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Along with the celebration of the new year, we celebrate many successes at Bioconjugate Chemistry. This includes additions and renewal of our editors, who play a critical role in service to our research community of authors, reviewers, and readers. As highlighted in our January 2023 editorial, (1) we sincerely thank Prof. Vince Rotello, who stepped down after a decade of success as Editor-in-Chief. We also extend a sincere thank you to Prof. Bradley Smith, who also stepped down after 10 years of service as Associate Editor for the journal. With great enthusiasm, we introduce the 2023 editorial team at Bioconjugate Chemistry, which includes five new additions to the editorial staff: Prof. Gonçalo Bernardes from the University of Cambridge, Prof. Peng Zou, from the Peking University, Mr. Nathan Quinn and Dr. Christina MacLaughlin from ACS Publications, and Prof. Theresa Reineke from the University of Minnesota. We also introduce and celebrate the team of four editors that are continuing in dedicated service to our community and ACS Publications: Prof. Zhifei Dai from Peking University, Prof. Jan van Hest from Eindhoven University of Technology, Prof. Erin Lavik from the University of Maryland Baltimore Country, and Prof. Gang Zheng from the University of Toronto. We wish our entire scientific community a happy, healthy, and productive 2023 and look forward to working with you all to disseminate many exciting advances in Bioconjugate Chemistry.

11 p.-7 fig.-1 tab.1 graph. abst., Dynamic binding events are key to arrive at functionality in nature, and these events are often governed by electrostatic or hydrophobic interactions. Synthetic supramolecular polymers are promising candidates to obtain biomaterials that mimic this dynamicity. Here, we created four new functional monomers based on the benzene-1,3,5-tricarboxamide (BTA) motif. Choline or atropine groups were introduced to obtain functional monomers capable of competing with the cell wall of Streptococcus pneumoniae for binding of essential choline-binding proteins (CBPs). Atropine-functionalized monomers BTA-Atr and BTA-Atr3 were too hydrophobic to form homogeneous assemblies, while choline-functionalized monomers BTA-Chol and BTA-Chol3 were unable to form fibers due to charge repulsion. However, copolymerization of BTA-Chol3 with non-functionalized BTA-(OH)3 yielded dynamic fibers, similar to BTA-(OH)3. These copolymers showed an increased affinity toward CBPs compared to free choline due to multivalent effects. BTA-based supramolecular copolymers are therefore a versatile platform to design bioactive and dynamic supramolecular polymers with novel biotechnological properties., The authors acknowledge the financial support from the Dutch Ministry of Education, Culture and Science (Gravity program 024.001.035), the ERC Advanced Grant (SYNMAT─788618), the Gravitation Program “Materials Driven Regeneration”, funded by the Netherlands Organization for Scientific Research (024.003.013), and the Agencia Estatal de Investigacion AEI/FEDER-EU-10.13039/501100011033- and Ministerio de Ciencia e Innovación, Spain (PID2019-105126RB-I00)

[Abstract] The use of supramolecular polymers to construct functional biomaterials is gaining more attention due to the tunable dynamic behavior and fibrous structures of supramolecular polymers, which resemble those found in natural systems, such as the extracellular matrix. Nevertheless, to obtain a biomaterial capable of mimicking native systems, complex biomolecules should be incorporated, as they allow one to achieve essential biological processes. In this study, supramolecular polymers based on water-soluble benzene-1,3,5-tricarboxamides (BTAs) were assembled in the presence of hyaluronic acid (HA) both in solution and hydrogel states. The coassembly of BTAs bearing tetra(ethylene glycol) at the periphery (BTA-OEG4) and HA at different ratios showed strong interactions between the two components that led to the formation of short fibers and heterogeneous hydrogels. BTAs were further covalently linked to HA (HA-BTA), resulting in a polymer that was unable to assemble into fibers or form hydrogels due to the high hydrophilicity of HA. However, coassembly of HA-BTA with BTA-OEG4 resulted in the formation of long fibers, similar to those formed by BTA-OEG4 alone, and hydrogels were produced with tunable stiffness ranging from 250 to 700 Pa, which is 10-fold higher than that of hydrogels assembled with only BTA-OEG4. Further coassembly of BTA-OEG4 fibers with other polysaccharides showed that except for dextran, all polysaccharides studied interacted with BTA-OEG4 fibers. The possibility of incorporating polysaccharides into BTA-based materials paves the way for the creation of dynamic complex biomaterials. The authors acknowledge the ICMS Animation Studio for providing the artwork. S.V.-A. and G.M. acknowledge the funding received by Gravitation Program “Materials Driven Regeneration,” funded by the Netherlands Organization for Scientific Research (024.003.013). J.M. acknowledges a Marie Skłodowska-Curie postdoctoral fellowship (794016) for financial support. G.M. acknowledges the funding received by the Swiss National Science Foundation (SNSF “Early PostDoc Mobility” P2EZP2-178435). R.C. acknowledges TA Instruments for providing the DHR-3 rheometer under the Young Distinguished Rheologist Award instrument grant. S.S. and E.W.M acknowledge the European Research Council (H2020-EU.1.1., SYNMAT project, ID 788618). Netherlands Organisation for Scientific Research; 024.003.013 Swiss National Science Foundation; P2EZP2-178435

