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Hydrogen Bonds and Molecular Orientations of Supramolecular Structure between Barbituric Acid and Melamine Derivative at the Air/Water Interface Revealed by Heterodyne-Detected Vibrational Sum Frequency Generation Spectroscopy
摘要： We studied the supramolecular structure between barbituric acid (pyrimidine-2,4,6(1H,3H,5H)-trione, BA) and an amphiphilic melamine derivative at the air/water interface by heterodyne-detected vibrational sum frequency generation (HD-VSFG) spectroscopy. HD-VSFG measurements in situ showed a positive broad band from 2300 to 2950 cm?1. By comparing the experimental results with ab initio molecular dynamics (AIMD) simulations, we assigned the broad band to the NH stretching modes of BA strongly hydrogen-bonded to the melamine derivative. In addition, we report in situ HD-VSFG spectra of the interfacial supramolecular structure in the CO stretching region. Two CO stretching bands were identified. On the basis of the signs of the C=O bands, we uniquely determined the orientation of BA. The strong hydrogen bonds and the molecular orientations are direct evidence for the supramolecular structure based on complementary hydrogen bonds at the air/water interface.
关键词： Supramolecular Structure,Molecular Orientations,Barbituric Acid,Melamine Derivative,Hydrogen Bonds,Air/Water Interface,Heterodyne-Detected Vibrational Sum Frequency Generation Spectroscopy
更新于2025-09-19 17:13:59
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Adsorption of Rose Bengal on a self-assembled fibrillar network affords a thermally switchable oxygenation photocatalyst and a thermochromic soft material
摘要： Adsorption of Rose Bengal on a self-assembled fibrillar network affords a thermally switchable oxygenation photocatalyst and a thermochromic soft material
关键词： self-assembly,photosensitizers,thermochromism,soft materials,supramolecular gels
更新于2025-09-16 10:30:52
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Guest Inclusion Modulates Concentration and Persistence of Photogenerated Radicals in Assembled Triphenylamine Macrocycles
摘要： Substituted triphenylamine (TPA) radical cations show great potential as oxidants and as spin containing units in polymer magnets. Their properties can be further tuned by supramolecular assembly. Here, we examine how the properties of photogenerated radical cations, intrinsic to TPA macrocycles, are altered upon their self-assembly into 1D columns. These macrocycles consist of two TPAs and two methylene ureas which drive the assembly into porous organic materials. Advantageously, upon activation the crystals can undergo guest exchange in a single-crystal-to-single-crystal transformation generating a series of isoskeletal host-guest complexes whose properties can be directly compared. Photoinduced electron transfer, initiated using 365 nm LED’s, affords radicals at room temperature as observed by EPR spectroscopy. The line shape of the EPR spectra and the quantity of radicals can be modulated by both polarity and heavy atom inclusion of the encapsulated guest. These photogenerated radicals are persistent, with half-lives between 1-7 days and display no degradation upon radical decay. Re-irradiation of the samples can restore the radical concentration back to a similar maximum concentration, a feature that is reproducible over several cycles. EPR simulations of a representative spectrum indicate two species, one containing two N hyperfine interactions and an additional broad signal with no resolvable hyperfine interaction. Intriguingly, TPA analogs without bromine substitution also exhibit similar quantities of photogenerated radicals, suggesting that supramolecular strategies can enable more flexibility in stable TPA radical structures. These studies will help guide the development of new photoactive materials.
关键词： photoinduced electron transfer,supramolecular assembly,radical cations,triphenylamine,EPR spectroscopy
更新于2025-09-12 10:27:22
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Step-growth polymerization of traptavidin-DNA conjugates for plasmonic nanostructures
摘要： Here, we use two important biomaterials, protein and DNA, to construct self-assembled nanostructures through Watson-Crick base-paring of DNAs. We apply a simple magnetic separation method to purify traptavidin-DNA conjugates, and demonstrate synthesis of linear arrays of traptavidin-DNA conjugates via the step-growth polymerization approach with pre-determined DNA sequences. Using the traptavidin-DNA array as a template, we assemble gold nanoparticles to form linear plasmonic nanostructures in a programmable manner. The traptavidin-DNA conjugates thus provide a convenient platform for one-dimensional assembly of biotinylated nanomaterials for many biomedical applications from drug delivery to bio-sensing.
