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1.
A new pyrene-containing fluorescent sensor has been synthesized from 2,3,3-trimethylindolenine. Spectroscopic and photophysical properties of sensor are presented. The large change in fluorescence intensity (I/I0 = 0.13) at 381 nm and affinity to Hg2+ over other cations such as K+, Na+, Ca2+, Mg2+, Pb2+, and Cu2+ make this compound a useful chemosensor for Hg2+ detection in hydrophilic media. The sensor (6.0 × 10−6 M) displays significant fluorescence quenching upon addition of Hg2+ in pH 7.4 HEPES buffer without excimer formation. Job’s plot analysis shows the binding stoichiometry to be 2:1 (host/guest).  相似文献   

2.
Poly(hydroxybutyrate-co-hydroxyhexanoate) (PHBHHx) microparticles were successfully prepared and their proliferative effects on cultured fibroblasts were studied. PHBHHx microparticles (0.005-0.1 g/L) promoted cell proliferation in murine fibroblast L929 and elevated intracellular calcium concentrations ([Ca2+]i). EGTA (ethylene glycol-bis(2-aminoethylether)-N,N,N′,N′-tetraacetic acid) inhibited PHBHHx microparticle-induced cell proliferation by chelating the extracellular Ca2+ and blocking the PHBHHx particle-induced [Ca2+]i increase. Transwell experiments demonstrated that PHBHHx microparticles stimulated fibroblast proliferation when separated from cells by a 0.4 μm filter as effectively as when applied directly to cells. Since PHBHHx microparticles had a diameter of 75 μm, the stimulatory effect of PHBHHx particles on cell growth was attributed to degradation products smaller than 0.4 μm in diameter. The trophic effect of these microparticles is consistent with our previous reports demonstrating good biocompatibility for PHBHHx.  相似文献   

3.
The complex formation constants of polyacrylic (PAA) ligands (1.4≤log N≤2.4, N=number of monomer units) with calcium and magnesium ions were determined in different ionic media at different ionic strengths, 0≤I≤1 mol l−1, at t=25 °C. Experimental pH-metric data in the presence of Ca2+ or Mg2+ were firstly analysed in terms of apparent protonation constants, log KH*, using the “three parameter model” proposed by Högfeldt; differences in log KH*, determined in different ionic media, were interpreted in terms of complex species formation. The only species present in the system M-PAA (M=Ca2+ or Mg2+) is ML2: attempts to find species of different stoichiometry were unsuccessful. The stability dependence of this species on ionic strength, on the degree of neutralisation (α) and on PAA molecular weight is discussed using empirical equations. The formation constant, log β2, is significantly higher for Ca2+ than for Mg2+: at I=0.1 mol l−1 (NaCl), log N=1.8 and α=0.5, log β2Ca=4.43 and log β2Mg=4.24. The formation of polyacrylate-alkaline earth metal complexes is discussed in the light of sequestering effects in natural waters.  相似文献   

4.
Zhaochao Xu  Jingnan Cui  Rong Zhang 《Tetrahedron》2006,62(43):10117-10122
The design, synthesis, and photophysical evaluation of a new naphthalimide-based fluorescent chemosensor, N-butyl-4-[di-(2-picolyl)amino]-5-(2-picolyl)amino-1,8-naphthalimide (1), were described for the detection of Zn2+ in aqueous acetonitrile solution at pH 7.0. Probe 1 showed absorption at 451 nm and a strong fluorescence emission at 537 nm (ΦF=0.33). The capture of Zn2+ by the receptor resulted in the deprotonation of the secondary amine conjugated to 1,8-naphthalimide so that the electron-donating ability of the N atom would be greatly enhanced; thus probe 1 showed a 56 nm red-shift in absorption (507 nm) and fluorescence spectra (593 nm, ΦF=0.14), respectively, from which one could sense Zn2+ ratiometrically and colorimetrically. The deprotonated complex, [(1-H)/Zn]+, was calculated at m/z 619.1800 and measured at m/z 618.9890. In contrast to these results, the emission of 1 was thoroughly quenched by Cu2+, Co2+, and Ni2+. The addition of other metal ions such as Li+, Na+, K+, Mg2+, Ca2+, Fe3+, Mn2+, Al3+, Cd2+, Hg2+, Ag+, and Pb2+ produced a nominal change in the optical properties of 1 due to their low affinity to probe 1. This means that probe 1 has a very high fluorescent imaging selectivity to Zn2+ among metal ions.  相似文献   

