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1.
基于痕量Se4+催化K2S2O8氧化靛红(Isa)的灵敏反应而导致体系的磷光剧烈猝灭的学术思想,建立了一种高灵敏(检出限(LD)为0.015 pg/mL)催化固体基质室温磷光法(SS RTP)测定痕量Se(IV)的新方法。方法的线性范围为4.00×10–8~4.00×10–6 μg/mL。工作曲线的回归方程为△IP=2.948+63.24CSe(IV)(pg/mL),n = 7。相关系数( r )为 0.9997。方法已成功用于水样中痕量Se(IV)的测定,结果与紫外分光光度法相吻合,并探讨了测定痕量Se(IV)的反应机理。 相似文献
2.
基于Bi(Ⅲ)能催化K2S2O8氧化亚甲基蓝(MB)的反应,使MB的室温磷光(RTP)强度剧烈猝灭,且Bi(Ⅲ)的含量与体系的?IP成线性关系,据此可建立Bi(Ⅲ)催化K2S2O8氧化R固体基质室温磷光法(SS RTP)测定痕量Bi(Ⅲ)的新方法。方法的线性范围为0.040~1.0 ×10-15 g/mL,工作曲线的回归方程?IP=2.336+27.26×10–15CBi3+(g/mL),n=6,相关系数r=0.9980,检出限(LD)为1.9 ×10–15 g/mL,RSD为2.1%。方法灵敏、简便、快速、选择性与重现性好,用于水样品中痕量Bi(Ⅲ)的测定,结果满意。同时,讨论了催化K2S2O8氧化MB SSRTP测定痕量Bi(Ⅲ)的反应机理。 相似文献
3.
4.
Changqing Lin Lihong Zhang Zhiyong Zheng Xuan Lin Liping Lin Xinxing Wang Shaoqin Lin Jiaming Liu 《中国化学》2010,28(11):2233-2239
Under the conditions of reacting at 100°C for 8 min and irradiating with the infrared light for 15 min, methylene blue (MEB) could emit weak room temperature phosphorescence (RTP) on the cellulose acetate membrane (CAM) using Pb2+ as the ion perturber in the NH3‐NH4Cl (pH=9.80) solution. MEB was oxidized by H2O2, which caused the RTP of the system to enhance. Cu2+ could catalyze the reaction of H2O2 oxidizing MEB, which caused the RTP of the system to enhance sharply. The ΔIp (Ip0?Ip, the Ip0 and Ip were RTP intensity of the blank reagent and RTP intensity of the test reagent, respectively) of the catalytic system was 133.6, which was 4.1 times larger than that without infrared light irradiation (33.1). Its ΔIp was proportional to the content of Cu2+. Thus, a new catalytic solid substrate room temperature phosphorimetry (SSRTP) for the determination of trace copper has been established. The limit of quantization (LOQ) of this method was 0.12 ag·spot?1 (sample volume: 0.40 µL·spot?1, corresponding concentration: 3.0×10?16 g·mL?1), showing high sensitivity. This method not only has been successfully applied to the determination of trace copper in the tobacco, tea and human serum, but also could predict human diseases. The catalytic reaction was first order reaction, whose activation energy (E) was 18.17 kJ·mol?1 and rate constant (k) was 3.4×10?4 s?1. At the same time, the mechanism of catalytic SSRTP for the determination of trace copper was discussed. 相似文献
5.
Guo Hui Zhu Zhi Ming Li Xiao Hua Chen Jia Ming Liu Tian Long Yang Wen Qian Zhang Shao Xian Lin Ping Zhou Department of Food Biological Engineering Zhangzhou Institute of Technology Zhangzhou China Department of Chemistry Environmental Science Zhangzhou Normal College Zhangzhou China 《中国化学快报》2007,18(6):711-713
In the H2SO4 medium and in the presence of dodecylbenzene sulfonic acid sodiumsalt (DBS), dimethyl yellow (R) could emit strong and stable solid substrate room temperature phosphorescence (RTP) on filter paper. And NaIO4 could oxidize R to cause the RTP quenching. Arsenic(V) could catalyze the reaction of NaIO4 oxidizing R, which caused the RTP sharply quenching. The reducing value of phosphorescence intensity (△Ip) for the system with DBS is 3.3 times higher than that without DBS. Moreover, the△Ip is proportional to the concentration of As(V). Based on the facts above, a new RTP quenching method for the determination of trace As(V) has been established. 相似文献
6.
