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1.
A dual‐emission ratiometric fluorescent sensing film for metal ion detection is designed. This dual‐emission film is successfully prepared from chitosan, graphitic carbon nitride (g‐C 3N 4), and gold nanoclusters (Au NCs). Here, it is shown that the g‐C 3N 4 not only serves as the fluorescence emission source, but also enhances the mechanical and thermal stability of the film. Meanwhile, the Au NCs are adsorbed on the surface of chitosan film by the electrostatic interaction. The as‐prepared dual‐emission film can selectively detect Cu 2+, leading to the quench of red fluorescence of Au NCs, whereas the blue fluorescence from g‐C 3N 4 persists. The ratio of the two fluorescence intensities depends on the Cu 2+ concentration and the fluorescence color changes from orange red to yellow, cyan, and finally to blue with increasing Cu 2+ concentration. Thus, the as‐prepared dual‐emission film can be worked as ratiometric sensing paper for Cu 2+ detection. Furthermore, the film shows high sensitivity and selectivity, with low limit of detection (LOD) (10 ppb). It is observed that this novel gold‐cluster‐based dual‐emission ratiometric fluorescent sensing paper is an easy and convenient way for detecting metal ions. It is believed that this research work have created another avenue for the detection of metal ions in the environment. 相似文献
2.
We describe the simple fabrication of SiO 2 sol-gel monoliths embedding highly luminescent carbon nanodots (CDs) sensitive to metal ions. The pristine CDs we synthesize display an intense dual emission consisting in two fluorescence bands in the green and violet region, and we demonstrate that this photoluminescence is substantially unchanged when the dots are incorporated in the SiO 2 matrix. The emission of these CDs is quenched by interactions with Cu 2+ ions, which can be used to detect these ions with a detection limit of 1 μM. The chromophores remain accessible to diffusing Cu 2+ ions even after embedding CDs in the sol-gel monolith, where their detection capabilities are preserved. Such a result provides the proof-of-principle of a new sensing scheme, where CDs are exploited as active sensing centers of metal transition ions within a solid-state device. The different interaction mechanisms of CDs with copper, in liquid and solid phase, are analyzed in detail and discussed in terms of different accessibility of their chromophores when the dots are incorporated in the SiO 2 matrix. 相似文献
3.
A simple uracil-appended fluorescent sensor (1) has been developed by one pot reaction and characterized by using common spectroscopic methods such as UV-vis, Fluorescence, HRMS and FT-IR analyses. Upon addition of various metal ions to the CH3CN solution of sensor 1, the fluorescence was quenched in the presence of Cu2+ / Hg2+ ions. The limit of detection for Cu2+ and Hg2+ was calculated to be 3.31 and 0.316 µM, respectively. Further, the sensor was applied for real-life applications in the determination of Vitamin B2 (riboflavin) and its presence in milk products. With the incorporation of different sources of vitamin-B to acetonitrile solution of it, there was discernible fluorescence enhancement only in the presence of vitamin B2. Also, it has been successfully applied for the detection of Vitamin B2 (riboflavin) in milk and curd. Moreover, based on the fluorescent color changes, the sensor was utilized for invisible ink applications. 相似文献
4.
A chemosensor, 2,2′-(1,4-phenylenedivinylene)bis-8-acetoxyquinoline ( 1), its fluorescent sensing behavior toward representative alkali ions (Na +, K +), alkaline earth ions (Mg 2+, Ca 2+), and transition-metal ions (Ni 2+, Cu 2+, Zn 2+, Hg 2+, Pb 2+, Cd 2+) was intensively investigated. The compound ( 1) exhibited pronounced Hg 2+ selective on–off-type fluoroionophoric properties among the representative ions in DMF/ethanol (1:9, v/v) solution. Moreover, the highly Hg 2+-selective fluorescence quenching property in conjunction with a visible colorimetric change from colorless to light yellow can be observed, leading to potential fabrication of both “naked-eye” and fluorescent detection of Hg 2+. 相似文献
5.
