共查询到20条相似文献,搜索用时 15 毫秒
1.
Artem I. Vedernikov Evgeny N. Ushakov Lyudmila G. Kuz'mina Andrei V. Churakov Yuri A. Strelenko Michael W?rner André M. Braun Judith A. K. Howard Michael V. Alfimov Sergey P. Gromov 《Journal of Physical Organic Chemistry》2010,23(3):195-206
Benzothiazole type butadienyl dyes containing a dithia‐15‐crown‐5 ( 2a ) or dithia‐18‐crown‐6 ether ( 2b ) moieties were synthesized. The structures of dyes 2a , b and their complexes with Ag+ and Pb2+ were studied by an X‐ray crystallography. It was found that the conformations of dithiacrown–ether moieties of dyes 2a , b are unfavorable for complex formation and change significantly upon binding of Ag+ or Pb2+. The complexation of 2a , b with Ag+, Cd2+, Pb2+, and Hg2+ in water–acetonitrile mixtures with different contents of water (PW = 0–75%, v/v) was studied by 1H NMR, UV–Vis spectroscopy, and polarography. In anhydrous acetonitrile, the stability constants of 1:1 complexes change in the sequence Cd2+ < Pb2+ ≤ Ag+ << Hg2+ in the case of 2a and in the sequence Cd2+ < Ag+ < Pb2+ << Hg2+ in the case of 2b . As PW increases, the thermodynamic stability of Ag+ complexes increases. The opposite effect is observed for the complexes with Cd2+, Pb2+, and Hg2+. When PW ~ 50%, the stability constants of complexes with Cd2+ and Pb2+ become too small to be measured. The selectivity of ligands 2a , b toward Hg2+ versus Ag+ is very high at any PW values (selectivity coefficients > 104). The complexation of 2a , b with Hg2+ at PW ≤ 50% is accompanied by a substantial hypsochromic effect. This allows dithiacrown‐containing butadienyl dyes to be used as selective optical molecular sensors for heavy metal ions, in particular, in aqueous solutions. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
2.
Chang-Chun Ding Shao-Yi Wu Qing-Sheng Zhu Guo-Liang Li Zhi-Hong Zhang Yong-Qiang Xu 《Molecular physics》2013,111(12):1478-1484
The local lattice distortions and the electron paramagnetic resonance (EPR) parameters (g factors, hyperfine structure constants and zero-field splittings) for Cu2+, Mn2+ and Fe3+ in ZnWO4 are theoretically studied based on the perturbation calculations for rhombically elongated octahedral 3d9 and 3d5 complexes. The impurity centres on Zn2+ sites undergo the local elongations of 0.01, 0.002 and 0.013 Å along the C2 axis and the planar bond angle variations of 8.1°, 8.0° and 8.6° for Cu2+, Mn2+ and Fe3+, respectively, due to the Jahn–Teller effect and size and charge mismatch. In contrast to the host Zn2+ site with obvious axial elongation (~0.31 Å) and perpendicular (angular) rhombic distortion, all the impurity centres demonstrate more regular octahedral due to the above local lattice distortions. The copper centre exhibits significant Jahn–Teller reductions for the spin-orbit coupling and orbital angular momentum interactions, characterised by the Jahn–Teller reduction factor J (≈0.29 ? 1). The calculated EPR parameters agree well with the experimental results. The local structures of the impurity centres are analysed in view of the corresponding lattice distortions. 相似文献
3.
