Nanostructured Micelle Nanotubes Self‐Assembled from Dinucleobase Monomers in Water

Despite the central importance of aqueous amphiphile assemblies in science and industry, the size and shape of these nano‐objects is often difficult to control with accuracy owing to the non‐directional nature of the hydrophobic interactions that sustain them. Here, using a bioinspired strategy that consists of programming an amphiphile with shielded directional Watson–Crick hydrogen‐bonding functions, its self‐assembly in water was guided toward a novel family of chiral micelle nanotubes with partially filled lipophilic pores of about 2 nm in diameter. Moreover, these tailored nanotubes are successfully demonstrated to extract and host molecules that are complementary in size and chemical affinity.     

Supramolecular Copolymerization as a Strategy to Control the Stability of Self‐Assembled Nanofibers

A major challenge in supramolecular polymerization is controlling the stability of the polymers formed, that is, controlling the rate of monomer exchange in the equilibrium between monomer and polymer. The exchange dynamics of supramolecular polymers based on benzene‐1,3,5‐tricarboxamide (BTA) can be regulated by copolymerizing molecules with dendronized (dBTA) and linear (nBTA) ethylene glycol‐based water‐soluble side chains. Whereas nBTAs form long nanofibers in water, dBTAs do not polymerize, forming instead small spherical aggregates. The copolymerization of the two BTAs results in long nanofibers. The exchange dynamics of both the BTA monomers in the copolymer are significantly slowed down in the mixed systems, leading to a more stable copolymer, while the morphology and spectroscopic signature of the copolymers are identical to that of nBTA homopolymer. This copolymerization is the supramolecular counterpart of styrene/ maleic anhydride copolymerization.     

Self‐Assembly of Three‐Dimensional Supramolecular Polymers through Cooperative Tetrathiafulvalene Radical Cation Dimerization

The self‐assembly of a new type of three‐dimensional (3D) supramolecular polymers from tetrahedral monomers in both organic and aqueous media is described. We have designed and synthesized two tetraphenylmethane derivatives T1 and T2 , both of which bear four tetrathiafulvalene (TTF) units. When the TTF units were oxidized to the radical cation TTF^.+, their pre‐organized tetrahedral arrangement remarkably enhanced their intermolecular dimerization, leading to the formation of new 3D spherical supramolecular polymers. The structure of the supramolecular polymers has been inferred on the basis of UV/Vis absorption, electron paramagnetic resonance, cyclic voltammetry, and dynamic light scattering (DLS) analysis, as well as by comparing these properties with those of the self‐assembled structures of mono‐, di‐, and tritopic control compounds. DLS experiments revealed that the spherical supramolecular polymers had hydrodynamic diameters of 68 nm for T1 (75 μM ) in acetonitrile and 105 nm for T2 (75 μM ) in water/acetonitrile (1:1). The 3D spherical structures of the supramolecular polymers formed in different solvents were also supported by SEM and AFM experiments.     

Self‐Assembling Supramolecular Hybrid Hydrogel Beads

With the goal of imposing shape and structure on supramolecular gels, we combine a low‐molecular‐weight gelator (LMWG) with the polymer gelator (PG) calcium alginate in a hybrid hydrogel. By imposing thermal and temporal control of the orthogonal gelation methods, the system either forms an extended interpenetrating network or core–shell‐structured gel beads—a rare example of a supramolecular gel formulated inside discrete gel spheres. The self‐assembled LMWG retains its unique properties within the beads, such as remediating Pd^II and reducing it in situ to yield catalytically active Pd⁰ nanoparticles. A single PdNP‐loaded gel bead can catalyse the Suzuki–Miyaura reaction, constituting a simple and easy‐to‐use reaction‐dosing form. These uniquely shaped and structured LMWG‐filled gel beads are a versatile platform technology with great potential in a range of applications.     

Supramolecular Self‐Assembly of Histidine‐Capped‐Dialkoxy‐Anthracene: A Visible‐Light‐Triggered Platform for Facile siRNA Delivery

Supramolecular self‐assembly of histidine‐capped‐dialkoxy‐anthracene (HDA) results in the formation of light‐responsive nanostructures. Single‐crystal X‐ray diffraction analysis of HDA shows two types of hydrogen bonding. The first hydrogen bond is established between the imidazole moieties while the second involves the oxygen atom of one amide group and the hydrogen atom of a second amide group. When protonated in acidic aqueous media, HDA successfully complexes siRNA yielding spherical nanostructures. This biocompatible platform controllably delivers siRNA with high efficacy upon visible‐light irradiation leading up to 90 % of gene silencing in live cells.     