Electron Paramagnetic Resonance (EPR) and optical absorption spectra of Cu 2+ ions in sodium–lead borophosphate glasses doped with different concentrations of Cu 2+ ions have been studied. EPR spectra of all the glass samples exhibit resonance signals characteristic of Cu 2+ ions. The values of spin-Hamiltonian parameters indicate that the Cu 2+ ions in sodium–lead borophosphate glasses are present in octahedral sites with tetragonal distortion. The optical absorption spectra of all the glass samples show a single broad band, which has been assigned to the 2B 1g→ 2B 2g transition of Cu 2+ ions. The optical band gap energy ( Eopt) and Urbach energy (Δ E) are calculated from their ultraviolet absorption edges. The emission bands observed in the ultraviolet and blue region are attributed to 3d 94s→3d 10 triplet transition in Cu + ion. The FT-IR spectra show that the glass system contains BO 3, BO 4 and PO 4 structural units. 相似文献
6.
Fluorescence probes serves as unique detection methods for its simplicity and low detection limit (LOD) and especially bioimaging ability. Research on the probes has already sprouted during the last decade with the help of its molecular recognition properties. This review spotlights recent progress in sensing and bioimaging biologically, environmentally and industrially important metal ions e.g. Zn 2+, Cu 2+, Hg 2+, Ag + etc. using suitable fluorescent chemosensors including carbon quantum dots (CQD). 相似文献
7.
Imbalance of zinc ion (Zn 2+) in human body causes diseases like Alzheimer’s and Parkinson’s and therefore Zn 2+ estimation in biological fluids has diagnostic values. Fluorescence “off-on” sensors have advantages of high sensitivity and in situ application over other sensors. A new fluorescent “off-on” Zn 2+ sensor, N-benzoate-N′ salicylaldehyde ethynelediamine ( L), has been synthesisied. In 1:1(v/v) CH 3OH:PBS (PBS?=?phosphate buffer solution), L shows ca. 20 times enhancement in fluorescence intensity on interaction with Zn 2+, due to snapping of photoinduced electron transfer (PET) process, which is selective over metal ions - Na +, K +, Ca 2+, Ni 2+, Cu 2+, Cd 2+, Hg 2+ and Pb 2+. These metal ions either individually or all together does not interfere the sensing ability of L towards Zn 2+. A 1:1 interaction between L and Zn 2+ ion with binding constant 10 4.25 has been established from spectroscopic data. 相似文献
8.
A novel and simple method is described for preparing colloidal Cu‐doped ZnSe(S) quantum dots (QDs) in aqueous media by introducing copper ions using the same method as to prepare colloidal ZnSe(S). More specifically, the Cu‐doped ZnSe(S) are prepared through the nucleation‐doping method in the presence of 3‐mercaptopropionic acid as stabilizers using zinc perchlorate, copper sulphate, and NaHSe as precursors. Confirmation of the preparation of Cu‐doped ZnSe(S) nanocrystals (NCs) is done with absorption and emission spectroscopies (UV–vis and PL) as the QDs show intensive green emissions. The reduction of ions Cu 2+ to Cu + is confirmed by using electron paramagnetic resonance (EPR), in which Cu + ions are silent. The size determination is performed by using transmission electron microscopy (TEM) and dynamic light scattering (DLS), resulting in Cu‐doped ZnSe(S) particles with a mean diameter of 4.6 ± 3.5 nm. The excellent stability observed for the nanoparticles overcomes the intrinsic instability of traditional aqueous Cu‐doped ZnSe(S) NCs. 相似文献
9.
