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1.
Two new three‐dimensional (3D) Ln III metal‐organic frameworks (MOFs) were designed and successfully obtained via a solvothermal reaction between lanthanide(III) nitrates and a semi‐flexible carbazole tetracarboxylate acid linker as a high‐performance chromophore. 1 and 2 possess porous 3D networks with channels along the a axis, and more importantly, they show a highly sensitive and selective fluorescence quenching response to Fe 3+ and Cr VI anions. The sensing mechanism investigation revealed that the weak interactions of Fe 3+ with nitrogen atoms of carbazole and deprotonated carboxylic acids protruding into the pores of MOFs quenched the luminescence of 1 and 2 effectively. In addition, the competition absorption also played an important role in the luminescence quenching detection of Fe 3+ based on 1 , and Cr VI anions based on 1 and 2 . Therefore, 1 and 2 represent an alternative example of regenerable luminescence based sensors for the quantitative detection of Fe 3+ and Cr VI anions. 相似文献
2.
Two macrobicyclic ligands derived from an 18‐membered tetralactam ring and 2,2′‐bipyridine or 2,6‐bis(pyrazol‐1‐yl)pyridine moieties, 1 and 2 , respectively, form stable complexes with Gd III, Eu III, and Tb III ions in aqueous solution. The ligand‐based luminescence is retained in the Gd III cryptates, whereas this radiative deactivation is quenched in the Eu III and Tb III cryptates by ligand‐to‐metal energy transfer, resulting in the usual metal‐centered emission spectra. Singlet‐ and triplet‐state energies, emission‐decay lifetimes, and luminescence yields were measured. [Tb⊂ 1 ] 3+ cryptate shows a long luminescence lifetime ( τ=1.12 ms) and a very high metal luminescence quantum yield ( Φ=0.25) in comparison with those reported in the literature for Tb 3+ complexes sensitized by a bipyridine chromophore. By comparison to [Ln⊂ 1 ] 3+, [Ln⊂ 2 ] 3+ presents markedly lower luminescence properties, due to worse interaction between the 2,6‐bis(pyrazol‐1‐yl)pyridine unit and the metal ion. Moreover, the luminescent metal and the triplet ligand energy levels of [Eu⊂ 2 ] 3+ do not match. The effects of H 2O molecules coordinated to the metal centre and of thermally activated decay processes on nonradiative deactivation to the ground‐state are also reported. 相似文献
3.
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 [CrN 6] 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). 相似文献
4.
Drug toxicity is a long‐standing concern of modern medicine. A typical anti‐pain/fever drug paracetamol often causes hepatotoxicity due to peroxynitrite ONOO −. Conventional blood tests fail to offer real‐time unambiguous visualization of such hepatotoxicity in vivo. Here we report a luminescent approach to evaluate acute hepatotoxicity in vivo by chromophore‐conjugated upconversion nanoparticles. Upon injection, these nanoprobes mainly accumulate in the liver and the luminescence of nanoparticles remains suppressed owing to energy transfer to the chromophore. ONOO − can readily bleach the chromophore and thus recover the luminescence, the presence of ONOO − in the liver leads to fast restoring of the near‐infrared emission. Taking advantages of the high tissue‐penetration capability of near‐infrared excitation/emission, these nanoprobes achieve real‐time monitoring of hepatotoxicity in living animals, thereby providing a convenient screening strategy for assessing hepatotoxicity of synthetic drugs. 相似文献
5.
Silylated guanine formed luminescent double-decker type octet complexes with trivalent lanthanide cations (lanthanide cation : guanine = 1:8) in organic media, while a deaminated guanine derivative gave only 1:2 complexes. The octet formation was evidenced by characteristic UV/Vis absorption changes, CSI-TOF MS and 1H NMR spectra. The octet with Tb 3+ showed intense green luminescence with a long lifetime by photo-excitation of the guanine chromophore. The trivalent lanthanie cations stabilized the octets more effectively than common mono- and divalent metal cations. 相似文献
6.
