Luminescence Tuning and White‐Light Emission of Co‐doped Ln–Cd–Organic Frameworks

Four new three‐dimensional isostructural lanthanide–cadmium metal–organic frameworks (Ln–Cd MOFs), [LnCd₂(imdc)₂(Ac)(H₂O)₂]?H₂O (Ln=Pr ( 1 ), Eu ( 2 ), Gd ( 3 ), and Tb ( 4 ); H₃imdc=4,5‐imidazoledicarboxylic acid; Ac=acetate), have been synthesized under hydrothermal conditions and characterized by IR, elemental analyses, inductively coupled plasma (ICP) analysis, and X‐ray diffraction. Single‐crystal X‐ray diffraction shows that two Ln^III ions are surrounded by four Cd^II ions to form a heteronuclear building block. The blocks are further linked to form 3D Ln–Cd MOFs by the bridging imdc^3? ligand. Furthermore, the left‐ and right‐handed helices array alternatively in the lattice. Eu–Cd and Tb–Cd MOFs can emit characteristic red light with the Eu^III ion and green light with the Tb^III ion, respectively, while both Gd–Cd and Pr–Cd MOFs generate blue emission when they are excited. Different concentrations of Eu³⁺ and Tb³⁺ ions were co‐doped into Gd–Cd/Pr–Cd MOFs, and tunable luminescence from yellow to white was achieved. White‐light emission was obtained successfully by adjusting the excitation wavelength or the co‐doping ratio of the co‐doped Gd–Cd and Pr–Cd MOFs. These results show that the relative emission intensity of white light for Gd–Cd:Eu³⁺,Tb³⁺ MOFs is stronger than that of Pr–Cd:Eu³⁺,Tb³⁺ MOFs, which implies that the Gd complex is a better matrix than the Pr complex to obtain white‐light emission materials.     

Novel bifunctional lanthanide‐centered nanophosphors for latent fingerprint detection and anti‐counterfeiting applications

Production of hybrid organic/inorganic complexes such as lanthanide phosphors in the nanodomain for human fingerprint visualization and anti‐counterfeiting ink under biocompatible UVA and blue light has not yet been studied that thoroughly. This paper presents the preparation of novel, bifunctional, green and red nanophosphors based on Eu³⁺ and Tb³⁺ complexes with quinolinone ligand (H₂L). They have been prepared and characterized for latent fingerprint detection and anti‐counterfeiting ink applications. The analytical data confirm that the ligand acts in a monoanionic bidentate manner through OO donor sites, forming mononuclear complexes, formulated as [Ln(HL)₃(C₂H₅OH)₃] (Ln = Eu³⁺ or Tb³⁺; L = 1‐ethyl‐4‐hydroxy‐3‐(nitroacetyl)quinolin‐2‐(1H)‐one). The Eu³⁺ and Tb³⁺ complexes have nanospherical morphologies with average particle sizes of 17 and 5 nm, respectively. Pure red and green photoluminescence with long lifetime values has been obtained from the Eu³⁺ and Tb³⁺ complexes, respectively, under non‐harmful UVA and blue illumination. Latent fingerprint details, including their characteristic three levels, have been clearly identified from various forensic (non‐porous, semi‐porous, highly fluorescent porous) substrates using red (Eu³⁺) and green (Tb³⁺) nanophosphors. The green nanophosphor powder has a greater capability for visualizing latent fingerprints from highly fluorescent porous surfaces as compared to the red one. Both nanophosphor complexes have been used to develop luminescent ink for anti‐counterfeiting applications.     

Three Lanthanide Metal‐Organic Frameworks Based on an Ether‐Decorated Polycarboxylic Acid Linker: Luminescence Modulation,CO2 Capture and Conversion Properties

Three new isostructural 3D lanthanide metal–organic frameworks (Ln‐MOFs), {H[LnL(H₂O)]?2 H₂O}_n ( 1‐Ln ) (Ln=Eu³⁺, Gd³⁺ and Tb³⁺), based on infinite lanthanide‐carboxylate chains were constructed by employing an ether‐separated 5,5′‐oxydiisophthalic acid (H₄L) ligand under solvothermal reaction. 1‐Eu and 1‐Tb exhibit strong red and green emission, respectively, through the antenna effect, as demonstrated through a combination of calculation and experimental results. Moreover, a series of dichromatic doped 1‐Eu_xTb_y MOFs were fabricated by introducing different concentrations of Eu³⁺ and Tb³⁺ ions, and they display an unusual variation of luminescent colors from green, yellow, orange to red. 1‐Eu with channels decorated by ether O atoms and the open metal sites displays good performance for CO₂ capture and conversion between CO₂ and epoxides into cyclic carbonates.     