Supramolecular copolymers formed by the noncovalent synthesis of multiple components expand the complexity of functional molecular systems. However, varying the composition and microstructure of copolymers through tuning the interactions between building blocks remains a challenge. Here, we report a remarkable discovery of the temperature-dependent supramolecular copolymerization of the two chiral monomers 4,4′,4″-(1,3,5-triazine-2,4,6-triyl)tribenzamide (S-T) and 4,4′,4″-(benzene-1,3,5-triyl)tribenzamide (S-B). We first demonstrate in the homopolymerization of the two individual monomers that a subtle change from the central triazine to benzene in the chemical structure of the monomers significantly affects the properties of the resulting homopolymers in solution. Homopolymers formed by S-T exhibit enhanced stability in comparison to S-B. More importantly, through a combination of spectroscopic analysis and theoretical simulation, we reveal the complex process of copolymerization: S-T aggregates into homopolymers at elevated temperature, and upon slow cooling S-B gradually intercalates into the copolymers, to finally give copolymers with almost 80% alternating bonds at 10 °C. The formation of the predominantly alternating copolymers is plausibly contributed by preferred heterointeractions between triazine and benzene cores in S-T and S-B, respectively, at lower temperatures. Overall, this work unravels the complexity of a supramolecular copolymerization process where an intermediate heterointeraction (higher than one homointeraction and lower than the other homointeraction) presents and proposes a general method to elucidate the microstructures of copolymers responsive to temperature changes.

Polymer composites have attracted increasing interest as thermal management materials for use in devices owing to their ease of processing and potential lower costs. However, most polymer composites have only modest thermal conductivities, even at high concentrations of additives, resulting in high costs and reduced mechanical properties, which limit their applications. To achieve high thermally conductive polymer materials with a low concentration of additives, anisotropic, solid-state drawn composite films were prepared using water-soluble polyvinyl alcohol (PVA) and dispersible graphene oxide (GO). A co-additive (sodium dodecyl benzenesulfonate) was used to improve both the dispersion of GO and consequently the thermal conductivity. The hydrogen bonding between GO and PVA and the simultaneous alignment of GO and PVA in drawn composite films contribute to an improved thermal conductivity (∼25 W m–1 K–1), which is higher than most reported polymer composites and an approximately 50-fold enhancement over isotropic PVA (0.3–0.5 W m–1 K–1). This work provides a new method for preparing water-processable, drawn polymer composite films with high thermal conductivity, which may be useful for thermal management applications.

While the impact of compositional parameters such as block length and ionic content on the micellization of (polymeric) amphiphiles is widely investigated, the influence of monomer sequence has received far less attention until recently. Here, we report the synthesis of two sequence-controlled polyurethane ionomers (PUIs) prepared via a stepwise coupling-deprotection strategy, and compare their solution association in aqueous-organic mixtures. The two PUIs are highly similar in mass and overall composition, yet differ markedly in the sequence of building blocks. PUI-A2 comprises a polytetrahydrofuran (pTHF) block connected to an alternation of isophorone diamine (IPDA) and dimethylolpropionic acid (DMPA) units that together are also arranged in a blockwise manner. The result is a macromolecular structure with a comparatively hydrophobic tail (pTHF) and a hydrophilic headgroup, which structure is reminiscent of those of traditional surfactants, albeit much larger in size. PUI-S2 instead resembles a bolaamphiphilic architecture with a pTHF midblock connected on either end to a singly charged segment comprising DMPA and IPDA. We detect micellization below a threshold cosolvent volume fraction (Csolv) of 0.4 in aqueous-organic mixtures with tetrahydrofuran (THF), ethanol, and isopropyl alcohol. We use scattering tools to compare the aggregation number (Nagg) and hydrodynamic radius (Rh) of PUI-S2 and PUI-A2 micelles. Irrespective of the solvent composition, we observe in the micellar window of Csolv < 0.4, lower Nagg for PUI-S2 micelles compared to PUI-A2, which we attribute to packing restraints associated with its bolaamphiphilic architecture. The increase in micellar size with increasing Csolv is much more pronounced for PUI-S2 than for PUI-A2. The micellar mass decreases with increasing Csolv for both PUIs; the effect is modest for PUI-S2 compared to PUI-A2 and is not observed in the most apolar cosolvent studied (THF). Upon the approach of the micellization boundary Csolv ≈ 0.4, both types of PUI micelles become less compact in structure, as (in most cases) PUIs are released and as micellar dimensions increase.

