Synthesis of mesoporous materials has become more and more important due to their wide application. Nowadays, there are two main ideas in their preparation. One is focused on the templating method. The other is based on metal-organic frameworks (MOFs) constructed from molecular building blocks. Herein, we exploit a new idea for their facile and general synthesis, namely, using "artificial atoms" (monodisperse nanoparticles) as uniform building blocks to construct ordered mesoporous materials. Mesoporous Ag, Ag2S, and Ag2Se have been obtained to demonstrate this concept. On the other hand, we also describe a facile method to prepare the "building blocks". Ag nanoparticles were obtained by direct thermal decomposition of AgNO3 in octadecylamine, and Ag2S/Ag2Se nanoparticles were synthesized by reaction between sulfur or selenium powder and Ag nanoparticles formed in situ. This approach for Ag, Ag2S, and Ag2Se nanoparticles is efficient, economical, and easy to scale up in industrial production.
A near-neutral pH near-infrared (NIR) fluorescent probe utilizing a fluorophore-spacer- receptor molecular framework that can modulate the fluorescence emission intensity through a fast photoinduced electron-transfer process was developed. Our strategy was to choose tricarbocyanine (Cy), a NIR fluorescent dye with high extinction coefficients, as a fluorophore, and 4'-(aminomethylphenyl)-2,2':6',2''-terpyridine (Tpy) as a receptor. The pH titration indicated that Tpy-Cy can monitor the minor physiological pH fluctuations with a pK(a) of approximately 7.10 near physiological pH, which is valuable for intracellular pH researches. The probe responds linearly and rapidly to minor pH fluctuations within the range of 6.70-7.90 and exhibits strong dependence on pH changes. As expected, the real-time imaging of cellular pH and the detection of pH in situ was achieved successfully in living HepG2 and HL-7702 cells by this probe. It is shown that the probe effectively avoids the influence of autofluorescence and native cellular species in biological systems and meanwhile exhibits high sensitivity, good photostability, and excellent cell membrane permeability.
Systematically shape-controlled synthesis of inorganic nanocrystals has attracted increasing attention recently for both fundamental and technological interest. The shape evolution of CdSe nanocrystals with wurtzite structure in a unified method has been previously well studied, while the study on shape evolution of CdSe nanocrystals with zinc blende structure still remains challenging. Here, we demonstrate a systematic shape variation of zinc blende CdSe nanocrystals in a modified organometallic approach, in which distinct shapes of cube-shaped, sphere-shaped, tetrahedron-shaped, and branched CdSe nanocrystals with high yield and good uniformity are obtained. The crucial factor that influences the shape-controlled process is the reactive temperature. This wide variation of shapes provides important information about the growth of CdSe nanocrystals, and it can also help in the shape-controlled synthesis of other nanocrystals that are bound with uniform crystal planes.
In this paper, single-crystal metallic nanoplatelets, such as cobalt, nickel, copper, and silver, have been successfully
synthesized based on a facile hydrothermal/solvothermal synthetic method. The as-prepared cobalt nanoplatelets had the {001}
crystal facets as the basal plane, while the exposed nanoplatelet planes were assigned to be {111} crystal facets of the face-centered
cubic nickel, copper, and silver crystals. Owing to the interesting combination of novel nanostructures, remarkable magnetic anisotropy
was found on the cobalt and nickel nanoplatelets. The anisotropic copper and silver nanoplatelets exhibited a distinct surface plasmon
resonance effect. These metallic nanoplatelets could be expected to bring new opportunities in the vast research areas of and application
in magnetic storage devices, catalysts, and surface-enhanced Raman scattering.
The first near-infrared fluorescent probe was developed toward Cu(2+). Based on the photo-induced electron transfer (PET) mechanism, the probe exhibited weak fluorescence. Upon the addition of Cu(2+), it fluoresced strongly. The probe offered this unique capability, and was successfully applied to living cells, tissues and in vivo to visualize Cu(2+).
A self-powered ultraviolet (UV) photodetector (PD) based on p-NiO and n-ZnO was fabricated using low-temperature sputtering technique on indium doped tin oxide (ITO) coated plastic polyethylene terephthalate (PET) substrates. The p-n heterojunction showed very fast temporal photoresponse with excellent quantum efficiency of over 63% under UV illumination at an applied reverse bias of 1.2 V. The engineered ultrathin Ti/Au top metal contacts and UV transparent PET/ITO substrates allowed the PDs to be illuminated through either front or back side. Morphology, structural, chemical and optical properties of sputtered NiO and ZnO films were also investigated.
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