Supramolecular Building Blocks Research Articles

Functionalization of Supramolecular Polymers by Dynamic Covalent Boroxine Chemistry.

Molecular scaffolds that enable the combinatorial synthesis of new supramolecular building blocks are promising targets for the construction of functional molecular systems. Here, we report a supramolecular scaffold based on boroxine that enables the formation of chiral and ordered 1D supramolecular polymers, which can be easily functionalized for circularly polarized luminescence. The boroxine monomers are quantitatively synthesized in situ, both in bulk and in solution, from boronic acid precursors and cooperatively polymerize into 1D helical aggregates stabilized by threefold hydrogen-bonding and π-π stacking. We then demonstrate amplification of asymmetry in the co-assembly of chiral/achiral monomers and the co-condensation of chiral/achiral precursors in classical and in situ sergeant-and-soldiers experiments, respectively, showing fast boronic acid exchange reactions occurring in the system. Remarkably, co-condensation of pyrene boronic acid with a hydrogen-bonding chiral boronic acid results in chiral pyrene aggregation with circularly polarized excimer emission and g-values in the order of 10-3. Yet, the electron deficiency of boron in boroxine makes them chemically addressable by nucleophiles, but also sensitive to hydrolysis. With this sensitivity in mind, we provide first insights into the prospects offered by boroxine-based supramolecular polymers to make chemically addressable, functional, and adaptive systems.

Functionalization of Supramolecular Polymers by Dynamic Covalent Boroxine Chemistry

AbstractMolecular scaffolds that enable the combinatorial synthesis of new supramolecular building blocks are promising targets for the construction of functional molecular systems. Here, we report a supramolecular scaffold based on boroxine that enables the formation of chiral and ordered 1D supramolecular polymers, which can be easily functionalized for circularly polarized luminescence. The boroxine monomers are quantitatively synthesized in situ, both in bulk and in solution, from boronic acid precursors and cooperatively polymerize into 1D helical aggregates stabilized by threefold hydrogen‐bonding and π–π stacking. We then demonstrate amplification of asymmetry in the co‐assembly of chiral/achiral monomers and the co‐condensation of chiral/achiral precursors in classical and in situ sergeant‐and‐soldiers experiments, respectively, showing fast boronic acid exchange reactions occurring in the system. Remarkably, co‐condensation of pyrene boronic acid with a hydrogen‐bonding chiral boronic acid results in chiral pyrene aggregation with circularly polarized excimer emission and g‐values in the order of 10−3. Yet, the electron deficiency of boron in boroxine makes them chemically addressable by nucleophiles, but also sensitive to hydrolysis. With this sensitivity in mind, we provide first insights into the prospects offered by boroxine‐based supramolecular polymers to make chemically addressable, functional, and adaptive systems.

Glucose-Driven Droplet Formation in Complexes of a Supramolecular Peptide and Therapeutic Protein.

Biology achieves remarkable function through processes arising from spontaneous or transient liquid-liquid phase separation (LLPS) of proteins and other biomolecules. While polymeric systems can achieve similar phenomena through simple or complex coacervation, LLPS with supramolecular materials has been less commonly shown. Functional applications for synthetic LLPS systems are an expanding area of emphasis, with particular focus on capturing the transient and dynamic state of these structures for use in biomedicine. Here, a net-cationic supramolecular peptide amphiphile building block with a glucose-binding motif is shown that forms LLPS structures when combined with a net-negatively charged therapeutic protein, dasiglucagon, in the presence of glucose. The droplets that arise are dynamic and coalesce quickly. However, the interface can be stabilized by addition of a 4-arm star PEG. When the stabilized droplets formed in glucose are transferred to a bulk phase containing different glucose concentrations, their stability and lifetime decrease according to bulk glucose concentration. This glucose-dependent formation translates into an accelerated release of dasiglucagon in the absence of glucose; this hormone analogue itself functions therapeutically to correct low blood glucose (hypoglycemia). These droplets also offer function in mitigating the most severe effects of hypoglycemia arising from an insulin overdose through delivery of dasiglucagon in a mouse model of hypoglycemic rescue. Accordingly, this approach to use complexation between a supramolecular peptide amphiphile and a therapeutic protein in the presence of glucose leads to droplets with functional potential to dissipate for the release of the therapeutic material in low blood glucose environments.

