High Luminescence Quantum Yield Research Articles

Bright chemiluminescent dioxetane probes for the detection of gaseous transmitter H2S

Hydrogen sulfide (H2S), the third gaseous transmitter after CO and NO, is a double-edged sword in the human body. A specific concentration of H2S can attenuate myocardial ischemia–reperfusion injury by preserving mitochondrial function, in contrast, cause illness, including inflammation and stroke. There are already some probes for the real-time monitoring of the level of H2S in the biological environment. However, they have some disadvantages, such as phototoxicity, low sensitivity, and low quantum yield. In this research, by linking 4-dinitrophenyl-ether (DNP), a specific recognition group for H2S, with a chemiluminophore 1,2-dioxetane, we designed and synthesized the probe SCL-1. To tackle the barrier that the traditional chemiluminescent group has a short emission wavelength and is not easy to penetrate deep tissues, an acrylonitrile electron-withdrawing substituent was installed to the ortho-position of the 1,2-dioxanol hydroxy group. According to the same design strategy as SCL-1, the probe SCL-2 was designed with the modified chemiluminescent group. Studies have shown that SCL-2 with electron-withdrawing acrylonitrile has higher luminescence quantum yield and high sensitivity than SCL-1, realizing real-time detection of H2S in vitro and in vivo. The LOD of SCL-2 was 0.185 μM, which was the best among the currently available luminescent probes for detecting H2S. We envisage that SCL-2 may be a practical toolbox for studying the biological functions of H2S and H2S-related diseases.

Synthesis, crystal structure and photophysical properties of deep-blue emitting cationic iridium(III) complexes with 2ʹ,6ʹ-difluoro-2,3ʹ-bipyridine cyclometalated ligand and pyrazole-type ancillary ligands

In this work, we report three deep-blue emitting cationic iridium complexes Ir1–Ir3 with 2ʹ,6ʹ-difluoro-2,3ʹ-bipyridine cyclometalated ligand and pyrazole-type ancillary ligands. Synthesis, crystal structure, photophysical and electrochemical properties of Ir1–Ir3 are studied in detail. Ir1–Ir3 exhibit efficient phosphorescence emissions at 439, 438 and 437 nm with CIE 1931 coordinates of (0.14, 0.12), (0.14, 0.12) and (0.14, 0.13), and luminescence quantum yields of 0.35, 0.27 and 0.50 in CH2Cl2 solutions, respectively, which are among the highest levels of ever reported cationic iridium(III) complexes emitting deep-blue light. High luminescence quantum yields, excellent color purity and short lifetimes demonstrates the great potential of Ir1–Ir3 for light-emitting electrochemical cells (LECs) and solution-processable organic light-emitting diodes (OLEDs) as efficient blue emitters.

Оптические свойства 2,2’-дигидрокси-1,1’-нафталазина

Люминесцентные пигменты способны поглощать энергию естественных или искусственных источников света и выделять ее в форме видимого свечения в темноте. По химической природе люминофоры подразделяются на неорганические и органические. В отличие от неорганических люминофоров, светящихся только в твердом состоянии, органические люминофоры, в большинстве случаев, люминесцируют в различных агрегатных состояниях. Это различие обусловлено тем, что свечение связано с определенным строением кристаллической решетки, в которую входят активирующие добавки. После разрушения кристаллической решетки люминесценция исчезает. В случае органических люминофоров люминесцируют отдельные молекулы. Хорошо известно, что квантовый выход флуоресценции органических хромофоров обычно уменьшается в твердом состоянии, хотя они имеют высокий квантовый выход свечения в растворе.

Оптические свойства 2,2’-дигидрокси-1,1’-нафталазина

Luminescent pigments are able to absorb the energy of natural or artificial light sources and release it in the form of a visible glow in the dark. By chemical nature, phosphors are divided into inorganic and organic. Unlike inorganic luminophors, which glow only in the solid state, organic luminophors, in most cases, luminesce in various aggregate states. This difference is due to the fact that the glow is associated with a certain structure of the crystal lattice, which includes activating additives. After the destruction of the crystal lattice, luminescence disappears. In the case of organic luminophors, individual molecules luminesce. It is well known that the quantum yield of fluorescence of organic chromophores usually decreases in the solid state, although they have a high quantum yield of luminescence in solution.

Ancillary ligand modulated stereoselective self-assembly of triple-stranded Eu(iii) helicate featuring circularly polarized luminescence.

