Macrocycles that assemble into nanotubes exhibit emergent properties stemming from their low dimensionality, structural regularity, and distinct interior environments. Here, we report a versatile strategy to synthesize diverse nanotube structures in a single, efficient reaction by using a conserved building block bearing a pyridine ring. Imine condensation of a 2,4,6-triphenylpyridine-based diamine with various aromatic

Optical analysis of reaction parameters such as enantiomeric excess (ee), diastereomeric excess (de), and yield are becoming increasingly useful as assays for differing functional groups become available. These assays typically exploit reversible covalent or noncovalent assemblies that impart optical signals, commonly circular dichroism (CD), that are indicative of the stereochemistry and ee at a stereocenter proximal to the functional group of interest. Very few assays have been reported that determine ee and de when two stereocenters are present, and none have targeted two different functional groups that are vicinal and lack chromophores entirely. Using a CD assay that targets chiral secondary alcohols, a separate CD assay for chiral primary amines, a UV–vis assay for de, and a fluorescence assay for concentration, we demonstrate a work-flow for speciation of the enantiomers and diastereomers of 2-aminocyclohexanol as a test-bed analyte. Because of the fact the functional groups are vicinal, we found that the ee determination at the two stereocenters is influenced by the adjacent center, and this led us to implement a chemometric patterning approach, resulting in a 4% absolute error in full speciation of the four stereoisomers. The procedure presented herein would allow for the total speciation of around 96 reactions in 27 min using a high-throughput experimentation routine. While 2-aminocyclohexanol is used to demonstrate the methods, the general workflow should be amenable to analysis of other stereoisomers when two stereocenters are present.

An irreversible, three-component assembly with 2-formylphenylboronic acid, catechol, and N-hydroxylamines was achieved in aqueous media. The boronate ester product was formed with substituted catechols including l-DOPA. Assembly was found to be orthogonal to common biological functional groups and both copper(I)-catalyzed alkyne-azide cycloaddition and aminoether/carbonyl condensations. Boronate ester formation and aminoether condensation were achieved in one pot with a hexameric peptide.

Organic electrochemical transistors (OECTs) are devices with broad potential in bioelectronic sensing, circuits, and neuromorphic hardware. Their unique properties arise from the use of organic mixed ionic/electronic conductors (OMIECs) as the active channel. Typical OMIECs are linear polymers, where defined and controlled microstructure/morphology, and reliable characterization of transport and charging can be elusive. Semiconducting two‐dimensional polymers (2DPs) present a new avenue in OMIEC materials development, enabling electronic transport along with precise control of well‐defined channels ideal for ion transport/intercalation. To this end, a recently reported 2DP, TIIP, is synthesized and patterned at 10 µm resolution as the channel of a transistor. The TIIP films demonstrate textured microstructure and show semiconducting properties with accessible oxidation states. Operating in an aqueous electrolyte, the 2DP‐OECT exhibits a device‐scale hole mobility of 0.05 cm2 V–1 s–1 and a µC* figure of merit of 1.75 F cm–1 V–1 s–1. 2DP OMIECs thus offer new synthetic degrees of freedom to control OECT performance and may enable additional opportunities such as ion selectivity or improved stability through reduced morphological modulation during device operation.

Herein, we report the oligopeptide-catalyzed site-selective acylation of partially protected monosaccharides. We identified catalysts that invert site-selectivity compared to N-methylimidazole, which was used to determine the intrinsic reactivity, for 4,6-O-protected glucopyranosides (trans-diols) as well as 4,6-O-protected mannopyranosides (cis-diols). The reaction yields up to 81% of the inherently unfavored 2-O-acetylated products with selectivities up to 15:1 using mild reaction conditions. We also determined the influence of protecting groups on the reaction and demonstrate that our protocol is suitable for one-pot reactions with multiple consecutive protection steps.

Supramolecular polymers are compelling platforms for the design of stimuli-responsive materials with emergent functions. Here, we report the assembly of an amphiphilic nanotube for Li-ion conduction that exhibits high ionic conductivity, mechanical integrity, electrochemical stability, and solution processability. Imine condensation of a pyridine-containing diamine with a triethylene glycol functionalized isophthalaldehyde yields pore-functionalized macrocycles. Atomic force microscopy, scanning electron microscopy, and in solvo X-ray diffraction reveal that macrocycle protonation during their mild synthesis drives assembly into high-aspect ratio (>103) nanotubes with three interior triethylene glycol groups. Electrochemical impedance spectroscopy demonstrates that lithiated nanotubes are efficient Li+ conductors, with an activation energy of 0.42 eV and a peak room temperature conductivity of 3.91 ± 0.38 × 10–5 S cm–1. 7Li NMR and Raman spectroscopy show that lithiation occurs exclusively within the nanotube interior and implicates the glycol groups in facilitating efficient Li+ transduction. Linear sweep voltammetry and galvanostatic lithium plating-stripping tests reveal that this nanotube-based electrolyte is stable over a wide potential range and supports long-term cyclability. These findings demonstrate how the coupling of synthetic design and supramolecular structural control can yield high-performance ionic transporters that are amenable to device-relevant fabrication, as well as the technological potential of chemically designed self-assembled nanotubes.

Supramolecular nanotubes prepared through macrocycle assembly offer unique properties that stem from their long-range order, structural predictability, and tunable microenvironments. However, assemblies that rely on weak non-covalent interactions often have...

Metrics & MoreArticle RecommendationsCONSPECTUS: Nanotubes offer a unique combination of structural precision, tunable interior environments, and high aspect ratios that will be useful for many applications. Despite these desirable attributes, widespread explorations into the properties and applications of chemically designed nanotubes have been limited by challenges related to their synthesis. This realization has motivated developing a unified synthetic nanotube design, which would enable wide-reaching explorations into onedimensional molecular architectures. In principle, supramolecular polymerization is a viable method to prepare such systems, but historically, this approach has yielded materials with poor mechanical properties and/or low aspect ratios whose chemical diversity is limited. This Account describes the development of an acid-mediated approach to macrocycle assembly that overcomes these limitations to yield robust, yet reversible, high-aspect-ratio nanotubes. Imine-linked macrocycles are prepared in high yield from readily accessible precursors by coupling dynamic imine exchange to an out-of-equilibrium macrocycle stacking event. Upon protonation, these macrocycles assemble into high-aspect-ratio nanotubes through electrostatic, solvophobic, and π−π interactions. The interplay between covalent and noncovalent processes are critical to guide macrocycle synthesis and assembly. Including basic pyridine groups into the macrocycle backbone leads to cooperative assembly, even in the presence of <1 equiv of acid per macrocycle. This design was elaborated to enable a general onepot nanotube synthesis from many functional aromatic dialdehydes. The development of structure−property relationships for nanotube assembly strength and ion conductivity are made possible because protonation-induced macrocycle assembly is modular and robust. For instance, supramolecular interactions endow synthetic nanotubes with robust cohesion and mechanical properties that surpass many covalent linear polymers. Tailoring the nanotube interior using site-selective chemical functionalization results in ion-conducting materials. Pyridinium-based nanotubes universally exhibit the ability to conduct protons and nanotubes functionalized with interior glycol groups promote efficient Li-ion transport. Overall, this versatile class of one-dimensional nanostructures shows substantial promise to merge the desirable properties of carbon nanotubes and biological filaments, all while being synthetically tailorable for many designed applications.