Primary Amine-Functionalized Chiral Covalent Organic Framework Enables High-Efficiency Asymmetric Catalysis in Water.

Aqueous asymmetric catalysis using chiral covalent organic frameworks (COFs) represents a significant advancement but remains to be explored. Herein, we present the first example of aqueous asymmetric catalysis catalyzed by a primary amine-tagged chiral -ADP-TAPB COF. The -ADP-TAPB COF was synthesized by the postsynthetic deprotection of -ADP-TAPB-Boc bearing a protective tert-butoxycarbonyl (Boc) group, which was constructed by a Schiff-base reaction between an alanine-derived chiral building block (-ADP-Boc) and 1,3,5-tris(4-aminophenyl)benzene (TAPB).

Construction of a Defective Chiral Covalent Organic Framework for Fluorescence Recognition of Amino Acids.

The design and synthesis of chiral covalent organic frameworks (COFs) with controlled defect sites are highly desirable but still remain largely unexplored. Herein, we report the synthesis of a defective chiral HD-TAPB-DMTP COF by modifying the chiral monomer helicid (HD) into the framework of an achiral imine-linked TAPB-DMTP COF using a chiral monomer exchange strategy. Upon the introduction of the chiral HD unit, the obtained defective chiral HD-TAPB-DMTP COF not only displays excellent crystallinity, large specific surface area (up to 2338 m/g) and rich accessible chiral functional sites but also exhibits fluorescence emission, rendering it a good candidate for discrimination of amino acids.

Hydrothermal and anion exchange synthesis of Mn(V)-doped Ba(PO)Cl nano-apatite toward NIR-II temperature sensing.

The second near-infrared window (NIR-II) in the range of 1000-1400 nm is ideal for imaging and sensing through reduced scattering, absorption, and autofluorescence. However, there are only a few nanophosphor systems with emission in the NIR-II region. Here, we report on Mn-doped Ba(PO)Cl nanoparticles (BPCl:Mn NPs, < 50 nm) toward NIR-II temperature sensing.

Preparation and characterization of functionalized chitosan/polyvinyl alcohol composite films incorporated with cinnamon essential oil as an active packaging material.

In this study, amphiphilic chitosan (NPCS-CA) was synthesized by grafting quaternary phosphonium salt and cholic acid onto the chain of chitosan, aiming to develop an active edible film based on NPCS-CA and polyvinyl alcohol (PVA) incorporated with cinnamon essential oil (CEO) by the casting method. The chemical structure of the chitosan derivative was characterized by FT-IR, H NMR and XRD. Through the characterization of FT-IR, TGA, mechanical and barrier properties of the composite films, the optimal proportion of NPCS-CA/PVA was determined as 5/5.

Preparation and wide band emission characteristics of Eu/Eu co-doped BaPO phosphors.

A series of phosphors BaPO:Eu ( = 0-0.1) were synthesized in a CO reduction atmosphere at a relatively low temperature (1113 K) by the solid-phase method. Crystallization and optical properties were investigated by using powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and fluorescence spectrophotometry (PL/PLE), respectively.

Site Occupancy Studies and Luminescence Properties of Emission Tunable Phosphors CaLa(PO):Re (Re = Ce, Eu).

The structure, site occupancies, and photoluminescence (PL) properties of Ce- or Eu-doped CaLa(PO) phosphors were investigated in this work. The powder X-ray diffraction (XRD) data and Rietveld refinement results showed that the phosphors are pure phases. The vacuum ultraviolet-ultraviolet-visible (VUV-UV-vis) spectra and decay curves confirmed that the Ce and Eu ions in CaLa(PO) occupied two crystal sites.

Optical properties of Eu /Eu mixed valence phosphor Ca SiO F :Eu /Eu.

The Eu /Eu mixed valence phosphor Ca SiO F :Eu /Eu was prepared using a solid-state reaction synthesis method in a CO atmosphere, and the optical properties were investigated. The spectroscopic properties revealed that Ca ions were occupied by both Eu and Eu ions in Ca SiO F , and both ions were able to generate their characteristic emissions. A broad 5d → 4f Eu band at ~470 nm and narrow 4f → 4f Eu peaks upon excitation with n-UV light were observed.

Luminescence properties of Ce in orthosilicate oxyapatite NaY (SiO ) O.

Ce -doped orthosilicate oxyapatite NaY (SiO ) O phosphors NaY (SiO ) O :xCe were prepared by a conventional high-temperature solid-state reaction method, and their spectroscopic characteristics were systematically investigated. The occupancies of Ce ions at two different sites (Wyckoff 6 h and 4f sites) in NaY (SiO ) O were determined. The influence of doping concentration on the emission intensity of Ce was investigated and the critical distance Rc was estimated in terms of the concentration quenching data.

Yellow-white emission of Ce3+ and Eu2+ doped Li2SrSiO4 under low-voltage electron-beam excitation.

Ce(3+) and Eu(2+) activated Li(2)SrSiO(4) phosphors were prepared using a high temperature solid-state reaction technique. The VUV-UV-vis photoluminescence (PL) of Ce(3+)-doped phosphors Li(2-x)Sr(1-x)Ce(x)SiO(4) and Eu(2+)-doped phosphors Li(2)Sr(1-x)Eu(x)SiO(4), the low-voltage cathodoluminescence (CL) of Eu(2+)-doped phosphor Li(2)Sr(0.991-x)Eu(0.

Bright green-emitting, energy transfer and quantum cutting of Ba3Ln(PO4)3: Tb3+ (Ln = La, Gd) under VUV-UV excitation.

Tb3+ doped Ba3Gd(PO4)3 and Ba3La(PO4)3 phosphors were synthesized using the traditional high temperature solid state reaction method. The excitation, emission, and decay spectra were measured at room temperature. Efficient energy transfer (ET) from Gd3+ to Tb3+ exists in Tb3+ doped Ba3Gd(PO4)3, and the ET efficiency increases with the increase of Tb3+ concentration.

The quantum cutting of Tb(3+) in Ca(6)Ln(2)Na(2)(PO(4))(6)F(2) (Ln = Gd, La) under VUV-UV excitation: with and without Gd(3+).

The VUV-vis spectroscopic properties of Tb(3+) activated fluoro-apatite phosphors Ca(6)Ln(2-x)Tb(x)Na(2)(PO(4))(6)F(2) (Ln = Gd, La) were studied. The results show that phosphors Ca(6)Gd(2-x)Tb(x)Na(2)(PO(4))(6)F(2) with Gd(3+) ions as sensitizers have intense absorption in the VUV range. The emission color of both phosphors can be tuned from blue to green by changing the doping concentration of Tb(3+) under 172 nm excitation.

Ca6Gd1.5Tb0.5Na2(PO4)6F2--an intense green-emitting phosphor under vacuum ultraviolet and low-voltage cathode ray excitation.

The investigations on photoluminescence and cathodoluminescence reveal that phosphor Ca(6)Gd(1.5)Tb(0.5)Na(2)(PO(4))(6)F(2) (CGPF-Tb) shows an intense green emission.