Aysel Ba?o?lu Semanur Parlayan Mira? Ocak Hakan Alp Halit Kantekin Mustafa ?zdemir ümmühan Ocak 《Journal of fluorescence》2009,19(4):655-662
A new cryptand compound carrying 2-hydroxy-1-naphthylidene Schiff base moiety (3) was designed and synthesized by reaction of the corresponding macrobicyclic amine compound (1) and 2-hydroxy-1-naphthaldehyde (2). The influence of metal cations such as Mg2+, Ca2+, Sr2+, Fe2+,Co2+, Mn2+, Zn2+, Cd2+, Hg2+, Al3+ and Pb2+ on the spectroscopic properties of the new fluoroionophore was investigated in acetonitrile-dichloromethane solution (9.5/0.5)
by means of absorption and emission spectrometry. The blue shifts on the fluorescence spectrum were observed for all metal
cations at 504nm. At the same time the fluorescence spectrum of the ligand showed quenching in the intensity of the signal
at 504 nm for all metal cations except for Zn2+. Interaction of Co2+ with the ligand caused quenching of naphtyl fluorescence higher than 84%. The method showed good selectivity and sensitivity
for Co2+ with respect to other metal cations with linear range and detection limit of 1.5 × 10−7 to 3.3 × 10−6M and 4.8 × 10−8M respectively. 相似文献
4.
Shyamaprosad Goswami Nirmal Kumar Das Krishnendu Aich Debabrata Sen 《Journal of luminescence》2011,131(10):2185-2188
A new macrocyclic receptor 1 having [1,8]-naphthyridine fluorophore is designed and synthesized for selective fluorescence sensing of Cd2+. Receptor 1 selectively responds to Cd2+ over other tested metal ions via a large enhancement of emission intensity due to the cation-induced CHEF (chelation enhanced fluorescence) effect. Receptor 1 although exhibits some affinity towards Zn2+, it selectively binds Cd2+ over Zn2+. Binding and selectivity were examined by 1H-NMR, fluorescence, UV-vis, mass and IR-spectroscopic techniques. 相似文献
5.
A Novel Hg<Superscript>2+</Superscript> Selective Ratiometric Fluorescent Chemodosimeter Based on an Intramolecular FRET Mechanism 总被引:1,自引:0,他引:1
A irreversible Hg2+ selective ratiometric fluorescence probe FR, a fluorescein fluorophore linked to a rhodamine B hydrazide by a thiourea spacer, was designed and synthesized. The developed
probe FR exhibited great ratiometric fluorescence enhancement and remarkable yellow-magenta color change toward Hg2+ with excellent selectivity in aqueous acetone solution, and the ratiometric fluorescence response to Hg2+ was not interfered by other metal cations including Fe3+, Co2+, Ni2+, Cr3+, Zn2+, Pb2+, Cd2+, Ca2+, Mg2+, Ba2+ and Mn2+. The linear range and the detection limit of this supposed ratiometric fluorescence method for Hg2+ were 0.0–10.0 × 10−6 and 5 × 10−8 M, respectively. 相似文献
6.
M. Rahimi-Nasrabadi F. Ahmadi S.M. Pourmortazavi M.R. Ganjali K. Alizadeh 《Journal of Molecular Liquids》2009,144(1-2):97-101
The complexation reactions between Cr3+, Cd2+, Co2+, Ni2+, Hg2+, Zn2+, Pb2+,and Ag+ metal ions with diethyl-3-(4-hydroxy-6-methylpyrimidin-2-yl) guanidine (L1), 2-amino,4-hydroxy,6-methylpyrimidine (L2), and 2-(diethylamin),4-hydroxy,6-methylpyrimidine (L3) in acetonitrile (AN) were studied using a conductometric method. The formation constants of the resulting complexes were determined from computer fitting conductance-mole ratio data. The results revealed that the formation constants of L1 with metal ions are varying in order of Cr3+ > Pb2+ > Zn2+ > Co2+ > Hg2+ > Ag+ ~ Cd2+ > Ni2+. For L2 and L3 the sequence of complex formation constants are follow as Cr3+ > Pb2+ > Zn2+ > Co2+ > Cd2+ > Hg2+ > Ag+ > Ni2+ and Cr3+ > Pb2+ > Zn2+ > Co2+ > Ni2+ ~ Hg2+ ~ Cd2+ ~ Ag+, respectively. The values of the thermodynamic parameters (ΔH, ΔS and ΔG) for complexation reactions were obtained from the temperature dependence of the stability constants. In all cases, the complexes were found to be enthalpy stabilized but entropy destabilized. In addition, some ab-initio quantum-mechanical calculations were carried out, in order to obtain a clue about the degree tendency of ligands to metal ions. 相似文献
7.