5.
An efficient fluorescent chemosensor for Hg2+ ion, based on 5-(dimethylamino)-N-(2-mercaptophenyl)naphthalene-1-sulfonamide, has been developed. It exhibits Hg2+-selective on–off fluorescence quenching behavior via twisted intramolecular charge transfer (TICT) mechanism, which is rationalized by time dependent density functional theory (TD-DFT) calculations. The system exhibits visible color change from colorless to gray upon Hg2+ binding with very high selectivity and sensitivity (as low as 5.0 × 10−10 mol L−1) over other metal ions such as K+, Na+, Ag+, Mn2+, Ca2+, Ba2+, Fe2+, Zn2+, Pb2+, Cu2+, Sn2+, Cd2+, Ni2+ and Co2+. The present sensing system is also successfully applied for the detection of Hg2+ ion in real samples.  相似文献   

6.
N-Tosyl-2,6-diisopropyl-4-(2,3-dimethoxylbenzoylamide)aniline (1) has been synthesized and its metal ion (Na+, K+, Ca2+, Mg2+) coordinating properties investigated by FT-IR, ESI-MS, and 1H NMR methods. Among the tested metal ions, the overall stability constant (log K) for Mg2+ (6.89) is the highest (Na+, 5.64; K+, 5.43; Ca2+, 5.51) in 10% water/THF at 25.0 ± 0.5 °C determined by UV-vis spectroscopy, indicating that 1 is a potent ionophore for Mg2+ ion.  相似文献   

7.
A novel red emitting phosphor, Eu3+-doped Ca2SnO4, was prepared by the solid-state reaction. X-ray powder diffraction (XRD) analysis confirmed the formation of Ca2SnO4: Eu3+. Field-emission scanning electron-microscopy (FE-SEM) observation indicated a narrow size-distribution of about 500 nm for the particles with spherical shape. Photoluminescence measurements indicated that the phosphor exhibits bright red emission at about 615 nm under UV excitation. The excellent luminescence properties make it possible as a good candidate for plasma display panels (PDP) application. Splitting of the 5D0-7FJ transitions of Ca2SnO4: Eu3+ suggests that the Eu3+ ions occupied two nonequivalent sites in the crystallite. The luminescence lifetime measurement showed a bi-exponential decay, providing other evidence for the existence of two different environments for Eu3+ ions.  相似文献   

8.
A simple method was developed to separate Pu and Am using single column extraction chromatography employing N,N,N′,N′-tetra-n-octyldiglycolamide (DGA) resin. Isotope dilution measurements of Am and Pu were performed using accelerator mass spectrometry (AMS) and alpha spectrometry. For maximum adsorption Pu was stabilized in the tetra valent oxidation state in 8 M HNO3 with 0.05 M NaNO2 before loading the sample onto the resin. Am(III) was adsorbed also onto the resin from concentrated HNO3, and desorbed with 0.1 M HCl while keeping the Pu adsorbed. The on-column reduction of Pu(IV) to Pu(III) with 0.02 M TiCl3 facilitated the complete desorption of Pu. Interferences (e.g. Ca2+, Fe3+) were washed off from the resin bed with excess HNO3. Using NdF3, micro-precipitates of the separated isotopes were prepared for analysis by both AMS and alpha spectrometry. The recovery was 97.7 ± 5.3% and 95.5 ± 4.6% for 241Am and 242Pu respectively in reagents without a matrix. The recoveries of the same isotopes were 99.1 ± 6.0 and 96.8 ± 5.3% respectively in garden soil. The robustness of the method was validated using certified reference materials (IAEA 384 and IAEA 385). The measurements agree with the certified values over a range of about 1–100 Bq kg−1. The single column separation of Pu and Am saves reagents, separation time, and cost.  相似文献   

9.
A new efficient blue phosphor, Eu2+ activated SrZnP2O7, has been synthesized at 1000 °C under reduced atmosphere and the crystal structure and photoluminescence properties have been investigated. The crystal structure of SrZnP2O7 was obtained via Rietveld refinement of powder X-ray diffraction (XRD) pattern. It was found that SrZnP2O7 crystallizes in space group of P21/n (no. 14), Z=4, and the unit cell dimensions are: a=5.30906(2) Å, b=8.21392(3) Å, c=12.73595(5) Å, β=90.1573(3)°, and V=555.390(3) Å3. Under ultraviolet excitation (200-400 nm), efficient Eu2+ emission peaked at 420 nm was observed, of which the luminescent efficiency at the optimal concentration of Eu2+ (4 mol%) was estimated to be 96% as that of BaMgAl10O17:Eu2+. Hence, the SrZnP2O7:Eu2+ exhibit great potential as a phosphor in different applications, such as ultraviolet light emitting diode and photo-therapy lamps.  相似文献   