It is demonstrated herein that a series of terbium ions (Tb 3+)‐doped layered yttrium hydroxide (LYH:Tb) nanocones (NCs) intercalating dodecyl sulfate (C 12H 25SO 4, DS) anions can be successfully synthesized in large quantities through a facile hydrothermal strategy. The DS anions in the interlayer gallery of LYH:Tb NCs can be readily modified with various anions (such as NO 3 −, Cl −, and CH 3COO −) through a convenient anion‐exchange procedure. The luminescent properties of LYH:Tb NCs are sensitively influenced by the dopant concentration and the interlayer anions. In particular, the original DS −‐intercalated form and the anion‐exchanged product can be topotactically converted into oxysulfates and oxides with original conical features through a calcination process at 750 °C for 2 h, respectively. Compared with Y 2O 3:Tb NCs, Y 2O 2SO 4:Tb NCs exhibit efficient luminescent properties due to the stronger deformation of the crystal field. More interestingly, the conical structures also exhibit superior luminescent properties over the lamellar objects, originating from the extreme curvature and perturbation of crystal field, which are promising candidates for potential applications in optical and display devices. 相似文献
10.
Ag/polypyrrole (PPy) coaxial nanocables (NCs) were synthesized by an ion adsorption method. In this method, the pre-made Ag
nanowires (NWs) were dispersed in the aqueous solution of copper acetate (Cu(Ac) 2), and the Cu 2+ ions adsorbed onto the surface of Ag NWs can oxidize pyrrole monomers to polymerize into uniform PPy sheath outside Ag NWs
after the Cu(Ac) 2-treated Ag NWs were re-dispersed in the aqueous solution of pyrrole. The morphology of NCs was characterized by transmission
electron microscope (TEM) and scanning electron microscope (SEM). The relationship between the thickness of polymer sheath
and the concentration of Cu(Ac) 2 was established. As Cu(Ac) 2 which served as the oxidant can also be replaced by AgNO 3 in this synthesis, the differences on the structure of polymer sheath caused by different oxidants were studied by surface-enhanced
Raman scattering (SERS), high-resolution transmission electron microscope (HR-TEM), Fourier transform infrared spectroscopy
(FT-IR), and X-ray photoelectron spectroscopy (XPS). Comparing with the characterization results of Ag/PPy NCs synthesized
using AgNO 3 as the oxidant which indicates the random arrangement of PPy chains at the interface between polymer sheath and Ag NWs, PPy
chain oxidized by Cu 2+ tends to show a relatively ordered conformation at the interface with the pyrrole rings identically taking the plane vertical
to the surface of Ag NWs. In addition, although the main part of the polymer sheath was composed of PPy whatever kind of oxidant
was used, the sheath of the NCs oxidized by Cu 2+ is typical for the existence of Cu(I)–pyrrole coordinate structures with strong Cu(I)–N bond signal shown in XPS characterization. 相似文献
11.
A new anisidine possessing benzothiaozle-based chemosensor ( 1) has been designed and synthesized. The chemosensor 1 was designed to provide hard base environment for ratiometric detection of comparatively less studied Al 3+ ions. In CH 3CN, the fluorescence spectra of chemosensor 1 red shifted from 368 to 430 nm with addition of Al 3+ and Hg 2+ ions; while Cu 2+ ions caused quenching of emission intensity of 1. These differential changes observed with Al 3+ and Cu 2+ ions addition enabled chemosensor 1 to construct “NOR” and “TRANSFER” logic gates. 相似文献
12.
Condensation product ( L) of salicylaldehyde and semicarbazide behaves as a fluorescent sensor for Cd 2+ ion, in 1:1 DMSO:H 2O, over Mn 2+, Fe 2+, Ni 2+, Co 2+, Cu 2+, Pb 2+ and Hg 2+ ions. The emission peak of L at λ max = 520 nm, on excitation with 420 nm wavelength photons, showed an enhancement in intensity of ca 60-fold when interacted with Cd 2+ ion. The intensity was however found to remain unaltered when interacted with metal ions—Mn 2+, Fe 2+, Ni 2+, Co 2+, Cu 2+, Pb 2+ and Hg 2+. The intensity increases by approximately 20 fold on interaction with Zn 2+ ion. The increase in the fluorescent peak can be explained on the basis of photo induced electron transfer (PET) mechanism.
A 1:1 complexation between Cd 2+ and L with log β = 4.25 has been proved. 相似文献
13.