New type photocatalytic materials of Zn2+–Ni2+–Fe3+–CO32?LDHs were prepared by complexing agent-assisted homogeneous precipitation technique and Zn(NO3)2·6H2O, Ni(NO3)·6H2O, Fe(NO3)3·9H2O used as raw materials in the case of molar ratio of Zn2+/Ni2+/Fe3+ = 1:6:2. Zn2+–Ni2+–Fe3+–CO32?LDHs having a specific surface area of 96.5 m2/g. The structure and catalytic properties of the material were systematically studied. The experimental results show that the Zn2+–Ni2+–Fe3+–CO32?LDHs has a higher adsorption performance and lower band gap which make it an excellent catalyst for reducing the degradation of the methyl orange. Study on the process of photocatalytic reaction shows that Methyl Orange was adsorbed to the layer of Zn2+–Ni2+–Fe3+–CO32?LDHs, and then it was photodecomposed to inorganic molecules and ions by Zn2+, Ni2+, and Fe3+ on the surface of Zn2+–Ni2+–Fe3+–CO32?LDHs. 相似文献
8.
A series of green phosphors Zn1.92−2xYxLixSiO4:0.08Mn2+ (0≤x≤0.03) were prepared by solid-state synthesis method. Phase and lattice parameters of the synthesized phosphors were characterized by powder X-ray diffractometer (XRD) and the co-doped effects of Y3+/Li+ upon emission intensity and decay time were investigated under 147 nm excitation. The results indicate that the co-doping of Y3+/Li+ has favorable influence on the photoluminescence properties of Zn2SiO4:Mn2+, and the optimal photoluminescence intensity of Zn1.90Y0.01Li0.01SiO4:0.08Mn2+ is 103% of that of commercial phosphor when the doping concentration of Y3+/Li+ is 0.01 mol. Additionally, the decay time of phosphor is much shortened and the decay time of Zn1.90Y0.01Li0.01SiO4:0.08Mn2+ is 3.39 ms, shorter by 1.83 ms than that of commercial product after Y3+/Li+ co-doping. 相似文献
9.
A new compound, 1-[p-(dimethylamino)benzoyl]-4′-phenyl-semicarbazide (1) was synthesized and showed highly selective response to Cu2+ over other metal ions such as Pb2+, Mg2+, Fe2+, Co2+, Zn2+, Cd2+, Hg2+, Ni2+, Ca2+, Ag+, Na+, K+, and Li+. The control compound, 1-[p-(dimethylamino)benzoyl]-4-phenyl-thiosemicarbazide (2), showed different fluorescence spectral response to Cu2+. A 1:1 complex between Cu2+ and 1 was formed while 1:1 and 1:2 complexes between Cu2+ and 2 were formed. The binding model between the receptor (1 or 2) and Cu2+ was supported by IR spectra, mass spectra, and computation model. 1 possessed higher selectivity towards Cu2+ compared with 2 owing to the difference of complexation ability between urea and thiourea groups. 相似文献
10.
A. A. El-bindary 《光谱学快报》2013,46(3):383-395
The dissociation constant of l-acetyl-2-(coumariniminecarboxamide-3-yl) hydrazine (ACCH) has been determined potentiometrically in 0.1 M KC1 and 40% (v/v) ethanol-water mixture. The stepwise stability constants of the formed complexes of Mn2+, Co2+, Ni2+, Cu2+, Zn2+ and UO2 2+ with ACCH have been determined. The stability constants were found to UO2 2+ > Cu2+> Zn2+ > Ni2+ < CO2+ < Mn2+. The effect of temperature on the dissociation of ACCH and the stability of its formed complexes were studied. The corresponding thermodynamic functions were also determined and discussed. The spectral data of ACCH were investigated in pure organic solvents as well as in Britton Robinson buffer solutions of varying pH values. The dissociation constant pKH 1 of ACCH and the overall stability constants logβ of their complexes were determined in 20% (v/v) ethanol-water mixture at 298K. 相似文献
11.
