共查询到20条相似文献,搜索用时 250 毫秒
1.
A Schiff-base fluorescent sensor, 7-methoxychromone-3-carbaldehyde-(3′,4′-dimethyl)pyrrole hydrazone (MCPH), was synthesized. The new sensor showed high selectivity for Al 3+ over other metal ions examined in acetonitrile. Upon binding Al 3+, a significant fluorescence enhancement with a turn-on ratio over 101-fold was triggered. The detection limit of MCPH for Al 3+ was 2.5?×?10 ?7?mol?L ?1. 相似文献
2.
This paper deals with a simplified multi-element profiling of inorganic arsenic, antimony, selenium and tellurium in the form of 75As, 82Se, 121Sb and 125Te by ICP-MS for amounts less than 10?µg?L ?1. Internal standards such as 72Ge and 209Bi were successfully used for the suppression of both influence of macro elements Na +, K +, Ca 2+, Mg 2+ or Al 3+, and interference of limited concentrations of heavy metal ions. Modified silica sorbents Separon? SGX C18, C8, CN, NH 2, RPS and Phenyl were tested for the preconcentration of As, Sb, Se and Te (0.25–5?µg?L ?1) in the form of ion associates with cationic surfactants from 50–250?mL sample volume. 1-etoxycarbonyl-pentadecyltrimethylammonium bromide (Septonex®, 0.005?mol?L ?1) was suitable for this purpose in the presence of 4-(2-pyridylazo) resorcinol, 2-pyrrolidinecarbodithioate and 8-hydroxyquinoline-5-sulphonic acid. The quantitative retention occurred at pH 7?±?0.2 and the mixture of acetone with ethanol in ratio 1?:?1 in the presence of 0.1?mol?L ?1 HCl was used for the quantitative elution. Organic solvents and the excess of acid were removed by evaporation prior to the determination by ICP-MS. The determination of the above trace metalloids in various kinds of water with enrichment factor till 50 times on silica Separon? SGX C18 and the above reagents were compared with the standard addition method. 相似文献
3.
Three coordination polymers of Robson-type macrocycles, {[Cu 4L 1(4,4′-bipy) 2]·4ClO 4·H 2O} ∞ ( 1), {[Cu 4L 2(4,4′-bipy) 4]·2CH 3CN·4ClO 4·2H 2O} ∞ ( 2), and {[Zn 2L 2(4,4′-bipy) 2]·(ClO 4) 2} ∞ ( 3) (where H 2L 1 and H 2L 2 are the [2?+?2] condensation products of 1,3-diaminopropane with 2,6-diformyl-4-methylphenol and 2,6-diformyl-4-fluorophenol, respectively), have been synthesized and characterized. Magnetic susceptibility was measured for 1 and 2 from 2 to 300?K. The optimized magnetic data were J?=?–368.5?cm ?1, J′?=?40.5?cm ?1 with R?=?1.69?×?10 ?6 for 1 and J?=?–291.22?cm ?1, J′?=?83.74?cm ?1, ρ = 0.00168 with R?=?1.8?×?10 ?11 for 2, respectively. The data reveal strong antiferromagnetic interactions between two Cu(II) ions in the macrocyclic unit and ferromagnetic interaction between the Cu(II) ions in two adjacent macrocyclic units for 1 and 2. 相似文献
4.
A simple colorimetric and fluorimetric ‘On–Off’ sensor L (3,3′-dimethyl -[1,1′-biphenyl]-4,4′-diyl)bis(azanylylidene)bis(methanylylidene)bis(naphthalen-2-ol) for Cu 2+ ions bearing o-tolidine substituents has been designed and synthesised, and exhibits significant fluorimetric and colorimetric response for Cu 2+ in DMSO/H 2O (8:2, v/v) HEPES buffer (pH 7.2) solution. The detection limit of the sensor towards Cu 2+ is 7.25 × 10 ? 8 M and the association constant Ka of 9.86 × 10 4 M ? 1 was determined. Furthermore, other anions, including Fe 3+, Hg 2+, Ag +, Ca 2+, Co 2+, Ni 2+, Cd 2+, Pb 2+, Zn 2+, Cr 3+ and Mg 2+ have almost no influence on the probe's behaviour. Test strips based on the sensor L were fabricated, which could act as convenient and efficient Cu 2+ test kits. 相似文献
5.