Liu J Yang T Zhu G Chen H Li P Lin X Huang X 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2008,69(3):1004-1009
A new method for the determination of trace formaldehyde by solid substrate-room temperature phosphorescence quenching method has been proposed. It is based on the facts that rose bengal (R) can emit intense and stable room temperature phosphorescence on the solid substrate of filter paper (SS-RTP). Potassium bromate (KBrO(3)) can oxidize R, which causes the quenching of RTP. In the presence of HCHO, it can react with KBrO(3) to form Br(2) and Br(2) can oxidize R, which causes smart quenching of RTP. The phosphorescence intensity (DeltaI(p)) is directly proportional to the concentration of HCHO. In the presence of Tween-80, the DeltaI(p) will be increased to 9.1 times higher than that without it. The linear range of this method is 0.016-1.6fgspot(-1) (corresponding concentration: 0.040-4.0 pgml(-1), 0.40 microlspot(-1)) with the detection limit of 4.5agspot(-1) (corresponding concentration: 1.1 x 10(-14) gml(-1)). The regression equation for working curve is DeltaI(p)=136.6+28.28m(HCHO)fgspot(-1) (r=0.9935, n=6). This method is sensitive, simple, rapid and has been applied to the determination of trace formaldehyde in real samples with satisfactory results. The mechanism of determination of trace formaldehyde by SS-RTP quenching method based on the rose bengal-KBrO(3)-Tween-80 system is also discussed. 相似文献
7.
Factors affecting the coordination mode of an amidato group on aluminum will be presented. The reaction of N-tert-butylalkylacetamide ((t)BuNHCR([double bond]O)) with 1.1 molar equiv of Me(3)Al in refluxing hexane affords a pentacoordinated, dimeric compound [Me(2)Al[eta(2)-(t)BuNC(R)(mu(2)-O)]](2) (3, R = p-(t)Bu-C(6)H(4); 4, R = 2,6-F,F-C(6)H(3); 5, R = Me; 6, R = CF(3); 7, R = p-F(3)C-C(6)H(4)). However, in the presence of 2.2 molar equiv of Me(3)Al, N-tert-butyl-4-tert-butylbenzamide ((t)BuNHC(p-(t)Bu-C(6)H(4))([double bond]O in refluxing hexane gives [Me(2)Al[eta(2)-(t)BuNC(p-(t)Bu-C(6)H(4))(mu(2)-O)]AlMe(3)], 8. In contrast, the reaction of R'NHCR' '([double bond]O) with 1 molar equiv of R(3)Al at room temperature produces tetracoordinated, dimeric, eight-membered ring aluminum compounds [R(2)Al[mu,eta(2)-R'NC(R' ')O]](2) (9, R = Me, R' = 2,6-(i)Pr, (i)()Pr-C(6)H(3), R' ' = Ph; 10, R = Me, R' = (i)Bu, R' ' = Ph; 11, R = Et, R' = Bn, R' ' = Ph; 12, R = Me, R' = Ph, R' ' = CF(3); 13, R = Me, R' = Bn, R' ' = CF(3)). On the other hand, 4'-chlorobenzanilide ((p-Cl-C(6)H(4))NHCPh([double bond]O)) reacts with R(3)Al to produce trimeric, twelve-membered ring aluminum compounds [R(2)Al[mu, eta(2)-(p-Cl-C(6)H(4))NC(Ph)O]](3) (14, R = Me; 15, R = Et). Furthermore, the reaction of 2'-methoxybenzanilide with 1 molar equiv of Me(3)Al in hexane yields a dinuclear aluminum complex [Me(2)Al(o-OMe-Ph)NC(Ph)(O)AlMe(3)], 16. 相似文献
8.