ABSTRACT A new multielement sensitive fluorescent probe, 1-(2-(phenylthio)ethyl)-2-(pyridin-2-yl)-1H-benzo[d]imidazole (L), has been synthesized by the reaction between 2-(pyridyl) benzimidazole and 2-chloroethyl phenyl sulfide. Excitation and emission wavelength of L are at 330 and 371 nm, respectively. Among various transition and nontransition metal ions, it can selectively read Zn2+ ion as the emission wavelength of L undergoes a red shift by 31 nm upon binding with Zn2+ in methanol. In the presence of Cd2+, Hg2+, and other common cations, the emission wavelength of L remains unchanged, and thus allows us to discriminate Zn2+ from its congeners. Both L and its Zn2+ complex are well characterized by different spectroscopic techniques like 1H-NMR, ESI-TOF (+) mass, FT-IR, and elemental analysis data. The binding constant value of the complexation reaction between L and Zn2+ is found as 724.6 M?1 in methanol. Density functional theoretical (DFT) studies nicely demonstrate the red shift in the emission wavelength of L upon binding with Zn2+. 相似文献
12.
13.
Spherical Zn2SiO4:Eu@SiO2 phosphor particles in core-shell structure: Synthesis and characterization
Spherical SiO2 particles have been coated with Zn2SiO4:Eu3+ phosphor layers by a Pechini sol-gel process. The microstructure and luminescent properties of the obtained Zn2SiO4:Eu3+@SiO2 particles were well characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), photoluminescence (PL) spectra, and lifetime. The results demonstrate that the Zn2SiO4:Eu3+@SiO2 particles, which have regular and uniform spherical morphology, emitted an intensive red light emission at 613 nm under excitation at 395 nm. Besides, the effects of the Eu3+ concentration, annealing temperature and charge compensators of Li+ ions on the PL emission intensities were investigated in detail. 相似文献
14.
Third order nonlinear optical susceptibilities χ<3> of ternary Zn1−xMgxSe and Cd1−xMgxSe crystals have been measured using standard degenerate four-wave mixing (DFWM) method at 532 nm. The nonlinear transmission
technique has been applied to check if our crystals exhibit two-photon absorption. The studied Zn1−xMgxSe and Cd1−xMgxSe solid solutions were grown from the melt by the modified high-pressure Bridgman method. For both crystals the energy gap
increases with increasing Mg content.
In the case of Zn1−xMgxSe, it was found that the value of third order nonlinear optical susceptibility χ<3> decreases with increasing Mg content. An explanation of this behaviour results from the dependence of optical nonlinearities
on the energy band gap Eg of the studied crystals. In the case of Cd1txMgxSe with low content of Mg, no response was observed for the studied wavelength since the energy gap in such crystals is smaller
than the photon energy of the used laser radiation.
It was also found that the value of third order nonlinear optical susceptibility χ<3> for Cd0.70Mg0.30Se is higher than for Zn0.67Mg0.33Se. This behaviour can be understood if one take into consideration that the free carrier concentration in Cd1−xMgxSe samples is about four orders of magnitude higher than that in Zn1txMgxSe ones with comparable Mg content respectively. It is commonly known that when the electric conductivity increases, the values
of nonlinear optical properties increase.
From the performed measurements one can conclude that the incorporation of Mg as constituent into ZnSe and CdSe crystals leads
to a change of the third order nonlinear optical susceptibilities. 相似文献
15.
Zhengping Dong Jun Jin Wenfeng Zhao Huamei Geng Ping Zhao Rong Li Jiantai Ma 《Applied Surface Science》2009,255(23):9526-9530
A carbon nanotube-based fluorescent chemosensor MWNTs-glycine-N-8-quinolylamide (MWNTs-GNQ) has been designed and synthesized. Steady-state fluorescence emission studies showed that this material displays high selectivity and sensitivity for the Cu2+ ion over other cations such as Zn2+, Cd2+, Mg2+, Ca2+, and Ni2+. 相似文献
16.
Fluoroionophores consisting of coumarin-153 linked to mono- and diaza-crown ethers are able to complex transition metal cations (Ni2+, Zn2+, Cd2+) and Pb2+, with concomitant large changes in photophysical properties. The stability constants in acetonitrile are higher than 3×106
M
–1 except for Ni2+. 相似文献
17.
