Stable color-tunable Ca3Y(GaO)3(BO3)4:Bi3+/Tb3+/Eu3+ phosphors for application in n-UV-pumped wLEDs.

For further development of light sources, white light-emitting diodes (wLEDs) have attracted widespread attention as promising next-generation light sources fabricated via the combination of phosphors and LED chips. However, latent defects, such as chemical/thermal instability, low color rendering index (CRI) and high correlated color temperature (CCT), of current mainstream wLEDs seriously hinder their further large-scale implementation. Herein, in order to overcome these limitations, single-phase color-tunable gaudefroyite (Ca3Y(GaO)3(BO3)4 (CYGB)) tridoped with Bi3+/Tb3+/Eu3+ ions was synthesized for the first time and detailed characterisation was performed via high-temperature solid-state reaction and structural/spectral analyses, respectively. Radius difference percentage calculations and Rietveld refinements indicate that dopants occupy both Y3+ and Ca2+ sites but preferably the Y3+ site over the Ca2+ site due to the same valence state. Through subtly regulating the (co)doping contents and skillfully utilizing the energy transfer (ET) strategy from the allowed transition of blue light-emitting Bi to the forbidden transition of green/red light-emitting Tb/Eu, the color hue (including white light) of highly efficient PL can be easily tuned according to the need. Meanwhile, composition/content-optimized white light-emitting CYGB:2%Bi/10%Tb/12%Eu also shows splendid chemical/thermal stability. Finally, as a proof-of-concept experiment, the CYGB:2%Bi/10%Tb/12%Eu phosphor-converted wLED (pc-wLED) was fabricated and encapsulated via the up-to-date remote 'capping' method, which imparted attractive performances. Altogether, the stable CYGB:Bi/Tb/Eu phosphor is a promising candidate for application in lighting/display fields.

Structure and luminescence properties of single-component melilite Sr2MgSi2O7:Ce/Tb/Sm for n-UV wLEDs.

Phosphor-converted white light-emitting diodes (pc-wLEDs) have attracted attention in the field of solid-state lighting. Selection and study of suitable single-phase phosphor and packaging modes are currently the main research hotspots. Herein, color-tunable photoluminescence (PL) and thermally stable tri-doped Melitite Sr2MgSi2O7:Ce/Tb/Sm are systematically studied via structural and static/dynamic spectral analyses. All dopants could only be accommodated in the Sr site due to similar ionic radii. Previous studies have concluded that green and red PL could be obtained from singly doped Tb and Sm phosphors with excellent reproduction, and color tunable PL can be achieved from Ce/Tb co-doped phosphors. The forbidden 4f-4f transitions of Tb/Sm cause low efficiency and Ce/Tb co-doping cannot achieve white light emissions. Alternatively, co-doping allowed 5d-4f transition sensitizer with emissions in the UV-blue region (i.e., Ce), color-tunable PL (including the white light); high efficiency of Sr2MgSi2O7:Ce/Tb/Sm could be achieved via energy transfer (ET) from Ce → Tb → Sm. The impossibly direct ET from Ce → Sm is associated with the side metal-metal charge transfer (MMCT) effect. Due to chemically nonequivalent substitutions, two positive Ce(Tb,Sm)Sr and one negative V''Sr were created to maintain the whole charge balance. To reduce the defects and allow more dopants to enter into the Sr site, Na+ was added as a charge balancer to enhance PL efficiency. Furthermore, an alkaline-earth-metal-ions blending strategy via partial replacement of Sr with Ba was investigated to regulate PL owing to the change in crystal field splitting. PL blue-shifted by Ba-co-doping, which could increase the degree of overlapping and enhance ET efficiency. As a proof-of-concept experiment, the pc-wLED fabricated via a combination of the optimal Sr(Ba)2MgSi2O7:Ce/Tb/Sm/Na and an n-UV LED chip based on a remote 'capping' packaging mode shows excellent performances, indicating its strong potential application in the field of solid-state lighting.

Structure-activity relationship (SAR) studies of synthetic glycogen synthase kinase-3ß inhibitors: A critical review.

Glycogen Synthase Kinase-3 (GSK-3) is a constitutively dynamic, omnipresent serine/threonine protein kinase regularly called as a "multitasking kinase" due to its pliable function in diverse signaling pathways. It exists in two isoforms i.e., GSK-3α and GSK-3ß. Inhibition of GSK-3 may be useful in curing various diseases such as Alzheimer's disease, type II diabetes, mood disorders, cancers, chronic inflammatory agents, stroke, bipolar disorders and so on, but the approach poses significant challenges. Lithium was the first GSK-3ß inhibitor to be used for therapeutic outcome and has been effectively used for many years. In recent years, a large number of structurally diverse potent GSK-3ß inhibitors are reported. The present review focuses on the recent developments in the area of medicinal chemistry to explore the diverse chemical structures of potent GSK-3ß inhibitors and also describes its structure-activity relationships (SAR) and molecular binding interactions of favorable applicability in various diseases.

Mesoporous nanoparticles Gd2O3@mSiO2/ZnGa2O4:Cr3+,Bi3+ as multifunctional probes for bioimaging.

Red/near infrared (NIR) persistent luminescent nanoparticles (PLNPs) hold great potential as a new generation of probes for the detection and imaging of biomolecules. Based upon the consideration that a single nanoprobe could serve multiple purposes, the development of a multimodal nanoprobe that combined the properties of rechargeable persistent emitting luminescence, magnetic resonance imaging (MRI) and drug delivery has attracted our attention as a promising prospect in the field of nanotechnology directed toward biomedical applications. Herein, Gd2O3@mSiO2/ZnGa2O4:Cr3+,Bi3+ (ZGOCB) mesoporous nanoparticles that exhibit enhancement of red (∼695 nm) persistent luminescence (∼18 d) properties were synthesized by using mesoporous silica nanospheres both as morphology-controlling templates and vessels. Being composed of hybrid shell/core architecture and through surface functionalization, Gd2O3@mSiO2/ZGOCB mesoporous nanoparticles possess the capacity for in vivo and in situ real-time monitoring, targeting tumors and drug delivery. Simultaneously, Gd2O3@mSiO2/ZGOCB exhibits a prominent longitudinal relaxivity, indicating that these nanoparticles could also be used as magnetic resonance imaging agents. We believe that this rechargeable red persistent luminescence and MRI-based core/shell structure of the multimodal nanoprobe offers a promising nano-platform for both diagnostics and therapeutics of reactive species in living cells or in vivo.