Jia-Ming Liu Fei Gao Tian-Long Yang Jian-Hua Lai Zhi-Ming Li 《International journal of environmental analytical chemistry》2013,93(9):613-624
A new catalytic solid substrate-room temperature phosphorimetry (SS-RTP) for the determination of trace arsenic(V) has been established. It is based on the fact that fullerenol (F-ol) emitted strong and stable room temperature phosphorescence (RTP) on nitric acid cellulose membrane (NCM) substrate. H2O2 could oxidise F-ol to cause the quenching of RTP. As(V) could catalyse H2O2 to oxidise F-ol and decrease the RTP signal of F-ol sharply. After adding tween-80 in the system, its ΔI p enhanced 7.7 times compared with the without-tween-80 levels. Under the optimum conditions, the linear dynamic range of this method was 0.016?11.2 ag spot?1 with a detection limit (LD) of 9.3 zg spot?1 (corresponding concentration: 2.3 × 10?17 g mL?1). This sensitive, simple and selective method has been successfully applied to the determination of trace As(V) in human hair and tea samples. The reaction mechanism for SS-RTP is also discussed. 相似文献
9.
Amako M Schinkel J Freiburger L Brook MA 《Dalton transactions (Cambridge, England : 2003)》2005,(1):74-81
Two different classes of silicone-modified ligands were prepared: nitrile derivatives, 4'-[3-(organosilyl)propoxy]biphenyl-4-carbonitrile R'3SiC3H6OC6H4C6H4CN (R'3Si- = a: Me3SiOSiMe2-, b: (Me(3)SiO)2SiMe-, c: Me3SiO(Me2SiO)3SiMe2-, d: Me3SiO(Me2SiO)25SiMe2-); and, pyridine derivatives, isonicotinic acid 2-methoxy-4-[3-(organosilyl)propyl]phenyl ester R'3SiC3H6Ph(O)MeOCOC5H4N . Compounds and were bound to Pd and Pt using ligand substitution reactions with organometallic precursors to give (R3SiC3H6OC6H4C6H4CN)2PdCl2, (R3SiC3H6OC6H4C6H4CN)2PtCl2 and (R3SiC3H6C6H3(OMe)OC(O)C5H4N)PtCl2(eta(2)-1-octene). The polydimethylsiloxane (PDMS)-supported Pt and Pd compounds and had excellent solubility in both organic solvents and polysiloxanes. All the Pt compounds exhibited good catalytic activity for hydrosilylation of vinylsilanes. The PDMS-supported Pd compound also was effective catalyst for hydrosilylation of a diene, isoprene, with 1,1,1,3,3-pentamethyldisiloxane MM(H) to produce the 1,4-adduct Me3SiOSiMe2CH2CH=CMeCH2-H as a major product. 相似文献
10.
Karlov SS Lermontova EKh Zabalov MV Selina AA Churakov AV Howard JA Antipin MY Zaitseva GS 《Inorganic chemistry》2005,44(13):4879-4886
Synthesis of the title compounds, viz. [RN(CH2CHR'O)2]2Ge (1, R = Me, R' = H; 2, R = Me, R' = Ph; 3, R = Ph, R' = H), by the reaction of 2 equiv of corresponding dialkanolamines RN(CH2CHR'OH)2 (4, R = Me, R' = H; 5, R = Me, R' = Ph; 6, R = Ph, R' = H) with (AlkO)4Ge is reported. Composition and structures of all novel compounds were established by 1H and 13C NMR spectroscopy and mass spectrometry as well as elemental analysis data. The single-crystal X-ray diffraction of 2 has clearly indicated the presence of two transannular interactions Ge<--N in the compound. N atoms are cis-orientated. The compound 3 possesses long Ge...N distances. The structural data obtained from geometry optimizations by DFT calculations on 1-3 reproduces experimental results. Both cis- and trans-isomers were studied, and cis-configuration was found to be more thermodynamically stable for all three compounds. The transition states for possible cis <--> trans rearrangement processes in 1-3 were calculated. The properties of the Ge-O and Ge<--N bonds in 1-3 were analyzed by the AIM approach. The interactions between the Ge atom and N atoms as well as O atoms possess predominantly ionic character. 相似文献
11.