Many mineral crystallization processes in aqueous solutions involve formation of nanoclusters with short-range order. Their transformation into crystalline products is not well understood. Here we investigate the formation of long-range crystalline order within networks of cobalt-based nanoclusters. High-resolution cryogenic transmission electron microscopy (cryoTEM) together with NMR and FTIR spectroscopies shows the formation of ∼0.8 nm sized (Co)(NH3)5CO3 complexes at the initial stage. By ligand exchange, those complexes become bridged by CO32-/OH- ligands and form ∼2 nm sized clusters, which subsequently aggregate into sheetlike networks due to the structural heterogeneity of the clusters. By further ligand change and adjustment in cluster orientations, long-range order is established, which leads to the nucleation of ammonium cobalt kambaldaite nanocrystals. Our observations demonstrate that nanoclusters with short-range order can form crystals via an oriented-attachment pathway, which provides new insights into multistep crystallization processes.

Supramolecular polymers are known to form strong and resilient hydrogels which can take up large amounts of water while exhibiting ease of processing and self-healing. They also possess similarities with networks of biological macromolecules. The combination of these features makes supramolecular polymers ideal candidates for studying mechanisms and consequences of self-assembly, which are relevant to biological materials. At the same time, this renders investigations of mixed hydrogels based on different supramolecular compounds necessary, since this substantially widens their applicability. Here, we address unusual viscoelastic properties of a class of binary hydrogels made by mixing fibrillar supramolecular polymers that are formed from two compounds: 1,3,5-benzene-tricarboxamide decorated with aliphatic chains terminated by tetra(ethylene glycol) (BTA) and a 20 kg/mol telechelic poly(ethylene glycol) decorated with the same hydrogen bonding BTA motif on both ends (BTA-PEG-BTA). Using a suite of experimental and simulation techniques, we find that the respective single-compound-based supramolecular systems form very different networks which exhibit drastically different rheology. More strikingly, mixing the compounds results in a non-monotonic dependence of modulus and viscosity on composition, suggesting a competition between interactions of the two compounds, which can then be used to fine-tune the mechanical properties. Simulations offer insight into the nature of this competition and their remarkable qualitative agreement with the experimental results is promising for the design of mixed hydrogels with desired and tunable properties. Their combination with a sensitive dynamic probe (here rheology) offer a powerful toolbox to explore the unique properties of binary hydrogel mixtures., A two-component hydrogel system, comprising two different supramolecular molecules based on the same hydrogen bonding motif, is shown to exhibit a non-monotonic dependence of modulus and viscosity on composition. This binary hydrogel consists of fibrillar supramolecular polymers formed from two compounds, 1,3,5-benzene-tricarboxamide decorated with aliphatic chains terminated by tetra(ethylene glycol) (BTA) and a 20 kg/mol telechelic poly(ethylene glycol) decorated with the same hydrogen bonding BTA motif on both ends (BTA-PEG-BTA). The powerful combination of rheometric and cryo-TEM experiments with simulations provides detailed insights into the origin of the observed behavior, which is the competition between the dynamic interactions of the two compounds. The coarse-grained model used in simulations implies a universal validity of these findings for a variety of different chemical compounds. It is concluded that interactions between not only the single associating units, but also their changing organization in space with changing relative composition, play a crucial role in the emerging mechanics of binary and multicomponent gels, and therefore have implications in understanding and tailoring the viscoelastic properties of biological networks or designing mixed hydrogels with desired properties.

