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Ventricular arrhythmias (VAs) triggered by myocardial infarction (MI) are the leading cause of sudden cardiac mortality worldwide. Current therapeutic strategies for managing MI-induced VAs, such as left stellate ganglion resection and ablation, are suboptimal, highlighting the need to explore safer and more effective intervention strategies. Herein, we rationally designed two supramolecular sonosensitizers RuA and RuB, engineered through acceptor modification to generate moderate reactive oxygen species (ROS) to modulate VAs. Both RuA and RuB demonstrated high ultrasound (US)-activated ROS production efficiency, with singlet oxygen (1O2) quantum yield (ΦΔ) of 0.70 and 0.88, respectively, surpassing ligand IR1105 and the conventional sonosensitizer ICG (ΦΔ =0.40). In vitro, RuB, at a modest concentration and under US intensity notably boosts pro-survival autophagy in microglia BV2 cell. To improve in vivo stability and biocompatibility, RuB was further encapsulated into DSPE-PEG5000 to prepare RuB NPs. In vivo studies after microinjection of RuB NPs into the paraventricular nucleus and subsequent US exposure, demonstrated that RuB NPs-mediated US modulation effectively suppresses sympathetic nervous activity (SNA) and inflammatory responses, thereby preventing VAs. Importantly, no tissue injury was observed post RuB NPs-mediated US modulation. This work pioneers the design of long-wave emission supramolecular sonosensitizers, offering new insights into regulating cardiovascular diseases.
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The World Health Organization has described the antimicrobial resistance crisis as one of the top ten global public health threats. New antimicrobial agents that can fight infections caused by antimicrobial resistant pathogens are therefore needed. A potential strategy is the development of small molecules that can selectively interact with bacterial membranes (or membranes of other microbial pathogens), and thereby rapidly kill the bacteria. Here, we report the structure-activity relationship within a group of 22 compounds that were designed to bind the bacterial lipid phosphatidylethanolamine (PE). Liposome-based studies reveal that the lipophilicity of the compounds has the strongest effect on both the affinity and selectivity for PE. The best results were obtained for compounds with logP ≈ 3.75, which showed a 5x to 7x selectivity for bacterial PE lipids over human PC (phosphatidylcholine) lipids. Furthermore, these compounds also showed potent antibacterial activity against the Gram-positive bacterium B. cereus, with minimum inhibitory concentrations (MICs) below 10 µM, a concentration where they showed minimal hemolytic activity against human red blood cells. These results not only show the possibility of PE-binding small molecules to function as antibiotics, but also provide guidelines for the development of compounds targeting other types of biologically relevant membrane lipids.
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Developing new methods to control the size and shape of the helical structures adopted by foldamers is highly important as the secondary structure displayed by these supramolecular scaffolds often dictates their activity and function. Herein, we report on a systematic study demonstrating that the helical pitch of ortho-azobenzene/2,6-pyridyldicarboamide foldamers can be readily controlled through the nature of the terminal functionality. Remarkably, simply through varying the end group of the foldamer, and without modifying any other structural features of the scaffold, the helical pitch can be over doubled in magnitude (from 3.4 Å to 7.3 Å). Additionally, crystallographic analysis of a library ten foldamers has identified general trends in the influence of a range of terminal functionalities, including carboxylbenzyl (Cbz), diphenylcarbamyl (N(Ph)2), ferrocene (Fc) and tert-butyloxycarbonyl (Boc), in controlling the folding behaviour of these supramolecular scaffolds. These studies could prove useful in the future development of functional foldamers which adopt specific sizes and shapes.
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Promoting the generation of triplet states is essential for developing efficient photocatalytic systems. This research presents a novel approach of host-stabilized through-space conjugation via the combination of covalent and non-covalent methods. The designed building block, 4,4'-(1,4(1,4)-dibenzene cyclohexaphane-1,4-diyl)bis(1-phenylpyridinium) chloride, features inherently stable through-space conjugation. When this block forms a 1:1 host-guest complex with cucurbit[8]uril, the through-space conjugation is further stabilized within the confined cavity. Both the generation and lifetime of triplet state are significantly increased, resulting from the host-stabilized through-space conjugation. Additionally, the ultrahigh binding constant of 6.58 × 1014 M-1 ensures the persistence of host-stabilization effect. As a result, the host-guest complex acts as a highly efficient catalyst in the photocatalytic oxidation of thioether and aromatic alcohol. In the photodegradation of lignin, a complex natural product, the host-guest complex also exhibits high efficiency, demonstrating its robustness. This line of research is anticipated to enrich the toolbox of supramolecular photochemistry and provide a strategy for fabricating efficient supramolecular photocatalysts.