Currently, tripositive lanthanide (Ln 3+) ions doped wide band-gap semiconductor nanocrystals (NCs) have been the focus of research interest due to their distinct optical properties and potential applications in optical devices and luminescent biolabels. Because of the low absorptions of parity-forbidden 4f-4f transitions for Ln 3+, it is highly anticipated that the luminescence of Ln 3+ ions embedded in wide band-gap NC lattices can be sensitized efficiently via exciton recombination in the host. For this purpose, the successful incorporation of Ln 3+ into the lattices of semiconductor NCs is of utmost importance, which still remains intractable via conventional wet chemical methods. Here, the most recent progress in the optical spectroscopy of Ln 3+ ions doped wide band-gap semiconductor NCs is discussed. Much attention was focused on the optical properties including electronic structures, luminescence dynamics, energy transfer as well as the up-conversion emissions of Ln 3+ ions in ZnO, TiO 2, SnO 2 and In 2O 3 NCs that were synthesized in our laboratory using wet chemical methods. 相似文献
14.
Recombination of Au 49+, Au 50+, and Au 51+ ions has been studied at the TSR. With Au 50+ ions a storage lifetime of only 2 to 4 s was observed with the magnetically expanded electron beam of the cooler at a density
of n e = 10 7 cm -3. This short storage time is a consequence of the highest recombination rate coefficient ever observed with an atomic ion
(1.8·10 -6 cm 3 s -1 at zero relative energy E rel = 0 between electrons and ions). At about 30 meV a huge dielectronic recombination resonance is found with a record small
width of only about 15 meV. Such resonances fortuitously occurring near E rel=0 are probably the main reason for the enhanced recombination rates observed with Au 50+, with Pb 53+ (in a recent experiment at LEAR) as well as with other complex ions. For Au 49+ and Au 51+ the recombination rates are smaller by an order of magnitude.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
15.
The fluorescence intensity of salicylaldehyde phenylhydrazone ( L), in 1:1 (v/v) CH 3OH:H 2O was enhanced by ca. 100 times with a blue shift in emission maximum, on interaction with Pb 2+ ion. No enhancement in fluorescent intensity of L was observed on interaction with metal ions - Na +, K +, Ca 2+, Cu 2+, Ni 2+, Zn 2+, Cd 2+ and Hg 2+. This signal transduction was found to occur via photoinduced electron transfer (PET) mechanism. A 1:1 complexation between Pb 2+ and L with log β?=?7.86 has been proved from fluorescent and UV/Visible spectroscopic data. The detection limit of Pb 2+ was calculated to be 6.3?×?10 ?7?M. 相似文献
16.
A new 7-nitrobenz-2-oxa-1,3-diazole (NBD) derived fluorescent probe ( 1) exhibiting high selectivity for Cu 2+ detection, produced significant fluorescence quenching in the presence of Cu 2+ ion, while the metal ions Ca 2+, Cd 2+, Co 2+, Fe 2+, Hg 2+, Mg 2+, Mn 2+, Ni 2+ and Zn 2+ produced only minor changes in fluorescence. The apparent association constant ( K
a) for Cu 2+ binding in chemosensor 1 was found to be 1.22 × 10 3 M −1. The maximum fluorescence quenching activity caused by Cu 2+ binding to 1 was observed over the pH range 6–10. 相似文献
17.
Ion-beam induced atomic mixing of Cu/Au bilayer thin film is studied using combined electrical resistivity measurements and Rutherford Backscattering Spectrometry (RBS). 400 keV Kr + ion irradiation with fluences ranging from 3.3×10 15 to 7.6×10 16 ions/cm 2 at room temperature have been used. Ion beam mixing lead to a uniformly mixed metal alloy. The formation of Cu/Au solid solutions depends on the initial composition and on the fluence of irradiating ions. For an initial composition of Cu 42Au 58, a Cu-rich solid solution of composition Cu 72Au 28 is formed after irradiation with 7.6×10 16 ions/cm 2. The kinematics of the intermixing process is also studied by in situ electrical resistivity measurements which confirmed the formation of the Cu/Au solid solutions. 相似文献
18.
