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1.
Novel chiral fluorescence sensors L‐1 and D‐1 incorporating N‐Boc‐protected alanine and acridine moieties were synthesized. The recognition ability of the sensors was studied by fluorescence titration, 1H NMR spectroscopy and density functional theory (DFT) calculations. The sensors exhibited good enantioselective fluorescent sensing ability toward enantiomers of tartrate anion for the selected carboxylate anions and formed 1: 1 complexes by multiple hydrogen bonding interactions. 相似文献
2.
Chiral discrimination of malates in aqueous solutions at near-neutral pH is achieved through fluorescence measurement and imaging using the europium-tetracycline complex (EuTc) as a fluorescent probe. The method is based on the significantly different fluorescence properties of the ternary complexes (Eu-Tc-malate) formed between EuTc and the enantiomeric malates. The enantiomeric excess (ee) of chiral malates can be quantified by both steady-state and time-resolved fluorescence, using either a conventional fluorescence microplate reader or fluorescence imaging. It offers a facile and sensitive method for high-throughput chiral discrimination. 相似文献
3.
Eu3+对山黧豆中的氨基酸及蛋白质代谢作用的研究 总被引:3,自引:1,他引:2
对山黧豆(Lathyrus sativus L.)幼苗整株,喷施一定浓度的Eu3+溶液吸收后,对其相关的生理指标进行测试,结果表明与水喷比较,根中丝氨酸、甘氨酸、丙氨酸、蛋氨酸、亮氨酸、脯氨酸、胱氨酸与对照持平,缬氨酸、酪氨酸、苯丙氨酸、组氨酸略有升高外,其余均低于对照;茎中除精氨酸、脯氨酸、色氨酸略高于对照外,其余均低于对照;叶中除蛋氨酸、色氨酸略高于对照外,其余均低于对照.游离氨基酸总量增加时,茎>根>叶,减少时,根<茎<叶.蛋白质含量经Eu3+ 处理茎中减少,根和叶中增加;水解酶比活性根>茎>叶;Na+、K+-ATPase活力却表现根>茎>叶的趋势.表明Eu3+ 对山黧豆生理活性代谢起到一定的调节作用. 相似文献
4.
Insights into the discrepant luminescence for BaSiO3:Eu2+ phosphors prepared by solid‐state reaction and precipitation reaction methods
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Jiao Xu Yang Zhao Jingjing Chen Zhiyong Mao Yanfang Yang Dajian Wang 《Luminescence》2017,32(6):957-963
Two synthesis routes, solid‐state reaction and precipitation reaction, were employed to prepare BaSiO3:Eu2+ phosphors in this study. Discrepancies in the luminescence green emission at 505 nm for the solid‐state reaction method sample and in the yellow emission at 570 nm for the sample prepared by the precipitation reaction method, were observed respectively. A detail investigation about the discrepant luminescence of BaSiO3:Eu2+ phosphors was performed by evaluation of X‐ray diffraction (XRD), photoluminescence (PL)/photoluminescence excitation (PLE), decay time and thermal quenching properties. The results showed that the yellow emission was generated from the BaSiO3:Eu2+ phosphor, while the green emission was ascribed to a small amount of Ba2SiO4:Eu2+ compound that was present in the solid‐state reaction sample. This work clarifies the luminescence properties of Eu2+ ions in BaSiO3 and Ba2SiO4 hosts. 相似文献
5.
Non‐cytotoxic and green‐emitting fluorescent hydrogels were constructed from a cellulose solution containing Ba2MgSi2O7:Eu2+ green phosphor in a NaOH/urea aqueous system. The structure, optical properties and cytotoxicity of these hydrogels were studied. The Ba2MgSi2O7:Eu2+ phosphor particles were dispersed evenly in the cellulose hydrogel matrix. Good luminescent properties of Ba2MgSi2O7:Eu2+ phosphor were maintained in the hydrogels, leading to strong green emission under ultraviolet excitation. Fluorescent hydrogels have no obvious cytotoxicity in a 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide (MTT) proliferation test, and have potential use in in vivo applications like optical imaging and drug delivery. 相似文献
6.
Hui Wang Lingling Wang Meihua Wu Minghao Fang Zhaohui Huang Xin Min 《Luminescence》2023,38(2):208-215
This paper reports a sequence of a Ca3YAl3B4O15:xEu3+ red phosphor prepared using a high-temperature solid-state reaction. At the excitation of 396 nm, the samples emitted intense red emission centred at ~623 nm, which could be attributed to the 5D0→7F2 transition of the Eu3+ ion. The results showed that the optimum Eu3+ doping concentration of Ca3YAl3B4O15:Eu3+ phosphor was x = 80 mol%, and the concentration quenching mechanism of Ca3YAl3B4O15:Eu3+ red phosphor belonged to the exchange coupling between Eu3+ ions. The Commission Internationale de l'éclairage (CIE) coordinates and colour purity of Ca3Y0.2Al3B4O15:0.8Eu3+ were calculated as (0.6375, 0.3476) and 95.5%, respectively. Moreover, the red emission of the obtained phosphor Ca3YAl3B4O15:0.8Eu3+ exhibited a low thermal quenching behaviour with an intensity retention rate of 92.85% at 150°C. The above results manifest that the Eu3+-activated Ca3YAl3B4O15 phosphor is predicted to be a promising red luminescent component for white light-emitting diodes. 相似文献
7.