Our recent results on the investigation of lanthanide metal polymer complexes were presented. Luminescence properties of Tb 3+ or Eu 3+ -polycarboxylate complexes in aqueous solution were investigated. The excitation band near 300 nm for Tb or Eu(polyacrylate) solutions were drastically enhanced by the addition of hydroxy radical generating reagents as well as ultrasonic irradiation. These spectral changes were attributed to the energy transfer from chromophore molecules formed by generated hydroxy radicals in both systems. Since the increase in the luminescence intensity was proportional to the hydroxy radical concentration, the Eu 3+ or Tb 3+ (PAA) system can provide a convenient method for the determination of hydroxy radical concentration in aqueous solution. We have also utilized lanthanide metal ion complexes as a luminescent emitter in electroluminescence (EL) devices. The configuration of the EL cell and experimental results were discussed. 相似文献
7.
The luminescence spectral properties of oligothiophenesilane dendrite macromolecules were studied. It was found that the chromophores
responsible for the formation of the absorption and luminescence spectra were dendrimer fragments separated by silicon atoms;
all the chromophores are equally involved in the formation of the absorption spectra of dendritic macromolecules of the zero,
first, second, and third generations. It was shown that for dendrites of the first, second, and third generations, the luminescence
spectrum is mainly formed by the chromophore fragments lying in the internal layers of the dendritic macromolecule due to
the induction resonance energy transfer of electronic excitation from peripheral to internal chromophore fragments. The conclusion
was drawn that synthesis of dendritic macromolecules with internal chromophore fragments possessing a high quantum yield of
fluorescence can give actively luminescing nanosized objects with the molar extinction coefficient proportional to the number
of fragments ɛ max ≈ 10 6 l/(mol cm). These compounds can find wide application in transducers for converting various types of ionizing radiation into
optical radiation in electroluminescent devices. 相似文献
8.
The luminescent properties of terbium ions are used to investigate the interaction of adriamycin and cisplatin with GH3/B6 pituitary tumor cells. Clinically relevant concentrations of adriamycin were found to quench the intensity ( IC50 = 0.6 μM) and excited-state lifetime (τ/τ 0 = 0.73) of the Tb 3+—GH3/B6 complex. Inspection of the Tb 3+—GH3/B6 emission spectrum and the visible absorption spectrum of adriamycin strongly strongly suggests that the quenching of Tb 3+ luminescence by adriamycin is due to dipole-dipole resonant energy transfer; and, according to Forster's theory ( R0 = 33.6 Å), the adriamycin receptor site is located ca. 40 Å away from the bound probe, at the lipid/protein interface. The quenching of Tb 3+ luminescence by cisplatin is best explained by a static energy-exchange mechanism; in that the cisplatin receptor site is contiguous with the Tb 3+ binding site at the outer surface of the membrane. The data suggest that, in the plasma membrane of tumorigenic cells, the adriamycin and ciplatin receptor sites are intimately associated with the same calcium-binding protein. 相似文献
9.
A lanthanide‐complex‐based ratiometric luminescence probe specific for peroxynitrite (ONOO ?), 4′‐(2,4‐dimethoxyphenyl)‐2,2′:6′,2′′‐terpyridine‐6,6′′‐diyl]bis(methylenenitrilo)tetrakis(acetate)‐Eu 3+/Tb 3+ ([Eu 3+/Tb 3+(DTTA)]), has been designed and synthesized. Both [Eu 3+(DTTA)] and [Tb 3+(DTTA)] are highly water soluble with large stability constants at ≈10 20, and strongly luminescent with luminescence quantum yields of 10.0 and 9.9 %, respectively, and long luminescence lifetimes of 1.38 and 0.26 ms, respectively. It was found that the luminescence of [Tb 3+(DTTA)] could be quenched by ONOO ? rapidly and specifically in aqueous buffers, while that of [Eu 3+(DTTA)] did not respond to the addition of ONOO ?. Thus, by simply mixing [Eu 3+(DTTA)] and [Tb 3+(DTTA)] in an aqueous buffer, a ratiometric luminescence probe specific for time‐gated luminescence detection of ONOO ? was obtained. The performance of [Tb 3+(DTTA)] and [Eu 3+/Tb 3+(DTTA)] as the probes for luminescence imaging detection of ONOO ? in living cells was investigated. The results demonstrated the efficacy and advantages of the new ratiometric luminescence probe for highly sensitive luminescence bioimaging application. 相似文献
10.