The Series of Rare Earth Complexes [Ln2Cl6(μ‐4,4′‐bipy)(py)6], Ln=Y,Pr, Nd,Sm‐Yb: A Molecular Model System for Luminescence Properties in MOFs Based on LnCl3 and 4,4′‐Bipyridine

A series of 12 dinuclear complexes [Ln₂Cl₆(μ‐4,4′‐bipy)(py)₆], Ln=Y, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, ( 1 – 12 , respectively) was synthesized by an anhydrous solvothermal reaction in pyridine. The complexes contain a 4,4′‐bipyridine bridge and exhibit a coordination sphere closely related to luminescent lanthanide MOFs based on LnCl₃ and 4,4‐bipyridine. The dinuclear complexes therefore function as a molecular model system to provide a better understanding of the luminescence mechanisms in the Ln‐N‐MOFs ${\hbox{}{{\hfill 2\atop \hfill \infty }}}$ [Ln₂Cl₆(4,4′‐bipy)₃] ? 2(4,4′‐bipy). Accordingly, the luminescence properties of the complexes with Ln=Y, Sm, Eu, Gd, Tb, Dy, ( 1 , 4 – 8 ) were determined, showing an antenna effect through a ligand–metal energy transfer. The highest efficiency of luminescence is observed for the terbium‐based compound 7 displaying a high quantum yield (QY of 86 %). Excitation with UV light reveals typical emission colors of lanthanide‐dependent intra 4f–4f‐transition emissions in the visible range (Tb^III: green, Eu^III: red, Sm^III: salmon red, Dy^III: yellow). For the Gd^III‐ and Y^III‐containing compounds 6 and 1 , blue emission based on triplet phosphorescence is observed. Furthermore, ligand‐to‐metal charge‐transfer (LMCT) states, based on the interaction of Cl^? with Eu^III, were observed for the Eu^III compound 5 including energy‐transfer processes to the Eu^III ion. Altogether, the model complexes give further insights into the luminescence of the related MOFs, for example, rationalization of Ln‐independent quantum yields in the related MOFs.     

Synthesis,Structure, and Photoluminescence Properties of Novel KBaSc2(PO4)3:Ce3+/Eu2+/Tb3+ Phosphors for White‐Light‐Emitting Diodes

A series of novel KBaSc₂(PO₄)₃:Ce³⁺/Eu²⁺/Tb³⁺phosphors are prepared using a solid‐state reaction. X‐ray diffraction analysis and Rietveld structure refinement are used to check the phase purity and crystal structure of the prepared samples. Ce³⁺‐ and Eu²⁺‐doped phosphors both have broad excitation and emission bands, owing to the spin‐ and orbital‐allowed electron transition between the 4f and 5d energy levels. By co‐doping the KBaSc₂(PO₄)₃:Eu²⁺ and KBaSc₂(PO₄)₃:Ce³⁺ phosphors with Tb³⁺ ions, tunable colors from blue to green can be obtained. The critical distance between the Eu²⁺ and Tb³⁺ ions is calculated by a concentration quenching method and the energy‐transfer mechanism for Eu²⁺→Tb³⁺ is studied by utilizing the Inokuti–Hirayama model. In addition, the quantum efficiencies of the prepared samples are measured. The results indicate that KBaSc₂(PO₄)₃:Eu²⁺,Tb³⁺ and KBaSc₂(PO₄)₃:Ce³⁺,Tb³⁺ phosphors might have potential applications in UV‐excited white‐light‐emitting diodes.     