Due to the advantages of good physicochemical properties, thermal stability, and optical properties, double perovskite compounds have received extensive attention. On this basis, a new type of red phosphor, Ca2YNbO6:xEu3+, was synthesized using a high-temperature solid-phase method. Its phase purity, morphology, elemental composition, absorption spectrum, photoluminescence, thermal stability, and Commission Internationale de l'éclairage (CIE) chromaticity coordinates were thoroughly investigated. The results display that there is no impurity phase in the samples and the convergence factor Rwp = 14.2%; the microscopic particles are uniform and full, and the distribution of each element is uniform. The energy band gap ΔE is between 3.71 eV and 3.65 eV. The luminescence intensity is the best when the doped Eu3+ concentration x reaches 0.4, and emits 612 nm red light (5D0→7F2) under 465 nm excitation, and the concentration quenching is attributed to a d–d interaction. The luminescence intensity at 425 K was still 75% of the room temperature luminescence intensity, which indicates that the thermal stability is extremely superior. The CIE chromaticity coordinates (0.6534, 0.3455) of the Ca2YNbO6:0.4Eu3+ phosphors are very close to National Television Standards Committee (0.670, 0.330), and the samples have low correlated colour temperature (2656 K) and high colour purity (99.90%). All findings suggest that Ca2YNbO6:Eu3+ can serve as a substitute for red phosphor in WLEDs. 相似文献
8.
Formation of fluorescent carbon nanodots from kitchen wastes and their application for detection of Fe3+
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This work reports a scalable synthesis of water‐dispersible fluorescent carbon nanodots based on the simple hydrothermal method (180 °C for 6 h) of kitchen wastes (grape peel for example). We discuss the feasibility of synthesis from kitchen wastes both experimentally and theoretically, and the as‐prepared nanodots have high selectivity for Fe3+ ions based on fluorescence quenching which is due to the complexes between nanodots and metal ions. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
9.
A novel method for chiral identification of glutamine enantiomers based on chiral carbon quantum dots (cCQDs) fluorescent probes. cCQDs were prepared using a one-step hydrothermal method with L-tryptophan as the carbon source and chiral source, producing spherical nanoparticles exhibiting a blue colour luminescence. The fluorescence intensity (F) of cCQDs was enhanced or quenched following the addition of chiral enantiomeric glutamine (L/D-Gln), and therefore cCQDs, as a fluorescence probe, could be used for enantioselective sensing of the L/D-Gln. The fluorescence enhancement value (∆FE) exhibited good linearity with L-Gln concentration in the range 0.23–10.00 mM, and the limit of detection was 0.14 mM. The fluorescence quenching value (∆FQ) showed a good linear relationship with D-Gln concentration in the range 0.29–10.00 mM, and the detection limit was 0.18 mM. The mechanism of fluorescence enhancement/quenching was explored by molecular modelling and the type of quenching. The method was applied to the determination of L-Gln content in real samples, and the recovery rate was satisfactory. This study provided a novel approach for the synthesis of cCQDs and the recognition of amino acid enantiomers. 相似文献
10.
This study synthesized BaMoO4:Eu3+ red phosphors using the microwave method. In addition, the phase composition, morphology, and luminescence properties of the red phosphors were characterized using X-ray diffraction, field-scanning electron microscopy, and photoluminescence spectroscopy. The results revealed that doping red phosphors with different concentrations of Eu3+ does not change the crystal structure of the matrix material. The BaMoO4:Eu3+ phosphors exhibited micron-scale irregular polyhedra, which could be excited by ultraviolet light with a wavelength of 395 nm to induce red-light emission. The optimal dosage of Eu3+ was 0.08, and the chromaticity coordinates of BaMoO4:0.08Eu3+ phosphors were (0.5869, 0.3099). White light-emitting diode (w-LED) devices manufactured by using a combination of BaMoO4:0.08Eu3+ phosphor and commercially available phosphors exhibited good white-light emission under the excitation of an ultraviolet chip. The BaMoO4:0.08Eu3+ red phosphors that rapidly synthesized under the microwave field are expected to be used in w-LED devices. 相似文献
11.
