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29 result(s) for "超分子"
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Applications of pillarenes, an emerging class of synthetic macrocycles
Synthetic macrocycles, a typical type of building block for molecular recognition and self-assembly, are crucial to supramolecular chemistry and materials science. Since 2008, a new generation of synthetic macrocyclic hosts, pillarenes and their abundant derivatives, which consist of hydroquinone units linked by methylene bridges at 2,5-positions, have been the focus of much research. Numerous studies on their host-guest properties and the fabrication of supramolecular assemblies have demon- strated that pillarenes and their derivatives possess many advantages that facilitate their applications in many research fields. Herein we summarize and classitfy the applications of pillarenes in terms of artificial transmembrane channels, controlled delivery systems, dispersion of carbon hybrid materials, extraction and absorption, liquid crystals, metal-organic frameworks, sensing and detection, stabilization of nanoparticles (Au/Ag/CdTe), and other typical biological applications. We also provide an overview of future developments in pillarene chemistry.
Structural organization of an intact phycobilisome and its association with photosystem II
Phycobilisomes (PBSs) are light-harvesting antennae that transfer energy to photosynthetic reaction centers in cyanobacteria and red algae. PBSs are supermolecular complexes composed of phycobiliproteins (PBPs) that bear chromophores for energy absorption and linker proteins. Although the structures of some individual components have been determined using crystallography, the three-dimensional structure of an entire PBS complex, which is crit- ical for understanding the energy transfer mechanism, remains unknown. Here, we report the structures of an intact PBS and a PBS in complex with photosystem II (PSII) from Anabaena sp. strain PCC 7120 using single-particle elec- tron microscopy in combination with biochemical and molecular analyses. In the PBS structure, all PBP trimers and the conserved linker protein domains were unambiguously located, and the global distribution of all chromophores was determined. We provide evidence that ApcE and ApcF are critical for the formation of a protrusion at the bot- tom of PBS, which plays an important role in mediating PBS interaction with PSII. Our results provide insights into the molecular architecture of an intact PBS at different assembly levels and provide the basis for understanding how the light energy absorbed by PBS is transferred to PSII.
Multicolor Luminescent Carbon Nanoparticles: Synthesis, Supramolecular Assembly with Porphyrin, Intrinsic Peroxidase-Like Catalytic Activity and Applications
Luminescent carbon nanoparticles (CNPs) are newcomers to the world of nanomaterials and have shown great impact in health and environmental applications as well as being promising building blocks for future nanodevices because of their fascinating photoluminescence and potential to serve as nontoxic replacements for traditional heavy-metals-based quantum dots. Herein, fluorescent CNPs have been prepared from candle soot by re fluxing with HNO3 and subsequently separated by a single centrifugation. The CNPs can be represented by the empirical formula C1Ho.677Oo.586No.o15Nao.069, and have a size of 20-100 nm, height of 3.0 nm, lifetime of 7.31 ns + 0.06 ns and quantum yield of -1.7%. Further studies demonstrate that: (1)the as-prepared CNPs exhibit excellent stability in biological media and their luminescence intensity does not change with ionic strength or pH in the physiological and pathological range of pH 4.5-8.8; (2) CNPs can act as electron donors and transporters and porphyrin can assemble onto CNPs through electrostatic and ~-stacking interactions to form porphyrin-CNPs supramolecular composites; (3)CNPs have strong intrinsic peroxidase-like activity. Based on this intrinsic peroxidase activity, a simple, cheap, and highly selective and sensitive colorimetric and quantitative assay has been developed for the detection of glucose levels. This assay has been used to analyze real samples, such as diluted blood and fruit juice.
POSS-embedded supramolecular hyperbranched polymers constructed from a 1→7 branching monomer with controllable morphology transitions
The research on the supramolecular hyperbranched polymers(SHPs) that combines the advantages of supramolecular polymer and hyperbranched architecture has attracted considerable interests in many applications. Here we demonstrate a simple approach to prepare POSS-embedded supramolecular hyperbranched polymers(POSS-SHPs) with varied morphology and size by controlling monomer concentration and mixed solvents. The SHPs formations can further transfer into the core-shell structured micelles by addition of competitive guests based on the double supramolecular driving forces.
Tracking morphologies at the nanoscale: Self-assembly of an amphiphilic designer peptide into a double helix superstructure
Hierarchical self-assembly is a fundamental principle in nature, which gives rise to astonishing supramolecular architectures that are an inspiration for the development of innovative materials in nanotechnolog)a Here, we present the unique structure of a cone-shaped amphiphilic designer peptide. While tracking its concentration-dependent morphologies, we observed elongated bilayered single tapes at the beginning of the assembly process, which further developed into novel double-helix-like superstructures at high concentrations. This architecture is characterized by a tight intertwisting of two individual helices, resulting in a periodic pitch size over their total lengths of several hundred nanometers. Solution X-ray scattering data revealed a marked 2-layered internal organization. All these characteristics remained unaltered for the investigated period of almost three months. In their collective morphology, the assemblies are integrated into a network with hydrogel characteristics. Such a peptide-based structure holds promise as a building block for next-generation nanostructured biomaterials.
