Luminescence Enhancement Effect Research Articles

A Turn‐On Fluorescence Probe Based on a New Salamo‐Co (II) Coordination Polymer for Tyrosine Detection and Its Application in Water Samples

ABSTRACTA novel salamo‐Co (II) coordination polymer probe CP was synthesized firstly, and its crystal structure, [Co3(L)2(PTA)(H2O)2]n·4nDMF, was determined by X‐ray diffraction analysis. The probe has a rare aggregation‐induced luminescence enhancement (AIEE) effect. When applied to amino acid detection, it was found to have a high selective recognition of tyrosine. With the increase of tyrosine, the fluorescent strength of the probe was enhanced in a short period of time. In addition, the binding ratio of probe to Tyr was determined by fluorescence titration experiment, and the detection limit LOD of probe CP for Tyr was calculated to be 2.57 × 10−9 M, and the binding constant Ka was 2.96 × 105 M−1. According to UV absorption spectrum, FT‐IR spectra, ESI mass spectrometry, and DFT calculation, it was speculated that Tyr can bind to the probe after adding Tyr into the probe solution, triggering FRET and ICT effects, resulting in increased fluorescence intensity and blue shift, and finally achieving the specific recognition of tyrosine by probe CP. Finally, the practical application of probe CP was studied. Through strip test and real water sample test, it was found that the probe can be used for qualitative and quantitative analysis of tyrosine.

Overcoming surface quenching in persistent luminescence nanoparticles with organic ligand coordination: Implications for enhanced optical imaging

Persistent luminescence nanoparticles (PLNPs) have been considered as excellent luminescent tools for sensitive optical imaging. However, the persistent luminescence (PL) properties of PLNPs are usually suppressed due to severe surface quenching caused by nanoscale size. Despite considerable efforts, the understanding of surface quenching mechanisms remains a challenge. Here we report a surface ligand coordination method to enhance the PL properties of ZnGa2O4:Al,Cr (ZGO:AC) PLNPs. ZGO:AC PLNPs coated with organic ligands containing carboxyl groups show enhanced PL intensity and prolonged decay time. Among the six ligands, the phthalic acid (PA) ligands yielded the largest luminescence enhancement effect, on which the PL intensity and decay time increased 3 and 2 times compared with ligand-free ZGO:AC PLNPs, respectively. Density functional theory (DFT) calculations and detailed characterizations demonstrated that surface quenching is suppressed due to the coordination of non-saturated Ga ions and -COO- of ligands. Finally, ZGO:AC@PA PLNPs were applied in autofluorescence-free bioimaging and exhibited high imaging sensitivity and contrast ratio. These findings provide insights into the surface quenching mechanisms of PLNPs and offer a platform for developing highly emissive PLNPs on nanoscale.

Luminescence enhancement of Y2O3 thin films based on LSPR effect of Ag nanolayers

Based on the local surface plasmon resonance effect of Ag nanolayer, the luminescence enhancement in the visible light range of multilayer thin film has been investigated combined with metal/spacer molecule/photoluminescence material structure. The luminescence enhancement effect of multilayer thin films can be improved by adjusting the spin-coating number of Ag nanolayer and SiO2 spacer in the multilayer structure. At the same time, the mechanism of enhanced luminescence has been analyzed according to the change in fluorescence lifetime. The effect of the coupling between Ag nanolayer and luminescence layer on the radiative transition rate and fluorescence quantum yield have been discussed. The up-conversion luminescence intensity of the noble metal-modified multilayer thin film can be further improved by combining the multilayer structure with sensitized layer.

1,2,3-Triazol-5-ylidene- vs. 1,2,3-triazole-based tricarbonylrhenium(I) complexes: influence of a mesoionic carbene ligand on the electronic and biological properties.

The tricarbonylrhenium complexes that incorporate a mesoionic carbene ligand represent an emerging and promising class of molecules, the solid-state optical properties of which have rarely been investigated. The aim of this comprehensive study is to compare three of these complexes with their 1,2,3-triazole-based analogues. The Hirshfeld surface analysis of the crystallographic data revealed that the triazolylidene derivatives are more prone to π-π interactions than their 1,2,3-triazole-based counterparts. The FT-IR and electrochemical data indicated a stronger electron donor effect from the organic ligand to the rhenium atom for triazolylidene derivatives, which was confirmed by DFT calculations. All compounds were phosphorescent in solution, where the 1,2,3-triazole-based complexes showed unusually strong dependence on dissolved oxygen. All compounds also emitted in the solid state, some of them exhibited marked solid-state luminescence enhancement (SLE) effect. The 1,2,3-triazole based complex Re-Phe even displayed astounding photoluminescence efficiency with quantum yield up to 0.69, and proved to be an excellent candidate for applications linked to aggregation-induced emission (AIE). Interestingly, one triazolylidene-based complex (Re-T-BOP) showed attractive antibacterial activity. This study highlights the potential of these new molecules for applications in the fields of photoluminescent and therapeutic materials, and provides the first bases for the design of efficient molecules in these research areas.

