Yellow-green Light Research Articles

LiSr2SiO4H, an Air-Stable Hydride as Host for Eu(II) Luminescence.

LiSr2SiO4H is synthesized by solid-state reaction of LiH and α-Sr2SiO4. It crystallizes in space group P21/ m ( a = 658.63(4) pm, b = 542.36(3) pm, c = 695.01(4) pm, β = 112.5637(9)°) as proven by X-ray and neutron diffraction, is isotypic to LiSr2SiO4F, and exhibits isolated SiO4 tetrahedra. Hydride anions are located in Li2Sr4 octahedra, which share faces to form columns, with H-H distances of 271.18(2) pm. NMR, IR, and Raman spectroscopy, density measurements, elemental analysis, and theoretical calculations confirm these results. Despite its hydridic nature, it is stable in air up to 550 K. When doped with europium, it emits bright yellow-green light with an intensity maximum at 560 nm for LiSr1.98Eu0.02SiO4H. Even after treatment in water for several hours, the solid shows luminescence. The broad emission peak is attributed to the allowed 4f65d → 4f7 transition of divalent europium. LiSr2SiO4H is the first silicate hydride, a class of compounds that might have potential as host for luminescent materials.

Multicolor emissions and photoluminescence properties for Ca3Al4ZnO10:Ce3+/Eu3+/Tb3+/Mn2+ phosphors

Ce3+/Eu3+/Tb3+/Mn2+ ion single- or codoped Ca3Al4ZnO10 (CAZO) luminescent materials were successfully synthesized by the high-temperature solid-state reaction. We studied the photoluminescence properties in detail. Under UV radiation, the CAZO:Ce3+ phosphor displays a strong and wide blue emitting band from the doping Ce3+ ion. The CAZO:Eu3+/Tb3+/Mn2+ samples emit the orange, blue-green and yellow-green light due to their characteristic f-f and d-d emissions, respectively. Moreover, the Tb3+ and Mn2+ codoped CAZO samples give simultaneous emissions of Tb3+ and Mn2+, leading to the emission colors changing from green to yellow. Under UV light excitation, multi-color emissions can be obtained by modifying the relative doping concentration of Tb3+ and Mn2+. More importantly, a near white emission was obtained in CAZO:0.003Tb3+, 0.007Mn2+ samples.

Beetle luciferases with naturally red- and blue-shifted emission.

The different colors of light emitted by bioluminescent beetles that use an identical substrate and chemiexcitation reaction sequence to generate light remain a challenging and controversial mechanistic conundrum. The crystal structures of two beetle luciferases with red- and blue-shifted light relative to the green yellow light of the common firefly species provide direct insight into the molecular origin of the bioluminescence color. The structure of a blue-shifted green-emitting luciferase from the firefly Amydetes vivianii is monomeric with a structural fold similar to the previously reported firefly luciferases. The only known naturally red-emitting luciferase from the glow-worm Phrixothrix hirtus exists as tetramers and octamers. Structural and computational analyses reveal varying aperture between the two domains enclosing the active site. Mutagenesis analysis identified two conserved loops that contribute to the color of the emitted light. These results are expected to advance comparative computational studies into the conformational landscape of the luciferase reaction sequence.

Exploration of highly efficient light conversion agents for agricultural film based on the bay-substituted perylene diimides derivatives

To explore highly efficient yellow-green light conversion agents used for agricultural film, six bay-substituted perylene diimides and their polyvinyl chloride doped films (by 0.5% weight addition) were prepared. The maximum absorption and emission peaks of the luminogens-doped polyvinyl chloride films are located at 581–609 nm and 647–667 nm, respectively. More importantly, the fluorescence quantum yields of PTCDA, t-BuOPTCDA and m-MeOPTCDA are up to 0.88, 0.84 and 0.78 in doping film, respectively. The strengthening solar radiation and outdoor exposure to sunlight last 160 min and two months respectively and the emission intensity of m-MeOPTCDA-doped film displays slight changes and 9% fluctuation in turn. Combined transmittance, compatibility, mechanical properties and thermal stability, m-MeOPTCDA is chosen as the best effective light conversion materials. To better understand the optical properties of the luminogens, molecular configuration optimization, electron cloud density distribution and molecular orbital energy levels were completed by theoretical calculation. Further, the double layer coextrusion film containing m-MeOPTCDA and Triphenyl acrylonitrile is succeed in dual band excitation(350 nm and 580 nm)and emission (430 nm and 651 nm), by optimizing the proportion of m-MeOPTCDA and Triphenyl acrylonitrile, the special light conversion films for different crops will be expected.