Cooperativity in Hydrogen‐Bonded Macrocycles Derived from Nucleobases

AbstractIntroducing a rigid linear π‐conjugated acetylene linker into a supramolecular building block consisting of a hydrogen‐bond donor side and a hydrogen‐bond acceptor side yields a decrease in cooperativity in the resulting formed quartet. This follows from our Kohn‐Sham molecular orbital and Voronoi deformation density analyses of hydrogen‐bonded macrocycles based on guanine and cytosine nucleobases. The acetylene linker abstracts electron density from the hydrogen‐bond acceptor and donor, making the hydrogen‐bond acceptor more negatively charged and the hydrogen‐bond donor more positively charged and hence suppressing the donor–acceptor charge transfer interaction between the interacting fragments. This, ultimately, hampers the cooperativity in the hydrogen‐bonded macrocycle. We envision that these findings could open the door to new design principles for the development of novel hydrogen‐bond supramolecular macrocycles.

Supramolecular Nucleic Acid-Based Organosilica Nanoparticles Responsive to Physical and Biological Inputs.

Organosilica nanoparticles that contain responsive organic building blocks as constitutive components of the silica network offer promising opportunities for the development of innovative drug formulations, biomolecule delivery, and diagnostic tools. However, the synthetic challenges required to introduce dynamic and multifunctional building blocks have hindered the realization of biomimicking nanoparticles. In this study, capitalizing on our previous research on responsive nucleic acid-based organosilica nanoparticles, we combine the supramolecular programmability of nucleic acid (NA) interactions with sol-gel chemistry. This approach allows us to create dynamic supramolecular bridging units of nucleic acids in a silica-based scaffold. Two peptide nucleic acid-based monoalkoxysilane derivatives, which self-assemble into a supramolecular bis-alkoxysilane through direct base pairing, were chosen as the noncovalent units inserted into the silica network. In addition, a bridging functional NA aptamer leads to the specific recognition of ATP molecules. In a one-step bottom-up approach, the resulting supramolecular building blocks can be used to prepare responsive organosilica nanoparticles. The supramolecular Watson-Crick-Franklin interactions of the organosilica nanoparticles result in a programmable response to external physical (i.e., temperature) and biological (i.e., DNA and ATP) inputs and thus pave the way for the rational design of multifunctional silica materials with application from drug delivery to theranostics.

Cooperative Assembly of Self-Adjusting α-Helical Coiled Coils along the Length of an mRNA Chain to Form a Thermodynamically Stable Nanotube Carrier.

Although mRNA delivery technology is very promising, problems in safety and transport arise due to the intrinsically low thermodynamic stability of the current mRNA carriers. Considering that mRNAs are filamentous and a nanotube is one of the most thermodynamically stable shapes among nanoassemblies, a nanotube is one of the most stable supramolecular structures that can be assembled with mRNA. Here, we develop a nanotube-shaped filamentous mRNA delivery platform that shows exceptionally high thermodynamic stability. The key to the development of the mRNA nanotube is the design of self-adjusting supramolecular building blocks (SABs) that have two disparate properties, i.e., dynamic property and stiffness, in a single molecule. The counterbalance of the dynamic property and stiffness in SABs enables the coating of mRNA by winding its way through the flexible and irregular mRNA chain via cooperative interactions. SAB nanotubes with targeting ligands installed show a high uptake efficiency in mammalian cells and controllable gene expression behavior. Thus, the mRNA nanotube provides an enabling technology toward the development of safe and stable mRNA vaccines and therapeutics.

Self-assembly mechanisms of cyclic peptide nanotubes in the presence of water molecules; study of hydrogen bonding, aggregation and Mir-210 gene delivery

Self-assembling cyclic peptides are a type of bioinspired supramolecular building blocks. They have the ability to stack together, forming supramolecular cyclic peptide nanotubes. This stacking is driven by β-sheet-like hydrogen bonding. In general, a single hydrogen bond is not strong enough to form ordered supramolecular structures. However, when multiple hydrogen bonds are aligned and built into arrays, they exhibit increased strength and directionality. This enables the formation of well-defined and organized supramolecular structures. The continuous advancements in understanding cyclic peptides and their unique properties open new doors for their application in functional materials, ion transport channels, and drug delivery systems, including gene therapy. When it comes to gene therapy, which involves introducing genetic material into cells to treat or prevent diseases, delivery systems play a crucial role. The use of cyclic peptides in these delivery systems can enhance the stability, specificity, and cellular uptake of the therapeutic cargo, thereby improving the overall success of gene therapy treatments. Hydrogen bond formation makes the cyclic peptide nanotube more stable and has an important role in its formation. The number of hydrogen bonds between cyclic peptides is 117 on average during the simulation time of 200 ns. Also, hydrogen bonds formation between Mir-210 and cyclic peptide nanotube during the simulation time observed which is an average of 17 bonds.