Rapid and Specific Enhanced Luminescent Switch of Aniline Gas by MOFs Assembled from a Planar Binuclear Cadmium(II) Metalloligand.

Due to the low vapor pressure of aniline, it is challenging to develop a specific rapid fluorescence detection material for low concentrations of aniline gas, which is suspected to result in carcinogenicity when people are exposed by ingestion, inhalation, and skin contact. Herein, the easy-preparing Schiff base ligands were employed to construct the binuclear cadmium(II) compounds featuring a good plane and fine luminescent property, and then, the end groups were changed, making the compounds metalloligands to further build the 3D metal-organic frameworks (MOFs), named MECS-2. It is found that MECS-2 can achieve specific luminescent enhancement response for aniline gas. Furthermore, a large-scale MECS-2a film could be easily prepared by electrospinning nanoMECS-2, which presents the highly efficient and visual detection for aniline gas with the luminescent enhancement effect up to 20 times and good repeatability. Our work provides a good example for the efficient construction of MOF-based films with the fluorescence detection function for organic aromatic gases.

Exciton-like luminescence of KCl matrix under thermoelastic, local and uniaxial deformation

The radiative relaxation of exciton-like formations in KCl-Na single crystal has been studied by experimental methods of luminescent spectroscopy. The amplifying effect of the radiation intensity with a maximum at 2.8 eV up to 500 times as compared to pure KCl has been detected in KCl-Na. The luminescence efficiency of an exciton-like formation increases with rise in: sodium ions concentration ( 10 ÷ 1000 ppm), thermal exposure ( 500◦C ÷ 600◦C ) and the degree of uniaxial deformation along <100> and <110> crystallographic directions. Previously, such a scale of the luminescence enhancement effect has not been registered in KCl matrix at room temperature. At high sodium concentrations (1000 ppm) in KCl-Na crystals, the additional intense emission with a maximum at 3.1 eV has also been revealed, which is typical for pair sodium ions. It is interpreted that the exciton-like formation in the sodium field with the maximum quantum yield of luminescence is formed by recombination assembly of electron-hole pairs due to the mobility of unrelaxed holes.

Luminescent properties of spatially ordered Ge/Si quantum dots epitaxially grown on a pit-patterned “silicon-on-insulator” substrate

The results of studying the luminescent properties of epitaxially grown structures with spatially ordered Ge/Si nanoislands (quantum dots), in which the pit-patterned “silicon-on-insulator” substrates serve both for the spatial ordering of quantum dots and for the two-dimensional photonic crystal formation, are presented. It is found that with a certain choice of pit-patterned substrate parameters (diameter of pits and their spatial period), in the photoluminescence spectra of such structures, the multiple narrow peaks are observed. In addition, a significant increase in the quantum dot luminescence signal intensity occurs in the near-infrared range. The effects are related to resonance interaction of quantum dot emitters with photonic crystal modes. The luminescence enhancement effect persists up to room temperatures.

Crystallization‐Enhanced Stability by Effectively Suppressing Photooxidation Defect for Optoelectronic Devices

AbstractEffective protection against photooxidation of organic wide‐bandgap semiconductors is a potential method to afford high efficient deep‐blue emission for full color displays. Herein, the crystallization effect of fluorene‐based blue emitter on suppressing the formation of long‐wavelength green band (g‐band) defect is demonstrated through the model of self‐assembled organic micro/nanocrystals. The selected molecule 2,2'‐bi(9,9‐dipropyl)fluorene (DDC3F), which easily generates strong g‐band emission (green index (Igreen/Iblue) of ≈5 under ultraviolet exposure for 3 h) in amorphous state, shows an excellent spectra stability of deep‐blue emission with a green index of ≈0 and an unchangeable CIE coordination of (0.18, 0.09) in crystalline nanorod morphologies. Such effect of crystallization‐induced stability enhancement can be further extended into other solution‐processing methods such as brushing. Molecular dynamic simulation reveals that crystalline nanorods with compact molecular packing enable to effectively block the diffusion of O2 and H2O molecules, which is crucial to suppress the occurrence of photooxidation reactions. Along with high quantum yield of 87% from crystallization‐induced luminescence enhancement effect, such ultrastable deep‐blue emission on crystalline film can also be maintained in solution‐processing organic light‐emitting diode devices. The supramolecular self‐assembled micro/nanocrystals strategy provides a potential platform to maintain ultrastable color purity in organic optoelectronic devices.