Synthesis and Self‐Assembly of Cyclic 2,7‐Anthrylene Ethynylene 1,3‐Phenylene Ethynylene Trimer with a Planar Conformation

Cyclic arylene ethynylene hexamer 1 , composed of alternating 2,7‐anthrylene ethynylene units and meta‐phenylene ethynylene units, was synthesized. It shows C₃ symmetry and possesses a flat and rigid conformation with a large equilateral triangle‐like cavity. Macrocycle 1 self‐associates through π–π stacking interactions between the anthracene‐containing macrocyclic aromatic cores with indefinite‐association constant K_E=6980 m ^?1 in CDCl₃ at 303 K. Macrocycle 1 also self‐assembles into π‐stacked nanofibers in the drop‐cast film.     

Pathway Complexity Versus Hierarchical Self‐Assembly in N‐Annulated Perylenes: Structural Effects in Seeded Supramolecular Polymerization

Studies were carried out on the hierarchical self‐assembly versus pathway complexity of N‐annulated perylenes 1 – 3 , which differ only in the nature of the linking groups connecting the perylene core and the side alkoxy chains. Despite the structural similarity, compounds 1 and 2 exhibit noticeable differences in their self‐assembly. Whereas 1 forms an off‐pathway aggregate I that converts over time (or by addition of seeds) into the thermodynamic, on‐pathway product, 2 undergoes a hierarchical process in which the kinetically trapped monomer species does not lead to a kinetically controlled supramolecular growth. Finally, compound 3 , which lacks the amide groups, is unable to self‐assemble under identical experimental conditions and highlights the key relevance of the amide groups and their position to govern the self‐assembly pathways.     

Host–Guest Binding‐Site‐Tunable Self‐Assembly of Stimuli‐Responsive Supramolecular Polymers

Despite the remarkable progress made in controllable self‐assembly of stimuli‐responsive supramolecular polymers (SSPs), a basic issue that has not been consideration to date is the essential binding site. The noncovalent binding sites, which connect the building blocks and endow supramolecular polymers with their ability to respond to stimuli, are expected to strongly affect the self‐assembly of SSPs. Herein, the design and synthesis of a dual‐stimuli thermo‐ and photoresponsive Y‐shaped supramolecular polymer (SSP2) with two adjacent β‐cyclodextrin/azobenzene (β‐CD/Azo) binding sites, and another SSP (SSP1) with similar building blocks, but only one β‐CD/Azo binding site as a control, are described. Upon gradually increasing the polymer solution temperature or irradiating with UV light, SSP2 self‐assemblies with a higher binding‐site distribution density; exhibits a flower‐like morphology, smaller size, and more stable dynamic aggregation process; and greater controllability for drug‐release behavior than those observed with SSP1 self‐assemblies. The host–guest binding‐site‐tunable self‐assembly was attributed to the positive cooperativity generated among adjacent binding sites on the surfaces of SSP2 self‐assemblies. This work is beneficial for precisely controlling the structural parameters and controlled release function of SSP self‐assemblies.     

Peculiar Triarylamine‐Based Co‐assembled Supramolecular Polymers That Exhibit Two Transition Temperatures in the Formation of a Coiled Helical Bundle

This paper describes the peculiar co‐assembly supramolecular polymerization behavior of triphenylamine trisamide derivatives with d ‐alanine ( T‐ala ) or glycine ( T‐gly ) moieties. Concentration and temperature‐dependent circular dichroism (CD) spectroscopy revealed that the heating curves of co‐assemblies obtained at various molar ratios of T‐ala to T‐gly exhibited two distinct transition temperatures. The first transition was due to the transformation from coiled helical bundles to single helical fibers without handedness. The second was due to a change from typical elongation to nucleation. These phenomena were confirmed by solvent‐dependent decoiling of coiled helical structures and concentration‐dependent morphological analysis. The two transitioning temperatures were dependent on the concentration of T‐ala in the co‐assemblies, suggesting that T‐ala concentration plays an important role in the formation of coiled helical bundles. Our study demonstrated the first observation of two distinct transition temperatures in supramolecular polymers.     