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The exploration of novel functionalized supramolecular coordination complexes (SCCs) can enable new applications in domains that include purification and sensing. In this study, employing a coordination-driven self-assembly strategy, we designed and prepared a series of benzochalcogenodiazole-based metallohelicates as high-efficiency charge transfer surface-enhanced Raman scattering (SERS) substrates, expanding the range of applications for these metallohelicates. Through structural modifications, including the substitution of single heteroatoms on ligands, replacement of coordinating metals, and alteration of ligand framework linkages, the Raman performance of these metallohelicates as substrates were systematically optimized. Notably, the SERS enhancement factors (EFs) of the metallohelicate-based SERS substrates were significantly enhanced to levels as high as 1.03 × 107, which rivals the EFs of noble metals devoid of "hot spots". Additionally, the underlying Raman enhancement mechanisms of these metallohelicates have been investigated through a combination of control experiments and theoretical calculations. This study not only demonstrates the utility of metallohelicates as SERS substrates but also offers insights and materials for the development of high-efficiency new charge transfer SERS substrates.
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Chemical reactions conducted in the solid phase (specifically, crystalline) are much less numerous than solution reactions, primarily due to reduced motion, flexibility, and reactivity. The main advantage of crystalline-state transformations is that reactant molecules can be designed to self-assemble into specific spatial arrangements, often leading to high control over product regiochemistry and/or stereochemistry. In crystalline-phase transformations, typically only one type of reaction occurs, and a sacrificial template molecule is frequently used to facilitate self-assembly, similar to a catalyst or enzyme. Here, we demonstrate the first system designed to undergo two chemically unique and orthogonal cycloaddition reactions simultaneously within a single crystalline solid. Well-controlled supramolecular self-assembly of two molecules containing different reactive moieties affords orthogonal reactivity without use of a sacrificial template. Using only UV light, the simultaneous [2+2] and [4+4] cycloadditions are achieved regiospecifically, stereospecifically, and products are obtained in high yield, whereas a simultaneous solution-state reaction affords a mixture of isomers in low yield. Application of dually-reactive systems toward (supra)molecular solar thermal storage materials is also discussed. This work demonstrates fundamental chemical approaches for orthogonal reactivity in the crystalline state and highlights the complexity and reversibility that can be achieved with supramolecular design.
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The 1-acyl thiourea family [R1C(O)NHC(S)NR2R3] exhibits the flexibility to incorporate a wide variety of substituents into their structure. The structural attributes of these compounds are intricately tied to the type and extent of substitution. In the case of 3-mono-substituted thioureas (R2 = H), the conformational behavior is predominantly shaped by the presence of an intramolecular N-H···O=C hydrogen bond. This study delves into the structural consequences stemming from the inclusion of substituents possessing hydrogen-donor capabilities within four novel 1-acyl-3-mono-substituted thiourea derivatives. A comprehensive suite of analytical techniques, encompassing FTIR, Raman spectroscopy, multinuclear (1H and 13C) NMR spectroscopy, single-crystal X-ray diffraction, and supported by computational methods, notably NBO (Natural Bond Orbital) population analysis, Hirshfeld analysis, and QTAIM (Quantum Theory of Atoms in Molecules), was harnessed to scrutinize and characterize these compounds. In the crystalline state, these compounds exhibit an intricate interplay of intermolecular interactions, prominently featuring an expansive network of hydrogen bonds between the hydroxy (-OH) groups and the carbonyl and thiocarbonyl bonds within the 1-acyl thiourea fragment. Notably, the topological analysis underscores significant distinctions in the properties of the acyl thiourea fragment and the intramolecular >C=O···H-N bond when transitioning from the isolated molecule to the crystalline environment.