10.
A novel biomimetic sensor for rutin determination based on a dinuclear complex [MnIIIMnII(Ldtb)(μ-OAc)2]BPh4 containing an unsymmetrical dinucleating ligand, 2-[N,N-bis(2-pyridylmethyl)-aminomethyl]-6-[N-(3,5-di-tert-butyl-2-oxidoben-zyl)-N-(2-pyridylamino)aminomethyl]-4-methylphenol (H2Ldtb), as a manganese peroxidase mimetic was developed. Several parameters were investigated to evaluate the performance of the biomimetic sensor obtained after the incorporation of the dinuclear complex in a carbon paste. The best performance was obtained in 75:15:10% (w/w/w) of the graphite powder:Nujol:MnIIIMnII complex, 0.1 mol L−1 phosphate buffer solution (pH 6.0) and 4.0 × 10−5 mol L−1 hydrogen peroxide. The response of the sensor towards rutin concentration was linear using square wave voltammetry in the range of 9.99 × 10−7 to 6.54 × 10−5 mol L−1 (r = 0.9998) with a detection limit of 1.75 × 10−7 mol L−1. The recovery study performed with pharmaceuticals ranged from 96.6% to 103.2% and the relative standard deviation was 1.85% for a solution containing 1.0 × 10−3 mol L−1 rutin (n = 6). The lifetime of this biomimetic sensor was 200 days (at least 750 determinations). The results obtained for rutin in pharmaceuticals using the biomimetic sensor and those obtained with the official method are in agreement at the 95% confidence level.  相似文献   

11.
The synthesis and characterization of new symmetrical FeII complexes, [FeLA(NCS)2] (1), and [FeLBx(NCS)2] (24), are reported (LA is the tetradentate Schiff base N,N′-bis(1-pyridin-2-ylethylidene)-2,2-dimethylpropane-1,3-diamine, and LBx stands for the family of tetradentate Schiff bases N,N′-bis[(2-R-1H-imidazol-4-yl)methylene]-2,2-dimethylpropane-1,3-diamine, with: R = H for LB1 in 2, R = Me for LB2 in 3, and R = Ph for LB3 in 4). Single-crystal X-ray structures have been determined for 1 (low-spin state at 293 K), 2 (high-spin (HS) state at 200 K), and 3 (HS state at 180 K). These complexes remain in the same spin-state over the whole temperature range [80–400 K]. The dissymmetrical tetradentate Schiff base ligands LCx, N-[(2-R2-1H-imidazol-4-yl)methylene]-N′-(1-pyridin-2-ylethylidene)-2,2-R1-propane-1,3-diamine (R1 = H, Me; R2 = H, Me, Ph), containing both pyridine and imidazole rings were obtained as their [FeLCx(NCS)2] complexes, 510, through reaction of the isolated aminal type ligands 2-methyl-2-pyridin-2-ylhexahydropyrimidine (R1 = H, 57) or 2,5,5-trimethyl-2-pyridin-2-ylhexahydropyrimidine (R1 = Me, 810) with imidazole-4-carboxaldehyde (R2 = H: 5, 8), 2-methylimidazole-4-carboxaldehyde (R2 = Me: 6, 9), and 2-phenyl-imidazole-4-carboxaldehyde (R2 = Ph: 7, 10) in the presence of iron(II) thiocyanate. Together with the single-crystal X-ray structures of 7 and 9, variable-temperature magnetic susceptibility and Mössbauer studies of 510 showed that it is possible to tune the spin crossover properties in the [FeLCx(NCS)2] series by changing the 2-imidazole and/or C2-propylene susbtituent of LCx.  相似文献   

12.
Eu3+-doped Ca2SnO4 (solid solutions of Ca2−xEu2xSn1−xO4, 0?x?0.3) and Eu3+ and Y3+-codoped Ca2SnO4 (Ca1.8Y0.2Eu0.2Sn0.8O4) were prepared by solid-state reaction at 1400 °C in air. Rietveld analysis of the X-ray powder diffraction patterns revealed that Eu3+ replaced Ca2+ and Sn4+ in Eu3+-doped Ca2SnO4, and that Eu3+ replaced Ca2+ and Y3+ replaced Sn4+ in Ca1.8Y0.2Eu0.2Sn0.8O4. Red luminescence at 616 nm due to the electric dipole transition 5Do7F2 was observed in the photoluminescence (PL) spectra of Ca2−xEu2xSn1−xO4 and Ca1.8Y0.2Eu0.2Sn0.8O4 at room temperature. The maximum PL intensity in the solid solutions of Ca2−xEu2xSn1−xO4 was obtained for x=0.1. The PL intensity of Ca1.8Y0.2Eu0.2Sn0.8O4 was 1.26 times greater than that of Ca2−xEu2xSn1−xO4 with x=0.1.  相似文献   