030 Light-controlled relaxation of rat penile corpus cavernosum by a novel NO donor, NO-Rosa

Phosphodiesterase-5 inhibitors are not always effective for patients with erectile dysfunction (ED) who also have diabetes mellitus or have had a radical prostatectomy, because of the reduction in nitric oxide (NO) production. The control of NO production may be useful as a therapy for ED. In this study, we focused on a light-controllable NO releaser. Previously, we developed a blue (470–500 nm) light-controllable NO releaser, NOBL-1. Subsequently, we improved NOBL-1, because blue light has low tissue permeability. We have now succeeded in the development of a yellow-green (530–590 nm) light-controllable NO releaser, NO-Rosa. We investigated whether we could control the relaxation of the corpus cavernosum smooth muscle by using an NO-Rosa derivative and light irradiation. Fluorescence imaging of the NO release from NO-Rosa in HEK-293 cells was performed using DAF-FM. Adult male Wistar-ST rats were used for the isometric tension study. The corpus cavernosum was treated by the addition of L-NAME (100 μM) to inhibit endogenous NO production and pre-contracted with noradrenaline (10 μM). The response of the corpus cavernosum smooth muscle to irradiation with yellow-green light, before and after the addition of an NO-Rosa derivative (10 μM), was measured and recorded.

Low Etendue Yellow-Green Solid-State Light Generation by Laser-Pumped LuAG:Ce Ceramic

A low Etendue (6.1 mm2) yellow-green solid-state light source with optical conversion efficiency up to 101.3 lumen/Watt is demonstrated by through high-power laser diode pumping of a static LuAG:Ce transparent ceramic plate. A 443-nm blue laser diode array with a full-width-half-maximum (FWHM) of <1.5 nm and a maximum output power of 15.2 W is used to attain a high spectral absorption efficiency. The output from the high-power laser diode array is collimated, shaped, despeckled, and focused to display a Gaussian-like profile with a 1.5-mm beam waist (1/e2 radius) to stimulate a 1.2-mm thick LuAG:Ce transparent ceramic plate with an emission FWHM spectra at 505–585 nm. No thermal quenching, pump absorption saturation, and obvious luminous flux decrease is found during test.

Effects of different LED sources on the growth and nitrogen metabolism of lettuce

Using a light-emitting diode (LED) as the light source, the effects of eight different light treatments [white light (control, W), purple light (P), blue light (B), red light (R), green light (G), yellow light (Y), red–blue light in a 9:1 ratio (9R/1B), and red–blue light in a 4:1 ratio (4R/1B)] on the growth, quality and nitrogen metabolism of lettuce were studied. The results showed that compared with the white light, the purple light, blue light, red light, and the red-blue light combination could all increase the biomass of the aboveground part of lettuce to various degrees, while green light and yellow light inhibited lettuce growth. Under blue light, the contents of soluble protein and flavonoid in lettuce were the highest; under red light, the soluble sugar content was the highest, while the contents of soluble protein, free amino acids, and vitamin C (VC) were relatively higher under the 4R/1B light condition. Compared with white light, the sources of purple, blue, and red lights as well as the red–blue light combination all significantly reduced nitrate accumulation in lettuce, and the activities of the nitrogen (N) metabolism-related enzymes such as nitrate reductase, nitrite reductase, glutamine synthetase, glutamate synthase, and glutamate dehydrogenase were increased to varying degrees. In contrast, the contents of nitrate and ammonium N were significantly accumulated in lettuce under green light, and the activities of relative enzymes were significantly reduced. Therefore, the purple light, blue light, and red–blue combination light sources could promote N assimilation and improve the aboveground biomass accumulation in lettuce by improving the activity of the N metabolism-related enzymes in lettuce. Particularly under the 4R/1B light source, the biomass, soluble protein, VC, and total amino acid content were rather high in lettuce, which indicated that the 4R/1B light source could better effectively improve the nutritional quality and promote the growth of lettuce, while yellow light and green light are not suitable to serve as direct sources in a plant factory. These results provide a certain theoretical basis for the regulation of the light environment in cultivation facilities.