Transparency and thermal conductivity of ultradrawn, ultrahigh-molecular-weight polyethylene films containing different contents of low-molecular-weight polyethylene wax (PEwax) are explored from experimental and theoretical viewpoints. It is shown that the addition of PEwax decreases light scattering in all directions, resulting from a reduction of defects while having little effect on crystallinity or chain orientation of ultradrawn films. In general, upon the addition of PEwax, the thermal conductivity of ultradrawn films increases with the highest conductivity being 47 (W m-1 K-1) and subsequently decreases at higher concentrations. The thermal conductivity also depends on draw ratio and number-average molecular weight (Mn) of the films. A model is presented which correlates the thermal conductivity of the films with the draw ratio and Mn, enabling explanation of the experimental results. Hence, the thermal conductivity of ultradrawn polyethylene films can be predicted as a function of Mn and draw ratio.

A new principle is developed to fabricate temperature-responsive, multicolor photonic coatings that are capable of switching color. The coating is composed of a non-cross-linked liquid crystal siloxane-based elastomer that is interpenetrated through an acrylate-based liquid crystal network. Discrete temperature changes induce phase separation and mixing between the siloxane and the acrylate polymers and change the reflective colors correspondingly. The temperature-responsive color change of the coatings can be programmed by the processing conditions and coating formulation, which allows for the fabrication of photopatterned multicolor images. The photonic ink can be coated on flexible poly(ethylene terephthalate) films using roll-to-roll flexographic printing, making these temperature-responsive, multicolor-changing polymers appealing for applications such as responsive color decors, optical sensors, and anticounterfeit labels.

To better understand the role of aromatic hydrocarbons in new-particle formation, we measured the particle-phase abundance and volatility of oxidation products following the reaction of aromatic hydrocarbons with OH radicals. For this we used thermal desorption in an iodide-adduct Time-of-Flight Chemical-Ionization Mass Spectrometer equipped with a Filter Inlet for Gases and AEROsols (FIGAERO-ToF-CIMS). The particle-phase volatility measurements confirm that oxidation products of toluene and naphthalene can contribute to the initial growth of newly formed particles. Toluene-derived (C7) oxidation products have a similar volatility distribution to that of α-pinene-derived (C10) oxidation products, while naphthalene-derived (C10) oxidation products are much less volatile than those from toluene or α-pinene; they are thus stronger contributors to growth. Rapid progression through multiple generations of oxidation is more pronounced in toluene and naphthalene than in α-pinene, resulting in more oxidation but also favoring functional groups with much lower volatility per added oxygen atom, such as hydroxyl and carboxylic groups instead of hydroperoxide groups. Under conditions typical of polluted urban settings, naphthalene may well contribute to nucleation and the growth of the smallest particles, whereas the more abundant alkyl benzenes may overtake naphthalene once the particles have grown beyond the point where the Kelvin effect strongly influences the condensation driving force. © 2020 American Chemical Society. ISSN:0013-936X ISSN:1520-5851

The ability to control antibody activity by pH has important applications in diagnostics, therapeutic antibody targeting, and antibody-guided imaging. Here, we report the rational design of bivalent peptide–DNA ligands that allow pH-dependent control of antibody activity. Our strategy uses a pH-responsive DNA triple helix to control switching from a tight-binding bivalent peptide–DNA lock into a weaker-binding monovalent ligand. Different designs are introduced that allow antibody activation at both basic and acidic pHs, either autonomously or in the presence of an additional oligonucleotide trigger. The pH of antibody activation could be precisely tuned by changing the DNA triple helix sequence. The peptide–DNA locks allowed pH-dependent antibody targeting of tumor cells both in bulk and for single cells confined in water-in-oil microdroplets. The latter approach enables high-throughput antibody-mediated detection of single tumor cells based on their distinctive metabolic activity., Bivalent, peptide−DNA ligands conditionally block antibody activity. Formation of a triple helix structure triggered by extracellular acidification results in antibody activation and tumor targeting.

Anfinsen's famous experiment showed that the restoration of catalytic activity of a completely unfolded ribonuclease A is only possible when the correct order of events is followed during the refolding process. Inspired by this work, the effect of structural constraints induced by covalent cross-links on the folding of a synthetic polymer chain via hydrogen-bonding interactions is investigated. Hereto, methacrylate-based monomers comprising either benzene-1,3,5-tricarboxamide (BTA)-based or coumarin-based pendants are copolymerized with n-butyl methacrylate in various ratios via reversible addition-fragmentation chain-transfer (RAFT) polymerization. To assess whether the folding and single-chain polymeric nanoparticle (SCPN) formation depend on the order of events, we compare two folding pathways. In the one case, we first covalently cross-link the coumarin pendants within the polymers in a solvent that prevents hydrogen bonding, after which hydrogen bonding is activated, inducing folding of the polymer. In the other case, we induce hydrogen-bonding interactions between tethered BTAs prior to covalent cross-linking of the coumarin pendants. A combination of circular dichroism (CD) spectroscopy, UV-vis spectroscopy, size-exclusion chromatography (SEC), and dynamic light scattering (DLS) is employed to understand the effect of the structural constraints on the folding behavior of these synthetic polymers. The results show that like in ribonuclease A, the order of events matters greatly and determines the outcome. Importantly, a hydrogen-bond-promoting solvent prevents the formation of SCPNs upon covalent cross-linking and results in multichain aggregates. In contrast, covalently cross-linking the polymer when no hydrogen bonds are present followed by inducing hydrogen bonding favors the formation of SCPNs above the UCST of the methacrylate-based polymer. To our surprise, the two systems show a fundamentally different response to changes in temperature, indicating that also in synthetic polymers differences in the folding pathway induce differences in the properties of the resultant nanostructures.