Amphiphilic Au Nanoclusters Modulated by Magnetic Gemini Surfactants as a Cysteine Chemosensor and an MRI Contrast Agent

Cationic magnetic Gemini surfactants (mag-G-surfs), [C14H29(CH3)2N(CH2)2N(CH3)2C14H29]2+·2[XCl3Br]- (14-2-14·2X, X = Ce, Gd, or Ho), efficiently induce the aggregation of glutathione-protected Au nanoclusters (NCs) (GSH-Au NCs). These magnetic luminescent aggregates not only possess aggregation-induced emission (AIE) behavior but also display aggregation-induced magnetic enhancement. In particular, 14-2-14·2Ce and 14-2-14·2Gd have a better effect on boosting the luminescence intensity, quantum yield (QY), and luminescence lifetime (τ). The luminescent aggregates of GSH-Au NCs triggered by 14-2-14·2Gd or 14-2-14·2Ho exhibit more favorable paramagnetic behavior. Other Au NCs containing a Au(I)-thiolate complex shell also exhibit the obvious AIE phenomenon after introducing 14-2-14·2Gd, demonstrating the luminescence enhancement effect of mag-G-surfs. The luminescent aggregate 14-2-14·2Ce@GSH-Au NCs can serve as a "light up" fluorometric probe to detect cysteine selectively with the detection limit (DL) of 36 μM, and the magnetic luminescent aggregate 14-2-14·2Gd@GSH-Au NCs has the potential to be a novel contrast agent in T1-weighted magnetic resonance (MR) imaging due to its satisfactory contrasting ability.

Effect of M3+ (M = Bi, Al) co-doping on the luminescence enhancement of Ca2ZnSi2O7:Sm3+ orange-red−emitting phosphors

In this paper, the luminescence properties of Ca2ZnSi2O7:Sm3+ phosphors were improved by co-doping with M3+ (M = Bi, Al) via the sol-combustion method. The structure and luminescence properties of the Ca2ZnSi2O7:Sm3+, M3+ samples were investigated in detail, especially the luminescence enhancement effect of Bi3+/Al3+ co-doping. XRD results indicated that moderate Bi3+/Al3+ co-doping in the host structure did not change the tetragonal structure of Ca2ZnSi2O7. The series of Ca2ZnSi2O7:Sm3+, M3+ phosphors could be excited by 402 nm near-ultraviolet light and several significant emission peaks were obtained at 567, 604 and 650 nm, which originated from the electron transitions of Sm3+ from 4G5/2 to 6H5/2, 6H7/2 and 6H9/2 levels, respectively. The luminescence intensity of Ca2ZnSi2O7:Sm3+ was markedly enhanced through Bi3+/Al3+ co-doping, which could be explained by Al3+ decreasing the crystal field symmetry and greatly increasing the red luminescence intensity, and Bi3+ functioning as a sensitizer to increasing the luminescence intensity through energy transfer from Bi3+ to Sm3+ ions. In conclusion, the excellent Ca2ZnSi2O7:Sm3+, M3+ phosphors have potential application as red phosphors in white light emitting diodes.

Discrimination of Various Amine Vapors by a Triemissive Metal-Organic Framework Composite via the Combination of a Three-Dimensional Ratiometric Approach and a Confinement-Induced Enhancement Effect.

Multiemissive sensors are being actively pursued, because of their ratiometric luminescent detection capabilities, which demonstrates better sensitivity and selectivity than conventional single-emission sensors. Herein, we present a trichromatic white-light-emitting metal-organic framework (MOF) composite (Z3) by simultaneously incorporating red/green-emitting Pt/Ru complex cations into porous blue-emitting bio-MOF-1 through post-synthetic modification. With the help of a three-dimensional (3-D) dual-ratiometric luminescence recognition method, and unique turn-on responses of the red emission toward amine compounds (ACs), including NH3 and aliphatic amines, via confinement-induced luminescence enhancement effect, Z3 can work as a dual-ratiometric luminescent sensor for discrimination of 7 out of 11 AC vapors. This work not only provides a new AC sensing mechanism (confinement effect) that can induce a "turn-on" response but also proves that the accuracy and selectivity of composite sensor can be greatly improved through the combination of 3-D recognition method and the confinement effect. Thus, it open up fresh opportunities to develop composite sensors with excellent sensing and differentiating ability.