Lanthanide(III) Complexes of Bis‐semicarbazone and Bis‐imine‐Substituted Phenanthroline Ligands: Solid‐State Structures,Photophysical Properties,and Anion Sensing

Phenanthroline‐based hexadentate ligands L¹ and L² bearing two achiral semicarbazone or two chiral imine moieties as well as the respective mononuclear complexes incorporating various lanthanide ions, such as La^III, Eu^III, Tb^III, Lu^III, and Y^III metal ions, were synthesized, and the crystal structures of [ML¹Cl₃] (M=La^III, Eu^III, Tb^III, Lu^III, or Y^III) complexes were determined. Solvent or water molecules act as coligands for the rare‐earth metals in addition to halide anions. The big Ln^III ion exhibits a coordination number (CN) of 10, whereas the corresponding Eu^III, Tb^III, Lu^III, and Y^III centers with smaller ionic radii show CN=9. Complexes of L², namely [ML²Cl₃] (M=Eu^III, Tb^III, Lu^III, or Y^III) ions could also be prepared. Only the complex of Eu^III showed red luminescence, whereas all the others were nonluminescent. The emission properties of the Eu derivative can be applied as a photophysical signal for sensing various anions. The addition of phosphate anions leads to a unique change in the luminescence behavior. As a case study, the quenching behavior of adenosine‐5′‐triphosphate (ATP) was investigated at physiological pH value in an aqueous solvent. A specificity of the sensor for ATP relative to adenosine‐5′‐diphosphate (ADP) and adenosine‐5′‐monophosphate (AMP) was found. ³¹P NMR spectroscopic studies revealed the formation of a [EuL²(ATP)] coordination species.     

Variable Luminescence and Chromaticity of Homoleptic Frameworks of the Lanthanides together with Pyridylpyrazolates

Homoleptic, 3D coordination polymers of the formula ³³_∞[Ln(3-PyPz)₃] and ³_∞[Ln(4-PyPz)₃], (3-PyPz)⁻=3-(3-pyridyl)pyrazolate anion, (4-PyPz)⁻=3-(4-pyridyl)pyrazolate anion, both C₈H₆N₃⁻, Ln=Sm, Eu, Gd, Tb, Dy, were obtained as highly luminescent frameworks by reaction of the lanthanide metals (Ln) with the aromatic heterocyclic amine ligands 3-PyPzH and 4-PyPzH. The compounds form two isotypic series of 3D coordination polymers and exhibit fair thermal stability up to 360 °C. The luminescence properties of all ten compounds were determined in the solid state, with an antenna effect through ligand–metal energy transfer leading to high efficiency of the luminescence displayed by good quantum yields of up to 74 %. The emission is mainly based on ion-specific lanthanide-dependent intra 4 f–4 f transitions for Tb³⁺: green, Dy³⁺: yellow, Sm³⁺: orange-red, Eu³⁺: red. For the Gd³⁺-containing compounds, the yellow emission of ligand triplet-based phosphorescence is observed at room temperature and 77 K. Co doping of the Gd-containing frameworks with Eu³⁺ and Tb³⁺ allow further shifting of the chromaticity towards white light emission.     

La_7O_6(BO_3)(PO_4)_2∶Eu~(3+)/Tb~(3+)荧光材料的制备及其光致发光性能

采用优化的高温固相方法制备了稀土离子Eu~(3+)和Tb~(3+)掺杂的La_7O_6(BO_3)(PO_4)_2系荧光材料,并对其物相行为、晶体结构、光致发光性能和热稳定性进行了详细研究。结果表明,La_7O_6(BO_3)(PO_4)_2∶Eu~(3+)材料在紫外光激发下能够发射出红光,发射光谱中最强发射峰位于616 nm处,为5D0→7F2特征能级跃迁,Eu~(3+)的最优掺杂浓度为0.08,对应的CIE坐标为(0.610 2,0.382 3);La_7O_6(BO_3)(PO_4)_2∶Tb~(3+)材料在紫外光激发下能够发射出绿光,发射光谱中最强发射峰位于544 nm处,对应Tb~(3+)的5D4→7F5能级跃迁,Tb~(3+)离子的最优掺杂浓度为0.15,对应的CIE坐标为(0.317 7,0.535 2)。此外,对2种材料的变温光谱分析发现Eu~(3+)和Tb~(3+)掺杂的La_7O_6(BO_3)(PO_4)_2荧光材料均具有良好的热稳定性。     

Ba3P5N10Br:Eu2+: A Natural‐White‐Light Single Emitter with a Zeolite Structure Type