关键词： Traptavidin,Plasmonic nanostructure,Supramolecular assembly,Protein-DNA conjugate,DNA nanostructure
更新于2025-09-12 10:27:22
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Formation of optical supramolecular structures in a fibre laser by tailoring long-range soliton interactions
摘要： Self-assembly of fundamental elements through weak, long-range interactions plays a central role in both supramolecular DNA assembly and bottom-up synthesis of nanostructures. Optical solitons, analogous in many ways to particles, arise from the balance between nonlinearity and dispersion and have been studied in numerous optical systems. Although both short- and long-range interactions between optical solitons have attracted extensive interest for decades, stable soliton supramolecules, with multiple aspects of complexity and flexibility, have thus far escaped experimental observation due to the absence of techniques for enhancing and controlling the long-range inter-soliton forces. Here we report that long-range soliton interactions originating from optoacoustic effects and dispersive-wave radiations can be precisely tailored in a fibre laser cavity, enabling self-assembly of large numbers of optical solitons into highly-ordered supramolecular structures. We demonstrate several features of such optical structures, highlighting their potential applications in optical information storage and ultrafast laser-field manipulation.
关键词： supramolecular structures,fibre laser,optoacoustic effects,optical solitons,long-range interactions
更新于2025-09-12 10:27:22
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Ultrasound‐assisted nanoscaled supramolecular coordination polymer as an efficient recyclable catalyst for photocatalytic degradation of dye pollutants
摘要： An ultrasound‐assisted nanoscaled supramolecular coordination polymer (nanosized 1′) has been synthesized using a self‐assembly reaction of K3[Cu(CN)4] and hexamethylenetetramine in the presence of Me3SnCl under ambient conditions. Nanosized1′ was examined using elemental analysis, Fourier transform–infrared, scanning electron microscopy, transmission electron microscopy and X‐ray powder diffractions. It was structurally compared with the single crystal 3[Cu6(CN)7(C6H12N4)2(OH3)]; SCP 1. The photocatalytic activities of nanosized 1′ and SCP 1 toward different hazardous organic dyes were determined under ambient, UV‐light irradiation and ultrasonic conditions. SCP 1 and nanosized 1′ as heterogeneous nanoparticles catalysts exhibited high catalytic activity for degradation of Congo Red, Methyl Violet 2B and Methylene Blue dyes. The effects of operational parameters on catalytic degradation process, identification of the degradation products and recycling of the catalyst were also investigated. SCP 1 and nanosized 1′ are recyclable heterogeneous catalysts and can be reused with efficient activities. The mechanism of degradation using different scavenger techniques is proposed and discussed. The catalytic oxidation process is mainly caused by ?OH radicals.
关键词： photocatalytic degradation,nanoscaled supramolecular coordination polymer,hazardous organic dyes
更新于2025-09-12 10:27:22
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Photo-controlled chirality transfer and FRET effects based on pseudo[3]rotaxane
摘要： The use of light to regulate the chirality of supramolecular assemblies in a non-invasive manner remains a challenge. Herein, we report a novel photochromic pseudo[3]rotaxane based on a (R/S)-2,20-binaphthyl secondary ammonium salt guest (2) and anthracene-bridged bis(dibenzo-24-crown-8) (1), which features a chirality transfer and fluorescence resonance energy transfer (FRET) from 2 to 1. Benefiting from the photo-oxidation of anthracene, the induced circular dichroism (ICD) signals of (R/S)-2@1 can be switched off/on by irradiation with 365 nm UV light and heating. This noncovalent supramolecular assembly strategy provides us with unique opportunities to design and construct further smart photo-responsive chiral molecular switches.
关键词： circular dichroism,supramolecular assemblies,FRET,chirality transfer,photo-oxidation
更新于2025-09-12 10:27:22
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Optically-controlled supramolecular self-assembly of an antibiotic for antibacterial regulation
摘要： We report a supramolecular photo-responsive antibiotic (azobenzene-norfloxacin/aCD). This supramolecule exhibited a higher ‘‘on–off’’ ratio of antibacterial ability than azobenzene-norfloxacin alone under UV irradiation. It offers an approach to efficiently regulate the activity of antibiotics by combining the supramolecular and light-regulating strategies together.