Subhodip Samanta 《Journal of luminescence》2008,128(10):1689-1700
The paper reports time-resolved emission and energy transfer (ET) studies of metal ion complexes of a specially designed rigid macrocyclic naphthalene cryptand (L) under different conditions. Complex formation of L with Li+ and H+ causes an appreciable increase in singlet state quantum yield and lifetime of L implying photoinduced electron transfer (PET) from the cryptand moiety to naphthalene unit in the free L. The system exhibits photoinduced ET at 77 K in its Tb3+ and Eu3+ complexes with either NO3−1 or Cl−1 as counter-anion. The extent of ET is higher for the Tb3+ complex as compared to that for the Eu3+ complex. In both Tb3+ and Eu3+ complex, the NO3−1 ions influence the relative orientation of donor (L) and acceptor (Ln3+) more in favour of ET than the Cl−1 ions. The rate constants for the ET from the naphthalene moiety of L to the acceptor (Ln3+) have been evaluated at 77 K. The results suggest ET from the triplet state of naphthalene using an exchange mechanism. The ground state geometries of the system L and its complexes with Li+, Cs+ and Tb3+ have been determined using DFT methods to interpret our results. 相似文献
18.
The electron paramagnetic resonance of Mn2+ and Gd3+ doped in Pr2Zn3(NO3)12.24H2O single crystals has been studied at X-band. Mn2+ substitutes for two Zn2+ sites, while Gd3+ substitutes for single type of Pr3+ sites. The spin-Hamiltonian analysis of the EPR spectra is presented at 298 K as well as 77 K. 相似文献
19.
Fei-Hui Li 《Applied Surface Science》2009,255(16):7394-7402
The reduction process of Bi3+, HTeO2+ and their mixtures on Au electrode surface was studied by cyclic voltammetry, linear sweep voltammetry, electrochemical impedance spectroscopy and chronoamperometry. XRD and EDS methods were also used to measure the reductive products prepared under different potentials and provide the evidences of the reactions. The results indicate that the reduction of HTeO2+ occurs at more positive potential than that of Bi3+, but its reduction rate is slower and adsorption phenomenon exists during its reduction process. Bi2Te3 compound can be obtained potentiostatically at a proper potential in all the mixed solutions with concentration ratio CHTe+O2/CBi3+ in our research range (0.1-10). But pure Bi2Te3 compound can only be obtained at 42 mV in the solution with concentration ratio CHTe+O2/CBi3+ equaling to 1. And the formation of Bi2Te3 compound is an inductive co-depositing process: (1) HTeO2+ + 4e− + 3H+ → Te0 + 2H2O, (2) 3Te0 + 2Bi3+ + 6e− → Bi2Te3. 相似文献
20.
Methylene blue (MB) was developed as a sensitive DNA probe for a comparative study of Cd2+, Pb2+ and Cr3+ ions binding with calf thymus DNA (ctDNA). The fluorescence intensity of the MB-ctDNA system increased dramatically when heavy metal ions (Cd2+, Pb2+ and Cr3+ ions) were added, which indicated that some of the bound MB molecules were released from the ctDNA base pairs. To compare the binding affinity of these three different heavy metal ions with ctDNA, the relationships between the fluorescence intensity of the MB-ctDNA-M (Metal ions) system and the concentration ratio of [M]/[DNA(p)] were investigated. The results showed that the order of the binding affinity of heavy metal ions with ctDNA had the following sequence: Cr3+> Cd2+>Pb2+. This order was further proved by the effects of heavy metal ions on the number of MB bound to ctDNA, the measurements of binding constants of these heavy metal ions to ctDNA, and the effects of heavy metal ions on the absorption of the MB-ctDNA system. In addition, the interaction mechanisms of Cd2+, Pb2+ and Cr3+ ions with ctDNA were also discussed in detail. These results indicated that their interaction mechanisms are related to the concentration ratios of heavy metal ions to DNA. 相似文献