Creating optically pure metal assemblies is a hot research topic in the realms of chiral supramolecules. Here, three new triple-stranded europium(iii) helicates Eu2L3(L′)2 [L = 4,4′-bis(4,4,4-trifluoro-1,3-dioxobutyl)diphenyl sulphide; L′ = 1,10-phenanthroline (Phen) or R/S-2,2′-bis(diphenylphosphinyl)-1,1′-binaphthyl (R/S-BINAPO)] were synthesized in order to investigate the effects of ancillary ligands on controlling the stereoselective self-assembly of lanthanide helicates. X-ray single crystal structure analysis showed that Eu2L3(Phen)2 crystalized in an achiral space group P1̄ with the equivalent amount of P and M helicates in one single cell. The isolated Eu2L3(S-BINAPO)2 and Eu2L3(R-BINAPO)2 were verified to be enantiopure by 1H, 19F, 31P NMR and DOSY NMR analyses. Additionally, the mirror-image CD spectra also demonstrated the successful syntheses of the enantiomers and the presence of an effective chirality transformation from BINAPO to achiral L. Furthermore, the perfect mirror-image circularly polarized luminescence (CPL) spectra of Eu2L3(S-BINAPO)2 and Eu2L3(R-BINAPO)2 indicated the existence of the excited state chirality of the Eu3+ center associated with |glum| values reaching 0.112. In addition, the photophysical properties of three helicates were also discussed.

Electrochemiluminescence of water-dispersed nitrogen and sulfur doped carbon dots synthesized from amino acids.

A facile one-pot hydrothermal approach for synthesizing water-dispersed nitrogen and sulfur doped carbon dots (NS-CDs) with high luminescence quantum yield was explored, using cysteine and tryptophan as precursors. The NS-CDs were characterized by means of FT-IR spectroscopy, XRD, TEM, etc. It was found that the absolute photoluminescence quantum yield (QY) of the NS-CDs determined with an integrating sphere can reach up to 73%, with an average decay time of 17.06 ns. Electrochemiluminescence (ECL) behaviors and mechanisms of the NS-CDs/K2S2O8 coreactant system were investigated. When the working electrode was modified with the prepared NS-CDs, the ECL efficiency of the NS-CDs with K2S2O8 was 24%, relative to Ru(bpy)3Cl2/K2S2O8. This work shows great potential for the NS-CDs to be used in bioanalytical applications.

Ultrastrong Red Circularly Polarized Luminescence Promoted from Chiral Transfer and Intermolecular Förster Resonance Energy Transfer in Ternary Chiral Emissive Nematic Liquid Crystals

Chiral emissive liquid crystals (N*-LCs) have been proved to greatly amplify the circularly polarized luminescence (CPL) signals due to highly regular spiral arrangement of dyes in a well-organized liquid crystals system. Normally, CPL materials with a high luminescence dissymmetry factor (glum) and quantum yield (QY) can meet the real application requirement. Here, four chiral aggregate-induced emission (AIE) active donors (Guests A1-A4: R-C2, R-C4, R-C6, R-C8, chiral dopant, and energy donor) and achiral AIE-active acceptors (Guest B: PBCy, CPL emitter) were doped into the commercial nematic liquid crystals E7 (N-LCs, Host) to form CPL-active ternary chiral emissive N-LCs (T-N*-LCs), respectively. This kind of T-N*-LCs could emit strong red CPL with QY = 16.56% and glum up to 1.51 through intermolecular energy transfer and chirality induction from the supramolecular self-assembly of T-N*-LCs. This work provides the effective strategy for the development of high glum CPL materials.

Blood-Brain Barrier Penetrating Luminescent Conjugates Based on Cyclometalated Platinum(II) Complexes.

Herein we report on the synthesis, structural characterization and photophysical properties of cyclometalated Pt(II) complexes [Pt(N^C)(PPh2(C6H4COOH))Cl] (where N^C ligands are 2-phenylpyridine, (2-benzofuran-3-yl)pyridine, and (2-benzo[b]tiophen-3-yl)pyridine) and their conjugates with the histidine-containing RRRRRRRRRRHVLPKVQA peptide. This peptide contains the RHVLPKVQA sequence, which is responsible for antiamyloid activity, and the Arg9 RRRRRRRRR domain, which shows improved translocation through cell membranes. The chemistry underpinning the conjugation is regioselective complexation between Pt(II) complexes and histidine residue in the peptide. The prepared conjugates have been characterized using high-resolution mass spectrometry and NMR spectroscopy. It was shown that the conjugates are easily soluble in aqueous media and display emission band profiles essentially similar to those of the starting complexes but considerably higher luminescence quantum yield and much longer phosphorescence lifetime. MTT assay on HeLa cell culture revealed no cytotoxicity up to 10 μM after 24 h of incubation. Ex vivo and in vivo neuroimaging experiments on both wild and amyloid peptide expressing strains of Drosophila melanogaster revealed that the conjugates penetrate the blood-brain barrier and are evenly distributed throughout the brain independently of the strain used.