AbstractSince conventional sensitive explosives have given rise to unforeseen accidents during storage and transport, the demand of modern armies for insensitive energetic materials is on the rise. There are very few determination methods for the most widely used insensitive energetic materials such as 3-nitro-1,2,4-triazole-5-one (NTO). Thus, the aim of this work is the development of a rapid and practical nanoparticle-based colorimetric sensor for determination of NTO. The detection principle of the sensor involved electrostatic attraction of NTO anion to the ammonium group of l-cysteine functionalized gold nanoparticles (AuNP-Cys), followed by the formation of a Cu 2+-coordination complex between particles to result in AuNPs agglomeration. The concomitant color change was from red to violet. The surface plasmon resonance band of AuNPs at 520?nm shifted to 650?nm upon chemical reaction and agglomeration. Spectroscopic evaluation was made by taking the ratio of 650?nm absorbance to that of 520?nm, and correlating this ratio to NTO concentration. The analytical performance characteristics of this ratiometric sensor for NTO as the molar absorptivity (ε); limits of detection (LOD) and quantification (LOQ) were: ε = (8.62?±?0.29) × 10 3 L mol ?1 cm ?1, LOD = 0.25?mg L ?1, and LOQ = 0.85?mg L ?1. The sensor was applied to various energetic material mixtures containing 2,4,6-trinitrotoluene, hexahydro-1,3,5-trinitro-1,3,5-triazine, octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine, and tetryl. Additionally, the possible interference effects of commonly found soil ions such as Cl –, NO 3–, SO 42–, PO 43–, Mg 2+, Ca 2+, Na +, and K + were studied. The proposed method was statistically validated against a literature liquid chromatography–tandem mass spectrometry (LC/MS-MS) method. 相似文献
6.
An α‐diimine‐stabilized Al? Al‐bonded compound [L 2?Al II? Al IIL 2?] (L=[{(2,6‐ iPr 2C 6H 3)NC(Me)} 2]; 1 ) consists of dianionic α‐diimine ligands and sub‐valent Al 2+ ions and thus could potentially behave as a multielectron reductant. The reactions of compound 1 with azo‐compounds afforded phenylimido‐bridged products [L ?Al III( μ2‐NPh)( μ2‐NAr)Al IIIL ?] ( 2 – 4 ). During the reaction, the dianionic ligands and Al 2+ ions were oxidized into monoanions and Al 3+, respectively, whilst the [NAr] 2? imides were produced by the four‐electron reductive cleavage of the N?N double bond. Upon further reduction by Na, the monoanionic ligands in compound 2 were reduced to the dianion to give [(L 2?) 2Al III2(μ 2‐NPh) 2Na 2(thf) 4] ( 5 ). Interestingly, when asymmetric azo‐compounds were used, the asymmetric adducts were isolated as the only products (compounds 3 and 4 ). DFT calculations indicated that the reaction was quite feasible in the singlet electronic state, but the final product with the triplet‐state monoanionic ligands could result from an exothermic singlet‐to‐triplet conversion during the reaction process. 相似文献
7.
A new diarylethene with ethylimidazo[2,1- b]thiazole-6-hydrazide unit was synthesized, and its photochromic and fluorescent behaviors have been systematically investigated by the stimulation of lights and metal ions in methanol. This new diarylethene exhibited high selectivity and sensitivity toward Al 3+ and Zn 2+. The addition of Al 3+ and Zn 2+ displayed excellent colorimetric response behaviour with the concomitant color change from colorless to yellow, which could be easily observed by the naked eye. Upon addition of Al 3+, the fluorescence intensity was enhanced by 180–fold and the emission peak of 1O–Al 3+ blue-shifted by 15?nm accompanied with a color change from colorless to bright blue. In contrast, when stimulated with Zn 2+, its fluorescence intensity was enhanced by 35–fold and the emission peak of 1O–Zn 2+ red-shifted by 16?nm with an evident color change from black to bright green. The LOD for Al 3+ and Zn 2+ were determined to be 2.97?×?10 ?9?mol?L ?1 and 5.98?×?10 ?9?mol?L ?1, respectively. Moreover, a logic circuit was constructed with the fluorescence intensity as the output signal responding to the light and chemical species as the inputs. 相似文献
8.
