Adsorptive stripping voltammetric determination of 1-(4′-bromophenyl)-3,3-dimethyltriazene

The optimum conditions were established for the determination of the genotoxic substance 1-(4-bromophenyl)-3,3-dimethyltriazene by differential-pulse voltammetry at a hanging mercury drop electrode in the concentration range 1 × 10^–4 to 1 × 10^–7 mol dm^–3. The sensitivity of the determination can be improved through adsorptive accumulation of the investigated substance on the surface of the hanging mercury drop electrode: differential pulse adsorptive stripping voltammetry can be used in the concentration range 1 × 10^–7 to 2 × 10^–10 mol dm^–3. The relative standard deviation (for ten determinations at 2 × 10^–10 mol dm^–3) was 7.5%.     

Copper–mercury film electrode for cathodic stripping voltammetric determination of Se(IV)

The copper-mercury film electrode has been suggested for the determination of Se(IV) in a wide range of concentration from 1x10(-9) to 1x10(-6) mol L(-1)by square-wave cathodic stripping voltammetry. Insufficient reproducibility and sensitivity of the mercury film electrode have been overcome by using copper(II) ions during the plating procedure. Copper(II) has been found to be reduced and form a reproducible copper-mercury film on a glassy carbon electrode surface. The plating potential and time, the concentration of copper(II) and the concentration of the supporting electrolyte have been optimised. Microscopy has been used for a study of the morphology of the copper-mercury film. It has been found that it is the same as for the mercury one. The preconcentration step consists in electrodeposition of copper selenide on the copper-mercury film. The relative standard deviation is 4.3% for 1x10(-6) mol L(-1) of Se(IV). The limit of detection is 8x10(-10) mol L(-1) for 5 min of accumulation.     

Coordination modes of diphosphines in silver(I)–diphosphine complexes mediated by 2,4,6-tri(2-pyridyl)-1,3,5-triazine (tptz)

Silver (I) complexes [Ag₂(tptz)(dppm)₂(DMF)](BF₄)₂·2DMF (1), [Ag(tptz)(dppe)]_n(BF₄)_n·2nH₂O·nMeOH (2), [Ag₂(tptz)₂(dppp)₂](BF₄)₂ (3) and [Ag₂(tptz)₂(dppb)](BF₄)₂ (4) were obtained from the reactions of AgBF₄ and diphosphine Ph₂P(CH₂) _nPPh₂ (L_pp, n=1–4) in the presence of 2,4,6-tris(2-pyridyl)-1,3,5-triazine (tptz) in MeOH–DMF. Single crystal analyses showed that the closed metallocyclic unit [Ag₂(L_pp)₂]²⁺ with double L_pp bridges was obtained in (1) and (3) with an odd number of n, while an open metallochain (Ag₂L_pp)²⁺ with a single bridge formed in (2) and (4) with n being even. Coordination modes for the diphosphines are directly related to the rigid tptz ligand with a large -system.     

Anodic stripping voltammetric analysis of trace arsenic(III) enhanced by mild hydrogen-evolution at a bimetallic Au–Pt nanoparticle modified glassy carbon electrode

A glassy carbon electrode (GCE) modified with electrodeposited bimetallic Au–Pt nanoparticles (Au–PtNPs) was applied to sensitively detect As(III) by linear sweep anodic stripping voltammetry (LSASV). In 0.5 M aqueous H₂SO₄, atomic hydrogen and molecular hydrogen were easily electrogenerated at the Pt sites on Au–PtNPs/GCE, which can chemically reduce As(III) to As(0) and enhance the cathodic preconcentration of As(0) at both the Pt sites and the neighboring Au sites. Since the As(0)–Au affinity is weaker than the As(0)–Pt affinity, the preconcentrated As(0) can be rapidly oxidized on/near the surface Au sites of Au–PtNPs/GCE, yielding sharper and higher LSASV current peaks. Under optimum conditions (700 s preconcentration at − 0.1 V, 5 V s^− 1), the LSASV peak current for the As(0)–As(III) oxidation responded linearly to As(III) concentration from 0.005 to 3.0 μM with a limit of detection (LOD) of 3.7 nM (0.28 ppb) (S/N = 3), while that for the As(III)–As(V) oxidation was linear with As(III) concentration from 0.01 to 3.0 μM with a LOD of 6.0 nM (0.45 ppb) (S/N = 3). This method was applied for analysis of As(III) in real water samples.     