Self‐Assembly of Pyridinium‐Tailored Anthracene Amphiphiles into Supramolecular Hydrogels

The mixing of a polyacid cross‐linker with a pyridinium‐functionalized anthracene amphiphile afforded a supramolecular hydrogel through a self‐assembly process that was primarily driven by π‐stacking and electrostatic interactions.     

Supramolecular Diblock Copolymers Featuring Well‐defined Telechelic Building Blocks

We report supramolecular AB diblock copolymers comprised of well‐defined telechelic building blocks. Helical motifs, formed via reversible addition‐fragmentation chain‐transfer (RAFT) or anionic polymerization, are assembled with coil‐forming and sheet‐featuring blocks obtained via atom‐transfer radical polymerization (ATRP) or ring‐opening metathesis polymerization (ROMP). Interpolymer hydrogen bonding or metal‐coordination achieves dynamic diblock architectures featuring hybrid topologies of coils, helices, and/or π‐stacked sheets that, on a basic level, mimic protein structural motifs in fully synthetic systems. The intrinsic properties of each block (e.g., circular dichroism and fluorescence) remain unaffected in the wake of self‐assembly. This strategy to develop complex synthetic polymer scaffolds from functional building blocks is significant in a field striving to produce architectures reminiscent of biosynthesis, yet fully synthetic in nature. This is the first plug‐and‐play approach to fabricate hybrid π‐sheet/helix, π‐sheet/coil, and helix/coil architectures via directional self‐assembly.     

Self‐Assembly of Proteins: Towards Supramolecular Materials

The study of protein self‐assembly has attracted great interest over the decades, due to the important role that proteins play in life. In contrast to the major achievements that have been made in the fields of DNA origami, RNA, and synthetic peptides, methods for the design of self‐assembling proteins have progressed more slowly. This Concept article provides a brief overview of studies on native protein and artificial scaffold assemblies and highlights advances in designing self‐assembling proteins. The discussions are focused on design strategies for self‐assembling proteins, including protein fusion, chemical conjugation, supramolecular, and computational‐aided de novo design.     

Self‐assembly and Cycling of a Three‐state PdxLy Metallosupramolecular System

The use of stimuli to induce reversible structural transformations in metallosupramolecular systems is of keen interest to chemists seeking to mimic the way that Nature effects conformational changes in biological machinery. While a wide array of stimuli have been deployed towards this end, stoichiometric changes have only been explored in a handful of examples. Furthermore, switching has generally been between only two distinct states. Here we use a simple 2‐(1‐(pyridine‐4‐methyl)‐1H‐1,2,3‐triazol‐4‐yl)pyridine “click” ligand in combination with Pd^II in various stoichiometries and concentrations to quantitatively access and cycle between three distinct species: a [PdL₂]²⁺ monomer, a [Pd₂L₂]⁴⁺ dimer, and a [Pd₉L₁₂]¹⁸⁺ cage.     

A Supramolecular Polymer as a Self‐Assembling Polyvalent Scaffold

Binding bacteria : Discotic molecules self‐assemble into columnar supramolecular polymers that show strong polyvalent binding to bacteria by virtue of mannose ligands attached at their periphery (orange; see picture). The reversible formation of the supramolecular polymers allows simple mixing of differently substituted monomers and the optimization of bacterial aggregation.

     

Light‐Harvesting Nanotubes Formed by Supramolecular Assembly of Aromatic Oligophosphates

A 2,7‐disubstituted phosphodiester‐linked phenanthrene trimer forms tubular structures in aqueous media. Chromophores are arranged in H‐aggregates. Incorporation of small quantities of pyrene results in the development of light‐harvesting nanotubes in which phenanthrenes act as antenna chromophores and pyrenes as energy acceptors. Energy collection is most efficient after excitation at the phenanthrene H‐band. Fluorescence quantum yields up to 23 % are reached in pyrene doped, supramolecular nanotubes.     

Hierarchical Self‐Assembly of Supramolecular Muscle‐Like Fibers

An acid–base switchable [c2]daisy chain rotaxane terminated with two 2,6‐diacetylamino pyridine units has been self‐assembled with a bis(uracil) linker. The complementary hydrogen‐bond recognition patterns, together with lateral van der Waals aggregations, result in the hierarchical formation of unidimensional supramolecular polymers associated in bundles of muscle‐like fibers. Microscopic and scattering techniques reveal that the mesoscopic structure of these bundles depends on the extended or contracted states that the rotaxanes show within individual polymer chains. The observed local dynamics span over several length scales because of a combination of supramolecular and mechanical bonds. This work illustrates the possibility to modify the hierarchical mesoscopic structuring of large polymeric systems by the integrated actuation of individual molecular machines.     