White-light-tunable LaMgAl11O19:x%Tb3+, y%Eu3+ series phosphors were prepared using the gel-combustion method. The structure and luminescence properties were studied, and the energy transfer of Eu3+ and Tb3+ in the LaMgAl11O19 system was also discussed. The results showed that the LaMgAl11O19 matrix exhibited strong emission in the blue-light region under the excitation of ultraviolet light, which resulted in conditions suitable for the preparation of white-light-tunable phosphors. The emission spectra of LaMgAl11O19:2%Tb3+, y%Eu3+ (y = 2%–9%) series phosphors were obtained through optimization experiments. It could be seen from the CIE diagram that by adjusting the doping quantities of Eu3+ and Tb3+ in the LaMgAl11O19 host, multicolor luminescence and white light emission in a single host could be achieved. By calculating the energy transfer efficiency and critical distance between Eu3+ and Tb3+ series phosphors, the mechanism of energy transfer between Tb3+ and Eu3+ was found to be the interaction between electric quadruples. 相似文献
12.
The new borate phosphor CaB2O4:Eu3+ was synthesized by solid‐state method and their photoluminescence properties were investigated. The results show that the pure phase of CaB2O4 could be available at 900°C, CaB2O4:Eu3+ phosphor could be effectively excited by the near ultraviolet light (NUV) (392 nm), and the luminescent intensity of CaB2O4:Eu3+ phosphor reached to the highest when the doped‐Eu3+ content was 4 mol%. The emission spectra of CaB2O4:Eu3+ phosphor could exhibit red emission at 612 nm and orange emission at 588 nm, which are ascribed to the 5D0–7F2 and 5D0–7F1 transitions of Eu3+ ions. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
13.
An orange‐emitting phosphor, Eu2+‐activated LiSr4(BO3)3, was synthesized using the conventional solid‐state reaction. The photoluminescence excitation and emission spectra, and temperature dependence of the luminescence intensity of the phosphor were investigated. The results showed that LiSr4(BO3)3:Eu2+ could be efficiently excited by incident light of 250–450 nm, and emits a strong orange light. With increasing temperature, the emission bands of LiSr4(BO3)3:Eu2+ show an abnormal blue‐shift with broadening bandwidth and decreasing emission intensity. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
14.
Highly efficient red‐emitting phosphors, CaAlSiN3:Eu2+, were successfully prepared by the solid‐state method using calcium cyanide (CaCN2) as the single calcium source. The influences of crystallization temperature, crystallization time, calcination mode and compounds ratio on the photoluminescent properties were investigated. The CaAlSiN3:Eu2+ phosphors were obtained with 1 mol% CaCN2 by a two‐step calcination procedure at 900°C for 2 h and subsequently at 1600°C for 8 h. The CaAlSiN3:Eu2+ phosphors showed the strongest luminescent intensity at 660 nm when excited by 468 nm. With an increase in crystallization time, the maximum wavelength of the emission was shifted from 644 nm to 660 nm. 相似文献
15.
Persistent luminescence of CaMgSi2O6:Eu2+,Dy3+ and CaMgSi2O6:Eu2+,Ce3+ phosphors prepared using the solid‐state reaction method
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CaMgSi2O6:Eu2+,Dy3+ and CaMgSi2O6:Eu2+,Ce3+ phosphors were synthesized using the solid‐state reaction method. X‐Ray diffraction (XRD) and photoluminescence (PL) analyses were used to characterize the phosphors. The XRD results revealed that the synthesized CaMgSi2O6:Eu2+,Dy3+ and CaMgSi2O6:Eu2+,Ce3+ phosphors were crystalline and are assigned to the monoclinic structure with a space group C2/c. The calculated crystal sizes of CaMgSi2O6:Eu2+,Dy3+ and CaMgSi2O6:Eu2+,Ce3+ phosphors with a main (221) diffraction peak were 44.87 and 53.51 nm, respectively. Energy‐dispersive X‐ray spectroscopy (EDX) confirmed the proper preparation of the sample. The PL emission spectra of CaMgSi2O6:Eu2+,Dy3+ and CaMgSi2O6:Eu2+,Ce3+ phosphors have a broad band peak at 444.5 and 466 nm, respectively, which is due to electronic transition from 4f65d1 to 4f7. The afterglow results indicate that the CaMgSi2O6:Eu2+,Dy3+ phosphor has better persistence luminescence than the CaMgSi2O6:Eu2+,Ce3+ phosphor. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
16.