The synthesis of benzoxaboroles and their applications in medicinal chemistry
Benzoxaborole, as a versatile scaffold, plays important roles in organic synthesis, molecular recognition and supramolecular chemistry. It is also a privileged structure in medicinal chemistry due to its desirable physicochemical and drug-like properties. Recently, benzoxaboroles were widely applied as antifungal, antibacterial, antiviral, anti-parasite, and anti-inflammatory agents. This review covers the properties, synthetic methods and applications of benzoxaboroles in medicinal chemistry.
Oxidative polymerization of hydroquinone using deoxycholic acid supramolecular template
Polyhydroquinone (PHQ) is a redox-active polymer with quinone/hydroquinone redox active units in the main chain and may have potential applications as a mediator in biosensors and biofuel cells. By the oxidative polymerization of hydroquinone (HQ), PHQ can be easily synthesized, but the reaction lacks control over the structure of the product. Deoxycholic acid (DCA) was introduced as a supramolecular template to control the reaction. The reaction rate is 14 times of that in deionized water and twice of that in buffer. The DCA template increases not only the reaction rate, but also the molecular weight of the polymer obtained. The template effect of DCA was attributed to the supramolecular assemblies of DCA formed in the solution. Cyclic voltammetry study indicated the resulting PHQ was redox-active. While the supramolecular assemblies of DCA provided a template for the oxidative polymerization of HQ, the protons released as a by-product of the oxidative polymerization of HQ in turn enhanced the self-assembly of DCA. As a result, DCA microfibers form and separate out of the solution.
Ternary supramolecular quantum-dot network flocculation for selective lectin detection
We present a versatile, tuneable, and selective nanoparficle-based lectin biosensor, based on flocculation of ternary supramolecular nanoparticle networks (NPN), formed through the sequential binding of three building blocks. The three building blocks are ~-cyclodextrin-capped CdTe quantum dots, tetraethylene glycol-tethered mannose-adamantane cross-linkers (ADTEGMan), and the tetravalent lectin Concanavalin A (ConA). The working principle of this selective sensor lies in the dual orthogonal molecular interactions of the linker, uniting adamantane-~-cyclodextrin and mannose-lectin interaction motifs, respectively. Only when the lectin is present, sequential binding takes place, leading to in situ self-organization of the sensor through the formation of ternary supramolecular networks. Monitoring the loss of fluorescence signal of the quantum dots in solution, caused by controlled network formation and consecutive flocculation and sedimentation, leads to selective, qualitative, and quantitative lectin detection. Fluorescent sedimented networks can be observed by the naked eye or under UV illumination for a lectin concentration of up to 10 8 M. Quantitative detection is possible at 100 min with a lower detection limit of approximately 5 × 10 ^-8 M.
Synthesis and self-assembly of novel oxacalix2arene2triazine amphiphiles
Heteracalixaromatics are an emerging generation of macrocyclic host molecules in supramolecular chemistry. As a typical example of heteracalixaromatics, oxacalix[2]arene[2]triazine adopts a shape-persistent 1,3-alternate conformation and can be easily functionalized. Taking it as a platform, a series of oxacalix[2]arene[2]triazine-based amphiphiles bearing long alkyl chains were synthesized through post-macrocyclization functionalization or 3+1 fragment coupling protocols. The self-assembly behavior of these arnphiphiles in a mixture of tetrahydrofuran (THF) and water was investigated. Dynamic light scattering (DLS) measurements revealed that the size of the self-assembled aggregates is dependent on the structure of the amphiphiles. The long alkyl chain substituents and/or interrnolecular hydrogen bonds were found to promote the self-assembly.
Peptide recognition by functional supramolecular nanopores with complementary size and binding sites
The precise control of the conformations of biomolecules adsorbed on a surface at the single-molecule level is significant. However, it remains a huge challenge because of the complex structure and conformation diversity of biomolecules. Herein, a "nanopore-confined recognition" strategy is proposed to manipulate the adsorption of individual valinomycin molecules at room temperature through precise design of functionalized conjugated macrocycle (CPN8) supramolecular nanopores with complementary architectures and binding sites. We revealed that CPN8 prefers to selectively recognizing valinomycin with complementary architecture because of the strong synergistic interactions between the isopropyl groups of valinomycin and the amino groups of CPN8, with valinomycin- highly oriented pyrolytic graphite (HOPG) interactions. Our perspectives at the single-molecule level will provide valuable insights to improve the design of supramolecular nanopores for conformation-selective recognition of non-conjugated molecules.