Design of Fe3O4@SiO2@mSiO2-organosilane carbon dots nanoparticles: Synthesis and fluorescence red-shift properties with concentration dependence

Organosilane-functionalized carbon dots (SiCDs) immobilized silica composite nanoparticles (Fe3O4@SiO2@mSiO2-SiCDs) with dually emissive properties have been prepared by a modified sol-gel method. Such Fe3O4@SiO2@mSiO2-SiCDs nanoparticles solution exhibits blue light emission with a maximum wavelength of 470 nm at lower concentrations, and red-shifts to yellow-green light emission with maximum wavelength of 565 nm at higher concentrations, which is different with traditional carbon dots composite materials displaying strong emission only in the blue-light region. The SiCDs are immobilized in the outer mesoporous silica layer by covalent bonds via proper blending ration, which enables the nanoparticles solution to possess excellent fluorescence stability. The Fe3O4@SiO2@mSiO2-SiCDs nanoparticles show good stability, high surface area (483.19 m2/g), high saturation magnetization (22.1 emu/g) and low remanence (0.217 emu/g). When the concentration of nanoparticles solution is increased, the distance between the nanoparticles decreases and exhibits the concentration-mediated scattering phenomena, which result in the red-shift of fluorescent peaks. The specific structure of the Fe3O4@SiO2@mSiO2-SiCDs nanoparticles and the concentration-mediated scattering phenomena play key roles in the red-shift appearing.

Firefly Luciferase Mutant with Enhanced Activity and Thermostability.

The luciferase isolated from the firefly Photinus pyralis (Ppy) catalyzes a two-step reaction that results in the oxidation of d-luciferin accompanied by emission of yellow–green light with a peak at 560 nm. Among many applications, Ppy luciferase has been used extensively as a reporter gene in living cells and organisms. However, some biological applications are limited by the low stability of the luciferase and limited intracellular luciferin concentration. To address these challenges, efforts to protein engineer Ppy luciferase have resulted in a number of mutants with improved properties such as thermostability, pH tolerance, and catalytic turn over. In this work, we combined amino acid mutations that were shown to enhance the enzyme’s thermostability (Mutant E) with those reported to enhance catalytic activity (LGR). The resulting mutant (YY5) contained eight amino acid changes from the wild-type luciferase and exhibited both improved thermostability and brighter luminescence at low luciferin concentrations. Therefore, YY5 may be useful for reporter gene applications.

Peering into the minds of mammals

With bioluminescence imaging techniques, as with emotions, it can be difficult to look beyond the surface and see what’s going on deep inside. Inspired by fireflies, this imaging method makes use of green-yellow light emitted when an enzyme called luciferase reacts with d-luciferin. Light of this wavelength doesn’t travel far through tissue, which has limited the technique’s depth of visualization. Now, researchers in Japan have engineered a synthetic bioluminescence system that emits red-shifted light that is up to 1,000 times as bright as light emitted by existing systems and can penetrate through the deep tissue of mice and marmosets (Science 2018, DOI: 10.1126/science.aaq1067). The researchers installed their new imaging system in the animals’ striatum, an area deep in the brain, in two steps. First, they injected a virus containing their improved luciferase, an enzyme called Akaluc discovered through directed evolution. Then they fed the animals or injected them with a

Oculogryphus chenghoiyanae sp. n. (Coleoptera, Lampyridae): a new ototretine firefly from Hong Kong with descriptions of its bioluminescent behavior and ultraviolet-induced fluorescence in females.