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The synthesis of [2]rotaxanes stoppered with one or two dipyrromethane groups opened a route for the construction of mechanically interlocked molecules incorporating various porphyrinoid stations. The exploitation of those precursors allowed for the creation of [3]rotaxanes and [2]catenanes based on the calix[4]phyrin motif, presenting intriguing molecular dynamics. The intrinsic flexibility of the porphyrinoid allowed the introduction of a new type of molecular motion within the rotaxanes, termed fluttering. The latter involved a bending of the axle, interconverting two angular-shaped stereoisomers of the rotaxane through a planarised transition state. Simple chemical transformations, i.e. methylation and (de)protonation of [3]rotaxane and [2]catenane allowed for the controllable transformations within the conformationally flexible calix[4]phyrin-incorporated mechanically interlocked porphyrinoids.
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The evolution of flexible sensors heavily relies on advances in soft-material design and sensing mechanisms. Supramolecular chemistry offers a powerful toolbox for manipulating nanoscale and molecular structures within soft materials, thus fostering recent advancements in flexible sensors and electronics. Supramolecular interactions have been utilized to nanoengineer functional sensing materials or construct chemical sensors with lower cost and broader targets. In this perspective, we will highlight the use of supramolecular interactions to regulate and optimize nanostructures within functional soft materials and illustrate their importance in expanding the nanocavities of bioreceptors for chemical sensing. Overall, a bridge between tissue-mimicking flexible sensors and cell-mimetic supramolecular chemistry has been built, which will further advance human healthcare innovation.
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Crownphyrinogens and crownphyrins constitute a group of macrocycles that combine the structural facets of porphyrinoids and crown ethers. The dual-nature cavity embedded in their molecules enables reactivity involving two structurally distinct parts of the macrocyclic ligand. Upon Ni(II) and Pd(II) insertion, coordination compounds are produced wherein the metal is incorporated into the porphyrinoid-like pocket, resulting in monomeric or accordion-like dimeric products, depending on the oxidation level of the macrocycle and metal cation. The reactions with Na(I) and K(I) resulted in the formation of complexes where only the crown ether segment of the molecule is involved in metal binding, yielding remarkable dimeric species. The exploitation of a crownphyrin large enough to accommodate two metal cations allowed the synthesis of an alkali/transition metal binuclear complexes wherein the macrocycle demonstrated the Janus reactivity with one cavity acting as a porphyrinoid, and the other mimicking the crown ether.
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Mimicking hierarchical assembly in nature to exploit atomically precise artificial systems with complex structures and versatile functions remains a long-standing challenge. Herein, we report two single-crystal supramolecular organic frameworks (MSOF-4 and MSOF-5) based on custom-designed atomically precise gold nanoclusters Au11(4-Mpy)3(PPh3)7, showing distinct and intriguing host-guest adaptation behaviors toward 1-/2-bromopropane (BPR) isomers. MSOF-4 exhibits sev topology and cylindrical channels with 4-mercaptopyridine (4-Mpy) ligands matching well with guest 1-BPR. Due to the confinement effect, solid MSOF-4 undergoes significant structural change upon selective adsorption of 1-BPR vapor over 2-BPR, resulting in strong near-infrared fluorescence. Single-crystal X-ray diffraction reveals that Au11(4-Mpy)3(PPh3)7 in MSOF-4 transforms into Au11Br3(PPh3)7 upon ligand exchange with 1-BPR, resulting in 1-BPR@MSOF-6 single crystals with a rarely reported helical assembly structure. Significantly, the double-helical structure of MSOF-6 facilitates efficient catalysis of the electron transfer (ET) reaction, resulting in a nearly 6 times increase of catalytic rates compared with MSOF-4. In sharp contrast, solid MSOF-5 possesses chb topology and cage-type channels with narrow windows, showing excellent selective physical adsorption toward 1-BPR vapor but a nonfluorescent feature upon guest adsorption. Our results demonstrate a powerful strategy for developing advanced assemblies with high-order complexity and engineering their functions in atomic precision.