A novel flake-shaped supramolecular building block based metal–organic framework: Structure analysis and selective dye adsorption properties

A new metal–organic framework, {[Cd2(tmtpb)2(dpa)2]·(DMF)2}n (DZU-200, tmtpb = 1,3,5-trimethyl-2,4,6-tris(4-pyridyl)benzene, H2dpa = 2,2′-diphenic acid, DMF = N,N-dimethylformamide), has been synthesized by solvothermal reaction and characterized by various methods. Interestingly, DZU-200 presents a 3D framework derived from a novel flake-shaped supramolecular building block (SBB) constructed by four tmtpb ligands and four Cd2+ ions. Furthermore, DZU-200 reveals high water stability, which is confirmed by PXRD. Moreover, dye adsorption studies show that DZU-200 could rapidly and selectively adsorb methyl orange (MO) with a saturated uptake of 374.7 mg g−1 from MO/RhB (rhodamine B) and MO/MB (methylene blue) mixed solutions.

Solvent-Induced Pathway Complexity of Supramolecular Polymerization Unveiled Using the Hansen Solubility Parameters.

Supramolecular building blocks assembling into helical aggregates are ubiquitous in the current literature, yet the role of solvents in these supramolecular polymerizations often remains elusive. Here, we present a systematic study that quantifies solvent-supramolecular polymer compatibility using the Hansen solubility parameters (δD, δH, and δP). We first studied the solubility space of the supramolecular building block triazine-1,3,5-tribenzenecarboxamide S-T. Due to its amphiphilic nature, a dual-sphere model based on 58 solvents was applied describing the solubility space of the monomeric state (green sphere) and supramolecular polymer state (blue sphere). To our surprise, further in-depth spectroscopic and morphological studies unveiled a distinct solubility region in-between the two spheres giving rise to the formation of higher-order aggregated structures. This phenomenon occurs due to subtle differences in polarity between the solvent and the side chains and highlights the solvent-induced pathway complexity of supramolecular polymerizations. Subsequent variations in concentration and temperature led to the expansion and contraction of both solubility spheres providing two additional features to tune the monomer and supramolecular polymer solubility. Finally, we applied our dual-sphere model on structurally disparate monomers, such as Zn-porphyrin (S-P) and triphenylamine (S-A), demonstrating the generality of the model and the importance of the supramolecular monomer design in connection with the solvent used. This work unravels the solvent-induced pathway complexity of discotic supramolecular building blocks using a parametrized approach in which interactions between the solvent and solute play a crucial role.

Magnetic control of self-assembly and disassembly in organic materials

Because organic molecules and materials are generally insensitive or weakly sensitive to magnetic fields, a certain means to enhance their magnetic responsiveness needs to be exploited. Here we show a strategy to amplify the magnetic responsiveness of self-assembled peptide nanostructures by synergistically combining the concepts of perfect α-helix and rod-coil supramolecular building blocks. Firstly, we develop a monomeric, nonpolar, and perfect α-helix (MNP-helix). Then, we employ the MNP-helix as the rod block of rod-coil amphiphiles (rod-coils) because rod-coils are well-suited for fabricating responsive assemblies. We show that the self-assembly processes of the designed rod-coils and disassembly of rod-coil/DNA complexes can be controlled in a magnetically responsive manner using the relatively weak magnetic field provided by the ordinary neodymium magnet [0.07 ~ 0.25 Tesla (T)]. These results demonstrate that magnetically responsive organic assemblies usable under practical conditions can be realized by using rod-coil supramolecular building blocks containing constructively organized diamagnetic moieties.