The first Oculogryphus species with associated males and female was found in Hong Kong and is described as new: O. chenghoiyanae sp. n. Adults of both sexes were collected live in the field and their bioluminescent behavior is reported for the first time in the genus. The captive males emit weak and continuous light from a pair of light spots on abdominal ventrite 6 or do so when disturbed. The larviform (highly paedomorphic) females can glow brightly from a pair of light-emitting organs on the abdomen. The females of Oculogryphus and Stenocladius are to date the only documented representatives of paedomorphism in ototretine fireflies. The finding is consistent with the evidence from male morphology and bioluminescent behavior, supporting the close relationship between the two genera. A key to the Oculogryphus species is provided. The Oculogryphus females can fluoresce with a blue-green light through the whole body under ultraviolet illumination, a phenomenon reported in the Lampyridae for the first time. The co-occurrence of bioluminescence and fluorescence is rare in terrestrial ecosystems, previously known only in some millipedes (Diplopoda). The fluorescence and bioluminescence abilities of Oculogryphus females are functionally independent: abdominal light-emitting organs producing bright yellowish green light while the body wall fluoresces with blue-green light. In contrast, fluorescence and bioluminescence in millipedes are biochemically linked, like in some jellyfish (Cnidaria: Medusozoa).

Efficiently Cooperative Energy Transfer Up‐Conversion Luminescence in Tb3+ /Yb3+ Co‐Doped Cubic Na5Lu9F32 Single Crystals by Vertical Bridgman Method

AbstractTb3+/Yb3+ co‐doped Na5Lu9F32 single crystals with ≈1.0 mol% Tb3+ concentrations and various Yb3+ are prepared by Bridgman method. Several visible up‐conversion (UC) luminescence are observed following the excitation of 980 nm laser diode (LD) as well as its pump power dependence on UC emission of the crystals. The quadratic dependence of pump power on UC emission reveals that two‐photon UC processes are mainly responsible for the 486 nm and 543 nm emissions of Tb3+/Yb3+ co‐doped system in Na5Lu9F32 single crystals. It is proposed that cooperative energy transfer (CET) from two excited Yb3+ ions to the ground state of Tb3+ ions is in charge of the ≈486 nm, ≈543 nm and ≈620 nm, which are attributing to 5D4 → 7F6, 5D4 → 7F4 and 5D4 → 7F3, respectively, are obtained in Tb3+/Yb3+ doped Na5Lu9F32 single crystals. Furthermore, a favorable yellowish green light performance can be achieved with certain Yb3+ concentrations and 1.0 mol% Tb3+ co‐doped samples, and its external quantum efficiency approached to 1.25% under 5.5 W cm−2 980 nm excitation which makes further research valuable in developing processable UC materials for electro‐optical devices.

Fluorescein Angiography.

Fluorescein angiography (FA) is an imaging modality used to study the circulation of the retina and choroid. About 5 mL of 10% sterile aqueous solution of fluorescein dye (or 2-3 mL of a 25% solution) is injected in the antecubital vein. The fluorescein molecules excited by a blue light (465-490 nm) emit green-yellow light (520-530 nm) (Fig. 2.1). The reflected blue light and green-yellow light are passed through a barrier filter that allows only the green-yellow fluorescent light to pass through and blocks the blue reflected light.

Mixed chelating ligands used to regulate the luminescence of Ln(iii) complexes and single-ion magnet behavior in Dy-based analogues.

The organic ligands 5,7-dibromo-2-methyl-8-quinolinol (L1), 1,10-phenanthroline (L2), and 5,7-dichloro-2-methyl-8-quinolinol (L3) were used to react with Dy(NO3)3·6H2O under solvothermal conditions at 80 °C to obtain the complexes [Dy(L1)3(H2O)] (1), [Dy(L2)2(NO3)3] (2), and [Dy(L3)3(H2O)] (3), respectively. The reaction of L1 and L2 with lanthanide(iii) nitrate salts in the presence of triethylamine as a base afforded four mononuclear complexes, namely, [Ln(L1)2(L2)(NO3)] [Ln = Dy (4), Ho (5), Er (6), and Tb (7)]. Complexes 1 and 2 emitted yellow-green and red light under excitation with light of a certain wavelength. Interestingly, 4-7 exhibited a superimposition of the luminescence of 1 and 2. To our knowledge, this is the first example of the use of different organic light-emitting ligands to adjust the fluorescence of Ln(iii) complexes. Moreover, the series of complexes [Ln(L3)2(L2)(NO3)] [Ln = Dy (8), Ho (9), Er (10), and Tb (11)] were also obtained under the same conditions by replacing L1 with L3. In the way that was expected, 8-11 exhibited a superimposition of the luminescence of 2 and 3. Density functional theory (DFT) calculations of electron cloud density showed that the electron cloud densities of complexes 4 and 8 are mainly concentrated in the quinoline rings. Furthermore, analysis of the molecular ion peaks of complexes 4-11 obtained by electrospray mass spectrometry (ESI-MS) showed that only the 1,10-phenanthroline ligand was discovered to dissociate in the solution state. Magnetic measurements of the Dy-containing complexes revealed features of field-induced single-ion magnet behavior.