Lanthanide-doped metal–organic frameworks (Ln-MOFs) have versatile luminescence properties, however it is challenging to achieve lanthanide-based upconversion luminescence in these materials. Here, 1,3,5-benzenetricarboxylic acid (BTC) and trivalent Yb 3+ ions were used to generate crystalline Yb-BTC MOF 1D-microrods with upconversion luminescence under near infrared excitation via cooperative luminescence. Subsequently, the Yb-BTC MOFs were doped with a variety of different lanthanides to evaluate the potential for Yb 3+-based upconversion and energy transfer. Yb-BTC MOFs doped with Er 3+, Ho 3+, Tb 3+, and Eu 3+ ions exhibit both the cooperative luminescence from Yb 3+ and the characteristic emission bands of these ions under 980 nm irradiation. In contrast, only the 497 nm upconversion emission band from Yb 3+ is observed in the MOFs doped with Tm 3+, Pr 3+, Sm 3+, and Dy 3+. The effects of different dopants on the efficiency of cooperative luminescence were established and will provide guidance for the exploitation of Ln-MOFs exhibiting upconversion. 相似文献
11.
This work demonstrates luminescence resonance energy transfer (LRET) sensors based on lanthanide‐doped nanoparticles as donors (D) and gold nanoparticles as acceptors (A), combined through electrostatic interactions between the oppositely charged nanoparticles. Negatively charged lanthanide‐doped nanoparticles, YVO 4:Eu and LaPO 4:Ce,Tb, with high luminescence quantum yield and good water‐solubility, are synthesized through a polymer‐assisted hydrothermal method. Positively charged polyhedral and spherical gold nanoparticles exhibit surface plasmon resonance (SPR) bands centered at 623 and 535 nm, respectively. These bands overlap well with the emission of the Eu 3+ and Tb 3+ ions within the lanthanide nanoparticles. Herein, the gold nanoparticles are synthesized through a seed‐mediated cetyltrimethylammonium bromide (CTAB)‐assisted method. The assemblies of the oppositely charged donors and acceptors are developed into LRET‐based sensors exhibiting a donor quenching efficiency close to 100 %. 相似文献
12.
The syntheses of three new ligands ( L1-3), which are based upon a DO3A core and appended with additional receptor sites for metal cations, are described, together with their corresponding Eu(III) complexes ( Eu- L1-3). The complexes are visibly luminescent in aqueous solution, following sensitization via the pyridine chromophore, showing characteristic narrow line-like emission from Eu(III). The luminescence properties show that water is effectively excluded from the inner coordination sphere of europium ( q = 0). Each of the complexes showed perturbed luminescence properties upon addition of a variety of d-block metal ions. For example, emission quenching was observed for each complex following addition of Cr(III) and Cu(II). Selectivity towards Hg(II) (over Cd(II), Cu(II) and Zn(II)) was demonstrated with Eu- L3, which possesses a receptor site incorporating a softer thiophene moiety. More specifically, Hg(II) binding resulted in changes in the form of the steady state emission spectrum, together with a corresponding reduction of the luminescence lifetime in water, which can be attributed to an increase in inner sphere hydration ( q = 2) and thus enhanced non-radiative deactivation of the 5D 0 state by proximate O-H oscillators. 相似文献
13.
Imaging Ca 2+ dynamics in living systems holds great potential to advance neuroscience and cellular biology. G‐GECO1.1 is an intensiometric fluorescent protein Ca 2+ biosensor with a Thr‐Tyr‐Gly chromophore. The protonated chromophore emits green upon photoexcitation via excited‐state proton transfer (ESPT). Upon Ca 2+ binding, a significant population of the chromophores becomes deprotonated. It remains elusive how the chromophore structurally evolves prior to and during ESPT, and how it is affected by Ca 2+. We use femtosecond stimulated Raman spectroscopy to dissect ESPT in both the Ca 2+‐free and bound states. The protein chromophores exhibit a sub‐200 fs vibrational frequency shift due to coherent small‐scale proton motions. After wavepackets move out of the Franck–Condon region, ESPT gets faster in the Ca 2+‐bound protein, indicative of the formation of a more hydrophilic environment. These results reveal the governing structure–function relationship of Ca 2+‐sensing protein biosensors. 相似文献
14.
The Raman spectra, infrared spectra and upconversion luminescence spectra were studied, and the effect mechanism of OH − groups on the upconversion luminescence of Er 3+-doped oxyhalide tellurite glasses was analyzed. The results show that the phonon energy of lead chloride tellurite (PCT) glass was lower than that of lead fluoride tellurite (PFT) glass, but upconversion luminescence intensity of Er 3+-doped PFT glass was higher than that of Er 3+-doped PCT glass. The analysis considers that it was attributed mainly to the effect of OH − groups. The lower the absorption coefficient of the OH − groups, the higher the fluorescence lifetime of Er 3+, and as a result the higher upconversion luminescence intensity of Er 3+. In this work, the effect of OH − groups on the upconversion luminescence of Er 3+ was bigger than that of the phonon energy. 相似文献
15.