Professor Takuzo Aida – A visionary leader in polymer science

Welcome to this special issue of the Journal of Polymer Science, celebrating the life and works of Professor Takuzo Aida on his 67th birthday. His journey starting from a small town in Oita to becoming a giant in the field of polymer science is truly inspiring. He is currently a Distinguished University Professor at the University of Tokyo, and a member of the U.S. National Academy of Engineering, the American Academy of Arts and Sciences, and the Royal Netherlands Academy of Art and Science. Through contributed works of friends and colleagues of Professor Aida, we aim to highlight the remarkable impact he has had in the field of polymer science. We hope that this special issue will not only honor the many incredible achievements of Professor Aida as a scientist, mentor, and visionary leader, but also encourage new generations of future scientists to follow in his footsteps and push the boundaries of scientific knowledge. Professor Aida was born and raised in Oita, a beautiful part of the southern island, famous for its rugged mountains and stunning coastline in Japan. He attended Yokohama National University, majoring in Physical Chemistry, and received his B.S. degree in 1979. During his graduate studies, he worked under the tutelage of Professor Shohei Inoue at the University of Tokyo. After earning his Ph.D. in Polymer Chemistry in 1984, he remained at the university to begin his academic career. Early in his career, he went to the IBM Almaden research center in San Jose in 1989 as a visiting scientist. This experience was an eye-opening one for him: He witnessed major innovations happening at the intersection of science through collaboration of scientists. With a newfound vision, Professor Aida returned to Tokyo and established an open and collaborative research environment where ideas could be freely discussed and shared, and as we all know, many innovations in polymer science were made. After returning to Tokyo, he was promoted to full professor in the Department of Chemistry and Biotechnology in 1996. Since then, he has led several of Japan's leading research projects, including the Japan Science and Technology Agency (JST)'s ERATO “AIDA Nanospace Project,” commenced in 2000, the ERATO-SORST project from 2005, and the Specially Promoted Research Program that began in 2013. He also served as the director of the RIKEN Advanced Science Institute from 2008 to 2012. Since 2013, he has been a Deputy Director of the RIKEN Center for Emergent Matter Science (CEMS). In 2022, he was appointed as a Distinguished Professor of the University of Tokyo. At the forefront of the rapidly evolving field of polymer science, Professor Aida has made significant contributions to numerous facets of this field. He is most well-known for the development of supramolecular polymers, in which he played a major role in the initiation of the basic concept, conceptual expansion, and development of functional materials. Importantly, his work bridged the gaps between conventional polymer chemistry and supramolecular polymerization and realized new properties from the noncovalent nature of supramolecular building blocks. He also pioneered the development of novel soft materials based on organizations of molecules, including bucky gels, aqua materials, protein-based nanotubular carriers, photoactuators, field-responsive liquid crystals, nanochannels for water transport, porous organic materials, and mechanically robust polymer glass. His accomplishments have been recognized with many prestigious awards, including the Medal with Purple Ribbon in 2010 in Japan, the Leona Ezaki Award in 2015, and the Japan Academy Prize in 2018. With his strong commitment to fostering an environment of open discussion, creativity, intellectual rigor, and curiosity, he has set a standard of excellence that has inspired many of his students. During his academic career at the University of Tokyo and RIKEN, he supervised 68 Ph.D. students, and more than 90 people from Aida Lab are now actively contributing to academia in Japan and other countries around the world. We invite readers to join us in honoring the legacy of Professor Aida. As a visionary leader in the field of polymer science, he shaped how we think about supramolecular polymerization and expanded the scope of what is possible. His mentorship set a strong foundation for the careers of many scientists and inspired them to push the boundaries of knowledge. We celebrate Professor Aida's life and achievements with great admiration and gratitude. Congratulations, and happy birthday, Professor Aida!

Hierarchical packing of racemic metallosupramolecular cages with Ni(II)-based triple-stranded helicate building blocks.

Three novel hierarchical Ni-based metallosupramolecular cages were constructed from nickel ions, pyridine dicarboxylates and isophthalate derivative ligands (the substituents on C5 of isophthalate are methyl, tert-butyl and bromo groups). In every cage, two multinuclear nickel clusters, assembled from four nickel atoms and three pyridine dicarboxylate ligands, are interlinked by three isophthalate-derivative ligands to form a nickel-based triple-stranded helicate (TSH), which then becomes the supramolecular building block for the fabrication of a metallocage. Six homochiral TSH supramolecular building blocks, either left (M)-handed or right (P)-handed, are connected by four linking nickel atoms to generate M6 and P6 discrete racemic cage molecules (M6 - cage with six M-TSHs; P6 - cage with six P-TSHs). The crystal packing of the racemic cages was characterized by single-crystal X-ray diffraction. An additional cobalt-based molecular cage with 5-methylisophthalate bridging ligands was synthesized for host-guest interaction studies. The methyl groups in Co- and Ni-TSH can act as guest units to be accommodated in the cone-shaped metal clusters (host) of an adjacent cage.

