Multiple Charge Transfer Bands Induced Broad Excitation Eu3+ Red Emission in a Vanadium Phosphate System for White Light-Emitting Diodes.

In order to realize broad excitation and narrow emission red light phosphor, a new vanadium phosphate Ba2BiV2PO11 was selected as a host for Eu3+. Monitored at 619 nm, a wide band from 240 to 400 nm could be observed and inferred to be composed of Eu3+-O2- and V5+-O2- charge transfer bands, which could make it match well with the UV chip and the blue chip along with the characteristic excitation of Eu3+ at 465 nm. Under 354 nm excitation, the sample could emit high color purity red light, and the thermal quenching integral intensity showed good thermal stability. The generation of charge transfer bands was investigated in detail combined with the luminescence properties and the structure of the matrix. Moreover, the as-prepared phosphor could improve the white light performance of blue chip-activated YAG:Ce3+ and n-UV chip-activated tricolor phosphors. All the results indicated the multiple application potential of Ba2BiV2PO11:Eu3+ for white light-emitting diodes.

MgGd4Si3O13:Ce3+, Mn2+: A Dual-Excitation Temperature Sensor.

A novel apatite-based phosphor MgGd4Si3O13[Mg2Gd8(SiO4)6O2]:Ce3+, Mn2+ was designed and successfully synthesized by a solid-state reaction. Based on the different luminescence properties under 298 and 340 nm excitations, its potential application as a dual-excitation luminescent ratiometric thermometer was studied in detail. Under the excitations of 298 and 340 nm, the fluorescent intensity ratio of Ce3+ and Mn2+ is linearly correlated in the temperature range of 303-473 K. The sensitivity showed an opposite trend with the increase of temperature, and the maximum value was 0.95% K-1. These results indicated that MgGd4Si3O13: Ce3+, Mn2+ can be used as an ideal dual-excitation luminescent ratiometric thermometer.

Novel narrow-band blue light-emitting phosphor of Eu2+-activated silicate used for WLEDs.

Owing to the broad application scope of phosphors for light and display, the development of narrow-band light-emitting phosphors has recently gained considerable research attention. In this study, a new type of narrow-band blue light-emitting phosphor, Rb2HfSi3O9:Eu2+, with a full width at half maximum (FWHM) of 64 nm was synthesized successfully. Upon the near visible ultraviolet (NUV) light excitation, the internal quantum efficiency of Rb2HfSi3O9:Eu2+ was 68%. It also exhibited good thermal stability, which was higher than that of a commercial blue phosphor (BaMgAl10O17:Eu2+) at 150 °C. The significant photoluminescence properties of Rb2HfSi3O9:Eu2+ were found to be related to its robust crystal structure, which was investigated in detail. The results indicate that Eu2+-activated Rb2HfSi3O9 is a promising phosphor for use in white light-emitting diodes.

A Highly Selective Turn-on and Reversible Fluorescent Chemosensor for Al3+ Detection Based on Novel Salicylidene Schiff Base-Terminated PEG in Pure Aqueous Solution.

The development of highly selective and sensitive chemosensors for Al3+ detection in pure aqueous solution is still a significant challenge. In this work, a novel water-soluble polymer PEGBAB based on salicylidene Schiff base has been designed and synthesized as a turn-on fluorescent chemosensor for the detection of Al3+ in 100% aqueous solution. PEGBAB exhibited high sensitivity and selectivity to Al3+ over other competitive metal ions with the detection limit as low as 4.05 × 10-9 M. PEGBAB displayed high selectivity to Al3+ in the pH range of 5⁻10. The fluorescence response of PEGBAB to Al3+ was reversible in the presence of ethylenediaminetetraacetic acid (EDTA). Based on the fluorescence response, an INHIBIT logic gate was constructed with Al3+ and EDTA as two inputs. Moreover, test strips based on PEGBAB were fabricated facilely for convenient on-site detection of Al3+.

A simple turn-on fluorescent chemosensor based on Schiff base-terminated water-soluble polymer for selective detection of Al3+ in 100% aqueous solution.

A simple water-soluble polymer PEGBHB based on polyethylene glycol bearing a Schiff base derivative moiety was successfully designed and synthesized. PEGBHB showed high selectivity and sensitivity towards Al3+ as a turn-on fluorescent chemosensor without influence by other competitive metal ions in 100% aqueous solution. The detection limit of PEGBHB for Al3+ was found to be 9.67 × 10-9 M. A 1:1 stoichiometry between PEGBHB and Al3+ has been confirmed by Job plot analysis. PEGBHB could detect Al3+ over a wide pH range from 4 to 10. The chemosensor was reversible by adding EDTA to the solution of PEGBHB-Al3+ complex. An INHIBIT molecular logic gate was constructed with the help of OFF-ON-OFF signal on alternate addition of Al3+ and EDTA to the chemosensor. Furthermore, test papers were fabricated facilely using PEGBHB for convenient and visual detection of practical Al3+.

A dual chemosensor for Cu2+ and Hg2+ based on a rhodamine-terminated water-soluble polymer in 100% aqueous solution.

A novel water-soluble polymer bearing a rhodamine receptor (PEGSRh) was synthesized as a dual chemosensor for the recognition of Cu2+ and Hg2+ in 100% aqueous solution. PEGSRh not only exhibited a sensitive colorimetric response towards Cu2+ and Hg2+ but also showed a selective turn-on fluorescence response towards Hg2+ over other metal ions. The binding stoichiometry for the complexation of PEGSRh with Cu2+ and Hg2+ was confirmed to be 1 : 1 by Job plot analysis. The low detection limits were found to be 5.92 × 10-7 M for Cu2+ and 2.85 × 10-6 M for Hg2+. The responses of PEGSRh to Cu2+ and Hg2+ were both stable over wide pH ranges. In addition, the fluorescence intensity changes of PEGSRh solution by the inputs of Hg2+, Cu2+ and EDTA have been used to construct a combinational logic gate. Again, an INHIBIT logic gate was also obtained by employing Cu2+ and EDTA as the chemical inputs and the absorbance signal as the output. Moreover, test papers were prepared facilely using PEGSRh for practical on-site detection of Cu2+ and Hg2+.

Bis(4-fluoro-benz-yl-κC)bis-(3-methyl-sulfanyl-1,2,4-thia-diazole-5-thiol-ato-κN,S)tin(IV).

The mononuclear title molecule, [Sn(C(7)H(6)F)(2)(C(3)H(3)N(2)S(3))(2)], has 2 symmetry. The Sn(IV) atom, located on a twofold rotation axis, is in a skew trapezoidal-bipyramidal geometry, with the basal plane defined by two S,N-chelating 3-methyl-sulfanyl-1,2,4-thia-diazole-5-thiol-ate ligands. The apical positions are occupied by the C atoms of two 4-fluoro-benzyl groups.

Bis(chloro-acetato-κO,O')bis-(2-fluoro-benzyl-κC)tin(IV).

In the title complex, [Sn(C(2)H(2)ClO(2))(2)(C(7)H(6)F)(2)], the Sn(IV) atom is located on a twofold rotation axis and forms a strongly distorted trans-octa-hedral geometry. The equatorial plane is defined by two chelating chloro-acetate ligands with asymmetrical Sn-O bond lengths, while the axial positions are occupied by the C atoms of two 2-fluoro-benzyl groups. In the crystal, infinite chains in the [010] direction are formed through inter-molecular Sn⋯O inter-actions [Sn⋯O separation = 3.682 (3) Å].