Atmospheric autoxidation of volatile organic compounds (VOC) leads to prompt formation of highly oxidized multifunctional compounds (HOM) that have been found crucial in forming ambient secondary organic aerosol (SOA). As a radical chain reaction mediated by oxidized peroxy (RO2) and alkoxy (RO) radical intermediates, the formation pathways can be intercepted by suitable reaction partners, preventing the production of the highest oxidized reaction products, and thus the formation of the most condensable material. Commonly, NO is expected to have a detrimental effect on RO2 chemistry, and thus on autoxidation, whereas the influence of NO2 is mostly neglected. Here it is shown by dedicated flow tube experiments, how high concentration of NO2 suppresses cyclohexene ozonolysis initiated autoxidation chain reaction. Importantly, the addition of NO2 ceases covalently bound dimer production, indicating their production involving acylperoxy radical (RC(O)OO•) intermediates. In related experiments NO was also shown to strongly suppress the highly oxidized product formation, but due to possibility for chain propagating reactions (as with RO2 and HO2 too), the suppression is not as absolute as with NO2. Furthermore, it is shown how NOx reactions with oxidized peroxy radicals lead into indistinguishable product compositions, complicating mass spectral assignments in any RO2 + NOx system. The present work was conducted with atmospheric pressure chemical ionization mass spectrometry (CIMS) as the detection method for the highly oxidized end-products and peroxy radical intermediates, under ambient conditions and at short few second reaction times. Specifically, the insight was gained by addition of a large amount of NO2 (and NO) to the oxidation system, upon which acylperoxy radicals reacted in RC(O)O2 + NO2 → RC(O)O2NO2 reaction to form peroxyacylnitrates, consequently shutting down the oxidation sequence. Keywords: acylperoxy radicals; Autoxidation; dimers; Highly oxidized multifunctional compounds; Highly oxygenated molecules; HOM; nitrogen oxides; peroxyacylnitrate

The noncovalent functionalization of surfaces has gained widespread interest in the scientific community, and it is progressively becoming an extremely productive research field offering brand new directions for both supramolecular and materials chemistry. As the end-groups often play a dominant role in the surface properties obtained, creating loops with end-groups only at the surface will lead to unexpected architectures and hence properties. Here we report the self-assembly of discrete block molecules-structures in-between block copolymers and liquid crystals-featuring oligodimethylsiloxanes (ODMS) end-capped with naphthalenediimides (NDIs) at the 1-phenyloctane/highly oriented pyrolytic graphite (1-PO/HOPG) interface. These structures produce unprecedented vertically nanophase-separated monolayers featuring NDI moieties that regularly arrange on the HOPG surface, while the highly dynamic ODMS segments form loops above them. Such arrangement is preserved upon drying and generates hydrophobic HOPG substrates in which the ODMS block length tunes the hydrophobicity. Thus, the exact structural fidelity of the discrete macromolecules allows for the correlation of nanoscopic organization with macroscopic properties of the self-assembled materials. We present a general strategy for tunable hydrophobic coatings on graphite based on molecularly combining crystalline aromatic moieties and immiscible oligodimethylsiloxanes. ispartof: CHEMISTRY OF MATERIALS vol:30 issue:10 pages:3372-3378 ispartof: location:United States status: published