Illumination sources based on phosphor‐converted light emitting diode (pcLED) technology are nowadays of great relevance. In particular, illumination‐grade pcLEDs are attracting increasing attention. Regarding this, the application of a single warm‐white‐emitting phosphor could be of great advantage. Herein, we report the synthesis of a novel nitridophosphate zeolite Ba₃P₅N₁₀Br:Eu²⁺. Upon excitation by near‐UV light, natural‐white‐light luminescence was detected. The synthesis of Ba₃P₅N₁₀Br:Eu²⁺ was carried out using the multianvil technique. The crystal structure of Ba₃P₅N₁₀Br:Eu²⁺ was solved and refined by single‐crystal X‐ray diffraction analysis and confirmed by Rietveld refinement and FTIR spectroscopy. Furthermore, spectroscopic luminescence measurements were performed. Through the synthesis of Ba₃P₅N₁₀Br:Eu²⁺, we have shown the great potential of nitridophosphate zeolites to serve as high‐performance luminescence materials.     

A new family of lanthanide coordination polymers based on 3,3′‐[(5‐carboxylato‐1,3‐phenylene)bis(oxy)]dibenzoate: synthesis,crystal structures and magnetic and luminescence properties

Six two‐dimensional (2D) coordination polymers (CPs), namely, poly[{μ₅‐3,3‐[(5‐carboxylato‐1,3‐phenylene)bis(oxy)]dibenzoato‐κ⁶O¹:O^1′:O³,O^3′:O⁵:O^5′}bis(N,N‐dimethylformamide‐κO)lanthanide(III)], [Ln(C₂₁H₁₁O₈)(C₃H₇NO)₂]_n, with lanthanide/Ln = cerium/Ce for CP1 , praseodymium/Pr for CP2 , neodymium/Nd for CP3 , samarium/Sm for CP4 , europium/Eu for CP5 and gadolinium/Gd for CP6 , have been prepared by solvothermal methods using the ligand 3,3′‐[(5‐carboxy‐1,3‐phenylene)bis(oxy)]dibenzoic acid (H₃cpboda) in the presence of Ln(NO₃)₃. The complexes were characterized by single‐crystal X‐ray and powder diffraction, IR spectroscopy, elemental analysis and thermogravimetric analysis (TGA). All the structures of this family of lanthanide CPs are isomorphous with the triclinic space group P and reveal that they have the same 2D network based on binuclear Ln^III units, which are further extended via interlayer C—H…π interactions into a three‐dimensional supramolecular structure. The carboxylate groups of the cpboda^3? ligands link adjacent Ln^III ions and form binuclear [Ln₂(RCOO)₄] secondary building units (SBUs), in which each binuclear Ln^III SBU contains four carboxylate groups from different cpboda^3? ligands. Moreover, with the increase of the rare‐earth Ln atomic radius, the dihedral angles between the aromatic rings gradually increase. Magnetically, CP6 shows weak antiferromagnetic coupling between the Gd^III ions. The solid‐state luminescence properties of CP2 , CP5 and CP6 were examined at ambient temperature and CP5 exhibits characteristic red emission bands derived from the Eu³⁺ ion (CIE 0.53, 0.31), with luminescence quantum yields of 22%. Therefore, CP5 should be regarded as a potential optical material.     

La7O6(BO3)(PO4)2:Eu3+/Tb3+荧光材料的制备及其光致发光性能

采用优化的高温固相方法制备了稀土离子Eu³⁺和Tb³⁺掺杂的La₇O₆（BO₃）（PO₄）₂系荧光材料,并对其物相行为、晶体结构、光致发光性能和热稳定性进行了详细研究。结果表明,La₇O₆（BO₃）（PO₄）₂：Eu³⁺材料在紫外光激发下能够发射出红光,发射光谱中最强发射峰位于616 nm处,为⁵D₀→⁷F₂特征能级跃迁,Eu³⁺的最优掺杂浓度为0.08,对应的CIE坐标为（0.610 2,0.382 3）;La₇O₆（BO₃）（PO₄）₂：Tb³⁺材料在紫外光激发下能够发射出绿光,发射光谱中最强发射峰位于544 nm处,对应Tb³⁺的⁵D₄→⁷F₅能级跃迁,Tb³⁺离子的最优掺杂浓度为0.15,对应的CIE坐标为（0.317 7,0.535 2）。此外,对2种材料的变温光谱分析发现Eu³⁺和Tb³⁺掺杂的La₇O₆（BO₃）（PO₄）₂荧光材料均具有良好的热稳定性。     