Toughening a Self‐Healable Supramolecular Polymer by Ionic Cluster‐Enhanced Iron‐Carboxylate Complexes

Supramolecular polymers that can heal themselves automatically usually exhibit weakness in mechanical toughness and stretchability. Here we exploit a toughening strategy for a dynamic dry supramolecular network by introducing ionic cluster‐enhanced iron‐carboxylate complexes. The resulting dry supramolecular network simultaneous exhibits tough mechanical strength, high stretchability, self‐healing ability, and processability at room temperature. The excellent performance of these distinct supramolecular polymers is attributed to the hierarchical existence of four types of dynamic combinations in the high‐density dry network, including dynamic covalent disulfide bonds, noncovalent H‐bonds, iron‐carboxylate complexes and ionic clustering interactions. The extremely facile preparation method of this self‐healing polymer offers prospects for high‐performance low‐cost material among others for coatings and wearable devices.     

Self‐Healing Supramolecular Materials Constructed by Copolymerization via Molecular Recognition of Cavitand‐Based Coordination Capsules

The repeating guest units of poly‐(R)‐ 2 were selectively encapsulated by the self‐assembled capsule poly‐ 1 possessing eight polymer side chains to form the supramolecular graft polymer (poly‐ 1 )_n?poly‐(R)‐ 2 . The encapsulation of the guest units was confirmed by ¹H NMR spectroscopy and the DOSY technique. The hydrodynamic radius of the graft polymer structure was greatly increased upon the complexation of poly‐ 1 . The supramolecular graft polymer (poly‐ 1 )_n?poly‐(R)‐ 2 was stably formed in the 1:1 host–guest ratio, which increased the glass transition temperature by more than 10 °C compared to that of poly‐ 1 . AFM visualized that (poly‐ 1 )_n?poly‐(R)‐ 2 formed the networked structure on mica. The (poly‐ 1 )_n?poly‐(R)‐ 2 gelled in 1,1,2,2‐tetrachloroethane, which led to fabrication of distinct viscoelastic materials that demonstrated self‐healing behavior in a tensile test.     

Supramolecular Self‐Assembly of Polymer‐Functionalized Carbon Nanotubes on Surfaces

Summary: Supramolecular self‐assembly of poly(methyl methacrylate)‐grafted multiwalled carbon nanotubes (MWNT‐g‐PMMA) was reported herein. The MWNT‐g‐PMMA (85 wt.‐% PMMA) dispersed in tetrahydrofuran could self‐assemble into suprastructures on surfaces such as gold, mica, silicon, quartz, or carbon films. With decreasing concentration of the MWNT‐g‐PMMA from 3 to 0.1 mg · mL⁻¹, the assembled structures changed from cellular and basketwork‐like forms to multilayer cellular networks and individual needles. SEM, AFM, and TEM measurements confirmed the morphology of the assembled suprastructures, and revealed the assembly mechanism. Phase separation during evaporation of the solvent drives the MWNT‐g‐PMMA nanohybrids to assemble and form the suprastructures, and the rigid MWNTs stabilize the structures.

SEM images of self‐assembled suprastructures of basketwork (a), cellular network (b), and needles (c) from the THF solution of the PMMA‐grafted MWNTs on gold surface.     

Cation‐Tuned Stimuli‐Responsive and Optical Properties of Supramolecular Hydrogels

Hierarchical self‐assembly of an amphiphilic tris‐urea in aqueous media is shown. A mixture of the amphiphilic tris‐urea and an alkaline solution gave a viscous solution composed of fibrous aggregates. This viscous solution transformed into supramolecular hydrogels, which are capable of hierarchically organizing into higher‐order aggregates in response to several cationic triggers. The resulting supramolecular hydrogels were relatively stiff and their storage moduli attained over 10³ Pa. The stimuli‐responsive and optical properties of the resulting hydrogels were influenced by the cationic trigger. Proton and calcium ion triggers gave pH‐ and chemical stimuli‐responsive hydrogels, respectively. A terbium ion trigger also provided a highly luminescent hydrogel through energy transfer from the tris‐urea to terbium.