Effect of transition metal ions on luminescence of MOFs

Three kinds of metal-organic framework materials (MOF-5, MLI-101(Cr), UiO-66) are synthesized, which are based on transition metal (Zn, Cr, Zr) as the center ions, and terephthalic acid (H2BDC) as organic ligand. At the same time, three kinds of MOFs were characterized and analyzed with X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-visible absorption spectrometer (UV-Vis), and fluorescence spectrometer (PL). This article analyzes the fluorescence effects of these three MOFs and investigates the role of different transition metal ions in MOF luminescence. The results show that the ionic radii of Zn2 + and Zr4 + are similar, which are 0.074 nm and 0.072 nm, respectively. MOF-5 and UiO-66 have similar fluorescence effects, both of which emit blue-violet light. However, MIL-101 (Cr) fluorescence centers on Cr3 + with an ionic radius of 0.0651 nm emits yellow-green light, which is different from the foregoing MOFs. Therefore, the ionic radius of the transition metal has an important effect on the fluorescence effect of the MOF. For larger ionic radii, the fluorescence of MOF is generally in the blue-violet square region.

Construction of Luminogen Exhibiting Multicolored Emission Switching through Combination of Twisted Conjugation Core and Donor-Acceptor Units.

Stimuli responsive luminescent materials, especially those exhibiting multicolor emission switching, have potential application in sensor, optical recording, security ink, and anti-counterfeit label. Through combination of twisted conjugation core and donor and acceptor units, a luminogen (2-(bis(4-(carbazol-9-yl)phenyl)methylene)malononitrile (1) was synthesized. Luminogen 1 can form three kinds of crystals emitting green (1GC, λem = 506 nm, ΦF = 19.8%), yellow-green (1YC, λem = 537 nm, ΦF = 17.8%), and orange (1OC, λem = 585 nm, ΦF = 30.0%) light upon 365 nm UV illumination. The emission of amorphous solid of 1 (1Am) overlaps with that of 1OC (λem = 585 nm), with quantum yield of 13.9%, which is seldom reported. Emission of 1 can be switched among green, yellow-green, and orange through morphology modulation upon exposure to thermal, solvent vapor, or mechanical stimuli. Finally, its potential application in optical recording was also investigated.

Mechanofluorochromic properties of tert-butylcarbazole-based AIE-active D-π-A fluorescent dye

Two new non-planar carbazole derivative DBTNC and NC were designed and synthesized. The D-π-A type conjugated compounds showed obvious intramolecular charge transfer (ICT) properties, which were evidenced by theoretical calculations and spectral analysis. Both of them exhibited evident AIE characteristic with high fluorescence quantum yield in the solid state with the fluorescence quantum yields of 0.37 and 0.33, respectively. DBTNC and NC were quite weakly fluorescent in THF, while a significant AIE effect were observed in water/THF mixtures with AIE factors of 10.7 and 9.7, respectively. Interestingly, DBTNC showed reversible mechanofluorochromism (MFC). The as-prepared solid of DBTNC emitted strong yellowish-green light and could be transformed into the powders emitting orange-yellow light after grinding with the fluorescence quantum yield decreased to 0.35, and the fluorescence could recover the original station when the ground powders were heated or fumed with DCM for 1 min. The powder XRD and DSC studies suggested that the mechanofluorochromic properties of DBTNC originating not from chemical changes but from the transformation of a crystalline state into an amorphous state. We deduced that tert-butyl can lead to the incompact packing of luminophore, which was more sensitive to external stimuli, so that multi-color solid-state luminescence can be afforded during mechanofluorochromic process. Herein, we provided the strategy for fabricating new mechanofluorochromic dyes via the introduction of non-planar π-skeletons and steric effect, which may possess potential applications in mechanosensors and anti-faked materials.

