Search Results (645)

Graphene quantum dots (GQDs) obtained by microwave-induced pyrolysis of glutamic acid and triethylenetetramine (trien) are fairly stable, emissive, water-soluble, and positively charged nano-systems able to interact with negatively charged meso-tetrakis(4-sulfonatophenyl) porphyrin (TPPS₄). The stoichiometric control during the preparation affords a supramolecular adduct, GQDs@TPPS₄, that exhibits a double fluorescence emission from both the GQDs and the TPPS₄ fluorophores. These supramolecular aggregates have an overall negative charge that is responsible for the condensation of cations in the nearby aqueous layer, and a three-fold acceleration of the metalation rates of Cu²⁺ ions has been observed with respect to the parent porphyrin. Addition of various metal ions leads to some changes in the UV/Vis spectra and has a different impact on the fluorescence emission of GQDs and TPPS₄. The quenching efficiency of the TPPS₄ emission follows the order Cu²⁺ > Hg²⁺ > Cd²⁺ > Pb²⁺ ~ Zn²⁺ ~ Co²⁺ ~ Ni²⁺ > Mn²⁺ ~ Cr³⁺ >> Mg²⁺ ~ Ca²⁺ ~ Ba²⁺, and it has been related to literature data and to the sitting-atop mechanism that large transition metal ions (e.g., Hg²⁺ and Cd²⁺) exhibit in their interaction with the macrocyclic nitrogen atoms of the porphyrin, inducing distortion and accelerating the insertion of smaller metal ions, such as Zn²⁺. For the most relevant metal ions, emission quenching of the porphyrin evidences a linear behavior in the micromolar range, with the emission of the GQDs being moderately affected through a filter effect. Deliberate pollution of the samples with Zn²⁺ reveals the ability of the GQDs@TPPS₄ adduct to detect sensitively Cu²⁺, Hg^2+, and Cd²⁺ ions. Full article

Background: During food processing and storage, traditional protein-based delivery systems encounter significant challenges in maintaining the structural and functional integrity of bioactive compounds, primarily due to their temporal instability. Methods: In this study, a nanocomposite hydrogel was prepared through the co-assembly of a self-assembling peptide, 9-Fluorenylmethoxycarbonyl-phenylalanine-arginine-glycine-aspartic acid-phenylalanine (Fmoc-FRGDF), and hyaluronic acid (HA). The stability of this hydrogel as a quercetin (Que) delivery carrier was systematically investigated. Furthermore, the impact of Que co-assembly on the microstructural evolution and physicochemical properties of the hydrogel was characterized. Concurrently, the encapsulation efficiency (EE%) and controlled release kinetics of Que were quantitatively evaluated. Results: The findings indicated that HA significantly reduced the storage modulus (G′) from 256.5 Pa for Fmoc-FRGDF to 21.1 Pa with the addition of 0.1 mg/mL HA. Despite this reduction, HA effectively slowed degradation rates; specifically, residue rates of 5.5% were observed for Fmoc-FRGDF alone compared to 14.1% with 0.5 mg/mL HA present. Notably, Que enhanced G′ within the ternary complex, increasing it from 256.5 Pa in Fmoc-FRGDF to an impressive 7527.0 Pa in the Que/HA/Fmoc-FRGDF hydrogel containing 0.1 mg/mL HA. The interactions among Que, HA, and Fmoc-FRGDF involved hydrogen bonding, electrostatic forces, and hydrophobic interactions; furthermore, the co-assembly process strengthened the β-sheet structure while significantly promoting supramolecular ordering. Interestingly, the release profile of Que adhered to the Korsmeyer–Peppas pharmacokinetic equations. Conclusions: Overall, this study examines the impact of polyphenol on the rheological properties, microstructural features, secondary structure conformation, and supramolecular ordering within peptide–polysaccharide–polyphenol ternary complexes, and the Fmoc-FRGDF/HA hydrogel system demonstrates a superior performance as a delivery vehicle for maintaining quercetin’s bioactivity, thereby establishing a multifunctional platform for bioactive agent encapsulation and controlled release. Full article