Phenanthroline chromophore as efficient antenna for Tb3+ green luminescence: A theoretical study

The photophysical processes, from excitation in the UV range, energy migration pathways to luminescence of Tb(phen)2(NO3)3 complex in the Vis region have been studied by theoretical approaches and spectroscopic measurements. The UV–Vis absorption, diffuse reflectance, excitation and luminescence spectra indicated that the ligand 1,10-phenanthroline (phen) was a suitable antenna chromophore for Tb3+ luminescence at excitation of wavelength range 350–352 nm, corresponding to the S1 state of phen. The energy level diagram and character of the singlet and triplet excited states of the ligand-chromophore and Tb(phen)2(NO3)3 in gas phase and polar solution were obtained by the DFT/TDDFT/ωB97xD/B1 method and multireference ab-initio calculations with perturbative spin-orbit coupling corrections. It was also established that the vibro-electronic contribution to the excitation energy is important for correct reproduction and interpretation of the experimental absorption and emission spectra of Tb(phen)2(NO3)3. The rate constants for competitive singlet-triplet intersystem crossing relaxation transitions, as well as radiative and non-radiative deactivation of the ligand-centered excited states were qualitatively estimated and the fastest electronic relaxation mechanism was revealed. The excitation channel S0→S1→T2→T1→5D4 was predicted as the most probable one for effective phen→Tb3+ energy transfer. The sensitization results in a high luminescent quantum yield of 13%, which suggests energy transfer rates, sufficiently higher than the rates of radiative and non-radiative depopulation of the T1 state.

Development of a lysosome-targetable visible-light-excited europium(III) complex-based luminescent probe to image hypochlorous acid in living cells

Lanthanide complex-based luminescent probes have shown great utilities in detecting various analytes by time-gated luminescence imaging technology. However, few lanthanide probes are suitable for the monitoring of bioactive species in organelles. Furthermore, the common UV excitation windows of most lanthanide probes limit their application in living biological samples. In this work, a novel visible-light-excited europium(III) complex-based luminescent probe, [Eu(Lyso-CDHH)3(DPBT)], was designed and synthesized for the detection of exogenous and endogenous hypochlorous acid (HOCl) in lysosomes. The probe exhibits a wide excitation window from ultraviolet to visible region with a maximum excitation wavelength at 400 nm and a high luminescence quantum yield (41.7%). Upon reaction with HOCl, the luminescence of the probe can be quenched within 5 s and displays strong resistance to the interferences from other reactive species. The designed probe also shows high sensitivity towards HOCl with a low detection limit at micromolar concentration level. In addition, the good cell-membrane permeability and the lysosome-targetability of the probe enabled its successful application in the time-gated luminescence imaging of exogenous and endogenous HOCl in lysosomes of RAW 264.7 cells. This work will shed lights on the design of visible-light-excited and organelle-targetable lanthanide molecular probes for broader time-gated luminescence application.

Two-dimensional tin perovskite nanoplate for pure red light-emitting diodes

Halide perovskites are rising as promising luminescent materials for display applications for their sharp emission peaks and high luminescence quantum yield. However, the heavy metal character of lead is one concern that shadows its application. In this work, monolayer Ruddlesden–Popper 2D structural tin perovskite (PEA)2SnI4 (PEA = C8H9NH3+) is explored for a pure red color light emitting diode (LED). The manipulation of crystal growth kinetics enables the formation of highly ordered nanoplates, bringing high luminescence yield approaching 10% with an emission peak at 630 nm. Meanwhile, the highly oriented and ordered nanoplates structure allows effective carrier injection. The LED shows a low turn on voltage of 2.2 V, an external quantum efficiency of 0.52% and a max luminance of 355 cd m−2. The luminescence quantum yield is comparable to the best performing device based on lead perovskites in the pure red emission region. This work provides a strategy to explore 2D structures for efficient macroscale LEDs.