Design of a Highly-Stable Pillar-Layer Zinc(II) Porous Framework for Rapid, Reversible, and Multi-Responsive Luminescent Sensor in Water

The hard–soft-acid–base (HSAB) and dual-ligand strategies have been used to construct a pillar-layer luminescent metal–organic framework (MOF) {[Zn2(TRZ)2(DBTDC-O2)]·DMAc}n (1), in which H2DBTDC-O2 = S,S-dioxodibenzothiophen-3,7-dicarboxylic acid and HTRZ = 1,2,4-triazole. Thanks to its high stability in water and quadrangle microporous channels, MOF 1 can be served as a platform of recyclable multi-responsive luminescent sensor for Fe3+, Al3+, SiF62–, Cr2O72–, nitrofurantoin (NFT), and nitrofurazone (NFZ) in water. This is the first MOF-based sensor for detecting SiF62– anion via luminescent enhancement effect. Significantly, 1 also represents a unique example to probe NFZ or NFT by using transition metal MOFs in water, which exhibits the most sensitive sensing ability for NFZ (Ksv = 5.2 × 104 M–1) and NFT (Ksv = 1.8 × 105 M–1) via luminescent quenching.

2,6-Diamino-1-N-methylpyrimidine as new fluorescent probe for palladium(II) determination using hyphenated technique

The selective and sensitive hyphenated technique for Pd(II) fluorescence and spectrophotometric determination was proposed. The procedure was based on preliminary solid-phase extraction of [PdCl4]2− onto silica modified with quaternary ammonium salts, with the subsequent elution from the surface by 2,6-diamino-1- N-methylpyrimidine solution and measurement of the fluorescence intensity. The luminescence enhancement effect of 2,6-diamino-1- N-methylpyrimidine in the presence of Pd(II) due to the complex formation was applied to the development of sorption-spectroscopic techniques for detecting trace amounts of palladium in solution.

Enhancement of near-infrared to near-infrared upconversion luminescence in sub-10-nm ultra-small LaF(3):Yb(3+)/Tm(3+) nanoparticles through lanthanide doping.

In this Letter, I present a versatile strategy to enhance the near-infrared to near-infrared (NIR-to-NIR) upconversion luminescence from sub-10-nm ultra-small LaF(3):Yb(3+)/Tm(3+) colloidal nanoparticles through lanthanide doping under 980 nm laser excitation. It is interesting that the NIR-to-NIR upconversion emission at 801 nm of LaF(3):Yb(3+)Tm(3+) nanoparticles can be improved by increasing the Tm(3+) doping concentration or by introducing another lanthanide activator (Er(3+) or Ho(3+)) as a sensitizer. The luminescence enhancement effect showed a strong dependence on the doping concentrations of activator ions (Tm(3+), Er(3+), or Ho(3+)). Particularly, adding 1 mol. % Ho(3+) ions into LaF(3):Yb(3+)Tm(3+) nanoparticles induced a 2.85-fold enhancement in NIR 801 nm emission of Tm(3+) ions. The related upconversion emission mechanisms were investigated and discussed.

Cyclometalated Platinum(II) Terpyridylacetylide with a Bis(arylamine) Donor as a Proton-Triggered Luminescence Chemosensor for Zn(2+).

A cyclometalated Pt(II) acetylide derivative bearing a bis(arylamine) donor (D) and a terpyridine (TPY) receptor (A) was successfully synthesized and characterized. This three-component D-π-A system displays an intense low-energy absorption band at λmax = 470 nm, resulting from overlapping the dπ(Pt) → π*(C^N^N) metal-to-ligand charge transfer and π(C≡C-Ar) → π*(C^N^N) ligand-to-ligand charge transfer transitions with the π(bis(arylamine)) → π*(C^N^N) intraligand charge transfer transition. Upon protonation of the bis(arylamine) donor, a strong emission from the phosphorescence Pt(II) complex unit is recovered at λmax = 580 nm. With introduction of the TPY receptor, this complex possesses quite high affinity for Zn(2+) (Ka = 6.86 × 10(9) mol(-2)·dm(6)) to form the heterotrinuclear Pt-Zn-Pt complex in CH2Cl2 solution. Though this coordination effect is seriously inhibited by protons in acidic medium, the 2.4-fold luminescence intensity enhancement is obtained yet, strongly suggesting the presence of the intramolecular energy transfer process from the Zn(II)-TPY complex core to the phosphorescence Pt(II) complex units at two ends. The H(+)-triggered and Zn(2+)-enhanced luminescence can be reversibly switched on and off upon successive additions of H(+) and OH(-). Furthermore, this complex displays an unexpected Zn(2+)-selective luminescence enhancement effect in acidic solution.