13.
Zhang L  Li W  Shi M  Kong J 《Talanta》2006,70(2):432-436
A novel film modified electrode for the determination of trace lead was developed in this work. The modified electrode was prepared by the electropolymerization of N,N′-(o-phenylene)-bis-benzenesulfonamide (PBSA) as the ion capturing reagent to create the functional film. The modified electrode shows a high selectivity towards Pb2+ over interfering cations, e.g. Cu2+, Cd2+, Co2+, Ni2+, Zn2+, Cr2+, and the calibration curve was linear in the concentration range of 2.0 × 10−9 to 1.0 × 10−7 M with correlation coefficient of 0.999. For 20 min accumulation, detection limit of 1.0 × 10−9 M was obtained at the signal to noise ratio of 3. Analytical availability of the modified electrode was demonstrated by the application for samples from pond water.  相似文献   

14.
Undoped and Eu2+ or Ce3+-doped SrYSi4N7 were synthesized by solid-state reaction method at 1400-1660 °C under nitrogen/hydrogen atmosphere. The crystal structure was refined from the X-ray powder diffraction data by the Rietveld method. SrYSi4N7 and EuYSi4N7, being isotypic with the family of compounds MYbSi4N7 (M=Sr, Eu, Ba) and BaYSi4N7, crystallize with the hexagonal symmetry: space group P63mc (No. 186), Z=2, a=6.0160 (1) Å, c=9.7894 (1) Å, V=306.83(3) Å3; and a=6.0123 (1) Å, c=9.7869 (1) Å, V=306.37(1) Å3, respectively. Photoluminescence properties have been studied for Sr1−xEuxYSi4N7 (x=0-1) and SrY1−xCexSi4N7 (x=0-0.03) at room temperature. Eu2+-doped SrYSi4N7 shows a broad yellow emission band peaking around 548-570 nm, while Ce3+-doped SrYSi4N7 exhibits a blue emission band with a maximum at about 450 nm. SrYSi4N7:Eu2+ can be very well excited by 390 nm radiation, which makes this material attractive as conversion phosphor for LED lighting applications.  相似文献   

15.
Novel heteroscorpionate-containing tin and organotin(IV) complexes, [SnRnX3 − n(L)], R = Me, Bun, Ph, or cy; X = Cl, Br or I, n = 0, 1, 2 or 3; L = bis(pyrazol-1-yl)acetate (bpza) or bis(3,5-dimethylpyrazol-1-yl)acetate (bdmpza), have been synthesized and characterized by spectral (IR, 1H, 13C and 119Sn NMR, 119mSn Mössbauer) and analytical data. In [SnI3(bdmpza)], the ligand is fac-N,N′,O-tridentate, the three iodine atoms thus also fac about the six-coordinate tin(IV) atom. Neutral bpzaH reacts with BunSnCl3, PhSnCl3 and SnCl4 in Et2O in the absence of base, yielding 1:1 adducts [XSnCl3(bpzaH)] (X = R or Cl).  相似文献   

16.
Europium titanate, EuTiO3, is a paraelectric/antiferromagnetic cubic perovskite with TN=5.5 K. It is predicted that compressive strain could induce simultaneous ferroelectricity and ferromagnetism in this material, leading to multiferroic behavior. As an alternative to epitaxial strain, we explored lattice contraction via chemical substitution of Eu2+ with the smaller Ca2+ cation as a mechanism to tune the magnetic properties of EuTiO3. A modified sol-gel process was used to form homogeneously mixed precursors containing Eu3+, Ca2+, and Ti4+, and reductive annealing was used to transform these precursors into crystalline powders of Eu1−xCaxTiO3 with x=0.00, 0.05, 0.10, 0.15, 0.25, 0.35, 0.50, 0.55, 0.60, 0.65, 0.80, and 1.00. Powder XRD data indicated that a continuous Eu1−xCaxTiO3 solid solution was readily accessible, and the lattice constants agreed well with those predicted by Vegard's law. SEM imaging and EDS element mapping indicated a homogeneous distribution of Eu, Ca, and Ti throughout the polycrystalline sample, and the actual Eu:Ca ratio agreed well with the nominal stoichiometry. Measurements of magnetic susceptibility vs. temperature indicated antiferromagnetic ordering in samples with x≤0.60, with TN decreasing from 5.4 K in EuTiO3 to 2.6 K in Eu0.40Ca0.60TiO3. No antiferromagnetic ordering above 1.8 K was detected in samples with x>0.60.  相似文献   