Novel high-saturated red-emitting phosphor Sr9(Mg0.5Mn0.5)K(PO4)7: Eu2+ with great quantum efficiency enhancement by La3+ codoping for white LED application

In this work, a novel whitlockite-structure red-emitting phosphor host, Sr₉(Mg_0.5Mn_0.5)K(PO₄)₇, is designed and successfully synthesized via a solid-state reaction. Upon X-ray diffractometer Rietveld refinement, it is revealed that this compound possesses compact Eu²⁺-Mn²⁺ distance (3.6809 Å) and large intra-Mn²⁺ distance (8.9905 Å), which is beneficial to the high-efficient Eu²⁺-Mn²⁺ energy transfer. By Eu²⁺ sensitization, our new phosphor exhibits a high-saturated and bright red Mn²⁺ emission at 620 nm with high color purity of 97.9%. Great emission enhancement up to 245 times than host is achieved by La³⁺ heterovalent substitution, which can be ascribed to the La³⁺-induced further structural confinement effect. Moreover, the quantum efficiency is boosted by twofold. The as-fabricated white phosphor-converted LEDs device shows bright warm white light with correlated color temperature (CCT) of 3,487 K, color-rendering index (CRI) of 92.4, and luminous efficacy of 31.59 lm/W. This work proves the feasibility of chemical unit co-substitution strategy in emission engineering of Mn²⁺-based phosphors, which can stimulate further studies on the red-emitting phosphor materials.     

Lanthanoid‐Based Ionic Liquids Incorporating the Dicyanonitrosomethanide Anion

A series of low‐melting‐point salts with hexakisdicyanonitrosomethanidolanthanoidate anions has been synthesised and characterised: (C₂mim)₃[Ln(dcnm)₆] ( 1 Ln ; 1 Ln = 1 La , 1 Ce , 1 Pr , 1 Nd ), (C₂C₁mim)₃[Pr(dcnm)₆] ( 2 Pr ), (C₄C₁pyr)₃[Ce(dcnm)₆] ( 3 Ce ), (N₁₁₁₄)₃[Ln(dcnm)₆] ( 4 Ln ; 4 Ln = 4 La , 4 Ce , 4 Pr , 4 Nd , 4 Sm , 4 Gd ), and (N_1112OH)₃[Ce(dcnm)₆] ( 5 Ce ) (C₂mim=1‐ethyl‐3‐methylimidazolium, C₂C₁mim=1‐ethyl‐2,3‐dimethylimidazolium, C₄C₁py=N‐butyl‐4‐methylpyridinium, N₁₁₁₄=butyltrimethylammonium, N_1112OH=2‐(hydroxyethyl)trimethylammonium=choline). X‐ray crystallography was used to determine the structures of complexes 1 La , 2 Pr , and 5 Ce , all of which contain [Ln(dcnm)₆]^3? ions. Complexes 1 Ln and 2 Pr were all ionic liquids (ILs), with complex 3 Ce melting at 38.1 °C, the lowest melting point of any known complex containing the [Ln(dcnm)₆]^3? trianion. The ammonium‐based cations proved to be less suitable for forming ILs, with complexes 4 Sm and 4 Gd being the only salts with the N₁₁₁₄ cation to have melting points below 100 °C. The choline‐containing complex 5 Ce did not melt up to 160 °C, with the increase in melting point possibly being due to extensive hydrogen bonding, which could be inferred from the crystal structure of the complex.     

Reversible SC‐SC Transformation involving [4+4] Cycloaddition of Anthracene: A Single‐Ion to Single‐Molecule Magnet and Yellow‐Green to Blue‐White Emission

In search of magneto‐optic materials, the mononuclear compounds Ln^III(depma)(NO₃)₃(hmpa)₂ (Ln=Dy, Gd) were synthesized. The anthracene moieties undergo [4+4] dimerization when irradiated at 365 nm without loss of crystallinity. The Dy compound switches from a single‐ion to a single‐molecule magnet with doubling of the spin reversal barrier energy and from yellow‐green to blue‐white emission. The dimerization is reversed by heating at 100 °C or partially on light irradiating at 254 nm. The results suggest that lanthanide phosphonates with anthracene are promising smart materials displaying synergistic magneto‐optic property.     