Lee BY Kwon HY Lee SY Na SJ Han SI Yun H Lee H Park YW 《Journal of the American Chemical Society》2005,127(9):3031-3037
Acyclic o-phenylene-bridged bis(anilido-aldimine) compounds, o-C(6)H(4){C(6)H(2)R(2)N=CH-C(6)H(4)-(H)N(C(6)H(3)R'(2))}(2) and related 30-membered macrocyclic compounds, o-C(6)H(4){C(6)H(2)R'(2)N=CH-C(6)H(4)-(H)N-C(6)H(2)R(2)}(2) (o-C(6)H(4)) are prepared. Successive additions of Me(2)Zn and SO(2) gas to the bis(anilido-aldimine) compounds afford quantitatively dinuclear mu-methylsulfinato zinc complexes, o-C(6)H(4){(C(6)H(2)R(2)N=CH-C(6)H(4)-N(C(6)H(3)R'(2))-kappa(2)-N,N)Zn(mu-OS(O)Me)}(2) (R = iPr and R' = iPr, 29; R = Et and R' = Et, 30; R = Me and R'= Me, 31; R = Me and R' = iPr, 32; R = Et and R' = Me, 33; R = Et and R' = iPr, 34; R = iPr and R' = Et, 35) and o-C(6)H(4){C(6)H(2)R'(2)N=CH-C(6)H(4)-N-C(6)H(2)R(2)-kappa(2)-N,N)Zn(mu-OS(O)Me)}(2) (o-C(6)H(4)) (R = Et and R'= Et, 36; R = Me and R' = Me, 37; R = iPr and R' = Me, 38; R = Et and R' = Me, 39; R = Me and R'= iPr, 40). Molecular structures of 34 and 40 are confirmed by X-ray crystallography. Complexes 30-35 show high activity for cyclohexene oxide/CO(2) copolymerization at low [Zn]/[monomer] ratio (1:5600), whereas the complex of mononucleating beta-diketiminate {[(C(6)H(3)Et(2))N=C(Me)CH=C(Me)N(C(6)H(3)Et(2))]Zn(mu-OS(O)Et)}(2) shows negligible activity in the same condition. Activity is sensitive to the N-aryl ortho substituents and the highest activity is observed with 32. Turnover number up to 2980 and molecular weight (M(n)) up to 284 000 are attained with 32 at such a highly diluted condition as [Zn]/[monomer] = 1:17 400. Macrocyclic complexes 36-40 show negligible activity for copolymerization. 相似文献
12.
Gehrhus B Hitchcock PB Parruci M 《Dalton transactions (Cambridge, England : 2003)》2005,(16):2720-2725
The thermally stable silylene Si[(NCH2But)2C6H4-1,2] 1 undergoes oxidative addition reactions with the lithium amides LiNRR'(R = SiMe3, R' = But; R = SiMe3, R' = C6H3Me2-2,6; R = R' = Me or R = R' = Pri) to afford the new lithium amides Li(THF)2[N(R)Si(SiMe3){(NCH2But)2C6H4-1,2}][R = But2 or R = C6H3Me2-2,6 (3a)] or the new tris(amino)functionalised silyllithiums Li(THF)x[Si{(NCH2But)2C6H4-1,2}NRR'][R = SiMe3, R' = C6H3Me2-2,6, x = 2 (3); R = R'= Me, x = 3 (4) or R = R' = Pri, x = 3 (5)]. Compounds 4 and 5 are stable at ambient temperature but compound 3 is thermally labile and converts into 3a upon heating. The pathway for the formation of 2 and 3 is discussed and the X-ray structures of 2-5 are presented. 相似文献
13.
