Synthesis of PbS nanocrystals from sulfur–amine …
T1 - Nonlinear optical properties of PbS nanocrystals grown in polymer solutions
13/01/2018 · Synthesis of PbS Nan..
, , , and (2017) The in situ synthesis of PbS nanocrystals from lead(II) n-octylxanthate within a 1,3-diisopropenylbenzene–bisphenol A dimethacrylate sulfur copolymer. Royal Society Open Science, 4 (8). ISSN 2054-5703
Cisplatin cannot effectively bind to albumin by non-covalent interaction. Therefore, a series of cisplatin prodrugs with axial ligands was designed to mimic the binding ability of fatty acids . Cisplatin could be released from prodrugs by intracellular reduction with the loss of axial ligands. Aliphatic tails with different lengths exhibited varied cellular uptakes and cytotoxicities. The cisplatin prodrug with hexadecyl chain was the most potent among the synthesized prodrugs. Computation showed that prodrug was buried inside albumin, which helped preserve its stability in the human blood. To improve the tumor-targeted drug delivery, a fatty acid-modified drug was loaded into the albumin and HER2-binding affibody fusion proteins . experiments demonstrated a specific cell uptake by the HER2 positive cells, which indicated a potential ability to perform tumor-targeted drug delivery.
Synthesis of PbS Nanocrystals by Heterogeneous Reaction
For the last 50 years, bulk lead-chalcogenide semiconductors have been key materials for infrared light sources and lasers, photodetectors and highperformance thermoelectrics. Meanwhile, the colloidal synthesis of chalcogenide semiconductor nanocrystals has provided a new pathway to producing optoelectronic materials with unique physical properties at low cost, including lead-chalcogenide nanocrystals. In this thesis, we synthesized various sizes of lead salt nancrystals that exhibit remarkable photoluminescence efficiencies across the near infrared region at room-temperature, which can be appealing active material for light emitting devices, photovoltaic devices, and bio-imaging. Meanwhile, we developed the catalyst-free self-attachment of PbS nanowires in hot colloidal solution using a combination of multiple surfactants. We demonstrate the controllable self-attachment of star-shaped nanocrystals can lead to radically-branched nanowires while the assembly of octahedral nanocrystals leads to zigzag nanowires. The synthesized nanowires exhibit strong position dependent quantum confinement, which occurs at the side arms and high faceted edges of the nanowires. Those novel structures give rise to the appealing optical properties of the nanowires, with strong photoluminescence in the near infrared region.
Abstract. PbS nanocrystals was synthesized by a heterogeneous reaction of hydrogen sulfide gas and lead nitrate solution containing EDTA in ethanol. The influenceof initial molar concentration ratio of EDTA/Pb(NO3)2 (CEDTA/CPb(NO3)2), volume ratio of ethanol/water (Vethanol/VH2O), pH value and flux of H2S on the particle size of PbS were investigated. The structure, morphology, particle size, and particle size distribution ranges of PbS were characterized by XRD, FE-SEM, and laser particle size analyzer, respectively. Increasing CEDTA/CPb(NO3)2, Vethanol/VH2O, and pH value, as well as decreasing the flux of H2S decrease the particle size of PbS. PbS nanocrystals have an average particle size of 69 nm, a narrow size distribution, and a quasi-spherical shape when CEDTA/CPb(NO3)2 is 1, Vethanol/VH2O is 1, pH is 3.5, and the flux of H2S is 20 ml/min.
PbS nanocrystal synthesis in Pb-containing silicate …
We report an efficient synthesis of copper indium sulfide nanocrystals with strong photoluminescence in the visible to near-infrared. This method can produce gram quantities of material with a chemical yield in excess of 90% with minimal solvent waste. The overgrowth of as-prepared nanocrystals with a few monolayers of CdS or ZnS increases the photoluminescence quantum efficiency to > 80%. On the basis of time-resolved spectroscopic studies of core/shell particles, we conclude that the emission is due to an optical transition that couples a quantized electron state to a localized hole state, which is most likely associated with an internal defect.
