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Ultra-small amorphous carbon dots: preparation, photoluminescence properties, and their application as TiO2 photosensitizers
摘要： Ultra-small carbon quantum dots (s-CQDs) with excitation wavelength-independent fluorescence had been obtained by hydrothermal-followed acid precipitation method and were characterized by FT-IR, TEM, XPS, UV–Vis and XRD. It was found that as-prepared s-CQDs were amorphous spherical particles with an average diameter of 1.51 nm, and there were abundant hydroxyl and carbonyl groups on their surfaces. Moreover, fluorescence emission study found that the luminescence of s-CQDs was aroused by oxygen group decorated on its surface, and the fluorescence properties of s-CQDs were much different from those of large CQDs (l-CQDs), which showed higher quantum yield and better photoluminescence (PL) property than that of l-CQDs. The PL of s-CQDs possessed two emission centers and was exhibited to be excitation independent. When s-CQDs was used as photosensitizer for TiO2 to photocatalytic degradation of methylene blue under visible light irradiation, it showed significantly improved photocatalytic activities compared with 1-CQDs, and the degradation efficiency of methylene blue reached up to 96.6%. The high degradation efficiency was attributed to the ultra-small particle size, abundant acidic groups, and excellent optical properties of s-CQDs.
关键词： Photocatalytic degradation,Ultra-small carbon quantum dots,TiO2 photosensitizers,Photoluminescence,Hydrothermal-followed acid precipitation method
更新于2025-09-04 15:30:14
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Synthesis, physicochemical and quantum chemical studies on a new organic NLO crystal: Cinnamoylproline
摘要： Cinnamoylproline was synthesized and the crystal was grown from solution by the slow evaporation method. The crystal belongs to the trigonal crystal system with non-centrosymmetric space group P31. The calculated geometry and experimental geometry from single crystal X-ray data were compared. Intermolecular interactions were studied using Hirshfeld surface analysis and its real space functions were calculated using Atoms In Molecules (AIM) and its isosurfaces were visualized using Non-covalent interaction analysis. Optical transparency of the crystal was analyzed by UV-Vis analysis and it was found that the crystal has good optical transparency in the visible range and the lower cut-off wavelength was found to be 326 nm. In the photoluminescence spectrum, a broad emission peak at 369 nm was observed. The functional groups were analyzed using FTIR techniques and the vibrational frequencies from experimental and theoretical values were compared. It was inferred from the TG-DTA studies that the crystal was thermally stable up to 375°C. Kurtz-Perry powder SHG analysis was also carried out with KDP as a reference. It showed that the crystal has 1.08 times greater efficiency than KDP. The first hyperpolarizability tensor of the molecule was calculated theoretically and theoretical second order susceptibility was obtained and compared with the experimental susceptibility.
关键词： Non Covalent Interaction (NCI),Crystal growth,Hirshfeld surface analysis,cinnamic acid,QTAIM,First hyperpolarizability
更新于2025-09-04 15:30:14
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Direct Observation of Ion Pairing in Aqueous Nitric Acid Using 2D Infrared Spectroscopy
摘要： Ion-ion interactions and ion pairing play an important role in the properties of concentrated electrolyte solutions, yet remain difficult to study due to the heterogeneous and highly dynamic behavior of these systems. In concentrated acid solutions these questions take on a further level of complexity, because the structure of the aqueous proton itself is uncertain, and may be influenced by the counterion. Here, we address these questions by studying the IR spectra of nitric acid as a function of concentration in H2O, and comparing these to the spectra of several alkali nitrate salts. We show how the close proximity between cations and NO3– ions in solution at high concentration affect the IR spectra, and therefore the molecular structures. Using 2D IR spectroscopy, we demonstrate the formation of contracted ion pair configurations in nitric acid solutions between NO3– ions and H+(aq) via the observation of a distinct anisotropic intermolecular crosspeak between these species. By studying the concentration dependence of this spectral feature, we show that this ion-paired configuration exists in solution at concentrations as low as 2M, and suggests that the structure of H+(aq) solvation complex in these ion pairs differs from the structure in bulk solution.