The efficient employment of chiral porous organic cages (POCs) for asymmetric catalysis is of great significance. In this work, we have synthesized a chiral N-rich organic cage constructed through chiral (S, S)-1,2-cyclohexanediamine and benzene-1,3,5-tricarbaldehyde utilizing dynamic imine chemistry according to the literature. Following reduction with NaBH₄, the resulting amine-based POCs (RCC3) feature appended chiral diamine moieties capable of coordinating Cu²⁺ cations. This Cu²⁺ coordination provides RCC3 with excellent enantioselectivity as a supramolecular nanoreactor in asymmetric decarboxylative Mannich reactions, providing up to 94% ee of the product. We found that the spatial distribution of chiral amine sites and the coordination of Cu²⁺ in the RCC3 have a significant impact on catalytic activity, especially enantioselectivity. This work provides insights into the structure–function relationship within supramolecular catalytic systems Full article

Aqueous solutions are not homogeneous and could be considered supramolecular systems. They can emit electromagnetic waves. Electromagnetic emission from one supramolecular system (“source”) can be received by another supramolecular system (“receiver”) without direct contact (distantly). This process represents a transfer of a “molecular signal” and causes changes in conformation and symmetry of the “receiver”. The aim of the current work is to theoretically describe such changes primarily using a solution of the chiral protein interferon-gamma (IFNγ) as an example. We provide theoretical evidence that supramolecular systems of highly diluted (HD) aqueous solutions formed by self-assembly after mechanical activation generate a stronger molecular signal compared to non-activated solutions, due to their higher energy-saturated state. Additionally, molecular signals cause supramolecular systems with complex (including chiral) structures to undergo easier changes in conformation and symmetry compared to simpler systems, enhancing their biological activity. Using statistical physics, we obtained the parameter Ic, characterizing the magnitude of conformational and symmetry changes in supramolecular (including chiral) systems caused by molecular signals. In quantum information science, there is an analogue of the parameter Ic, which characterizes the entanglement depth of quantum systems. This study contributes to the understanding of the physico-chemical basis of distant molecular interactions and opens up new possibilities for controlling the properties of complex biological and chemical systems. Full article

Arginine plays a critical role in biomolecular interactions due to its guanidinium side chain, which enables multivalent electrostatic and hydrogen bonding contacts. In this study, atomistic molecular dynamics simulations were conducted across a broad concentration range (26–605 mM) to investigate the thermodynamic and structural features of arginine self-assembly in aqueous solution. Key observables—including hydrogen bond count, radius of gyration, contact number, and isobaric heat capacity—were analyzed to characterize emergent behavior. A three-regime aggregation pattern (dilute, cooperative, and saturated) was identified and quantitatively modeled using the Hill equation, revealing a non-linear transition in clustering behavior. Spatial analyses were supplemented with trajectory-based clustering and radial distribution functions. The heat capacity peak observed near 360 mM was interpreted as a thermodynamic signature of hydration rearrangement. Trajectory analyses utilized both GROMACS tools and the MDAnalysis library. While force field limitations and single-replica sampling are acknowledged, the results offer mechanistic insight into how arginine concentration modulates molecular organization—informing the understanding of biomolecular condensates, protein–nucleic acid complexes, and the design of functional supramolecular systems. The findings are in strong agreement with experimental observations from small-angle X-ray scattering and differential scanning calorimetry. Overall, this work establishes a cohesive framework for understanding amino acid condensation and reveals arginine’s concentration-dependent behavior as a model for weak, reversible molecular association. Full article

This work presents the synthesis and structural characterization of a novel type of biscyclometalated Ir(III) complex, which is equipped with two iodoethynyl moieties on its 2,2′-bipyridine (bpy) ligand. Iodoethynyl moieties represent prominent donor systems for the formation of supramolecular structures via halogen bonding (X-bonding). The synthesis of bis(2-phenylpyridinato)-[4,4′-bis(iodoethynyl)-2,2′-bipyridine]iridium(III) hexafluorophosphate, (2)(PF₆), is straightforward and involves post-complexation iodination, thus expanding the already rich toolbox for performing “chemistry on the complex”. The formation of the iodoethynyl moieties was unequivocally proven by ¹H-NMR spectroscopy, ESI-TOF mass spectrometry, and single-crystal XRD analysis. Full article