A new chemically modified carbon paste electrode by 2,2?-((pyridine-2,6-diylbis(azanylylidene))bis(methanylylidene))diphenol ( L) ligand has been made and used as a sensor for determination of trace mercury and cadmium ions with cyclic voltammetry (CV) and differential pulse voltammetry (DPV) methods. Complexation studies of the ligand with Cu 2+, Zn 2+, Hg 2+, Ni 2+ and Cd 2+ ions by conductometric method in acetonitrile–ethanol mixture at 25°C show that the ML complexes have formed. The formation constants of complexes were calculated from the computer fitting of the molar conductance–mole ratio data, and the stability of the resulting complexes varied in order of Cd 2+ > Hg 2+ > Cu 2+ > Zn 2+ > Ni 2+. Then a simple and effective chemically modified carbon paste electrode with L was prepared, and the electrochemical properties and applications of the modified electrode were investigated. Under the optimal conditions, the detection limit was 0.0494 μg L ?1 and 0.0782 μg L ?1 for cadmium and mercury ions, respectively, and the linear range for both metal ions were from 1 to 100 μg L ?1. The electrode shows high sensitivity, reproducibility and low cost, and was successfully applied to determination of Cd 2+ and Hg 2+ ions in water samples with recovery in the range of 97–101%. 相似文献
9.
Copper hexacyanoferrate (CuHCF) film‐modified carbon paste electrode (CPE) has been prepared from various electrolytic aqueous solutions using consecutive cyclic voltammetry. The cyclic voltammograms showed the direct deposition of CuHCF films from the mixing of Cu 2+ and Fe(CN) 63? ions and each time with one of the six cations: H +, Na +, K +, NH 4+, Mg 2+, and Al 3+. The CuHCF film showed a single redox couple that exhibited a cation effect (Na +, K +, Mg 2+, and NH 4+) and anion effect (Cl ?, NO 3?, SO 42?, ClO 4?, and BrO 3?) in the cyclic voltammograms. Voltammetric studies have indicated that in presence of nitrite, the cathodic peak current of CuHCF increases, followed by a decrease in the corresponding anodic current. This indicated that nitrite was reduced by the redox mediator immobilized on the electrode surface via an electrocatalytic mechanism. The process of reduction and its kinetics were investigated by using cyclic voltammetry, differential pulse voltammetry, chronoamperometry and chronocoulometry techniques. The electrocatalytic ability about 800 mV can be seen. The rate constant of the catalytic reduction of nitrite was found to be 7.9×10 5 cm 3 mol ?1 s ?1. Linearity range obtained was 5×10 ?5?8.4×10 ?3 by cyclic voltammetry and 8×10 ?6?1.3×10 ?3 and 4×10 ?3?2×10 ?2 by differential pulse voltammetry. 相似文献
10.
Abstract A carbon paste electrode modified with cobalt phthalocyanine (CPECoPc) was developed and applied to the determination of hydrazine [N 2H 4] in industrial boiler feed water. The CPECoPc exhibited good electrocatalytical activity for hydrazine oxidation at pH 13. A linear correlation was obtained between anodic peak current (I ap) and hydrazine concentration in the range of 1.25 × 10 ?4 to 9.80 × 10 ?4 mol L ?1, fit by the equation I ap = 1.47 + 4.90 × 10 5 [N 2H 4] with a correlation coefficient of 0.9967. A detection limit of 7.35 × 10 ?5 mol L ?1 was obtained. Recovery of hydrazine from three samples ranged between 99.0% and 102.9%. The modified electrode showed no interference by cations commonly present in boiler water, such as K +, Na +, Ca 2+, Mg 2+, Al 3+, Pb 2+, and Zn 2+. The results obtained for hydrazine in boiler water using the proposed modified electrode are in agreement with the data obtained by a standard spectrophotometric method, at the 95% confidence level. 相似文献
11.
In this study a cobalt film electrodeposited on a copper disk (Ø=3.1 mm) was tested as electrode to measure nitrite ions in raw water. This electrode was able to determine the nitrite ions concentration in nondeaerated synthetic media and in natural water. The electrode reached a detection limit of 0.2 μmol L ?1 and has a linear concentration range of 0.4 to 2 μmol L ?1 NO 2?. The influence of several ions such as NO 3?, Cl ?, SO 42?, Mg 2+, HCO 3? and NH 4+ was also tested. The electrode was used to determine the concentration of nitrite ions in a real sample. 相似文献
12.