Site‐Selective Occupancy of Eu2+ Toward Blue‐Light‐Excited Red Emission in a Rb3YSi2O7:Eu Phosphor

Establishing an effective design principle in solid‐state materials for a blue‐light‐excited Eu²⁺‐doped red‐emitting oxide‐based phosphors remains one of the significant challenges for white light‐emitting diodes (WLEDs). Selective occupation of Eu²⁺ in inorganic polyhedra with small coordination numbers results in broad‐band red emission as a result of enhanced crystal‐field splitting of 5d levels. Rb₃YSi₂O₇:Eu exhibits a broad emission band at λ_max=622 nm under 450 nm excitation, and structural analysis and DFT calculations support the concept that Eu²⁺ ions preferably occupy RbO₆ and YO₆ polyhedra and show the characteristic red emission band of Eu²⁺. The excellent thermal quenching resistance, high color‐rendering index R_a (93), and low CCT (4013 K) of the WLEDs clearly demonstrate that site engineering of rare‐earth phosphors is an effective strategy to target tailored optical performance.     

Lanthanide(III) (Eu,Gd, Tb,Dy) Complexes Derived from 4‐(Pyridin‐2‐yl)methyleneamino‐1,2,4‐triazole: Crystal Structure,Magnetic Properties,and Photoluminescence

The reaction of lanthanide(III) nitrates with 4‐(pyridin‐2‐yl)methyleneamino‐1,2,4‐triazole (L) was studied. The compounds [Ln(NO₃)₃(H₂O)₃] ? 2 L, in which Ln=Eu ( 1 ), Gd ( 2 ), Tb ( 3 ), or Dy ( 4 ), obtained in a mixture of MeCN/EtOH have the same structure, as shown by XRD. In the crystals of these compounds, the mononuclear complex units [Ln(NO₃)₃(H₂O)₃] are linked to L molecules through intermolecular hydrogen‐bonding interactions to form a 2D polymeric supramolecular architecture. An investigation into the optical characteristics of the Eu³⁺‐, Tb³⁺‐, and Dy³⁺‐containing compounds ( 1 , 3 , and 4 ) showed that these complexes displayed metal‐centered luminescence. According to magnetic measurements, compound 4 exhibits single‐ion magnet behavior, with ΔE_eff/k_B=86 K in a field of 1500 Oe.     

White‐Light Emission from a Semi‐Conductive Borate‐Stannate

In response to ever‐increasing application requirements in lighting and displays, a tremendous emphasis is being placed on single‐component white‐light emission. Single‐component inorganic borates doped with rare earth metal ions have shown prominent achievements in white‐light emission. The first environmentally friendly defect‐induced white‐light emitting crystalline inorganic borate, Ba₂[Sn(OH)₆][B(OH)₄]₂, has been prepared. Additionally, it is the first borate‐stannate without a Sn?O?B linkage. Notably, Ba₂[Sn(OH)₆][B(OH)₄]₂ shows Commission Internationale de l'Eclairage (CIE) chromaticity coordinates of (0.42, 0.38), an ultrahigh color rendering index (CRI) of 94.1, and an appropriate correlated color temperature (CCT) of 3083 K. Such a promising material will provide a new approach in the development of white‐light emitting applications.     

Ultra‐Narrow‐Band Blue‐Emitting Oxoberyllates AELi2[Be4O6]:Eu2+ (AE=Sr,Ba) Paving the Way to Efficient RGB pc‐LEDs

Highly efficient phosphor‐converted light‐emitting diodes (pc‐LEDs) are popular in lighting and high‐tech electronics applications. The main goals of present LED research are increasing light quality, preserving color point stability and reducing energy consumption. For those purposes excellent phosphors in all spectral regions are required. Here, we report on ultra‐narrow band blue emitting oxoberyllates AELi₂[Be₄O₆]:Eu²⁺ (AE=Sr,Ba) exhibiting a rigid covalent network isotypic to the nitridoalumosilicate BaLi₂[(Al₂Si₂)N₆]:Eu²⁺. The oxoberyllates’ extremely small Stokes shift and unprecedented ultra‐narrow band blue emission with fwhm ≈25 nm (≈1200 cm^?1) at λ_em=454–456 nm result from its rigid, highly condensed tetrahedra network. AELi₂[Be₄O₆]:Eu²⁺ allows for using short‐wavelength blue LEDs (λ_em<440 nm) for efficient excitation of the ultra‐narrow band blue phosphor, for application in violet pumped white RGB phosphor LEDs with improved color point stability, excellent color rendering, and high energy efficiency.     