关键词： photo-responsive,antibiotic,antibacterial regulation,supramolecular,azobenzene-norfloxacin
更新于2025-09-12 10:27:22
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Precursor-Mediated Synthesis of Shape-controlled Colloidal CsPbBr <sub/>3</sub> Perovskite Nanocrystals and their Nanofiber-Directed Self-assembly
摘要： Shape control is often necessary to tune the optical and electronic properties of nanocrystals (NCs) and is mostly achieved through manipulation of surface ligands and processing conditions. Here we present a versatile synthesis of colloidal CsPbBr3 perovskite NCs of various shapes (nanorods, nanocubes and nanoplatelets) from an inexpensive steroidal Cs precursor: cesium cholate (CsCh). Cesium cholate has several advantages over the most commonly used Cs-precursor (cesium oleate or Cs2CO3 or CsOAc) such as low-cost, non-hygroscopicity and better reproducibility in the perovskite synthesis. Due to the solubility of this Cs-precursor in polar solvents such as methanol, a miniscule polar environment is created during the nucleation and growth of the nanocrystals leading to the serendipitous formation of nanorods at 180 ℃, whereas using a biphasic mixture of 1-octadecene and methanol, the morphology changes to nanocubes. By lowering the reaction temperature (90 ℃), nanoplatelets with 8-9 monolayers thicknesses are formed. These colloidal NCs of variety of shapes are strongly luminescent with a green emission having narrow emission linewidths (16-17 nm) and high quantum yields (96% for nanocubes, 94% for nanoplatelets). Furthermore, hybrid materials of nanocubes and organogel of a dimeric bile acid-derived ester gelator are obtained through co-assembly in which nanocubes arrange along nanofibers with stable, sharp and bright green emission. This enables spatial ordering of nanocubes ranging from micron to centimeter scale in thin films, which is crucial for advanced optoelectronic applications. To date, there is no report in literature on the anisotropic organization of perovskite CsPbBr3 nanocubes triggered by supramolecular co-assembly involving organogel nanofibers.
关键词： nanocubes,organogel,Shape control,hybrid materials,nanorods,cesium cholate,nanoplatelets,supramolecular co-assembly,colloidal CsPbBr3 perovskite NCs
更新于2025-09-12 10:27:22
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Monodisperse gold cuboctahedral nanocrystals directly synthesized in reverse micelles: Preparation, colloidal dispersion in organic solvents and water, reversible self-assembly and plasmonic properties
摘要： The synthesis of organic-solvent-dispersible gold nanoparticles in reverse micelles of didodecyldimethylammonium bromide (DDAB) is revisited in the present investigation. Some parameters of synthesis, specifically the reaction volume and the concentration of the reducing agent, were slightly modified obtaining directly monodisperse gold nanocrystals (AuNCs) without the need to use additional active surfactants or additional treatments such as digestive ripening. Interestingly, most of the obtained AuNCs display the same exposed crystalline faces composed of six bounding facets (four {111} faces and two {002} faces), corresponding to single-crystalline face-centered cubic (fcc) nanoparticles with a cuboctahedron shape. When these AuNCs are subsequently functionalized with 1-decanethiol (C10H21SH) or 1-dodecanethiol (C12H25SH) they don′t experience significant changes in their size or crystalline texture, however, they self-aggregate directly in the suspension at room temperature into faceted supramolecular structures, and exhibit collective plasmonic excitations. Such self-organization is reversible under heating treatments allowing the observation of the influence of the AuNCs aggregation state on their plasmonic properties. Fast Fourier infrared spectroscopy reveals that thiols only replace partially the DDAB molecules, thus, DDAB molecules remain present in the thiol-capped AuNCs. In order to turn the thiol-capped nanocrystals into water-dispersible nanocrystals and extend their technological potential, they are stabilized with poloxamer 407 obtaining highly stable purple colloids in water.
关键词： collective behaviors,gold,self-assembly,supramolecular structures,nanocrystals
更新于2025-09-12 10:27:22