A series of luminescent ion exchanged zeolite are synthesized by introducing various ions into NaY zeolite. Monometal ion (Eu 3+, Tb 3+, Ce 3+, Y 3+, Zn 2+, Cd 2+, Cu 2+) exchanged zeolite, rare‐earth ion (Eu 3+, Tb 3+, Ce 3+) exchanged zeolite modified with Y 3+ and rare‐earth ion (Eu 3+, Tb 3+, Ce 3+) exchanged zeolite modified with Zn 2+ are discussed here. The resulting materials are characterized by Fourier transform infrared spectrum radiometer (FTIR), XRD, scanning electronic microscope (SEM), PLE, PL and luminescence lifetime measurements. The photoluminescence spectrum of NaY indicates that emission band of host matrix exhibits a blueshift of about 70 nm after monometal ion exchange process. The results show that transition metal ion exchanged zeolites possess a similar emission band due to dominant host luminescence. A variety of luminescence phenomenon of rare‐earth ion broadens the application of zeolite as a luminescent host. The Eu 3+ ion exchanged zeolite shows white light luminescence with a great application value and Ce 3+ exchanged zeolite steadily exhibits its characteristic luminescence in ultraviolet region no matter in monometal ion exchanged zeolite or bimetal ions exchanged zeolite. 相似文献
16.
Lanthanide sensitized luminescence and chemiluminescence (CL) are of great importance because of the unique spectral properties, such as long lifetime, large Stokes shifts, and narrow emission bands characteristic to lanthanide ions (Ln 3+). With the fluoroquinolone (FQ) compounds including enoxacin (ENX), norfloxacin (NFLX), lomefloxacin (LMFX), fleroxacin (FLRX), ofloxacin (OFLX), rufloxacin (RFX), gatifloxacin (GFLX) and sparfloxacin (SPFX), the luminescence and CL properties of Tb 3+–FQ and Eu 3+–FQ complexes have been investigated in this contribution. Ce 4+–SO 32− in acidic conditions was taken as the CL system and sensitized CL intensities of Tb 3+–FQ and Eu 3+–FQ complexes were determined by flow-injection analysis. The luminescence and CL spectra of Tb 3+–FQ complexes show characteristic peaks of Tb 3+ at 490 nm, 545 nm, 585 nm and 620 nm. Complexes of Tb 3+–ENX, Tb 3+–NFLX, Tb 3+–LMFX and Tb 3+–FLRX display relatively strong emission intensity compared with Tb 3+–OFLX, Tb 3+–RFX, Tb 3+–GFLX and Tb 3+–SPFX. Quite weak peaks with unique characters of Eu 3+ at 590 nm and 617 nm appear in the luminescence and CL spectra of Eu 3+–ENX, but no notable sensitized luminescence and CL of Eu 3+ could be observed when Eu 3+ is added into other FQ. The distinct differences on emission intensity of Tb 3+–FQ and Eu 3+–FQ might originate from the different energy gap between the triplet levels of FQ and the excited levels of the Ln 3+. The different sensitized luminescence and CL signals among Tb 3+–FQ complexes could be attributed to different optical properties and substituents of these FQ compounds. The detailed mechanism involved in the luminescence and CL properties of Tb 3+–FQ and Eu 3+–FQ complexes has been investigated by analyzing the luminescence and CL spectra, quantum yields, and theoretical calculation results. 相似文献
17.