Dynamic monomers for Hot Lithography: The UPy motif as a versatile tool towards stress relaxation, reprocessability, and 3D printing

AbstractSupramolecular polymers can substantially influence the dynamic mechanical properties in slightly crosslinked polymer networks. One prominent example of supramolecular building blocks is 2‐ureido‐4[1H]‐pyrimidinones (UPy). Combining UPy‐terminated supramolecular segments with classical covalent‐reactive monomers implements dynamic behavior in photopolymerizable systems. In this work, a UPy‐based methacrylic monomer (up to 20 mol%) was introduced in a classical photopolymerizable methacrylate matrix. The influence of the UPy‐motif on the reactivity and (thermo)mechanical properties was investigated via RT‐NIR photorheology, DMTA, and tensile testing. The dynamic behavior was characterized via stress relaxation and reprocessing studies to demonstrate the dynamic effects of photopolymers containing the UPy building block compared to difunctional photopolymers with similar structural features. In a final step, the UPy‐based photopolymerizable system was applied in bulk in a Hot Lithography printing process at elevated temperatures yielding complex 3D‐printed parts with high resolution and precision.

Structural Engineering and Electronic Properties of Halide-Specific Supramolecular Architectures: Effective for Stabilizing H5O2+and Fabricating Semiconducting Photoresponsive Diodes

Two different halides containing chloride- and bromide-assisted dissimilar crystalline supramolecular building blocks of 4′-(1H-imidazol-2-yl)-4,2′:6′,4″-terpyridine (ITP) have been achieved. The dissimilar supramolecular associations with hydrogen-bonded networks have been engineered by the role of halides in the ITP-based crystal systems (i.e., ITP-Cl and ITP-Br for Cl– and Br–, respectively). Hirshfeld surface analyses of these supramolecular assemblies have been performed. The π-systems of protonated pyridine and imidazole rings play a pivotal role in establishing the noncovalent π···π type supramolecular interactions in both the crystals, and the π-system-directed associations certainly assist in forming the 3D supramolecular architectures of ITP-Cl and ITP-Br in the solid state. Most intriguingly, the supramolecular association of ITP-Cl uniquely stabilizes the cationic unit of hydroxonium hydrate (i.e., H5O2+) in the solid state, and such solid-state stabilization of H5O2+ by the imidazole-connected terpyridine-based system is one of the pioneering challenges in crystal engineering. Distinctly, the hydrogen-bonded cluster-like assembly of H5O2+ and Cl– has been observed in the ITP-Cl system through hydrogen donor–acceptor balance. Subsequently, a special drive has been endeavored to unveil the semiconducting features, including the charge transport property and photoresponsive behavior, of these synthesized ITP-Cl and ITP-Br-based devices. Fascinatingly, the chloride-mediated ITP-Cl-based device shows remarkably higher electrical conductivity with respect to the ITP-Br-based device under photoirradiation conditions, and this implies the tuning effect of different halides toward the applicability of thin-film-based device performance. The device efficiency-based experimental outcomes have been rationalized through a density functional theory-level analysis.

How Subtle Changes Can Make a Difference: Reproducibility in Complex Supramolecular Systems.

The desire to construct complex molecular systems is driven by the need for technological (r)evolution and our intrinsic curiosity to comprehend the origin of life. Supramolecular chemists tackle this challenge by combining covalent and noncovalent reactions leading to multicomponent systems with emerging complexity. However, this synthetic strategy often coincides with difficult preparation protocols and a narrow window of suitable conditions. Here, we report on unsuspected observations of our group that highlight the impact of subtle "irregularities" on supramolecular systems. Based on the effects of pathway complexity, minute amounts of water in organic solvents or small impurities in the supramolecular building block, we discuss potential pitfalls in the study of complex systems. This article is intended to draw attention to often overlooked details and to initiate an open discussion on the importance of reporting experimental details to increase reproducibility in supramolecular chemistry.

How Subtle Changes Can Make a Difference: Reproducibility in Complex Supramolecular Systems

AbstractThe desire to construct complex molecular systems is driven by the need for technological (r)evolution and our intrinsic curiosity to comprehend the origin of life. Supramolecular chemists tackle this challenge by combining covalent and noncovalent reactions leading to multicomponent systems with emerging complexity. However, this synthetic strategy often coincides with difficult preparation protocols and a narrow window of suitable conditions. Here, we report on unsuspected observations of our group that highlight the impact of subtle “irregularities” on supramolecular systems. Based on the effects of pathway complexity, minute amounts of water in organic solvents or small impurities in the supramolecular building block, we discuss potential pitfalls in the study of complex systems. This article is intended to draw attention to often overlooked details and to initiate an open discussion on the importance of reporting experimental details to increase reproducibility in supramolecular chemistry.