The mechanism of enhanced luminescence in ion-codoped Lu2SiO5:Ce3+ phosphors

(Lu0.995−xMxCe0.005)2SiO5 (M=Li, Mg and Sc, x=0.00–0.01) phosphors were synthesized via a sol–gel technique, the luminescence enhancement effect by Li+, Mg2+, or Sc3+ codoping is comprehensively investigated by XRD, Raman, thermoluminescence and X-ray absorption near edge structure (XANES) spectra. The underlying reason of enhanced luminescence by ion codoping is revealed, and a mechanism of the luminescence enhancement effect based on the valence state variation of cerium is proposed. It can be safely concluded that the enhanced luminescence of Lu2SiO5:Ce3+ by ion codoping essentially originates from the increase in the population of Ce3+, which is directly proved by XANES. The difference in luminescence enhancement effect for different codopants can be reasonably explained by the electronegativity of the codopant.

Selective Binding of Amino Acids on Europium‐Substituted Polyoxometalates and the Interaction‐Induced Luminescent Enhancement Effect

AbstractA europium‐substituted polyoxometalate (K13[Eu(SiW10MoO39)2]⋅28 H2O, EuSiWMo) can selectively bind to basic amino acids, namely, lysine, arginine, and histidine, and induce the emission enhancement of Eu3+ significantly. The mechanism is attributed to electrostatic interactions and hydrogen bonds between basic residues of the amino acids and negative charges of EuSiWMo based on the 1H NMR titration spectra of amino acids and time‐resolved fluorescence decay curves of EuSiWMo.

Enhancing NIR emission of Yb3+ by silver nanoclusters in oxyfluoride glass

Oxyfluoride glass comprising Yb3+ ions and Ag nanoclusters was prepared via a melt-quenching method. The molecule-like Ag clusters (ML-Ag) in the glass displayed broad absorption and emission bands in the ultraviolet (UV) and visible spectral regions, respectively. The luminescence quantum yield (QY) was determined to be higher than 90%. We observed energy transfer from ML-Ag nanoclusters to Yb3+ ions as evidenced by time resolved luminescence spectra, which resulted in a four-fold enhancement in NIR emission of Yb3+. The luminescence enhancement effect described here would be applied to boost the efficiency of solar cells by converting high energy UV photons into NIR photons that better match the absorption of photovoltaic devices.

Enhanced luminescence induced by change of cerium oxidation states in Li-codoped Lu2SiO5:Ce3+ phosphors

(Lu0.995−xCe0.005Lix)2SiO5 (x=0.0000–0.0100) phosphors were synthesized by sol–gel route, the luminescence intensity of the phosphor was improved by a factor of 2.3 at x=0.01 in comparison with the Li-free sample. This luminescence enhancement effect has been investigated by Ce LIII-edge X-ray absorption near edge structure spectroscopy. The underlying reason of enhanced luminescence was revealed. It is safely concluded that the enhanced luminescence by Li+ codoping in Lu2SiO5:Ce3+ phosphors is originated from the increase of the population of Ce3+. This result could also help us to understand the luminescence enhancement effect by Ca2+, Mg2+ or Na+ codoping in Lu2SiO5:Ce3+ phosphors.

Highly Sensitive Luminescence Assessment of Bile Acid Using a Balofloxacin-Europium(III) Probe in Micellar Medium

E-mail: nlz837037@163.comReceived August 5, 2012, Accepted September 28, 2012A novel and simple method of luminescence enhancement effect for the determination of trace amounts of bileacid was proposed. The procedure was based on the luminescence intensity of the balofloxacin-europium(III)complex that could be strongly enhanced by bile acid in the presence of sodium dodecyl benzene sulfonate(SDBS). Under the optimum conditions, the enhanced luminescence intensity of the system exhibited a goodlinear relationship with the bile acid concentration in the range 5.0 × 10