Time-resolved luminescence bioassay technique using lanthanide complexes as luminescent probes/sensors has shown great utilities in clinical diagnostics and biotechnology discoveries. In this work, a novel terpyridine polyacid derivative that can form highly stable complexes with lanthanide ions in aqueous media, (4′-hydroxy-2,2′:6′,2′′-terpyridine-6,6′′-diyl) bis(methylenenitrilo) tetrakis(acetic acid) (HTTA), was designed and synthesized for developing time-resolved luminescence pH sensors based on its Eu 3+ and Tb 3+ complexes. The luminescence characterization results reveal that the luminescence intensity of HTTA–Eu 3+ is strongly dependent on the pH values in weakly acidic to neutral media (p Ka = 5.8, pH 4.8–7.5), while that of HTTA–Tb 3+ is pH-independent. This unique luminescence response allows the mixture of HTTA–Eu 3+ and HTTA–Tb 3+ (the HTTA–Eu 3+/Tb 3+ mixture) to be used as a ratiometric luminescence sensor for the time-resolved luminescence detection of pH with the intensity ratio of its Tb 3+ emission at 540 nm to its Eu 3+ emission at 610 nm, I540 nm/ I610 nm, as a signal. Moreover, the UV absorption spectrum changes of the HTTA–Eu 3+/Tb 3+ mixture at different pHs (pH 4.0–7.0) also display a ratiometric response to the pH changes with the ratio of absorbance at 290 nm to that at 325 nm, A290 nm/ A325 nm, as a signal. This feature enables the HTTA–Eu 3+/Tb 3+ mixture to have an additional function for the pH detection with the absorption spectrometry technique. For loading the complexes into the living cells, the acetoxymethyl ester of HTTA was synthesized and used for loading HTTA–Eu 3+ and HTTA–Tb 3+ into the cultured HeLa cells. The luminescence imaging results demonstrated the practical utility of the new sensor for the time-resolved luminescence cell imaging application. 相似文献
18.
A series of donor-acceptor dyes based on polyfluoro-substituted triarylpyrazolines (as a donor block) and a dicyanoisophorone group (as an acceptor) were synthesized using the Knoevenagel condensation. The dyes have an absorption in the region of 509–514 nm and intense luminescence at 648–663 nm in chloroform with a large Stokes shift (up to 4410 cm–1). Based on the synthesized dyes, chromophore–polymer (guest–host) films were obtained in a polycarbonate matrix with a chromophore content up to 27 wt.%. Poling of chromophore–polymer films was carried out in an electric field of a corona discharge and the coefficient of nonlinear optical response d33 was measured by the second-harmonic generation method of the fundamental frequency of a Nd-YAG laser (1064 nm). The obtained films have a high initial thermal stability and a nonlinear optical response up to 80 pm V–1, which persists up to 115 °С. 相似文献
19.
The luminescence of several Sb 3+-activated rare earth orthoborates ( LnBO 3Sb 3+; Ln = Sc, Y, La, Gd, Lu) are reported. In all compositions the Stokes shift of the Sb 3+ luminescence is rather large, resulting in rather low quenching temperatures (200 K or lower). The Stokes shift appears to be dependent on the coordination number and on the radius of the host lattice cation. This is explained from the assumed tendency of the Sb 3+ ion to occupy an off-center position which becomes more apparent when the space available for the Sb 3+ ion increases. The present results are compared with those on LnBO 3Bi 3+. It appears that the Stokes shift of the Bi 3+ luminescence is more sensitive to the host lattice and is smaller than the Stokes shift of the Sb 3+ luminescence. This is explained by the large radius of the Bi 3+ ion compared to the Sb 3+ ion. In GdBO 3Sb 3+ thermally activated energy transfer is observed from Gd 3+ to Sb 3+. 相似文献
20.
Protein post-translational modifications (PTMs) are regulatory mechanisms carried out by different enzymes in a cell. Kinase catalyzed phosphorylation is one of the most important PTM affecting the protein activity and function. We have developed a single-label quenching resonance energy transfer (QRET) assay to monitor tyrosine phosphorylation in a homogeneous high throughput compatible format. Epidermal growth factor receptor (EGFR) induced phosphorylation was monitored using Eu 3+-chelate labeled peptide and label-free phosphotyrosine specific antibody in presence of a soluble quencher molecule. In the QRET kinase assay, antibody binding to phosphorylated Eu 3+-peptide protects the Eu 3+-chelate from luminescence quenching, monitoring high time-resolved luminescence (TRL) signals. In the presence of specific kinase inhibitor, antibody recognition and Eu 3+-chelate protection is prevented, allowing an efficient luminescence quenching. The assay functionality was demonstrated with a panel of EGFR inhibitors (AG-1478, compound 56, erlotinib, PD174265, and staurosporine). The monitored IC 50 values ranged from 0.08 to 155.3 nM and were comparable to those found in the literature. EGFR activity and inhibition assays were performed using low nanomolar enzyme and antibody concentration in a 384-well plate format, demonstrating its compatibility for high throughput screening (HTS). 相似文献
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