Synthesis, Structure, and Luminescence of Copper(I) Halide Complexes of Chiral Bis(phosphines)

For investigation of structure-property relationships in copper phosphine halide complexes, treatment of copper(I) halides with chiral bis(phosphines) gave dinuclear [Cu((R,R)-i-Pr-DuPhos)(μ-X)]2 [X = I (1), Br (2), Cl (3)], [Cu(μ-((R,R)-Me-FerroLANE)(μ-I)]2 (5), and [Cu((S,S)-Et-FerroTANE)(I)]2 (6), pentanuclear cluster Cu5I5((S,S)-Et-FerroTANE)3 (7), and the monomeric Josiphos complexes Cu((R,S)-CyPF-t-Bu)(I) (8) and Cu((R,S)-PPF-t-Bu)(I) (9); 1-3, 5, and 7-9 were structurally characterized by X-ray crystallography. Treatment of iodide 1 with AgF gave [Cu((R,R)-i-Pr-DuPhos)(μ-F)]2 (4). DuPhos complexes 1-4 emitted yellow-green light upon UV irradiation at room temperature in the solid state. This process was studied by low-temperature emission spectroscopy and density functional theory (DFT) calculations, which assigned the luminescence to (M + X)LCT (Cu2X2 to DuPhos aryl) excited states. Including Grimme's dispersion corrections in the DFT calculations (B3LYP-D3) gave significantly shorter Cu-Cu distances than those obtained using B3LYP, with the nondispersion-corrected calculations better matching the crystallographic data; other intramolecular metrics are better reproduced using B3LYP-D3. A discussion of the factors leading to this unusual observation is presented.

Visible Emission in Nanocrystalline Rutile: Free Exciton and Water as Probes for Midgap States in Adsorption/Desorption Using “Conventional” and Synchronous Luminescence Spectroscopy

We studied absorption and emission transitions in the visible range through three distinct electronic midgap states in nanocrystalline rutile TiO2 using absorption spectroscopy, “conventional” photoluminescence (PL) spectroscopy, synchronous luminescence spectroscopy for the first time, and complementary methods. We have used free exciton in rutile as an intrinsic midgap state (obtained under the subbandgap photoexcitation at 430 nm) to assign luminescence bands of “green light” (ca. 520 nm) and “green–yellow light” (ca. 560 nm) at 25 °C. Further, we utilized water in the vapor phase as spectroscopic probe to learn about origin of visible emission in rutile. Visible photoluminescence is increased by factor ×20 after water desorption and reversibly decreased (quenched) upon water adsorption in air under ambient conditions. Preferential quenching of “green–yellow light” by adsorbed water occurs versus “green light” as originating from surface vs subsurface oxygen vacancies. Water “adsorption/desorption” was...

Highly efficient up-conversion luminescence in Er3+/Yb3+ co-doped Na5Lu9F32 single crystals by vertical Bridgman method

Er3+/Yb3+ co-doped Na5Lu9F32 single crystals with different concentrations of Yb3+ ions were prepared to investigate their phase structure, up-conversion (UC) properties and mechanism of UC luminescence by Bridgman method. Under 980 nm near-infrared (NIR) excitation, three sharp UC emission bands topping at green ~525 nm, ~548 nm and red ~669 nm were obtained in Er3+/Yb3+ doped Na5Lu9F32 single crystals which are attributing to the transitions of 2H11/2 → 4I15/2, 4S3/2 → 4I15/2 and 4F9/2 → 4I15/2, respectively. The quadratic dependence of pump power on UC emission indicated that two-photon process is in charge of the transition from excited state of Yb3+ ions to lower state of Er3+ ion in Na5Lu9F32 single crystals. The long-accepted mechanism for the production of red and green emissions through up-conversion (UC) under 980 nm excitation in Er3+/Yb3+ co-doped materials apply in the Na5Lu9F32 host was displayed. The enhancement of the red emission was observed due to a cross-relaxation (CR) process of the form: 4F7/2 + 4I11/2 → 4F9/2 + 4F9/2. Furthermore, an ideal yellowish green light performance could be achieved with 1.0 mol% Er3+ doped certain Yb3+ concentrations samples, and its external quantum efficiency approached to 6.80% under 5.5 Wcm−2 980 nm excitation which can be applied in developing UC displays for electro-optical devices.