Combination of broad emission bands of Ti3+,4+/ Eu2+,3+ co-doped OH− free low silica calcium aluminosilicate glasses as emitting phosphors for white lighting devices

In this report, Ti3+, 4+/Eu2+, 3+ co-doped OH− free low silica calcium aluminosilicate glasses (LSCAS) were synthesized and their optical properties investigated aiming applications as phosphors for white light generation. This research explores the possibility of combining the broad emission bands in the visible of these glasses co-doped with Ti3+,4+/Eu2+ ions with those in the red emitted by Eu3+, in addition to the high luminescence quantum yield they present. The excitation and emission results show that exciting the samples at 300 nm, a broad emission band is generated, embracing very well the visible region. The emission spectra were analyzed by (x-y) CIE-1931 chromaticity diagram and the color rendering index (CRI) presented Ra values up to 80, with the correlate color temperature (CCT) varying from 4995 to 6609 K. The luminescence quantum yield determined by Thermal Lens Spectroscopy showed values of 38 and 42% for the samples with (in wt%) 0.1Eu2O3-2.0TiO2 and 0.5Eu2O3-2.0TiO2, respectively. Finally, the energy transfer processes between these luminescent ions were discussed, highlighting the potential of the Eu–Ti LSCAS glasses as candidates for the development of devices for white light generation.

Functional DNA Structures and Their Biomedical Applications

Since the discovery of the double-helix structure in 1953, nucleic acids have been developed from natural genetic codes into functional building blocks in a wide range of biotechnology and material...

Remote-Type Quantum Dot Lens-Based LEDs Fabricated with Stereolithagraphy 3D Printing

Quantum dots (QDs) have a great potential for next generation luminescence materials due to their unique properties, e.g., size-tunable bandgap, high luminescence quantum yield (QY) and narrow emission bandwidth. Thus, a wide-color-gamut display can be realized by introducing QDs in QD light-emitting diode application (QD-LED) instead of traditional phosphors. It has been found that photo and thermal oxidation can cause degradation of QDs.1 In the present study, a remote-type QD-LED in the structure of a QD color-convertor lens, prepared with stereolithagraphy (STL) 3D printing, on a blue InGaN chip has been presented. Different from traditionally fused-deposition-modeling (FDM) 3D printing, STL has advantages of fast forming process, direct laser curing without post-thermal curing, more intricate details and smooth surface. Comparing the reliability of QD-lens-based QD-LED with that of on-chip-package-type one, the QD lens are about 3.14 times longer in T50 and 78% lower in decaying rate than that of on-chip-package one after 528 h operated at 20 mA. A better reliability of the QD lens is attributed to smaller thermal and photo doses compared with those QDs in the on-chip package. The remote QD lens-based QD-LEDs are promising in lighting and display applications. 1. C. Huang, C. W. Yeh, G. H. Chen, M. C. Liu, and H. S. Chen, ACS Appl. Mater. Interfaces, 11, 2516 (2018). Figure 1

Luminescence and Light‐Driven Energy and Electron Transfer from an Exceptionally Long‐Lived Excited State of a Non‐Innocent Chromium(III) Complex

AbstractPhotoactive metal complexes employing Earth‐abundant metal ions are a key to sustainable photophysical and photochemical applications. We exploit the effects of an inversion center and ligand non‐innocence to tune the luminescence and photochemistry of the excited state of the [CrN6] chromophore [Cr(tpe)2]3+ with close to octahedral symmetry (tpe=1,1,1‐tris(pyrid‐2‐yl)ethane). [Cr(tpe)2]3+ exhibits the longest luminescence lifetime (τ=4500 μs) reported up to date for a molecular polypyridyl chromium(III) complex together with a very high luminescence quantum yield of Φ=8.2 % at room temperature in fluid solution. Furthermore, the tpe ligands in [Cr(tpe)2]3+ are redox non‐innocent, leading to reversible reductive chemistry. The excited state redox potential and lifetime of [Cr(tpe)2]3+ surpass those of the classical photosensitizer [Ru(bpy)3]2+ (bpy=2,2′‐bipyridine) enabling energy transfer (to oxygen) and photoredox processes (with azulene and tri(n‐butyl)amine).

Luminescence and Light-Driven Energy and Electron Transfer from an Exceptionally Long-Lived Excited State of a Non-Innocent Chromium(III) Complex.

