60 research outputs found

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

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    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.</p

    Temperature Directs the Majority-Rules Principle in Supramolecular Copolymers Driven by Triazine–Benzene Interactions

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    Supramolecular copolymers have typically been studied in the extreme cases, such as self-sorting or highly mixed copolymer systems, while the intermediate systems have been less understood. We have reported the temperature-dependent microstructure in copolymers of triazine- and benzene-derivatives based on charge-transfer interactions with a highly alternating microstructure at low temperatures. Here, we investigate the temperature-dependent copolymerization further and increase the complexity by combining triazine- and benzene-derivatives with opposite preferred helicities. In this case, intercalation of the benzene-derivative into the triazine-derivative assemblies causes a helical inversion. The inversion of the net helicity was rationalized by comparing the mismatch penalties of the individual monomers, which indicated that the benzene-derivative dictates the helical screw-sense of the supramolecular copolymers. Surprisingly, this was not reflected in further investigations of slightly modified triazine- and benzene-derivatives, thus highlighting that the outcome is a subtle balance between structural features, where small differences can be amplified due to the competitive nature of the interactions. Overall, these findings suggest that the temperature-dependent microstructure of triazine- and benzene-based supramolecular copolymers determines the copolymer helicity of the presented system in a similar way as the mixed majority-rules phenomenon.</p

    Controlling Helical Asymmetry in Supramolecular Copolymers by In Situ Chemical Modification

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    Amplification of asymmetry in complex molecular systems results from a delicate interplay of chiral supramolecular structures and their chemical reactivity. In this work, we show how the helicity of supramolecular assemblies can be controlled by performing a non-stereoselective methylation reaction on comonomers. By methylating chiral glutamic acid side chains in benzene-1,3,5-tricarboxamide (BTA) derivatives to form methyl esters, the assembly properties are modulated. As reacted comonomers, the methyl ester-BTAs induce a stronger bias in the screw-sense of helical fibers predominantly composed of stacked achiral alkyl-BTA monomers. Hence, applying the in situ methylation in a system with the glutamic acid-BTA comonomer induces asymmetry amplification. Moreover, mixing small quantities of enantiomers of glutamic acid-BTA and glutamate methyl ester-BTA in the presence of the achiral alkyl-BTAs leads to deracemization and inversion of the helical structures in solution via the in situ reaction toward a thermodynamic equilibrium. Theoretical modeling suggests that the observed effects are caused by enhanced comonomer interactions after the chemical modification. Our presented methodology enables on-demand control over asymmetry in ordered functional supramolecular materials.</p

    Controlling the length of porphyrin supramolecular polymers via coupled equilibria and dilution-induced supramolecular polymerization

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    Multi-component systems often display convoluted behavior, pathway complexity and coupled equilibria. In recent years, several ways to control complex systems by manipulating the subtle balances of interaction energies between the individual components have been explored and thereby shifting the equilibrium between different aggregate states. Here we show the enantioselective chain-capping and dilution-induced supramolecular polymerization with a Zn(2+)-porphyrin-based supramolecular system when going from long, highly cooperative supramolecular polymers to short, disordered aggregates by adding a monotopic Mn(3+)-porphyrin monomer. When mixing the zinc and manganese centered monomers, the Mn(3+)-porphyrins act as chain-cappers for Zn(2+)-porphyrin supramolecular polymers, effectively hindering growth of the copolymer and reducing the length. Upon dilution, the interaction between chain-capper and monomers weakens as the equilibria shift and long supramolecular polymers form again. This dynamic modulation of aggregate morphology and length is achieved through enantioselectivity in the aggregation pathways and concentration-sensitive equilibria. All-atom and coarse-grained molecular simulations provide further insights into the mixing of the species and their exchange dynamics. Our combined experimental and theoretical approach allows for precise control of molecular self-assembly and chiral discrimination in complex systems

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

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    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

    Supramolecular copolymers: structure and composition revealed by theoretical modeling

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    Supramolecular copolymers, non-covalent analogues of synthetic copolymers, constitute a new and promising class of polymers. In contrast to their covalent counterparts, the details of their mechanism of formation, as well as the factors determining their composition and length, are still poorly understood. Here, the supramolecular copolymerization between two slightly structurally different benzene-1,3,5-tricarboxamide (BTA) monomers functionalized with either oligodimethylsiloxane (oDMSi) or alkyl side chains is unraveled by combining experimental and theoretical approaches. By applying the “sergeant-and-soldiers” approach using circular dichroism (CD) experiments, we are able to obtain detailed insights into the structure and composition of these supramolecular copolymers. Moreover, we observe an unexpected chiral induction upon mixing two independently CD-silent solutions of the achiral (soldier) and chiral (sergeant) monomers. We find that the subtle differences in the chemical structure of the two monomers impact their homopolymerization mechanism: whereas alkyl-BTAs cooperatively self-assemble, oDMSi-BTAs self-assemble in an isodesmic manner. The effect of these mechanistic differences in the supramolecular copolymerization process is investigated as a function of the composition of the two monomers and explicitly rationalized by mathematical modeling. The results show that, at low fractions of oDMSi-BTA sergeants (25 mol%), the isodesmic assembly of the increasing amounts of sergeant becomes more dominant, and different species start to coexist in the copolymerization process. The analysis of the experimental data with a newly developed theoretical model allows us to quantify the thermodynamic parameters, the distribution of different species, and the compositions and stack lengths of the formed supramolecular copolymers existing at various feed ratios of the two monomers.This work was financially supported by The Netherlands Organization for Scientific Research (NWO-TOP PUNT Grant 10018944) and the Dutch Ministry of Education, Culture and Science (Gravity Program 024.001.035)