Synthesis and Structure of E-2-(2,4,6-tri tert butylphenylphosphinyl)-2-〔N-(tert-butyldimethylsilyl)-N-(p-chrolophenyl)〕amino-1-(2,4,6-tri tert-butyl-phenyl)phosphacthylene

1　INTRODUCTIONItwaswellknown thatelementsofthesecondary and higherrow are in generaldifficulty to form multiplebondsin which apπ hybridized stateisinvolved〔1〕.Thus,simple compounds containing multiple phosphorus carbon bonds,such as methyl dynephosphine( HC≡P) 〔2 - 3〕 and methylenephosphine( H2 C=PH〔4〕,are notstableat room temperature.Three methods to stabilize compounds containing double ormultiple bond involving phosphorusatom in the pπ hybridized state are often used.The f…     

Luminescent nine-coordinate lanthanide complexes derived from fluorinated β-diketone and 2,4,6-tris(2-pyridyl)-1,3,5-triazine

The synthesis, photoluminescence, 4f–4f absorptions, and NMR studies of nine-coordinate lanthanide(III) complexes, [Ln(tfaa)₃(tptz)] (Ln?=?La, Nd, Sm, and Eu; tfaa is the anion of 1,1,1-trifluoro-2,4-pantanedione; and tptz?=?2,4,6-tris(2-pyridyl)-1,3,5-triazine), are reported. These complexes are synthesized in a single pot by in situ method and thoroughly characterized. The β-diketone and tptz chemical shifts, in the cases of paramagnetic complexes, are in the opposite directions. The lanthanide-induced shifts are dipolar in nature. The luminescence and 4f–4f absorptions are analyzed and discussed. The samarium and europium complexes emit strong pink and red luminescences due to ⁴G_5/2?→?⁶H_j (j?=?5/2, 7/2, 9/2) and ⁵D₀?→?⁷F_j (j?=?0–4) transitions, respectively. The ⁴G_5/2→⁶H_7/2 (607?nm) emission transition of Sm(III) has no Stark components and indicates a higher local symmetry around Sm(III). The very strong hypersensitive ⁵D₀?→?⁷F₂ transition of Eu reflects a highly polarizable chemical environment around Eu(III). The absorption spectra of the neodymium complex are investigated and analyzed.     

Complexes of Iron(III) and Chrom(III) Salen and Saloph Schiff Bases with Bridging 2,4,6-tris(4-nitrophenylimino-4′-formylphenoxy)-1,3,5-triazine

Four new trinuclear Fe(III) and Cr(III) complexes involving tetradenta Schiff bases N,N′-bis(salicylidene)ethylenediamine-(salenH₂) or bis(salicylidene)-o-phenylenediamine-(saloph H₂) with 2,4,6-tris(4-nitrophenylimino-4′-formylphenoxy)-1,3,5-triazine (TNPI-TRIPOD) have been synthesized and characterized by means of elemental analysis carrying out ¹H-NMR., IR spectroscopy, thermal analyses and magnetic susceptibility measurements. The complexes can also be characterized as high-spin distorted octahedral Fe(III) and Cr(III) bridged by nitro. The nitro play a role as bridges for weak anti-ferromagnetic intramolecular exchange.     

2,4,6-Tri[(S)-1′-methylbenzylamino]-1,3,5-triazine: a new NMR chiral solvating agent for 3,5-dinitrophenyl derivatives; an attempt at a chiral discrimination rationale

The use of 2,4,6-tri[(S)-1′-methylbenzylamino]-1,3,5-triazine as a chiral solvating agent for the NMR evaluation of the enantiomeric excess of 3,5-dinitrophenyl derivatives is reported along with an investigation into the origin of the enantiodiscrimination process.     