Precise control over molecular dispersity and supramolecular assembly is essential for designing nanostructures with targeted properties and functionalities. In this study, we explore the impact of molecular dispersity in BTA-oligo(AA)₃ oligomers on the formation and structural organization of Au nanomaterials in an aqueous system. Discrete and polydisperse BTA-oligo(AA)₃ samples are systematically synthesized and characterized to evaluate their role as templates for nanostructure formation. UV-vis spectroscopy and TEM analyses reveal distinct differences in the resulting nanostructures. Specifically, discrete oligomers facilitate the formation of well-defined, interconnected Au nanonetworks with high structural uniformity, even at elevated concentrations. In contrast, polydisperse oligomers facilitated the formation of isolated Au nanoparticles with limited control over morphology and connectivity. These differences are attributed to the greater molecular uniformity and enhanced self-assembly capabilities of the discrete oligomers, which serve as effective templates for directing Au precursor organization and reduction into ordered nanostructures. This study provides mechanistic insight into how molecular dispersity affects the templating and assembly of gold nanomaterials. The findings offer a promising strategy for developing tailored nanostructures with interconnected morphologies and controlled optical and structural properties, paving the way for advanced applications. Full article

This review highlights how advances in silico techniques have shed new light on phenomena in confined supramolecular resorcinarene-based systems. Computational studies have provided detailed insights into capsule formation, their dynamic behavior, guest encapsulation and reaction mechanisms within these hosts, often revealing information that experimental methods cannot reach. The focus is placed on the self-assembly of resorcin[4]arenes, pyrogallol[4]arenes, velcrands, and octa acid systems. These computational studies complement experimental findings and, in many cases, offer new perspectives that are inaccessible using experimental techniques alone. Supramolecular architectures are growing in complexity the role of in silico approaches is becoming indispensable. They offer a way to design rationally and understand host–guest chemistry more deeply. Full article

A promising direction in polymer material processing is the development of self-reinforced polymer composites (SRPMs), representing a relatively new group of composite materials. The self-reinforcement method allows for materials of one polymer to be combined with different molecular, supramolecular, and structural features. The high adhesive and mechanical properties of SRPMs are due to the formation of a homogeneous system with no inter-phase boundary. Moreover, self-reinforcement considers the possibility of using polymer waste to create high-strength composites, which reduces the environmental load. In the current work, the phase composition, structure, and properties of SRPMs based on polytetrafluoroethylene (PTFE) were studied. SRPMs were prepared by mixing industrial and regenerated PTFE powders and then subjected to pressing and sintering. Two types of regenerated PTFE were used for the SRPM preparation: a commercial PTFE of the TOMFLON^TM trademark and mechanically grinded PTFE waste. The degree of crystallinity of the obtained materials (41–68%) was calculated by XRD analysis; the crystallite size was determined to be 30–69 nm. Thermal analysis of the composites was carried out by the DSC method in the temperature range of 25–370 °C. The characteristics of thermal processes in self-reinforced composites correlate with the data from structural studies of XRD and FTIR analyses. The results of dynamic mechanical analysis showed that the introduction of regenerated PTFE powder into an industrial one increased the elasticity modulus from 0.6 GPa up to 2.0–3.1 GPa. It was shown that the phase state of the SRPMs depended on the method of processing polymer waste (the type of regenerated PTFE) that determined the heat resistance and mechanical properties of the obtained composite material. Full article

A single-molecule magnet (SMM) is a molecule that functions as a magnet. SMMs can be explored not only for emerging technology but also the fundamental science of their quantum nature, nanometer sizes, and their ease of engineering. This review encompasses the state-of-the-art experiments and theories developed so far for SMMs. We briefly explore their experimental synthesis and characterization. In the experimental synthesis, we cover ‘Click Chemistry’ and supramolecular chemistry. The main experimental characterizations comprise superconducting quantum interference devices, electron paramagnetic resonance, neutron scattering, and X-ray magnetic circular dichroism. The theoretical and computational works based on the density functional theory, the post-Hartree–Fock methods, and the theory of open quantum systems are discussed. Moreover, we exemplify the numerous promising research areas for SMMs by discussing quantum technologies. We envision a brilliant future for the fundamental research and emerging applications of SMMs. Full article

Receptors capable of binding both positive and negative ions are an important domain of supramolecular chemistry with valuable application potential. A Complete thermodynamic description of the equilibria related to ion pair recognition is beneficial in developing the optimized receptor systems, although it represents a difficult task that is rarely resolved due to various coupled processes. Here, we present a comprehensive study of ion pair (NaCl, NaHSO₄, and NaH₂PO₄) binding by a ureido–amide calix[4]arene host in acetonitrile using a series of experimental techniques and molecular dynamics simulations. We devoted particular attention to characterizing the side processes (ion association and salt precipitation) and included them in the models describing ion pair complex formation. For this purpose, a multimethod approach (potentiometry, conductometry, ITC, flame AES) was employed, generating reliable data which provided insight into the thermodynamic effect of each included equilibrium. Positive cooperativity was observed in the context of NaCl and NaHSO₄ binding by the studied calixarene. Computational results related to the NaCl complex in acetonitrile revealed that favorable Coulombic interactions, changes in affinity for solvent molecule inclusion, and intramolecular hydrogen bonding contributed to cation-induced cooperativity. Full article