关键词： 2D IR spectroscopy,Proton hydration,Aqueous nitric acid,Ion pairing,Vibrational spectroscopy
更新于2025-09-04 15:30:14
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The impact of a hyaluronic acid-grafted layer on the surface properties of model silicone hydrogel contact lenses
摘要： The introduction of high oxygen transmissibility silicone hydrogel lenses ameliorated hypoxia-related complications, making them the most prescribed type of contact lens. Despite the progress made over the last two decades to improve their clinical performance, symptoms of ocular dryness and discomfort and a variety of adverse clinical events are still reported. Consequently, the rate of contact lens wear discontinuation has not been appreciably diminished by their introduction. Aiming to improve the interfacial interactions of silicone hydrogel contact lenses with the ocular surface, a biomimetic layer of the hydrophilic glycosaminoglycan hyaluronic acid (HA) (100 kDa), was covalently attached to the surface of model poly(2-hydroxyethyl methacrylate-co-3-methacryloxypropyl-tris-(trimethylsiloxy)silane) (pHEMA-co-TRIS) silicone hydrogel materials via UV-induced thiol-ene “click” chemistry. The surface structural changes after each modification step were studied by FTIR-ATR and XPS. Successful grafting of a homogenous HA layer to the surface of the model silicone hydrogels was confirmed by the consistent appearance of N (1s) and the significant decrease of the Si (2p) peaks, as determined by the low-resolution angle-resolved XPS. The HA-grafted surfaces demonstrated reduced contact angles, dehydration rate and nonspecific deposition of lysozyme and albumin, while maintaining their optical transparency (>90%). In vitro studies demonstrated that the HA-grafted pHEMA-co-TRIS materials did not show any toxicity to human corneal epithelial cells. These results suggest that surface immobilization of HA via thiol-ene “click” chemistry can be used as a promising surface treatment for silicone hydrogel contact lenses.
关键词： surface modification,dehydration,contact lenses,hyaluronic acid,MTT assay,thiol-ene chemistry,protein deposition,Silicone hydrogel
更新于2025-09-04 15:30:14
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Syntheses, structures, photoluminescence, and magnetism of a series of 3,5-di(3,4-dicarboxylphenyloxy)benzoate-based complexes tuned by N-donor co-ligands and transition metal ions
摘要： Six transition metal–organic complexes based on 3,5-di(3,4-dicarboxylphenyloxy)benzoic acid (H5L) and different N-donor co-ligands, namely, Cu(H3L)(2,20-bpy)(cid:2)H2O (1), Zn2(HL)(2,20-bpy)2 (2), Cd2(HL)(2,20-bpy)2(H2O) (3), Cd2(HL)(phen)4(cid:2)5H2O (4), Cu(H3L)(phen) (5), and Cu(H3L)(4,40-bpy)(cid:2)H2O (6) (2,20-bpy = 2,20-bipyridine, phen = 1,10-phenanthroline, 4,40-bpy = 4,40-bipyridine), were successfully synthesized under hydrothermal conditions. Their structures were determined by single-crystal X-ray diffraction analyses and further characterized by elemental analyses, IR, powder X-ray diffraction (PXRD), and thermogravimetric analyses (TGA). Complexes 1 and 5 possess discrete zero-dimensional (0D) structures which are further assembled into three-dimensional (3D) supramolecular frameworks by hydrogen-bonding interactions and p–p stacking interactions. Complexes 2 and 3 display similar 3D frameworks with different topologies. Complex 4 shows a one-dimensional (1D) chain which is further connected into a two-dimensional (2D) supramolecular layer via p–p stacking interactions. Complex 6 exhibits a 1D chain which is further extended into a 3D supramolecular network through hydrogen-bonding interactions. The H5L ligand is partially deprotonated in 1–6. The N-donor co-ligands and transition metal ions have important effects on the architectures of 1–6. The photoluminescent properties of 2–4 and the magnetic properties of 1 and 6 were also studied.
关键词： 3,5-Di(3,4-dicarboxylphenyloxy)benzoic acid,Magnetic property,N-donor co-ligand,Photoluminescent property,Transition metal
更新于2025-09-04 15:30:14
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Detection of binary amino acid in aqueous solution using double gate graphene nano-ribbon field effect transistor
摘要： The study proposes an amperometric biosensor which provides a new approach to the detection of binary amino acid using Graphene Nanoribbon Field Effect Transistor. The high dielectric properties of the binary amino acids groups (L-proline, glycine, L-alanine, and L-serine) in aqueous solution pave the way for precise detection of these molecules using the proposed nano biosensor. High dielectrics as gate insulation materials result in a change of one-dimensional electron density of the device. As a result, the presence of the amino acid groups can be realized through the change in the subthreshold swing of the nanobiosensor. The implementation of this method in Graphene nanobiosensor can be further extended in cases of other non-polar, non-charged biomolecules and acids.