We have prepared nanoporous polymers from columnar hexagonal hydrogen-bonded complexes, whose order is fixed by coumarin photoinduced [2 + 2] cycloaddition (photodimerization). Two different hydrogen-bonded complexes were used and consisted of a melamine (M) or tris(triazolyl)triazine (T) derivative acting as central templates and three peripheral carboxylic acids containing coumarin units. These coumarin units were employed for the cross-linking process by photodimerization in order to fix the LC arrangement. Template removal leads to the formation of self-standing nanoporous polymers keeping the columnar hexagonal order. Two nanoporous polymers with different pore diameters were obtained depending on size of the utilized template. These polymers with carboxylic acids at the pore surface demonstrate the ability to selectively adsorb certain molecules depending on their size. Moreover, after base treatment of the nanoporous polymers, they are able to adsorb cationic dyes over anionic and larger cations, demonstrating size- and charge-selective adsorption., This work was supported by the MINECO-FEDER funds (project CTQ2015-70174), Gobierno de Aragon-FSE (Research Group E04). The authors acknowledge the use of the SAI (UZ) and CEQMA (UZ-CSIC) Services. A. Concellon thanks MINECO (Spain) for his PhD grant.

Dynamic single-chain polymeric nanoparticles (SCPNs) are intriguing, bioinspired architectures that result from the collapse or folding of an individual polymer chain into a nanometer-sized particle. Here we present a detailed biophysical study on the behavior of dynamic SCPNs in living cells and an evaluation of their catalytic functionality in such a complex medium. We first developed a number of delivery strategies that allowed the selective localization of SCPNs in different cellular compartments. Live/dead tests showed that the SCPNs were not toxic to cells while spectral imaging revealed that SCPNs provide a structural shielding and reduced the influence from the outer biological media. The ability of SCPNs to act as catalysts in biological media was first assessed by investigating their potential for reactive oxygen species generation. With porphyrins covalently attached to the SCPNs, singlet oxygen was generated upon irradiation with light, inducing spatially controlled cell death. In addition, Cu(I)- and Pd(II)-based SCPNs were prepared and these catalysts were screened in vitro and studied in cellular environments for the carbamate cleavage reaction of rhodamine-based substrates. This is a model reaction for the uncaging of bioactive compounds such as cytotoxic drugs for catalysis-based cancer therapy. We observed that the rate of the deprotection depends on both the organometallic catalysts and the nature of the protective group. The rate reduces from in vitro to the biological environment, indicating a strong influence of biomolecules on catalyst performance. The Cu(I)-based SCPNs in combination with the dimethylpropargyloxycarbonyl protective group showed the best performances both in vitro and in biological environment, making this group promising in biomedical applications.

We demonstrate a novel approach to quantify the interparticle distance in colloidal dimers using Mie scattering. The interparticle distance is varied in a controlled way by changing the ionic strength of the solution and the magnetic attraction between the particles. The measured scaling behavior is interpreted using an energy-distance model that includes the repulsive electrostatic and attractive magnetic interactions. The center-to-center distances of particles with a 525 nm radius can be determined with a root-mean-square accuracy of 12 nm. The data show that the center-to-center distance is larger by 83 nm compared to perfect spheres. The underlying distance offset can be attributed to repulsion by charged protrusions caused by particle surface roughness. The measurement method accurately quantifies interparticle distances that can be used to study cluster formation and colloid aggregation in complex systems, e.g., in biosensing applications.

In this work, the decisive role of rigidity, orientation, and order in the smectic liquid crystalline network on the anisotropic proton and adsorbent properties is reported. The rigidity in the hydrogen-bonded polymer network has been altered by changing the cross-link density, the order by using different mesophases (smectic, nematic, and isotropic phases), whereas the orientation of the mesogens was controlled by alignment layers. Adding more cross-linkers improved the integrity of the polymer films. For the proton conduction, an optimum was found in the amount of cross-linker and the smectic organization results in the highest anhydrous proton conduction. The polymer films show anisotropic proton conductivity with a 54 times higher conductivity in the direction perpendicular to the molecular director. After a base treatment of the smectic liquid crystalline network, a nanoporous polymer film is obtained that also shows anisotropic adsorption of dye molecules and again straight smectic pores are favored over disordered pores in nematic and isotropic networks. The highly cross-linked films show size-selective adsorption of dyes. Low cross-linked materials do not show this difference due to swelling, which decreases the order and creates openings in the two-dimensional polymer layers. The latter is, however, beneficial for fast adsorption kinetics.

The specific recognition of protein surface elements is a fundamental challenge in the life sciences. New developments in this field will form the basis of advanced therapeutic approaches and lead to applications such as sensors, affinity tags, immobilization techniques, and protein-based materials. Synthetic supramolecular molecules and materials are creating new opportunities for protein recognition that are orthogonal to classical small molecule and protein-based approaches. As outlined here, their unique molecular features enable the recognition of amino acids, peptides, and even whole protein surfaces, which can be applied to the modulation and assembly of proteins. We believe that structural insights into these processes are of great value for the further development of this field and have therefore focused this Perspective on contributions that provide such structural data.