The crystal structure of the hydrated form of 7-chloro-4-(4-methyl-1-piperazinyl)quinoline (BPIP) was determined by single-crystal X-ray diffraction analysis. This study revealed a one-dimensional supramolecular network stabilized by hydrogen bonding interactions between BPIP and water molecules. This compound represents one-half of a piperaquine molecule, a member of the 4-aminoquinoline class of antimalarial treatments, currently employed as a partner agent in modern combination therapies. As a simplified structural analog, BPIP can serve as a critical model system for probing the intermolecular interactions, physicochemical properties, and structural behavior of the parent compound. As a result, conducting a thorough solid-state characterization of BPIP is critical for gaining insight into its physical properties and verifying the material’s identity and purity. Full article

The detection of zinc ions plays an essential role in protecting public health and maintaining ecological balance. However, traditional fluorescent probes for Zn²⁺ are limited in their specificity, especially under complex environments, due to their single-mode optical signal and inadequate recognization capacities. Herein we report a dual-mode supramolecular sensing system constructed from a unique three-component assembly involving a terpyridine platinum (II) complex, oxalate, and Zn²⁺, enabling highly specific detection performance for Zn²⁺. The supramolecular sensing system exhibits excellent selectivity among various interfering substances, accompanied by ultra-low detection limit (0.199 μM) and fast response (<3 s). The high recognization capacity comes from tri-component-based supramolecular assembly, while the dual-mode response arises from the generation of intermelcular Pt-Pt and π-π interactions, which yields absorption and emission originating from low-energy metal–metal-to-ligand charge transfer (MMLCT) transitions. This work marks a pioneering demonstration for highly specific detection of Zn²⁺ and inspires an alternative strategy for designing cation probes. Full article

The creation of surface relief gratings using hydrogels for label-free biomolecule detection represents a significant advance in the development of versatile, cutting-edge biosensors. Central to this innovation is the formulation of materials with enhanced mechanical properties, especially for applications in soft, wearable technologies. In this work, we have developed novel biofunctional hydrogels that incorporate slide-ring supramolecular structures into their network, enabling the production of surface relief gratings with superior mechanical characteristics for biomolecule detection without the need for labels. These hydrogels, functionalized with bovine serum albumin and goat anti-rabbit antibodies, demonstrated excellent selectivity and sensitivity toward anti-bovine serum albumin and rabbit IgGs in blood serum, evaluated using a label-free format. Remarkably, the new materials matched the analytical performance of conventional hydrogels based on static networks while offering dramatically improved toughness and elasticity, with a compressive modulus comparable to human skin. This demonstrates the potential of slide-ring hydrogels for fabricating robust, label-free biosensing platforms. Furthermore, the flexibility of this system allows for the incorporation of various recognition elements tailored to specific applications. Full article

We demonstrate a rapid and sensitive boron detection method through current amplification mediated by supramolecular interaction. Oxidation peak currents obtained by cyclic voltammetry (CV) measurements of a ferrocene/catechol-functionalized β-cyclodextrin inclusion complex were amplified through an EC’ reaction (where EC’ denotes an electrochemical step followed by a catalytic chemical step). However, the amplified current was decreased by boric acid (the primary form of boron in water) addition at pH 8.6 owing to interactions of boron with the cis-diol structure of dihydroxybenzoic acid-β-cyclodextrin and ferrocene for ester formation. We determined the optimum CyD functionalization sites and measurement conditions and obtained a limit of detection of 0.16 mg B L⁻¹ for ferrocene/3,4-dihydroxybenzoic acid-β-cyclodextrin (Fc/3,4-DHBA-β-CyD). The binding constant (assuming a 1:1 binding model) for the interaction between Fc/3,4-DHBA-β-CyD and boric acid was estimated to be approximately 1500 M⁻¹. Boron concentrations in spiked real samples showed good recoveries and linear calibration curves. The electrochemical response of this system was not significantly affected by the presence of other anions or cations. We also found that an aqueous solution of 3,4-DHBA-β-CyD remained stable for at least 112 days. Full article