关键词： Dielectric modulation,Field effect transistor,Graphene nanoribbon,Biosensor,Binary amino acid
更新于2025-09-04 15:30:14
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Self-healable electroluminescent devices
摘要： Electroluminescent (EL) devices have been extensively integrated into multi-functionalized electronic systems in the role of the vitally constituent light-emitting part. However, the lifetime and reliability of EL devices are often severely restricted by concomitant damage, especially when the strain exceeds the mechanical withstanding limit. We report a self-healable EL device by adopting a modified self-healable polyacrylic acid hydrogel as the electrode and a self-healable polyurethane as a phosphor host to realize the first omni-layer-healable light-emitting device. The physicochemical properties of each functionalized layer can be efficiently restored after experiencing substantial catastrophic damage. As a result, the luminescent performance of the self-healable EL devices is well recovered with a high healing efficiency (83.2% for 10 healing cycles at unfixed spots, and 57.7% for 20 healing cycles at a fixed spot). In addition, inter-device healing has also been developed to realize a conceptual “LEGO”-like assembly process at the device level for light-emitting devices. The design and realization of the self-healable EL devices may revive their performance and expand their lifetime even after undergoing a deadly cut. Our self-healable EL devices may serve as model systems for electroluminescent applications of the recently developed ionically conductive healable hydrogels and dielectric polymers.
关键词： Self-healable,LEGO assembly,Electroluminescent devices,Polyurethane,Polyacrylic acid hydrogel
更新于2025-09-04 15:30:14
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Study on the Light Stability of Poly(p-phenylenebenzobisoxazole) Fiber
摘要： Although poly(p-phenylenebenzobisoxazole) (PBO) fiber has outstanding mechanical performances and thermal stability but its application was hindered seriously due to low light stability. Thus, main aim in present work is to increase the light stability of PBO fiber. Four means, such as reacted sol-gel means, mixed sol-gel means, silane sol-gel means and physical adhesion means, were performed for light stabilizers to adhere on the surface of PBO fiber. The experimental results indicate that the PBO fibers processed by reacted sol-gel means exhibit flat surface without obvious particle accumulation. Contrasted with those fibers processed by other three means, these fibers show better light stability. After 130 h of light irradiation, the mechanical tensile strength of the fibers processed by reacted sol-gel means is still over 75 % of strength of unaged fiber and the strength is much higher than the aged original fibers whose strength is ca. 40 % of that of unaged original fiber.
关键词： Reacted sol-gel means,Mixed sol-gel means,Ferrocenecarboxylic acid
更新于2025-09-04 15:30:14
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Tuning Nitrogen Content in Graphitic Carbon Nitride by Isonicotinic acid for Highly Efficient Photocatalytic Hydrogen Evolution
摘要： Graphitic carbon nitride (CN) with various nitrogen contents can be prepared to regulate its electronic structure and energy band levels. The newly-prepared graphitic carbon nitride manifests high photocatalytic activity. In this work, nitrogen-rich CN (CN-NR100) and nitrogen-deficient CN (CN-ND500) were prepared by tuning nitrogen contents in CN while using isonicotinic acid (IA) as an additive in the precursors. It is found that IA reacting with urea can introduce its nitrogen to CN, while reacting with CN can take away the amino group of CN, thus reduces its nitrogen content. Interestingly, the gas that comes from the decomposition of IA is essential for the formation of porous morphology in CN. Both CN-NR100 and CN-ND500 can provide more photocatalytic sites, narrow bandgaps to enhance the absorption of visible light and significantly improve the charge carrier separation efficiency. Therefore, CN-NR100 and CN-ND500 manifest an excellent photocatalytic hydrogen evolution rate of 73 μmol h-1 (about 4 times of that of CN) and 120 μmol h-1 (6.7 times of that of CN), respectively. This work provides an efficient strategy to prepare CN with different nitrogen contents by pyrolysis of precursors modified by IA for high photocatalytic hydrogen evolution.
关键词： Graphitic carbon nitride,Nitrogen content,Isonicotinic acid,Hydrogen evolution
更新于2025-09-04 15:30:14
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Lanthanide-Based Coordination Polymers With 1,4-Carboxyphenylboronic Ligand: Multiemissive Compounds for Multisensitive Luminescent Thermometric Probes
摘要： Reactions in water of lanthanide chlorides with the sodium salt of 1,4-carboxyphenylboronic acid lead to two series of isostructural compounds with respective general chemical formulas [Ln(cpb)3(H2O)2]∞ for Ln = La or Ce and ·(cpb)]∞ for Ln = Pr?Lu (except Pm) plus Y. Hetero-lanthanide coordination polymers that are isostructural to the second series have been synthesized, and their photophysical properties have been studied. This study evidences that it is possible to design multiemissive lanthanide-based coordination polymers that could ?nd their application as multigauge luminescent thermometric probes.
关键词： 1,4-carboxyphenylboronic acid,lanthanide,luminescent thermometric probes,coordination polymers
更新于2025-09-04 15:30:14