17.
A novel red light-emitting material, Ca3Al2O6:Eu3+, which is the first example found in the Ca3Al2O6 host, was prepared by calcination of a layered double hydroxide precursor at 1350 °C. The precursor, [Ca2.9−xAl2Eux(OH)9.8](NO3)2+x·2.5H2O, was prepared by coprecipitation of metal nitrates with sodium hydroxide. The material is a loose powder composed of irregular particles formed from aggregation of particles of a few nanometers, as shown in scanning electron microscope (SEM) images. It was found that the photoluminescence intensity reached the maximum when the calcination temperature was 1350 °C and the concentration of Eu3+ was 1.0%. The material emits bright red emission at 614 nm under a radiation of λ=250 nm.  相似文献   

18.
The reaction of N9,N9′-(tri or tetramethylene)-bisadenines (Ade2Cx; x = 3 or 4) in HCl 2 M at 50 °C with MCl2 · 2H2O [M = Zn(II), Cd(II)] yields outer sphere compounds like the previously described [(H-Ade)2C3][ZnCl4] · H2O (3) and [(H-Ade)2C3]2[Cd2Cl8(H2O)2] · 4H2O (4) for Ade2C3 and the new {[(H-Ade)2C4][Cd2Cl6(H2O)2] · 2H2O}n (5) for Ade2C4. On the other hand, only in case of Zn(II) complexes by changing [HCl] to 0.1 M, the inner sphere compounds [H-(Ade)2C3(ZnCl3)] (6) and [H-(Ade)2C4(ZnCl3)] · 1.5H2O (7) are obtained. X-ray diffraction study of compound 6, which represents the first inner sphere complex with a N9,N9′-bisadenine, shows a zwitterionic form with one adenine ring protonated at N(1) while the other ring is coordinated via N(7) to a ZnCl3 moiety as in other alkyl-adenine derivatives. In addition, with Ade2C4, is also possible to obtain another inner sphere complex: [(H-Ade)2C4(ZnCl3)2] · 3H2O (8).  相似文献   

19.
Microscopic information on the complexation of Be2+ with cyclo-tri-μ-imidotriphosphate anions in aqueous solution has been gained by both 9Be and 31P NMR techniques at −2.3 °C. Separate NMR signals corresponding to free and complexed species have been observed in both spectra. Based on an empirical additivity rule, i.e., proportionality observed between the 9Be NMR chemical shift values and the number of coordinating atoms of ligand molecules, the 9Be NMR spectra have been deconvoluted. By precise equilibrium analyses, the formation of [BeX(H2O)3]+ and [BeX2(H2O)2]0 (X = non-bridging oxygen donor as a coordination atom in the phosphate groups) has been verified, and the formation of complexes coordinating with the nitrogen atoms of the cyclic framework in the ligand molecule has been excluded. Instead, the formation of one-to-one (ML) complexes, one-to-two (ML2), together with two-to-one (M2L) complexes (L = cP3O6(NH)3) has been disclosed, the stability constants of which have been evaluated as log KML = 3.87 ± 0.03 (mol dm−3)−1, log KML2 = 2.43 ± 0.03 (mol dm−3)−2 and log KM2L = 1.30 ± 0.02 (mol dm−3)−2, respectively. 31P NMR spectra measured concurrently have verified the formation of the complexes estimated by the 9Be NMR measurement. Intrinsic 31P NMR chemical shift values of the phosphorus atoms belonging to ligand molecules complexed with Be2+, together with the 31P-31P spin-spin coupling constants have been determined.  相似文献   

20.
In the present work, hydride generation, as one of widespread application techniques in elemental analysis with the advantage of the excellent matrix separation, was attempted into the chemiluminescence. The experiment exhibited that the strong chemiluminescence emission can be obtained during the reaction between hydrogen telluride and luminol in basic medium, and a novel sensitive hydride generation-chemiluminescence (HG-CL) methodology for the determination of tellurium was proposed. Under the optimized conditions, the linear range of CL intensity versus concentration of tellurium (IV) was 10-200 μg L− 1, with a coefficient (R) of 0.997 and a limit of detection (S/N = 3) of 2 μg L− 1. The results showed that the method provided superior performance with respect to tolerance to various coexisting ions such as Mg2+, Ca2+, Fe3+, Zn2+, Pb2+, As3+, Ge2+, and Hg2+. The proposed method has the advantages of simplicity, selectivity, and sensitivity, with a potential of detecting tellurium in environmental and biological samples.  相似文献   

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