    Constitutional dynamic networks : metalloselection - photoselection - adaptation

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    Le domaine de la chimie supramoléculaire met en oeuvre des systèmes chimiques complexes formés de composants moléculaires assemblés par des forces intermoléculaires non covalentes dans le but de créer des procédés fonctionnels. La chimie dynamique, fondée sur la constitution de composants réversibles ouvre la voie à la chimie adaptative, où la diversité constitutionnelle d’un système s’organise par sélection sous l’action d’agents externes. Dans l’élaboration de systèmes complexes, l’interconnectivité structurelle entre les différentes molécules peut être représentée de manière schématique par un réseau dynamique constitutionnel. L’utilisation de réseaux de pyridyl-hydrazones et des pyridyl-acylhydrazones met en évidence leurs adaptations orthogonales à des stimuli externes par métallosélection et par photosélection grâce aux dynamiques constitutionnelles, conformationnelles et configurationnelles de ces molécules. Ainsi, une réponse constitutionnelle du système est apportée à un changement d’informations conformationnelles et configurationnelles. Ces systèmes dynamiques permettent aussi la formation de matériaux adaptatifs, et la réalisation de séparations de phases et de modulations de pH photoinduites.The field of supramolecular chemistry implements complex chemical systems formed from molecular components assembled by non covalent intermolecular forces to generate functional processes. Thedynamic chemistry, based on the ability of supramolecular species to exchange their constituents, gives access to an adaptative chemistry, where the constitutional diversity of a system self-organizesby selection in response to external factors. In the progress towards systems presenting higher levels of complexity, the set of dynamically interconverting constituents of a constitutional dynamic libraryforms a constitutional dynamic network, which can be represented in a schematic way by a weighted graph. The use of pyridyl-hydrazones and pyridyl-acylhydrazones networks allows for orthogonaladaptation to external stimuli by metalloselection and photoselection due to the dynamic properties of constitution, conformation and configuration of these molecules. A constitutional response is expressed by conformational and configurational information changes. These dynamic systems afford also the formation of adaptative materials, and the realization of photoinduced phase separation and pH modulation

    Site selectivity steps in

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    Réseaux dynamiques constitutionnels : métallosélection - photosélection - adaptation

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    The field of supramolecular chemistry implements complex chemical systems formed from molecular components assembled by non covalent intermolecular forces to generate functional processes. Thedynamic chemistry, based on the ability of supramolecular species to exchange their constituents, gives access to an adaptative chemistry, where the constitutional diversity of a system self-organizesby selection in response to external factors. In the progress towards systems presenting higher levels of complexity, the set of dynamically interconverting constituents of a constitutional dynamic libraryforms a constitutional dynamic network, which can be represented in a schematic way by a weighted graph. The use of pyridyl-hydrazones and pyridyl-acylhydrazones networks allows for orthogonaladaptation to external stimuli by metalloselection and photoselection due to the dynamic properties of constitution, conformation and configuration of these molecules. A constitutional response is expressed by conformational and configurational information changes. These dynamic systems afford also the formation of adaptative materials, and the realization of photoinduced phase separation and pH modulation.Le domaine de la chimie supramoléculaire met en oeuvre des systèmes chimiques complexes formés de composants moléculaires assemblés par des forces intermoléculaires non covalentes dans le but de créer des procédés fonctionnels. La chimie dynamique, fondée sur la constitution de composants réversibles ouvre la voie à la chimie adaptative, où la diversité constitutionnelle d’un système s’organise par sélection sous l’action d’agents externes. Dans l’élaboration de systèmes complexes, l’interconnectivité structurelle entre les différentes molécules peut être représentée de manière schématique par un réseau dynamique constitutionnel. L’utilisation de réseaux de pyridyl-hydrazones et des pyridyl-acylhydrazones met en évidence leurs adaptations orthogonales à des stimuli externes par métallosélection et par photosélection grâce aux dynamiques constitutionnelles, conformationnelles et configurationnelles de ces molécules. Ainsi, une réponse constitutionnelle du système est apportée à un changement d’informations conformationnelles et configurationnelles. Ces systèmes dynamiques permettent aussi la formation de matériaux adaptatifs, et la réalisation de séparations de phases et de modulations de pH photoinduites
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