Temperature‐controlled down‐conversion luminescence behavior of Eu3+‐doped transparent MF2 (M = Ba,Ca, Sr) glass ceramics
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Eu3+‐doped transparent glass ceramics containing MF2 (M = Ba, Ca, Sr) nanocrystals were fabricated using a melt–quenching method, and the resulting structures were studied using X‐ray diffraction. Levels 5D1 and 5D0 of Eu3+ ions were verified as thermally coupled levels using the fluorescence intensity ratio method. The fluorescence intensity ratios, optical temperature sensitivity and thermal quenching ratios of the transparent glass ceramics were studied as a function of temperature. With an increase in temperature, the relative sensitivity (S R) decreased sharply at first, then slowly increased, before finally decreasing. The minimum S R values of GCBaF2 (GCB), GCCaF2 (GCC) and GCSrF2 (GCS) were 2.8 × 10?4, 0.8 × 10?4 and 1.9 × 10?4 K?1 at 360, 269 and 319 K, respectively. Glass ceramics with an intense emission intensity can be used to convert the measured spectrum into temperature and may have an important role in temperature detectors. 相似文献
17.
For the manufacture of hollow nanospheres that had different shapes, three distinct templates—urea, carbon microspheres, and polyethylene glycol 20,000—were used. The relationship between microspheres with various hollow structures and their luminescent properties were investigated. Furthermore, the effects of annealing temperature and the proportion of rare earth Eu3+/Tb3+ions in the reaction were investigated using the structural characteristics of the microspheres and fluorescent materials. The fluorescent materials were wrapped on the outer surface of the microspheres. The ideal balance between the best structure and superior luminescent performance was found, to create reasonably good white light. 相似文献
18.
Three Rhodamine B derivatives were synthesized and characterized by ESI‐MS, NMR, HR‐MS and IR. The probes exhibit high selectivity and sensitivity towards Fe3+ over other metal ions in CH3CN–water. Upon the addition of Fe3+, the spirocyclic ring of the probe was opened and a significant enhancement of visible color and fluorescence within the range of 540–700 nm was observed. The colorimetric and fluorescent response to Fe3+ can be conveniently detected even by the naked eye, which provides a facile method for the visual detection of Fe3+. Job's plot, fluorescence titration and MS indicated the formation of 1:2 complexes between the probes and Fe3+. The reversibility of the reaction establishes the potential of these probes as chemosensors for Fe3+ detection. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
19.
A facile chemical method was employed to prepare fine BiPO4:Eu3+ phosphor particles calcined at the same temperature. Introducing lithium greatly affected the morphology of the samples and further affected the luminescence intensity. The samples were characterized by X‐ray diffraction (XRD), scanning electron microscopy (SEM) and photoluminescence (PL) spectroscopy. The XRD patterns of BiPO4:Eu3+ indicated a monoclinic phase. From the fluorescence spectra, the emission transition 5D0 → 7F1 is more prominent than the normal red emission transition 5D0 → 7F2. Based on the intensity ratios of 5D0 → 7F2 to 5D0 → 7F1 in the emission spectra, it can be concluded that introducing Li+ can improve the symmetry of the crystal lattice and modify the emission intensity. Sharp lines at 395 nm are the strongest of the f–f transitions and match well with near‐UV LED chips. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
20.
Structural,morphological and steady state photoluminescence spectroscopy studies of red Eu3+‐doped Y2O3 nanophosphors prepared by the sol‐gel method
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Lyes Lamiri Lakhdar Guerbous Madani Samah Allaoua Boukerika Salim Ouhenia 《Luminescence》2015,30(8):1336-1343
Europium trivalent (Eu3+)‐doped Y2O3 nanopowders of different concentrations (0.5, 2.5, 5 or 7 at.%) were synthesized by the sol‐gel method, at different pH values (pH 2, 5 or 8) and annealing temperatures (600°C, 800°C or 1000°C). The nanopowders samples were characterized by X‐ray diffraction (XRD), field emission scanning electron microscopy (FE‐SEM), Fourier transform infrared spectroscopy (FT‐IR) and steady state photoluminescence spectroscopy. The effect of pH of solution and annealing temperatures on structural, morphological and photoluminescence properties of Eu3+‐doped Y2O3 were studied and are discussed. It was found that the average crystallite size of the nanopowders increased with increasing pH and annealing temperature values. The Y2O3:Eu3+ material presented different morphology and its evolution depended on the pH value and the annealing temperature. Activation energies at different pH values were determined and are discussed. Under ultraviolet (UV) light excitation, Y2O3:Eu3+ showed narrow emission peaks corresponding to the 5D0–7FJ (J = 0, 1, 2 and 3) transitions of the Eu3+ ion, with the most intense red emission at 611 assigned to forced electric dipole 5D0→7F2. The emission intensity became more intense with increasing annealing temperature and pH values, related to the improvement of crystalline quality. For the 1000°C annealing temperature, the emission intensity presented a maximum at pH 5 related to the uniform cubic‐shaped particles. It was found that for lower annealing temperatures (small crystallite size) the CTB (charge transfer band) position presented a red shift. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献