supramolecular catalysis. Here, we report that by utilizing the host-guest interaction of cucurbit[7]uril (CB[7]), the reactivity of anionic enolate and cationic oxonium, the intermediates of H/D exchange of the α-carbonyl hydrogen in alkali and acid conditions, respectively, could be modulated effectively. On one hand, in alkaline conditions, both the electrostatic effect and the steric hindrance effect of CB[7] disfavored formation of the enolate anion intermediate. On the other hand, in acidic conditions, the oxonium was stabilized and the solvent effect was weakened by the electrostatic effect of CB[7]. As a result, the H/D exchange of 1-(4-acetylphenyl)-N,N,N-trimethylmethanaminium bromide is decelerated in alkaline and accelerated in acidic conditions. It is promising that the highly polar portals of CB[n] molecules together with their well-defined host-guest chemistry may be applied to modulate the reactivity of other kinds of ionic intermediates in an effective and convenient way, thus enriching the toolkit of supramolecular catalysis.

Photoregulated Morphological Transformation of Spiropyran Derivatives Achieving the Tunability of Interfacial Hydrophilicity

Regulation of self-assembly morphology is an effective strategy to obtain advanced functional materials with expected properties. However, achieving remarkable morphological transformation by light irradiation is still a challenge. Herein, three simple spiropyran derivatives (SP1, SP2, and SP3) are constructed, achieving different degrees of morphological transformation from nanospheres to hollow tadpole-like structures (SP3), tubular structures (SP2), and microsheets (SP1) after ultraviolet light irradiation. Interestingly, the hollow tadpole-like structures (SP3) can further extend to Y-shaped or T-shaped tubular morphology. In the process, SP1, SP2, and SP3 can be isomerized from a closed-ring form (hydrophobicity) to an open-ring form (hydrophilicity) in different degrees, interacting differently with methanol solvent molecules. The formation of hollow structures or microsheets along with the isomerization of spiropyran derivatives contributes to the adjustment of the hydrophilicity of the interface. Therefore, SP1, SP2, and SP3 with photoregulated morphological transformation show promising applications in tunable interface materials.