Photoactive metal complexes employing Earth‐abundant metal ions are a key to sustainable photophysical and photochemical applications. We exploit the effects of an inversion center and ligand non‐innocence to tune the luminescence and photochemistry of the excited state of the [CrN6] chromophore [Cr(tpe)2]3+ with close to octahedral symmetry (tpe=1,1,1‐tris(pyrid‐2‐yl)ethane). [Cr(tpe)2]3+ exhibits the longest luminescence lifetime (τ=4500 μs) reported up to date for a molecular polypyridyl chromium(III) complex together with a very high luminescence quantum yield of Φ=8.2 % at room temperature in fluid solution. Furthermore, the tpe ligands in [Cr(tpe)2]3+ are redox non‐innocent, leading to reversible reductive chemistry. The excited state redox potential and lifetime of [Cr(tpe)2]3+ surpass those of the classical photosensitizer [Ru(bpy)3]2+ (bpy=2,2′‐bipyridine) enabling energy transfer (to oxygen) and photoredox processes (with azulene and tri(n‐butyl)amine).

Single-step direct laser writing of halide perovskite microlasers

Halide perovskites are a family of materials with a high potential for realization of microlasers, due to their high luminescence quantum yield and broad spectral tunability. We demonstrate a single-step process for lasing microdisk fabrication from a thin film of methylammonium lead iodide (MAPbI3) perovskite through its patterning with tightly focused femtosecond (fs) laser pulses. By using kHz-scale pulse bursts destructive overheating of the material was suppressed. Perovskite microdisks fabricated under such optimized conditions showed stable lasing upon pumping with fs-laser both at lower (50 kHz) and higher (80 MHz) repetition rates and operation temperatures of 300 K and 6 K, respectively.

Quantum dot scaffold phosphors: Maximizing luminescence quantum yield via different stock environments

This paper presents a novel concept for quantum-dots (QDs) phosphor plates using a polymer scaffold matrix. Here, graphene quantum-dots (GQDs) has utilized as the luminescent material in a polymeric scaffold prepared by free-radical polymerization followed by freeze-drying. The highly porous scaffold (porosity: ~60%, pore size in broad micron size) maintained the individual identity of the quantum dots for the beauty of high luminescence quantum yield, which is necessary for fabricating efficient phosphors. These outcomes were strongly reinforced by time-resolved photoluminescence. This study offers a systematic approach for tuning the luminescence property of quantum dots in different states such as powders, liquids, hydrogels, and freeze-dried scaffolds.

Enhanced stability of the optical responses from all-inorganic perovskite nanocrystals embedded in a synthetic opal matrix

Nanostructured luminescent materials based on perovskite nanocrystals (p-NCs) are attractive since their optical properties can be tuned in a wide spectral range with high luminescence quantum yields and lifetimes, however, they lack stability. In this work, the optical properties of highly luminescent colloidal p-NCs (CsPbX3, where X = Cl/Br, Br, I) embedded in porous opal matrices are presented. It is shown that the photoluminescence of the p-NCs embedded into opal matrices possess increased longtime stability of its spectral and kinetic parameters under ambient conditions. LEDs based on the developed materials show pure color p-NC emission with stability of its parameters. The results of this work may expand the knowledge of interactions between luminescent nanoparticles within multicomponent nanostructured materials for further photonic applications.

Crystal growth and luminescence properties of organic crystal scintillators for α-rays detection

Scintillation and luminescence properties of a novel organic crystal scintillator, 1,4-bis(2-methylstyryl) benzene (bis-MSB), were measured and compared with those of the conventional trans-stilbene organic crystal scintillator. Although trans-stilbene has been used for beta or neutron detection, trans-stilbene cannot be applied at high temperature conditions due to a lower melting point (124 °C). Liquid scintillators or plastic scintillators also cannot be used at high temperature. Usually, bis-MSB has been used as dopant in liquid scintillators to obtain fast scintillation decay and high luminescence quantum yield, and its melting point is 181 °C higher than that of trans-stilbene. In this paper, we focused on bis-MSB in solid state. The bis-MSB and trans-stilbene crystals were grown by the self-seeding vertical Bridgman method using double quartz ampoules. The bis-MSB crystal had the fast decay time of ∼4.2 ns and the increased light yield of ∼12,000 ph/5.5 MeV(α), while trans-stilbene had the decay time of ∼8.5 ns and the light yield of ∼8500 ph/5.5 MeV(α). The photoluminescence quantum yield was almost constant up to 125 °C for bis-MSB and only up to 50 °C for trans-stilbene. We succeeded in obtaining the novel organic crystal scintillator which can operate even at higher temperature up to 125 °C.