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The amplification of asymmetry in supramolecular polymers has recently garnered significant attention. While asymmetry amplification has predominantly been explored under thermodynamic conditions, the kinetic aspect of this process unveils intriguing observations, yet is scarcely reported in the literature. Herein, drawing inspiration from macromolecular systems, we propose a novel strategy for enhancing asymmetry in supramolecular polymers through a seed-induced supramolecular polymerization approach under kinetic conditions, employing a naphthalene diimide-derived monomer (ANSG) for template-induced supramolecular polymerization, utilizing adenosine triphosphate (ATP) and pyrophosphate (PPi) as templates. A chiral seed comprising [ANSG-ATP]S effectively amplifies the overall supramolecular asymmetry when exposed to a mixture of achiral templates (PPi) and monomers (ANSG), owing to its efficient seeding characteristics under kinetic conditions. As a result of efficient co-operativity, conversely, employing an achiral seed [ANSG-PPi]S in a mixture of chiral templates (ATP) and monomers (ANSG) results in the attenuation of asymmetry, highlighting the effective modulation achievable through the seeding approach, -an unprecedented observation in the field. Exploiting the efficient aggregation-induced emission enhancement (AIEE) of the resultant supramolecular polymers further extends the amplification and attenuation of circularly polarized luminescence (CPL) as a potential function.
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The creation of ordered structures of molecules assembled from solution onto a substrate is a fundamental technological necessity across various disciplines, spanning from crystallography to organic electronics. However, achieving macroscopic order poses significant challenges, since the process of deposition is inherently impacted by factors like solvent evaporation and dewetting flows, which hinder the formation of well-organized structures. Traditional methods like drop casting or spin coating encounter limitations due to the rapid kinetics of solvent evaporation, leading to limited control over final uniformity and order. In response to these challenges, Solvent Vapour Annealing (SVA) has emerged as a promising solution for realizing ordered molecular structures at scales ranging from nano- to milli- meters. SVA decouples the self-assembly stage from the deposition stage by utilizing solvent vapours which can enable rearrangement, movement, and diffusion of large molecules on the surface even on a macroscopic scale. Essentially acting as "molecular lubricants," solvent vapours enable the formation of well-ordered molecular films. This review discusses the advancements, obstacles, and promising strategies associated with utilizing SVA for the development of innovative nanostructured thin films, and emphasizes the originality and effectiveness of molecular assembly on substrates achieved through this approach.
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Radicals, with their unpaired electrons, exhibit unique chemical and physical properties that have long intrigued chemists. Despite early skepticism about their stability, the discovery of persistent radicals has opened new possibilities for molecular interactions. This review examines the mechanisms and applications of radically driven self-assembly, focusing on key motifs such as naphthalene diimides, tetrathiafulvalenes, and viologens, which serve as models for radical assembly. The potential of radical interactions in the development of artificial molecular machines (AMMs) are also discussed. These AMMs, powered by radical-radical interactions, represent significant advancements in non-equilibrium chemistry, mimicking the functionalities of biological systems. From molecular switches to ratchets and pumps, the versatility and unique properties of radically powered AMMs are highlighted. Additionally, the applications of radical assembly in materials science are explored, particularly in creating smart materials with redox-responsive properties. The review concludes by comparing AMMs to biological molecular machines, offering insights into future directions. This overview underscores the impact of radical chemistry on molecular assembly and its promising applications in both synthetic and biological systems.
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We report on dual, light-responsive and redox-active foldamers that demonstrate reversible and robust stimuli-induced behaviour. Herein, UV/Vis, 1H NMR and circular dichroism (CD) spectroscopy and cyclic voltammetry have been used to establish the reversibility and highly robust nature of the light- and redox-driven behaviour of these new foldamers with minimal levels of fatigue observed even upon multiple cyclic treatments with irradiative/non-irradiative and oxidative/reductive conditions. This proof-of-concept work paves the way towards the creation of novel stimuli-responsive foldamers of increasing sophistication capable of demonstrating reversible and robust responses to multiple distinct stimuli.
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Cage-type structures based on coordination and dynamic covalent chemistry have the characteristics of facile and efficient preparation but poor stability. Chemically stable organic cages, generally involving fragment coupling and multi-step reactions, are relatively difficult to synthesize. Herein, we offer a general and modular strategy to customize covalent organic cages with diverse skeletons and sizes. First, one skeleton (S) module with three extension (E) modules and three reaction (R) modules are connected by one- or two-step coupling to get the triangular monomer bearing three reaction sites. Then one-pot Friedel-Crafts condensation of the monomer and linking module of paraformaldehyde produces the designed organic cages. The cage forming could be regulated by the geometrical configuration of monomeric blocks. The S-E-R angles in the monomer is crucial; only 120o (2,4-dimethoxyphen as reaction module) or 60o (2,5-dimethoxyphen as reaction module) angle between S-E-R successfully affords the resulting cages. By the rational design of the three modules, a series of organic cages have been constructed. In addition, the host-guest properties show that the representative cages could strongly encapsulate neutral aromatic diimine guests driven by solvophobic interactions in polar solvents, giving the highest association constant of (2.58 ± 0.18) × 105 M-1.