[Image: see text] Multivalency is an important instrument in the supramolecular chemistry toolkit for the creation of strong specific interactions. In this paper we investigate the multivalency effect in a dendritic host–guest system using molecular dynamics simulations. Specifically, we consider urea–adamantyl decorated poly(propyleneimine) dendrimers that together with compatible mono-, bi-, and tetravalent ureidoacetic acid guests can form dynamic patchy nanoparticles. First, we simulate the self-assembly of these particles into macromolecular nanostructures, showing guest-controlled reduction of dendrimer aggregation. Subsequently, we systematically study guest concentration dependent multivalent binding. At low guest concentrations multivalency of the guests clearly increases relative binding as tethered headgroups bind more often than free guests’ headgroups. We find that despite an abundance of binding sites, most of the tethered headgroups bind in close proximity, irrespective of the spacer length; nevertheless, longer spacers do increase binding. At high guest concentrations the dendrimer becomes saturated with bound headgroups, independent of guest valency. However, in direct competition the tetravalent guests prevail over the monovalent ones. This demonstrates the benefit of multivalency at high as well as low concentrations.

The formation of isocyanurates via cyclotrimerization of aromatic isocyanates is widely used to enhance the physical properties of a variety of polyurethanes. The most commonly used catalysts in industries are carboxylates for which the exact catalytically active species have remained controversial. We investigated how acetate and other carboxylates react with aromatic isocyanates in a stepwise manner and identified that the carboxylates are only precatalysts in the reaction. The reaction of carboxylates with an excess of aromatic isocyanates leads to irreversible formation of corresponding deprotonated amide species that are strongly nucleophilic and basic. As a result, they are active catalysts during the nucleophilic anionic trimerization, but can also deprotonate urethane and urea species present, which in turn catalyze the isocyanurate formation. The current study also shows how quantum chemical calculations can be used to direct spectroscopic identification of reactive intermediates formed during the active catalytic cycle with predictive accuracy.

The biofunctionalization of particles with specific targeting moieties forms the foundation for molecular recognition in biomedical applications such as targeted nanomedicine and particle-based biosensing. To achieve a high precision of targeting for nanomedicine and high precision of sensing for biosensing, it is important to understand the consequences of heterogeneities of particle properties. Here, we present a comprehensive methodology to study with experiments and simulations the collective consequences of particle heterogeneities on multiple length scales, called superpositional heterogeneities, in generating reactivity variability per particle. Single-molecule techniques are used to quantify stochastic, interparticle, and intraparticle variabilities, in order to show how these variabilities collectively contribute to reactivity variability per particle, and how the influence of each contributor changes as a function of the system parameters such as particle interaction area, the particle size, the targeting moiety density, and the number of particles. The results give insights into the consequences of superpositional heterogeneities for the reactivity variability in biomedical applications and give guidelines on how the precision can be optimized in the presence of multiple independent sources of variability.

A synthetic method for the end-functionalization of vinylidene fluoride oligomers (OVDF) via a radical reaction between terminal olefins and I-OVDF is described. The method shows a wide substrate scope and excellent conversions, and permits the preparation of different disc-shaped cores such as benzene-1,3,5-tricarboxamides (BTAs), perylenes bisimide and phthalocyanines (Pc) bearing three to eight ferroelectric oligomers at their periphery. The formation, purity, OVDF conformation, and morphology of the final adducts has been assessed by a combination of techniques, such as NMR, size exclusion chromatography, differential scanning calorimetry, polarized optical microscopy, and atomic force microscopy. Finally, PBI-OVDF and Pc-OVDF materials show ferroelectric hysteresis behavior together with high remnant polarizations, with values as high as P-r approximate to 37 mC/m(2) for Pc-OVDF. This work demonstrates the potential of preparing a new set of ferroelectric materials simply by attaching OVDF oligomers to different small molecules. The use of carefully chosen small molecules paves the way to new functional materials in which ferroelectricity and electrical conductivity or light-harvesting properties coexist in a single compound. Funding Agencies|Dutch Polymer Institute (DPI) [765]; Dutch Ministry of Education, Culture and Science [024.001.035]; European Research Council [246829]

Patterns of white light are projected on liquid crystal (LC) polymer films containing gold nanospheres (NS) or nanorods (NR) to induce out-of-plane buckling through a photothermal effect. Straightforward synthetic techniques are used to provide well-dispersed nanocomposite films, with NRs exhibiting self-alignment with the LC director. Using a combination of prepatterned director orientation and spatiotemporal variations in light intensity, these nanocomposite films can be reversibly configured into different 3D states. Fine control over shape is demonstrated through variations in size, shape, and intensity of the illuminated region. Switching time scales are found to be of order a few seconds or below, likely reflecting the intrinsic relaxation time of the LC materials.