Takashi Tomiyasu Satoshi Aikou Katsuro Anazawa Hayao Sakamoto 《Analytical sciences》2005,21(8):917-922
A catalytic spectrophotometric method for the determination of traces of copper(II) is proposed. 3-Methyl-2-benzothiazolinone hydrazone (MBTH) is oxidized by hydrogen peroxide to form a yellowish-brown compound. The reaction is accelerated by trace amounts of copper(II), and can be followed by measuring the increase in the absorbance at 390 nm. Since the absorbance at 40 min from the reaction start increases with an increase in the copper(II) concentration, the absorbance value is used as a parameter for copper(II) determination. Under the optimum experimental conditions (8.4 x 10(-3) mol dm(-3) MBTH, 0.7 mol dm(-3) hydrogen peroxide, pH 5.2, 35 degrees C), copper(II) can be determined in the range 0-50 microg dm(-3). The relative standard deviations are 6.9, 3.5, 2.7% for 2, 20 and 40 microg dm(-3), respectively. The detection limit of this method (3sigma) is 0.27 microg dm(-3). It was successfully applied to a determination of copper(II) in river water, tap water and ground-water samples. According to the results of a kinetic study, a mechanism is proposed which leads to the following rate equation: R0(cat) = kK1K2[MBTH][H2O2][Cu(II)]0/{(1 + K2[H2O2])[H+]}. 相似文献
14.
Clenbuterol hydrochloride (CLB) could catalyze NaIO4 oxidation of eosine Y (R), which caused the room temperature phosphorescence (RTP) signal of R to quench sharply. The ΔIP (=IP2 − IP1, IP2 was RTP intensities of reagent blank and IP1 was RTP intensities of test solution) of the system was directly proportional to the content of CLB. According to that academic thought, a new solid substrate-room temperature phosphorimetry (SS-RTP) for the determination of trace CLB has been established. This method has high sensitivity (detection limit (LD): 0.021 zg spot−1, corresponding concentration: 5.2 × 10−20 g mL−1) and good selectivity (Er = ±5%, interfering species were of no interference). It has been applied to the determination of residual CLB in the practical samples. The results were verified using HPLC and GC/MS methods. The reaction mechanism of catalytic SS-RTP for the determination of residual CLB was also discussed. 相似文献
15.
Milde B Schaarschmidt D Rüffer T Lang H 《Dalton transactions (Cambridge, England : 2003)》2012,41(17):5377-5390
The consecutive syntheses of imidazoles 1-(4-X-C(6)H(4))-4,5-R(2)-(c)C(3)HN(2) (3a, X = Br, R = H; 3b, X = I, R = Me; 3c, X = H, R = Me; 5, X = Fc, R = H; 7, X = C≡CFc, R = H; 9, X = C(6)H(5), R = Me; Fc = Fe(η(5)-C(5)H(4))(η(5)-C(5)H(5))), phosphino imidazoles 1-(4-X-C(6)H(4))-2-PR'(2)-4,5-R(2)-(c)C(3)N(2) (11a-k; X = Br, I, Fc, FcC≡C, Ph; R = H, Me; R' = Ph, (c)C(6)H(11), (c)C(4)H(3)O), imidazolium salts [1-(4-X-C(6)H(4))-3-R'-4,5-R(2)-(c)C(3)HN(2)]I (16a; X = Br, R = H, R' = n-Bu; 16b, X = Br, R = H, R' = n-C(8)H(17); 16c, X = I, R = Me, R' = n-C(8)H(17), 16d, X = H, R = Me, R' = n-C(8)H(17)) and phosphino imidazolium salts [1-C(6)H(5)-2-PR'(2)-3-n-C(8)H(17)-4,5-Me(2)-(c)C(3)N(2)]PF(6) (17a, R' = C(6)H(5); 