A colorimetric and fluorescent indicator based on cinnamamide group-containing rhodamine derivative was synthesized for the detection of Hg 2+. The rhodamine B and cinnamamide were connected via ethylenediamine as a bridging molecule through a condensation reaction to obtain a colorimetric and fluorescent indicator for the detection of Hg 2+ in H 2O-EtOH (4:1, v/v). The indicator was excellent in the selectivity of Hg 2+ and was almost unaffected by other common ions such as Na +, K +, Mg 2+, Fe 3+, Cu 2+, Zn 2+, Cr 3+. The Hg 2+-containing aqueous solution turned from colorless to red within 7 min after the addition of the indicator, and had an absorption peak at 564 nm in UV-vis, which implies a significant colorimetric phenomenon. Their characteristic peaks varied with the Hg 2+ content, and they reached a linear relationship at low concentrations. The binding stoichiometry proved to be 1:1. The lowest detection limit was 4.1?×?10 ?7 mol/L, ranging from acidic to neutral. 相似文献
19.
The Mössbauer effect technique has been employed for the study of magnetic properties of spinel series Ni 1?xCu xMn yFe 2?yO 4 with 0.0≤x≤1.0, and y=0.6. The substitution of Mn 3+ and Cu 2+ ions results in a slight decrease of the hyperfine field at B‐ as well as A‐sites. The area ratio of Fe 3+ ions at the A‐ and B‐site at 77 K indicates that Cu 2+, Ni 2+ and Mn 3+ ions occupy the octahedral sites in an evidence for complete inverse spinel in this system. The temperature dependence of the hyperfine parameters has been studied for composition with x=0.5 where Nèel point T N and Debye temperature θ D are found to be 650 and 679 K, respectively. The temperature dependence of the sublattice magnetization σ(T) obeys a one‐third‐power law in the range 0.5 N<0.99. 相似文献
20.
Tris(2,2′‐bipyridine)ruthenium(II) complex‐based carbonic anhydrase (CA) inhibitors, [Ru(bpy) 2(bpydbs)] 2+ {bpy = 2,2′‐bipyridine and bpydbs = 2,2′‐bipyridinyl‐4,4′‐dicarboxilic acid bis[(2‐{2‐[2‐(4‐sulfamoylbenzoylamino)ethoxy]ethoxy}ethyl)amide]} and [Ru(bpydbs) 3] 2+, tethering plural benzenesulfonamide groups have been prepared. The CA catalytic activity was effectively suppressed by these synthetic [Ru(bpy) 2(bpydbs)] 2+ and [Ru(bpydbs) 3] 2+ inhibitors, and their dissociation constants at pH = 7.2 and at 25°C were determined to be KI = 0.93 ± 0.02 μM and KI = 0.24 ± 0.03 μM, respectively. Next, 2 photoinduced electron‐transfer (ET) systems comprising a Ru 2+‐CA complex and an electron acceptor, such as chloropentaamminecobalt(III) ([CoCl(NH 3) 5] 2+) or methylviologen (MV 2+) were studied. In the presence of CA and a sacrificial electron acceptor, such as pentaamminechlorocobalt(III) complex, the photoexcited triplet state of 3([Ru(II)] 2+)* was quenched through an intermolecular photoinduced ET mechanism. In case of the [Ru(bpydbs) 3] 2+‐CA‐MV 2+ system, the photoexcited triplet state of 3([Ru(bpydbs) 3] 2+)* was quenched by sacrificial quencher through an intermolecular photoinduced ET mechanism, giving the oxidized [Ru(bpydbs) 3] 3+. Then the following intramolecular ET from the amino acid residue, Tyr6, near the active site of CA proceeded. We observed a transient absorption around at 410 nm, arising from the formation of a Tyr ?+ in the [Ru(bpydbs) 3] 2+‐CA‐MV 2+ system. These artificial Ru(II)‐CA systems may clearly demonstrate both intermolecular and intramolecular photoinduced ET reactions of protein and could be one of the interesting models of the ET proteins. Their photophysical properties and the detailed ET mechanisms are discussed in order to clarify the multistep ET reactions. 相似文献
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