Supramolecular Assembly of Halide Perovskite Building Blocks.

The structural diversity and tunable optoelectronic properties of halide perovskites originate from the rich chemistry of the metal halide ionic octahedron [MX6]n- (M = Pb2+, Sb3+, Te4+, Sn4+, Pt4+, etc.; X = Cl-, Br-, and I-). The properties of the extended perovskite solids are dictated by the assembly, connectivity, and interaction of these octahedra within the lattice environment. Hence, the ability to manipulate and control the assembly of the octahedral building blocks is paramount for constructing new perovskite materials. Here, we propose a systematic supramolecular strategy for the assembly of [MX6]n- octahedra into a solid extended network. Interaction of alkali metal-bound crown ethers with the [M(IV)X6]2- octahedron resulted in a structurally and optoelectronically tunable "dumbbell" structural unit in solution. Single crystals with diverse packing geometries and symmetries will form as the solid assembly of this new supramolecular building block. This supramolecular assembly route introduces a new general strategy for designing halide perovskite structures with potentially new optoelectronic properties.

Hybrid Photochromic Lanthanide Phosphonate with Multiple Photoresponsive Functionalities.

Hybrid photochromic materials (HPMs) with specific photoresponsive functionality have applications in many fields. The photoinduced electron-transfer (ET) strategy has been proved to be effective in the synthesis of HPMs with diverse photomodulated properties. The exploitation of new electron acceptors (EAs) is meaningful for promoting the development of HPMs. In this work, we introduced a rigid tetraimidazole derivative, 3,3,5,5-tetra(imidazol-1-yl)-1,1-biphenyl (TIBP) as a potential EA, into a metal-diphosphonate (1-hydroxyethylidene-1,1-diphosphonic acid, H4-HEDP) system to explore HPMs and finally obtained a hybrid metal phosphonate (H4-TIBP)0.5·[Dy(H-HEDP) (H2-HEDP)]·H2O (1). 1 features anionic chains composed of diphosphonate and Dy3+ ions. The extra charge is balanced by protonated TIBP cations, which exist in the void of adjacent chains and form H-bonds with Ophosphonate (N-H···O). Upon photostimulation with a Xe lamp (300 W), the crystalline sample 1 exhibited coloration by changing from colorless to pale yellow because of the presence of photoinduced radicals that originated from the ET from Ophosphonate to NTIBP. Along with the coloration, photomodulated fluorescence, magnetism, and proton conductivity were also detected in the photoactivated samples. Different from the reported HPMs based on polypyridine derivatives and photoactive species such as pyridinium and naphthalimide derivatives as EAs, our study provides a new category of EA units to yield HPMs with fascinating photoresponsive functionality via the assembly of polyimidazole derivatives and phosphonate-based supramolecular building blocks.

Quinoid-viologen conjugates: Redox properties and host-guest complex with cucurbiturils

Viologens are known as an excellent electron acceptor and a versatile supramolecular building block, the physical property of which can be tuned by varying the N-substitution. Herein, we present a class of unprecedented quinoid-viologen conjugates wherein a quinoidal unit is incorporated as part of an extended π-system of the viologen units through N-substitution. Such class of molecules show intriguing optical and electronic properties inherited from both the viologen and the quinoid constituents, displaying stronger electron accepting characters, visible absorption, reversible redox activity, modulated electrochromism, and characteristic binding towards Cucurbit [n]urils (n = 7 and 8). This molecular design strategy points to a new direction to diversify viologens for functional electroactive materials and complex architectures.

Structure and Dynamics of Supramolecular Polymers: Wait and See.

The introduction of stereogenic centers in supramolecular building blocks is used to unveil subtle changes in supramolecular structure and dynamics over time. Three stereogenic centers based on deuterium atoms were introduced in the side chains of a benzene-1,3,5-tricarboxamide (BTA) resulting in a supramolecular polymer in water that at first glance has a structure and dynamics identical to its achiral counterpart. Using three different techniques, the properties of the double helical polymers are compared after 1 day and 4 weeks. An increase in helical preference is observed over time as well as a decrease in the helical pitch and monomer exchange dynamics. It is proposed that the polymer of the chiral monomer needs time to arrive at its maximal preference in helical bias. These results indicate that the order and tight packing increase over time, while the dynamics of this supramolecular polymer decrease over time, an effect that is typically overlooked but unveiled by the isotopic chirality.