The complexity of biomolecular systems inevitably leads to a degree of competition between the noncovalent interactions involved. However, the outcome of biological processes is generally very well-defined often due to the competition of these interactions. In contrast, specificity in synthetic supramolecular systems is usually based on the presence of a minimum set of alternative assembly pathways. While the latter might simplify the system, it prevents the selection of specific structures and thereby limits the adaptivity of the system. Therefore, artificial systems containing competing interactions are vital to stimulate the development of more adaptive and lifelike synthetic systems. Here, we present a detailed study on the self-assembly behavior of a C2v-symmetrical tritopic molecule, functionalized with three self-complementary ureidopyrimidinone (UPy) motifs. Due to a shorter linker connecting one of these UPys, two types of cycles with different stabilities can be formed, which subsequently dimerize intermolecularly via the third UPy. The UPy complementary 2,7-diamido-1,8-naphthyridine (NaPy) motif was gradually added to this mixture in order to examine its effect on the cycle distribution. As a result of the C2v-symmetry of the tritopic UPy, together with small differences in binding strength, the cycle ratio can be regulated by altering the concentration of NaPy. We show that this ratio can be increased to an extent where one type of cycle is formed almost exclusively.

We demonstrate that the enantiomers of chiral macromolecules at an aqueous interface can be distinguished with monolayer sensitivity using heterodyne-detected vibrational sum-frequency generation (VSFG). We perform VSFG spectroscopy with a polarization combination that selectively probes chiral molecular structures. By using frequencies far detuned from electronic resonances, we probe the chiral macromolecular structures with high surface specificity. The phase of the sum-frequency light generated by the chiral molecules is determined using heterodyne detection. With this approach, we can distinguish right-handed and left-handed helical peptides at a water-air interface. We thus show that heterodyne-detected VSFG is sensitive to the absolute configuration of complex, interfacial macromolecules and has the potential to determine the absolute configuration of enantiomers at interfaces.

We study the ice-binding site (IBS) of a hyperactive antifreeze protein from the beetle Dendroides canadensis (DAFP-1) using vibrational sum-frequency generation spectroscopy. We find that DAFP-1 accumulates at the air-water interface due to the hydrophobic character of its threonine-rich IBS while retaining its highly regular β-helical fold. We observe a narrow band at 3485 cm(-1) that we assign to the O-H stretch vibration of threonine hydroxyl groups of the IBS. The narrow character of the 3485 cm(-1) band suggests that the hydrogen bonds between the threonine residues at the IBS and adjacent water molecules are quite similar in strength, indicating that the IBS of DAFP-1 is extremely well-ordered, with the threonine side chains showing identical rotameric confirmations. The hydrogen-bonded water molecules do not form an ordered ice-like layer, as was recently observed for the moderate antifreeze protein type III. It thus appears that the antifreeze action of DAFP-1 does not require the presence of ordered water but likely results from the direct binding of its highly ordered array of threonine residues to the ice surface.

A dilute (30 mM) dichloromethane solution of the copper(I) complex 1·Cu+ of a [2]-catenane composed of two identical 28-membered macrocyclic alkenes featuring a phenanthroline moiety in the backbone was subjected to ring-opening metathesis polymerization (ROMP) with second-generation Grubbs catalyst. Shortly after mixing of reactants, the dark red solution transformed into a gel. The bis(phenanthroline)copper(I) units were effectively preserved during ROMP, as evinced by spectroscopic analysis. This implies that the putative metal alkylidene pseudorotaxane intermediates did not undergo dethreading processes but were involved in ring-chain equilibria strongly biased toward the ring products at the low monomer concentration employed in the ROMP reactions. MALDI-TOF mass spectra of the reaction mixtures obtained at an early stage of the reaction revealed a distribution of interlocked oligomers (1·Cu+)n(PF6 -)n-1 with n up to 7, with no traces of peaks ascribable to open chain species. Rheological and mechanical analyses of the gel products provided independent evidence in support of the conclusion that the fraction of linear species in the polymer is negligible. Indications were obtained that the major portion of the polymeric material is composed of fully interlocked species.