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Thiol-disulfide interchange has been an active field of study for biochemists and physical organic chemists alike due to its prevalence within biological systems and fundamentally interesting dynamic nature. More recently, efforts have been made to harness the power of this reversible reaction to make self-assembling systems of macrocyclic and cage-like molecules. However, less effort has focused on the fundamental study of isolating these assemblies and analyzing the factors that control the assembly and sorting of these emerging cyclic systems. We have shown previously that pnictogen-assisted self-assembly enables formation of discrete disulfide macrocycles and cages without competition from polymer formation for a wide variety of alkyl thiols. Herein we report the expansion of these methods to form disulfide macrocycles from aryl thiol containing ligands, allowing access to previously unreported molecules. More importantly, the development of this new self-assembly chemistry allows for a comparison of aryl vs alkyl disulfide exchange and self-assembly. These studies complement classical physical organic and chemical biology studies on the kinetics and thermodynamics of aryl thiol oxidation to disulfides, and we show that this self-assembly method revises some prevailing wisdom from these key classical studies by providing new product distributions and new isolable products in cyclic disulfide formation.
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Supramolecular chemistry achieves higher-order molecular self-assembly through non-covalent interactions. Utilizing supramolecular methods to explore the polymorphism of proteins, the building blocks of life, from a "bottom-up" perspective is essential for constructing diverse and functional biomaterials. In recent years, significant progress has been achieved in the design strategies and functional applications of supramolecular protein self-assembly, becoming a focal point for researchers. This paper reviews classical supramolecular strategies driving protein self-assembly, including electrostatic interactions, metal coordination, hydrogen bonding, hydrophobic interactions, host-guest interactions, and other mechanisms. We discuss how these supramolecular interactions regulate protein assembly processes and highlight protein supramolecular assemblies' unique structural and functional advantages in constructing artificial photosynthetic systems, protein hydrogels, bio-delivery systems, and other functional materials. The enormous potential and significance of supramolecular protein materials are elucidated. Finally, the challenges in preparing and applying protein supramolecular assemblies are summarized, and future development directions are projected.
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Helical nanostructures fabricated via the self-assembly of artificial motifs have been a captivating subject because of their structural aesthetics and multiple functionalities. Herein, we report the facile construction of a self-assembled nanohelix (NH) by leveraging an achiral aggregation-induced emission (AIE) luminogen (G) and pillar[5]arene (H), driven by host-guest interactions and metal coordination. Inspired by the "sergeants and soldiers" effect and "majority rule" principle, the host-guest complexation between G and H is employed to fixate the twisted conformation of G for the generation of "contortion sites", which further induced the emergence of helicity as the 1D assemblies are formed via Ag(I) coordination and hexagonally packed into nano-sized fibers. The strategy has proved feasible in both homogeneous and heterogeneous syntheses. Along with the formation of NH, boosted luminescence and enhanced productivity of reactive oxygen species (ROS) are afforded because of the efficient restriction on G, indicating the concurrent regulation of NH's morphology and photophysical properties by supramolecular assembly. In addition, NH also exhibits the capacity for bacteria imaging and photodynamic antibacterial activities against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli).
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An adaptable Fe(II) tetrahedral cage, [Fe4L4][BF4]8 (L = tris(4-(((E)-pyridin-2-ylmethylene)amino)phenyl) phosphate), has been synthesised via self-assembly. By modulating the orientation of its pendant P=O groups, the cage was found to be capable of encapsulating anionic, neutral, and cationic guests, which was confirmed in the solid state via single-crystal X-ray diffraction (SCXRD) and in solution by high-resolution mass spectroscopy (HR-MS), as well as by NMR (1H, 19F, 31P) studies where possible.