We show that nanocrystals (NCs) with well-established synthetic protocols for high shape and size monodispersity can be used as templates to independently control the NC composition through successive cation exchange reactions. Chemical transformations like cation exchange reactions overcome a limitation in traditional colloidal synthesis, where the NC shape often reflects the inherent symmetry of the underlying lattice. Specifically we show that full or partial interconversion between wurtzite CdS, chalcocite Cu2S, and rock salt PbS NCs can occur while preserving anisotropic shapes unique to the as-synthesized materials. The exchange reactions are driven by disparate solubilites between the two cations by using ligands that preferentially coordinate to either monovalent or divalent transition metals. Starting with CdS, highly anisotropic PbS nanorods are created, which serve as an important material for studying strong two-dimensional quantum confinement, as well as for optoelectronic applications. In NC heterostructures containing segments of different materials, the exchange reaction can be made highly selective for just one of the components of the heterostructure. Thus, through precise control over ion insertion and removal, we can obtain interesting CdS|PbS heterostructure nanorods, where the spatial arrangement of materials is controlled through an intermediate exchange reaction.
Synthesis and characterization of PbS nanocrystals in ..
Synthesis of monodispersed Au–PbS hybrid nanocrystals via …
Synthesis of PbS Nanorods and Other Ionic Nanocrystals of Complex Morphology by Sequential Cation Exchange Reactions.
Synthesis of PbS nanocrystals from sulfur-amine …
06/06/2011 · Different sizes of PbS nanocrystals (NCs) were synthesized from sulfur–amine solution
Photoluminescence quantum yield of PbS nanocrystals …
2014 China Functional Materials Technology and Industry Forum: Synthesis of PbS Nanocrystals by Heterogeneous Reaction
yield of PbS nanocrystals in colloidal suspensions ..
The sizes and morphologies of the cubic PbS nanocrystalscan be modified by controlling the concentration of ions, the volumeratio of water to surfactant and the reaction temperature.
Nonlinear optical properties of PbS nanocrystals …
AB - Lead sulfide nanocrystals were grown in toluene solutions of poly(2-methoxy-5-(2′-ethyl-hexyloxy)-p-phenylene vinylene, polyethylene, poly(1-butene), poly(1-decene), and polystyrene. The PbS nanocrystal diameter was controlled by the polymer used for synthesis and ranged from 4 to 9 nm. Strong nonlinear absorption was observed in open aperture Z-scan measurements of solutions containing the synthesized nanocomposites. The best fit to the experimental data gave high values for βeff in the range of 100-200 cm/GW. The nonlinear absorption of these polymer grown nanocrystals was not observed in nanocrystals grown in polyvinyl alcohol or with oleic acid capping. These differences in nonlinear optical absorption were due to surface chemistry, as the polymer synthesized nanocrystals were free of strongly bonding groups such as surfactant capping or hydroxyl groups. The βeff values in these materials also showed no dependence on nanocrystal size.
Nonlinear optical properties of PbS nanocrystals grown in ..
Cecile Reynaud has her expertise in the synthesis and chemical physics of nanomaterials. Her work has mainly dealt with silicon nanocrystals and aligned carbon nanotubes. She was for 15 years at the head of the Laboratory of Nanometric Assemblies (LEDNA) in the fundamental research division of Saclay CEA center. The LEDNA group follows the "bottom-up" approach of nanosciences. It develops its own synthesis methods and obtains nanostructured materials with well-controlled characteristics. The applications are relevant for energy, health, environmental issues and the development of composite materials. The group also develop the up-scaling of its processes to allow their industrial transfer.
Synthesis of colloidal CdTe nanocrystals - Duration: 1:22
A one-step colloidal process was adopted to prepare face-centered-cubic PbS nanocrystals with different shapes such as octahedral, starlike, cubic, truncated octahedral, and truncated cubic. The features of this approach avoid the presynthesis of any organometallic precursor and the injection of a toxic phosphine agent. A layered intermediate compound (lead thiolate) forms in the initial stage of the reaction, which effectively acts as the precursor to decompose into the PbS nanocrystals. The size and shape of the PbS nanocrystals can be easily controlled by varying the reaction time, the reactant concentrations, the reaction temperatures, and the amount of surfactants. In particular, additional surfactants other than dodecanethiol, such as oleylamine, oleic acid, and octadecene, play an important role in the shape control of the products. The possible formation mechanism for the PbS nanocrystals with various shapes is presented on the basis of the different growth directions of the nanocrystals with the assistance of the different surfactants. This method provides a facile, low-cost, highly reproducible process for the synthesis of PbS nanocrystals that may have potential applications in the fabrication of photovoltaic devices and photodetectors.
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