Search

A collection of GdF 3 core-shell structured (CSS) phosphors were synthesized by hydrothermal method. The as-prepared (AP) phosphors were coated with SiO 2 layers to avoid aggregation and sintering during thermal annealing at 800 °C, after which the SiO 2 layers were etched off and the annealed phosphors became highly dispersible. The annealed CSS phosphor a GdF 3 :Eu 3+ @GdF 3 :Ce 3+ ,Dy 3+ shows excellent multicolor luminescence performance with the aid of dual-channel excitation and energy migration (EM) procedure of Gd 3+ ions. By inserting pyromellitic acid (PMA) organic ligands into the interfaces between annealed core and AP shell layer regions, the so-called antenna effect of organic ligands of PMA forms a new excitation channel, which makes the CSS phosphor a GdF 3 :Eu 3+ @PMA@GdF 3 :Ce 3+ ,Dy 3+ exhibit significantly enhanced multicolor luminescence via multi-channel excitation and EM process. The prepared CSS phosphors in this work are excellent candidates for applications in solid-state lighting. [ABSTRACT FROM AUTHOR]

A collection of β-NaGdF 4 core-shell structured (CSS) phosphors were synthesized by Hydrothermal method, both the core and shell regions of which are hexagonal phase. The as-prepared core particles have the microrods shape, and the shell was formed upon them via epitaxial growth. After thermal annealing treatment of the core phosphors at 600 °C, the corresponding core-shell structure can still be effectively constructed. The photoluminescence (PL) spectra reveal that the CSS phosphors grown upon the as-prepared core particles own superior luminescent properties; for the annealed CSS phosphor β-NaGdF 4 :Eu 3+ @β-NaGdF 4 , a large amount of defects existed on the interfaces between the core and shell regions severely quenched the emission intensity of the core region; on co-doped Ce 3+ and Dy 3+ ions into the null shell layer of the annealed CSS phosphor, the obtained phosphor shows excellent multicolor luminescence performance due to quenching phenomenon effectively suppressed by dual-channel excitation and energy migration procedure of Gd 3+ ions. The prepared CSS phosphors in this work are excellent candidates for applications in solid-state lighting. [ABSTRACT FROM AUTHOR]

Abstract: In this work, undoped YVO4 nanocrystals (10–15nm in size) were first synthesized by a solvothermal method, and they were ion exchanged for Eu3+ ions to form YVO4:Eu3+ nanocrystals, which were then used to prepare YVO4:Eu3+–thenoyltrifluoroacetone hybrid nanostructures. As expected, the ion exchanged YVO4:Eu3+ nanocrystals exhibited the characteristic V–O charge transfer excitation band. Much stronger luminescence has been observed in the YVO4:Eu3+–thenoyltrifluoroacetone hybrid nanostructures due to energy transfer from thenoyltrifluoroacetone ligands to Eu3+ ions. The dependence of luminescence of the YVO4:Eu3+–thenoyltrifluoroacetone hybrid nanostructures on the Eu3+ concentration and amount of thenoyltrifluoroacetone ligands was investigated in detail, and optimal preparation conditions were determined. Their UV–Vis absorption spectra and BET specific surface area were measured. X-ray diffraction technique, transmission electron microscopy, and Fourier transform infrared spectroscopy were used to study their microstructural characteristics. [Copyright &y& Elsevier]

A novel and convenient approach to the synthesis of polysubstituted isochromanones is described. Irradiation of 2-formyl phenylalkeno-derivatives with UV light in benzene solution afforded the corresponding products in up to 98% yield. The possible reaction mechanism is proposed and further supported by the isotopic experiments. [ABSTRACT FROM AUTHOR]

Electrical manipulation of charged ions in electrolyte-gated transistors is crucial for enhancing the electric-double-layer (EDL) gating effect, thereby improving their sensing abilities. Here, indium-zinc-oxide (IZO) based thin-film-transistors (TFTs) are fabricated on flexible plastic substrate. Acid doped chitosan-based biopolymer electrolyte is used as the gate dielectric, exhibiting an extremely high EDL capacitance. By regulating the dynamic EDL charging process with special gate potential profiles, the EDL gating effect of the chitosan-gated TFT is enhanced, and then resulting in higher pH sensitivities. An extremely high sensitivity of ∼57.8 mV/pH close to Nernst limit is achieved when the gate bias of the TFT sensor sweeps at a rate of 10 mV/s. Additionally, an enhanced sensitivity of 2630% in terms of current variation with pH range from 11 to 3 is realized when the device is operated in the ion depletion mode with a negative gate bias of −0.7 V. Robust ionic modulation is demonstrated in such chitosan-gated sensors. Efficiently driving the charged ions in the chitosan-gated IZO-TFT provides a new route for ultrasensitive, low voltage, and low-cost biochemical sensing technologies. [ABSTRACT FROM AUTHOR]

Highly luminescent GdVO 4 :Eu3+/carbon dots (CDs) nanocomposite was synthesized by hydrothermal deposition method for the first time. With the use of dialyzed CDs solution as precursor, the synthetized composite shows negligible emission intensity of CDs. On replacing the dialyzed CDs solution with the crude one, highly luminescent composite can be obtained successfully. Based on the analysis of XPS and FT-IR spectra, one can deduce that the existence of a large amount of citrate anions, ethylenediamine cations and polymer-like CDs in the crude CDs solution make it as nutrient solution of CDs, which can not only facilitate growth of CDs on the surface of GVE, but also greatly prevent nitrogen atoms from falling off the particles during the hydrothermal deposition process. For the dialyzed CDs solution, due to the ions and polymer-like CDs being thoroughly dialyzed, the coated CDs are fragile during hydrothermal deposition process. Besides, the effects of different dosages of ammonia on emission intensities of the two composites are studied. Based on the designable patterns for security application, one can think that the highly luminescent composite is one of the most promising candidates in the anti-counterfeiting field. • Highly luminescent GdVO 4 :Eu3+/CDs nanocomposite was synthesized by hydrothermal deposition method. • The hydrothermal deposition method was used to synthesize highly luminescent composite related to CDs for the first time. • The crude CDs solution was used as precursor, which acts as the nutrient solution of N-CDs. • The nutrient solution can not only facilitate growth of CDs on the surface of GVE, but also greatly prevents nitrogen atoms from falling off the particles during hydrothermal deposition process. • The prepared composite is one of the most promising candidates in the anti-counterfeiting field. [ABSTRACT FROM AUTHOR]

The optimized conditions allow the synthesis of 3-bromoquinoline derivatives in good yields from gem-dibromovinylanilines and tert-butylisocyanide. [ABSTRACT FROM AUTHOR]

Irradiation of terminal aromatic γ,δ-epoxy ketones (I) leads to Norrish type II cyclization-semi-pinacol rearrangement cascade giving rise to the formation of benzocyclobutanones (II) containing a full-carbon quaternary center. [ABSTRACT FROM AUTHOR]