Study on the Ultrahigh Quantum Yield of Fluorescent P,O‐g‐C3N4 Nanodots and its Application in Cell Imaging

Graphitic carbon nitride nanodots (g‐C₃N₄ nanodots), as a new kind of heavy‐metal‐free quantum dots, have attracted considerable attention because of their unique physical and chemical properties. Although various methods to obtain g‐C₃N₄ nanodots have been reported, it is still a challenge to synthesize g‐C₃N₄ nanodots with ultrahigh fluorescence quantum yield (QY). In this study, highly fluorescent phosphorus/oxygen‐doped graphitic carbon nitride (P,O‐g‐C₃N₄) nanodots were prepared by chemical oxidation and hydrothermal etching of bulk P‐g‐C₃N₄ derived from the pyrolysis of phytic acid and melamine. The as‐prepared P,O‐g‐C₃N₄ nanodots showed strong blue fluorescence and a relatively high QY of up to 90.2 %, which can be ascribed to intrinsic phosphorus/oxygen‐containing groups, and surface‐oxidation‐related fluorescence enhancement. In addition, the P,O‐g‐C₃N₄ nanodots were explored for cell imaging with excellent stability and biocompatibility, which suggest that they have great potential in biological applications.     

Systematic Investigation of Reaction‐Time Dependence of Three Series of Copper–Lanthanide/Lanthanide Coordination Polymers: Syntheses,Structures, Photoluminescence,and Magnetism

Three series of copper–lanthanide/lanthanide coordination polymers (CPs) Ln^IIICu^IICu^I(bct)₃(H₂O)₂ [Ln=La ( 1 ), Ce ( 2 ), Pr ( 3 ), Nd ( 4 ), Sm ( 5 ), Eu ( 6 ), Gd ( 7 ), Tb ( 8 ), Dy ( 9 ), Er ( 10 ), Yb ( 11 ), and Lu ( 12 ), H₂bct=2,5‐bis(carboxymethylmercapto)‐1,3,4‐thiadiazole acid], Ln^IIICu^I(bct)₂ [Ln=Ce ( 2 a ), Pr ( 3 a ), Nd ( 4 a ), Sm ( 5 a ), Eu ( 6 a ), Gd ( 7 a ), Tb ( 8 a ), Dy ( 9 a ), Er ( 10 a ), Yb ( 11 a ), and Lu ( 12 a )], and Ln^III₂(bct)₃(H₂O)₅ [Ln=La ( 1 b ), Ce ( 2 b ), Pr ( 3 b ), Nd ( 4 b ), Sm ( 5 b ), Eu ( 6 b ), Gd ( 7 b ), Tb ( 8 b ), and Dy ( 9 b )] have been successfully constructed under hydrothermal conditions by modulating the reaction time. Structural characterization has revealed that CPs 1 – 12 possess a unique one‐dimensional (1D) strip‐shaped structure containing two types of double‐helical chains and a double‐helical channel. CPs 2 a – 12 a show a three‐dimensional (3D) framework formed by Cu^I linking two types of homochiral layers with double‐helical channels. CPs 1 b – 9 b exhibit a 3D framework with single‐helical channels. CPs 6 b and 8 b display visible red and green luminescence of the Eu^III and Tb^III ions, respectively, sensitized by the bct ligand, and microsecond‐level lifetimes. CP 8 b shows a rare magnetic transition between short‐range ferromagnetic ordering at 110 K and long‐range ferromagnetic ordering below 10 K. CPs 9 a and 9 b display field‐induced single‐chain magnet (SCM) and/or single‐molecule magnet (SMM) behaviors, with U_eff values of 51.7 and 36.5 K, respectively.