17b, R' = (c)C(6)H(11)) or [1-(4-P(C(6)H(5))(2)-C(6)H(4))-3-n-C(8)H(17)-4,5-Me(2)-(c)C(3)HN(2)]PF(6), (20) and their selenium derivatives 1-(4-X-C(6)H(4))-2-P([double bond, length as m-dash]Se)R'(2)-4,5-R(2)-(c)C(3)N(2) (11a-Se-f-Se; X = Br, I; R = H, Me; R' = C(6)H(5), (c)C(6)H(11), (c)C(4)H(3)O) are reported. The structures of 11a-Se and [(1-(4-Br-C(6)H(4))-(c)C(3)H(2)N(2)-3-n-Bu)(2)PdI(2)] (19) in the solid state were determined. Cyclovoltammetric measurements were performed with the ferrocenyl-containing molecules 5 and 7 showing reversible redox events at E(0) = 0.108 V (ΔE(p) = 0.114 V) (5) and E(0) = 0.183 V (ΔE(p) = 0.102 V) (7) indicating that 7 is more difficult to oxidise. Imidazole oxidation does not occur up to 1.3 V in dichloromethane using [(n-Bu)(4)N][B(C(6)F(5))(4)] as supporting electrolyte, whereas an irreversible reduction is observed between -1.2 - -1.5 V. The phosphino imidazoles 11a-k and the imidazolium salts 17a,b and 20, respectively, were applied in the Suzuki C-C cross-coupling of 2-bromo toluene with phenylboronic acid applying [Pd(OAc)(2)] as palladium source. Depending on the electronic character of 11a-k, 17a,b and 20 the catalytic performance of the in situ generated catalytic active species can be predicted. As assumed, more electron-rich phosphines with their higher donor capability show higher activity and productivity. Additionally, 11e was applied in the coupling of 4-chloro toluene with phenylboronic acid showing an excellent catalytic performance when compared to catalysts used by Fu, Beller and Buchwald. Furthermore, 11e is eligible for the synthesis of sterically hindered biaryls under mild reaction conditions. C-C Coupling reactions with the phosphino imidazolium salts 17b and 20 in ionic liquids [BMIM][PF(6)] and [BDMIM][BF(4)] were performed, showing less activity than in common organic solvents. 相似文献
16.
R2Bi-BiR2 [1; R = 2,6-(Me2NCH2)2C6H3], a dibismuthane that exists in different forms in the crystalline state, reacts in air with the formation of the peroxide [R(2)Bi]2(O2) (2) and partial oxidation of the pendant (dimethylamino)methyl groups, yielding the mononuclear bismuth complex R'R' 'Bi (3) [R' = 2-(Me2NCH2)-6-{Me2N(O)CH2}C6H3; R' ' = 2-(Me2NCH2)-6-{O(O)C}C6H3]. 相似文献
17.
At atmospheric pressure and at 130-160 degrees C, primary aromatic amines (p-XC6H4NH2, X = H, Cl, NO2) are mono-N-alkylated in a single step, with symmetrical and asymmetrical dialkyl carbonates [ROCOOR', R = Me, R' = MeO(CH2)2O(CH2)2; R = R' = Et; R = R' = benzyl; R = R' = allyl; R = Et, R' = MeO(CH2)2O(CH2)2], in the presence of a commercially available NaY faujasite. No solvents are required. Mono-N-alkyl anilines are obtained with a very high selectivity (90-97%), in good to excellent yields (68-94%), on a preparative scale. In the presence of triglyme as a solvent, the mono-N-alkyl selectivity is independent of concentration and polarity factors. The reaction probably takes place within the polar zeolite cavities, and through the combined effect of the dual acid-base properties of the catalyst. 相似文献
18.