Metal Complexes of Biologically Important Ligands. CLXVI Metal Complexes with Ferrocenylmethylcysteinate and 1,1′‐Ferrocenylbis‐(methylcysteinate) as Ligands A series of complexes of transition metal ions ( Cr 3+, Mn 2+, Co 2+, Ni 2+, Cu 2+, Zn 2+ ) and of lanthanide ions ( La 3+, Nd 3+, Gd 3+, Dy 3+, Lu 3+ ) with the anions of ferrocenylmethyl‐L‐cysteine [(C 5H 5)Fe(C 5H 4CH(R)SCH 2CH(NH 3+)CO 2?] (L 1) and with the dianions of 1,1′‐ferrocenylbis(methyl‐L‐cysteine) [Fe(C 5H 4CH(R)SCH 2CH(NH 3+) CO 2?) 2] (R = H, Me, Ph) (L 2) as N,O,S‐donors were prepared. With the monocysteine ferrocene derivative L 1 as ligands complexes [M IIL 12] or [Cr IIIL 12]Cl type complexes are formed whereas the bis(cysteine) ligand L 2 yields insoluble complexes of type [ML 2] n, presumably as coordination polymers. The magnetic moments of [Mn IIL 2] n, [Pr IIIL 2] n(OH) n and [Dy IIIL 2] n(OH) n exhibit “normal” paramagnetism. 相似文献
13.
The binding of cations Li +, Na +, K +, Cs +, Ag +, Zn 2+, Ni 2+, Co 2+, NH 4
+ (group I), H +, Mg 2+, Al 3+, Ga 3+ (group II), and Ca 2+, Pb 2+ (group III) by 2 1,3 1-diphenyl-l 2,4 2-dioxo- 7,10,13-trioxa-l,4(3,1)-diquinoxalina-2(2,3),3(3,2)-diindolizinacyclopentadecaphane ( 1), which contains two indolizine and two quinoxaline fragments and 3,6,9-trioxaundecanes spacer, and by its acyclic analog
( 2) was studied using cyclic voltammetry in MeCN/0.1 M Bu 4NBF 4. It was concluded that the ions of group I are not bound by these compounds, the ions of group II exhibit the reversible
redox-switched binding by the carbamoyl groups of the quinoxaline fragments, whereas the ions of group III are bound not only
by the initial compounds and radical cations 1 and 2, but also by dication 1. This binding of the Ca 2+ and Pb 2+ ions stabilizes dication 1. 相似文献
14.
A simultaneous preconcentration and separation method for determination of trace amount of dissolved Ag +, Pb 2+ and Pd 2+ ions by modified octadecyl silica membrane disks with DBzDA18C6 was developed. The adsorbed metal complexes were eluted from disk with 10?mL of 4?M KCl and determined by flame atomic absorption spectroscopy. Several parameters such as anion effect, pH of sample solution, type of eluent, amount of ligand, sample and elution flow rate were evaluated. The effect of diverse ions on preconcentration was also investigated. A precocentration factor of 110 can easily be achieved depending on the volume of the sample. For 100?mL of the solution the linear dynamic rang were found to be 30–1000, 140–6000, 60–900?μg?l ?1 for Ag +, Pb 2+ and Pd 2+, respectively. Based on three standard deviation of the blank the detection limit was obtained as 1.8, 8.0 and 4.2?μg?L ?1 for Ag +, Pb 2+, Pd 2+, respectively. The formation constants of Ag + and Pb 2+ ions with DBzDA18C6 at 25?°C were determined from the molar conductance–mole ratio data. This method was applied for the determination of Ag +, Pb 2+ and Pd 2+ in environmental water, tea and soil samples. 相似文献
15.
L-DOPA is an important neurotransmitter that is found in the brain and as a hormone in the circulatory system. We report in this article the similarities and differences in behaviour of this important neurotransmitter as a chelating agent among some divalent and trivalent metal ions using potentiometric titration in aqueous solutions at 25.0?±?1.0°C. The careful and detailed potentiometric titrations of L-DOPA with Al 3+, Cr 3+, Fe 3+, Cu 2+, and Zn 2+ are discussed and compared. UV-Vis-spectroscopy is utilized for both the free L-DOPA and for the Fe 3+/ L-DOPA system. The characteristic peak due to the π?→?π* transition of the free L-DOPA at ~280?nm (ε 280?nm?=?1927?±?65?M ?1?cm ?1 between pH values of 2.0 to 3.0) disappeared when the iron solution was added to the L-DOPA sample in the same pH range. For the Fe 3+/ L-DOPA system we have observed a new peak at 470?nm with ε 470?=?800?±?50?M ?1?cm ?1. These comparison studies of the similarities and differences among these di- and tri-valent metal ions shed light on these systems in aqueous solutions. The appropriate metal simulation and speciation diagrams were constructed using the model that fit the titration data points. 相似文献
16.
