A dual-mode fluorescent probe based on carbon dots for detecting solution polarity.

Fluorescent probes always attract huge attention. In particular, carbon dots, due to their unique biocompatibility and variable fluorescence characteristics, can be used in multiple fields and were fulled of expectation by researchers. Since the advent of the dual-mode carbon dots probe, which greatly improved the accuracy of quantitative detection, there are higher hopes for dual-mode carbon dots probes. Herein, we have successfully developed a new dual-mode fluorescent carbon dots probe based on 1,10-phenanthroline (Ph-CDs). Ph-CDs detect the object to be measured based on both down-conversion luminescence and up-conversion luminescence at the same time, different from the reported dual-mode fluorescent probes which are based on the wavelength and intensity changes in down-conversion luminescence. As-prepared Ph-CDs have good linear relationships with the polarity of solvents in down-conversion luminescence (R2 = 0.9909) and up-conversion luminescence (R2 = 0.9374), respectively. Hence, Ph-CDs provide a new in-depth insight into the design of fluorescent probes with dual-mode detection and they can give more accurate, reliable and convenient detection results.

Inclusion complex of 20(S)-protopanaxatriol with modified ß-cyclodextrin: Characterization, solubility, and interaction with bovine serum albumin.

20(S)-protopanaxatriol (PPT) is one of the ginsenosides isolated from Panax ginseng which have many pharmaceutical activities. However, the poor water solubility of PPT restrict its applications. Herein, a novel bridged-bis-[6-(3,3'-(ethylenedioxy) bis (propylamine))-6-deoxy-ß-cyclodextrin] (EDBA-bis-ß-CD) was designed and synthesized, and the inclusion complex (IC) of EDBA-bis-ß-CD with PPT was successfully prepared in the solid state, and characterized by UV, 1H NMR, 2D ROESY, FT-IR, XRD and SEM and molecular modelling methods. The continuous variation method analysis indicated that the stoichiometry of the IC was 1:1. UV-vis spectral analysis demonstrated the binding constant Ks was 995.94 M-1, and the solubility study showed that the solubility of PPT improved 290 times. The interaction of the IC with bovine serum albumin (BSA) was investigated via fluorescence spectroscopy. The results indicated that fluorescence quenching of BSA by IC was static quenching. Thermodynamic studies showed that van der Waals forces and hydrogen bonding play significant roles in interaction. The esterase-like activity of BSA in the presence of IC showed that it reduce the esterase activity of BSA in a competitive manner. Furthermore, molecular docking and molecular dynamics simulations for EDBA-bis-ß-CD/PPT and BSA/IC systems were generated to provide information on the stability and the forces in the binding.

Correction: Red-emitting phosphors APF6:Mn4+ (A = Cs+, Rb+, K+): synthesis, luminescence properties and application in solid-state lighting.

Correction for 'Red-emitting phosphors APF6:Mn4+ (A = Cs+, Rb+, K+): synthesis, luminescence properties and application in solid-state lighting' by Yu Chen et al., Dalton Trans., 2019, 48, 10901-10906.

Red-emitting phosphors APF6:Mn4+ (A = Cs+, Rb+, K+): synthesis, luminescence properties and application in solid-state lighting.

A series of APF6:Mn4+ (A = Cs+, Rb+, K+) phosphors with single phases were obtained via a simple ion exchange method. These phosphors can exhibit red emission with a broad excitation band in the blue region. The optimized concentration of Mn4+ in APF6:Mn4+ was determined. The Racah parameters B and C of Mn4+ in APF6:Mn4+ were also calculated. The results indicate that Mn4+ in CsPF6:Mn4+ experiences the weakest crystal field among APF6:Mn4+. The phosphor CsPF6:Mn4+ prepared with the HPF6/K2MnF6 molar ratio of 10 : 1 has the strongest red emission and the highest external quantum efficiency of 50.4% among the samples. It has high thermal quenching resistance and its emission intensity at 160 °C is about 1.1 times higher than that at room temperature. This sample also can remarkably improve the color rendering index and decrease the colour rendering index of white light-emitting diodes (w-LEDs). Hence, CsPF6:Mn4+ could be used as a red-emitting phosphor for warm w-LEDs.

Novel red-emitting phosphors A2HfF6:Mn4+ (A = Rb+, Cs+) for solid-state lighting.

New red-emitting phosphors A2HfF6:Mn4+ (A = Rb+, Cs+) with a single phase have been successfully synthesized via a simple ion exchange method, and their structures and luminescence properties were investigated. It was found that Mn4+ ions in Rb2HfF6 and Cs2HfF6 who share wide band gaps can possess broad excitation bands in the blue regions and intense red emission with internal quantum yields of 0.556 and 0.652, respectively. Meanwhile, these red phosphors exhibit high chemical and thermal stabilities. A series of LED devices with a tunable color rendering index and color temperature were fabricated with these samples which can remarkably optimize the optical performances of white light-emitting diodes (w-LEDs). These results indicate that A2HfF6:Mn4+ phosphors can be promising red phosphors in w-LEDs.

Luminescence behaviour of Mn(4+) ions in seven coordination environments of K3ZrF7.

A single-phased Mn(4+) doped fluorozirconate red phosphor, K3ZrF7:Mn(4+), has been successfully synthesized. Its structure, morphology, composition and optical properties were investigated by X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, atomic absorption spectroscopy, diffuse reflectance spectroscopy, photoluminescence spectroscopy and by using luminescence decay curves. It was found that Mn(4+) ions only coordinating with seven F(-) anions in a K3ZrF7 crystal field can possess intense red emission under blue light illumination. Mixing the obtained K3ZrF7:Mn(4+) red phosphor with commercial Y3Al5O12:Ce(3+) and coating the mixture on a blue-GaN chip, obvious warm white light with a low correlated color temperature (2970 K) and a high color rendering index (Ra = 91.4 and R9 = 72) were achieved from white light-emitting diode devices.