Regioselective nucleophilic aromatic substitution of an o-fluorine occurs to afford fluorine-substituted o-phenylene-bridged bis(anilido-aldimine) compounds o-C6H4[(C6H2R2)N=CH-C6F4-(H)N(C6H3R'2)]2 when Li(H)N-C6H3R'2 (R' = iPr, Et, Me) is reacted with o-C6H4[(C6H2R2)N=CH-C6F5]2 (R = iPr, Et, Me) in a nonpolar solvent such as diethyl ether or toluene. Successive additions of Me2Zn and SO2 gas to the bis(anilido-aldimine) compounds afford quantitatively dinuclear mu-methylsulfinato zinc complexes o-C6H4[[(C6H2R2)N=CH-C6F4-N(C6H3R'2)-kappa2N,N]Zn(mu-OS(O)Me)]2 (R = iPr, R' = iPr, 3a; R = iPr, R' = Me, 3c; R = Et, R' = (i)Pr, 3d; R = Et, R' = Et, 3e; R = Et, R' = Me, 3f; R = Me, R' = iPr, 3g; R = Me, R' = Et, 3h; R = Me, R' = Me, 3i). The molecular structure of 3c was confirmed by X-ray crystallography. Fluorine-substituted complexes 3a-i show significantly higher TOF (turnover frequencies) than the unfluorinated analogues for CO2/(cyclohexene oxide) copolymerization. The TOF is highly sensitive to the substituents R and R', and the highest TOF (2480 h(-1)) is obtained with 3g (R = Me, R' = iPr). Complex 3g is less sensitive to the residual protic impurities present in the monomers and shows activity at such a low catalyst concentration as [Zn]:[cyclohexene oxide] = 1:50,000, at which the unfluorinated analogue is completely inactive. By realizing the activity at such an extremely low [Zn]:[cyclohexene oxide] ratio, we achieve a high TON (turnover number) up to 10,100. High-molecular-weight polymers (M(n), 100,000-200,000) are obtained with a rather broad molecular-weight distribution (M(w)/M(n), 1.3-2.5). The obtained polymers are not perfectly alternating, and variable carbonate linkages (65-85%) are observed depending on the N-aryl ortho substituents R and R' and the polymerization conditions. 相似文献
19.
A catalytic spectrophotometric method for the determination of trace amounts of nitrite is proposed. In acidic solution, chlorpromazine (CP) is oxidized by nitric acid to form a red compound, which is further oxidized to a colorless compound. The reaction is accelerated by trace amounts of nitrite and can be followed by measuring the absorbance at 525 nm: nitrite ion is regenerated and multiplied by nitric acid. The absorbance of the reaction increased with an increase in the reaction time, reached a maximum and decreased rapidly. Since the time required for the absorbance to reach the maximum decreased with increasing nitrite concentration, this value was used as the measured parameter for the nitrite determination. Under the optimum experimental conditions (2.3 M nitric acid, 1.2 x 10(-5) M CP, 40 degrees C), nitrite can be determined in the range 0-100 microg l(-1). The relative standard deviations (n = 6) are 4.7 and 1.8% for 40 and 100 microg l(-1) nitrite, respectively. The detection limit of this method (3sigma) is 1.2 microg l(-1). This method was successfully applied to a determination of nitrite in natural water samples. 相似文献
20.
Stenson PA Board A Marin-Becerra A Blake AJ Davies ES Wilson C McMaster J Schröder M 《Chemistry (Weinheim an der Bergstrasse, Germany)》2008,14(8):2564-2576
The dithiosalicylidenediamine Ni II complexes [Ni(L)] (R=tBu, R'=CH2C(CH3)2CH2 1, R'=C6H4 2; R=H, R'=CH2C(CH3)2CH2 3, R'=C6H4 4) have been prepared by transmetallation of the tetrahedral complexes [Zn(L)] (R=tBu, R'=CH2C(CH3)2CH2 7, R'=C6H4 8; R=H, R'=CH2C(CH3)2CH2 9, R'=C6H4 10) formed by condensation of 2,4-di-R-thiosalicylaldehyde with diamines H2N-R'-NH2 in the presence of Zn II salts. The diamagnetic mononuclear complexes [Ni(L)] show a distorted square-planar N2S2 coordination environment and have been characterized by 1H- and 13C NMR and UV/Vis spectroscopies and by single-crystal X-ray crystallography. Cyclic voltammetry and coulombic measurements have established that complexes 1 and 2, incorporating tBu functionalities on the thiophenolate ligands, undergo reversible one-electron oxidation processes, whereas the analogous redox processes for complexes 3 and 4 are not reversible. The one-electron oxidized species, 1+ and 2+, can be generated quantitatively either electrochemically or chemically with 70 % HClO4. EPR and UV/Vis spectroscopic studies and supporting DFT calculations suggest that the SOMOs of 1+ and 2+ possess thiyl radical character, whereas those of 1(py)2 + and 2(py)2 + possess formal Ni III centers. Species 2+ dimerizes at low temperature, and an X-ray crystallographic determination of the dimer [(2)2](ClO4)2.2 CH2Cl2 confirms that this dimerization involves the formation of a S-S bond (S...S=2.202(5) A). 相似文献