The polydentate ligands, 3-(2-aminocyclohexylamino)-2-(2-aminocyclohexyl aminomethyl) propionic acid ( L1 ), 4,7,10-triazatridecanedinitrile trihydrochloride ( L2 ), and 2,2′-(ethane-1,2-diyl) bis(methylazanediyl) diethanol ( L3 ) were prepared and their structures investigated by FT-IR, NMR, and MS. The kinetics of complex formation between Cu(II) and L 1, L 2, and L 3 were investigated in acidic aqueous solutions using the stopped-flow method. The stability constants of the complexes were determined by spectrophotometric titration (T?=?293?K, μ?=?0.1?mol?L ?1 NaClO 4), using a diode array UV-Vis spectrophotometer equipped with peristaltic pump and pH meter. The stability constants for the complexes were CuL 1?>?CuL 2?>?CuL 3. Activation enthalpies (ΔH#) of these complexes were 55?kJ?mol ?1 for CuL 1, 61?kJ?mol ?1 for CuL 2, and 36?kJ?mol ?1 for CuL 3, respectively. 相似文献
17.
A novel “on–off” Al3+ ions fluorescence-enhanced sensor (E)-1-(((2-hydroxyphenyl) imino)methyl)naphthalen-2-ol (AH-2) and its hydrogel hybrid (PAMN) were synthesized. AH-2 showed excellent selectivity and ultrasensitive to Al3+ ions; the detection limit was 2.36?×?10–9 M. The most plausible complexation mechanism was studied by 1H NMR, FT-IR, HR-MS, Job’s plot and theoretical calculation. And, it was interesting that PAMN could adsorb Al3+ ions with a removal rate of over 99%, which also could easily be distinguished by the naked eye in UV lamp (365 nm). Before and after adsorption of Al3+ ions, the microstructures of PAMN were analyzed by scanning electron microscope and X-ray energy spectrometer. The silica gel detect plates prepared in this work could rapidly and conveniently detect Al3+ ions with a concentration greater than 5?×?10–6 M (0.13 mg/L) in aqueous solution, and the detection concentration (0.13 mg/L) was lower than the national standard concentration of Al3+ ions (0.2 mg/L) in city tap water of china. 相似文献
18.
A novel pyrene-based receptor bearing benzothiazole was synthesized as a good turn-on fluorescent sensor for the recognition of Zn 2+. The probe showed an excellent selectivity for Zn 2+over most other competing ions (eg, Cr 3+, Li +, Cd 2+, Al 3+, Pb 2+, Li +, Mg 2+, Ag +, Ca 2+, Ni 2+, Mn 2+, Fe 3+, Hg 2+, Ba 2+, K +, Na +, Cu 2+, Fe 2+) in EtOH-HEPES (65:35, v/v, pH?=?7.20), which might be attributed to the photoinduced electron transfer (PET) mechanism. The formation of 1:1 stoichiometric PBZ-Zn 2+ complex was determined based on the Job's plot, 1H NMR titration and ESI-MS. The binding constant of the complex was 4.04?×?10 4?M ?1 with a detection limit of 2.58?×?10 ?7?M. The potential application of the PBZ in real water samples for recognizing Zn 2+ was investigated. Bio-imaging study also revealed that PBZ could be applied to detecting Zn 2+ in live cells. These results indicated that PBZ could be a favorable probe for Zn 2+. 相似文献
19.
Investigations in the System Al 3+? WO 42?? H 2O? H 3O + The composition of the tungstoaluminate anion [AlW 12O 40] 5? was determined by means of the molar ratio and JOB 's method of continuous variations modified by us. The optimum conditions for the complex formation in the system Al 3+? WO 42?? H 2O? H 3O + were determined: 1.33 ≤ acid degree Z ≤ 2.5; 105°C; 2–6h (c = 7.15 · 10 ?2–6 · 10 ?3 moles · l ?1). The complex formation in dependence on the acid degree Z is complete at Z = 16 H 3O +/12 WO 42? = 1.33. 相似文献
20.
A simple and nontoxic fluorescent chemosensor of di‐ O‐methyl curcumin has been prepared from curcumin. The sensor exhibited selective and sensitive fluorescent responses toward Al 3+ over a wide range of metal ions, such as Mn 2+, Ce 3+, Pt 2+, Sn 4+, Hg +, Sb 3+, K +, Ca 2+, Mg 2+, Ba 2+, Cu 2+, Ni 2+, Na +, NH 4+, Ag +, Pb 2+, Zn 2+, Fe 2+, Fe 3+, Hg 2+ and Cr 3+ in ethanol/water. The free ligand showed quite weak fluorescence emission due to the isomerization of C?O double bond in the excited state, however, after addition of Al 3+, fluorescence emission results in a prominent fluorescence enhancement. 相似文献
|