Zn(NO_3)_2·6H_2O/2,4,6-trichloro-1,3,5-triazine(TCT) a mild and selective system for nitration of phenols

<正>Certain phenols and naphthols were nitrated regioselectively with Zn(NO_3)_2·6H_2O/TCT in acetonitrile as solvent at room temperature and short reaction time in good yields.The reaction condition was mild.TCT is a cheap and commercially available reagent.It performed as an acid catalyst in this transformation.     

Cathodic stripping voltammetric determination of β-cyfluthrin,a pyrethroid insecticide,using polished silver solid amalgam electrode

Journal of Solid State Electrochemistry - This work describes an electroanalytical procedure for determination of beta-cyfluthrin (βCF), a pyrethroid insecticide, using polished silver solid...     

Synthesis of Some New 2-(4-Methoxybenzothiazol-2′-yl amino)-4-(2-chloro-4-trifluoromethylanilino)-6-(substituted thioureido)-1,3,5-triazine as Antifungal Agents

2,4,6-Trichloro 1,3,5-triazine was selectively reacted with new nucleophilic reagents such as 4-methoxy-2-aminobenzothiazole, 2-chloro-4-trifluoromethyl-aniline, and phenylsubstituted thiourea in alkaline medium to give 2-(4-methoxybenzothiazol-2′-ylamino)-4-(phenylthioureido)-6-(substitutedthioureido)-1,3,5-triazines. The structures of these compounds were confirmed by IR, ¹H NMR, ¹⁹F NMR, mass spectral data, and elemental analysis. The compounds show fungicidal activity against Alternaria alternata, Aspergillus niger, and Macrofomina.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.     

Kinetics and mechanism of substitution of bis(2,4,6-tripyridyl 1,3,5-triazine)iron(II) by 2,2′,6,2″-terpyridine

The substitution of bis(2,4,6-tripyridyl 1,3,5-triazine)iron(II), \textFe(TPTZ) ₂ ^{2 +} {\text{Fe(TPTZ)}}_{ 2}^{{ 2 { + }}} by 2,2′,6,2″-terpyridine (terpy) occurs on a time scale of about 6 m. The kinetics of this reaction was followed by stopped-flow spectrophotometry in the pH range of 3.6–5.6 in acetate buffer. The data indicate that the reaction occurs in two consecutive steps: kinetic data for both steps were acquired simultaneously and analyzed independently. The first step is assigned to the reaction between \textFe(TPTZ) ₂ ^{2 +} {\text{Fe(TPTZ)}}_{ 2}^{{ 2 { + }}} and terpy to give Fe(TPTZ)(terpy)²⁺, followed by its reaction with another terpy molecule to give the final product, \textFe(terpy) ₂ ^{2 +} {\text{Fe(terpy)}}_{ 2}^{{ 2 { + }}} . The rate of the reaction increases with increases in [terpy] and pH. The kinetic and activation parameters determined for both steps suggest that they involve both associative and dissociative paths. The ternary complex Fe(TPTZ)(terpy)²⁺ has been prepared, and the kinetics of its reaction with terpy suggest that this reaction is identical with the second step of the \textFe(TPTZ) ₂ ^{2 +} {\text{Fe(TPTZ)}}_{ 2}^{{ 2 { + }}} -terpy system, supporting the proposed mechanism.     

2,4,6-三(2′-吡啶基)-1,3,5-三嗪分光光度法测定Fe(Ⅱ)和Fe(Ⅲ)的研究

研究了F-掩蔽Fe(Ⅲ ) ,2 ,4,6 三 (2′ 吡啶基 ) 1 ,3 ,5 三嗪 (TPTZ)作显色剂测定Fe(Ⅱ )和Fe(Ⅲ )的适宜条件。实验结果显示 :在 0～ 2 .0 μg mLFe(Ⅱ )范围内符合比耳定律 ,RSD≤ 2 .4% ,回收率范围 95 .6 %～ 1 0 3 .5 % ,吸光度至少稳定 1 2h ,ε593 =2 .2 7×1 0 4L·mol-1 ·cm-1 ,灵敏度是邻菲口罗啉法的 2倍。适用于同时测定水中Fe(Ⅱ )和Fe(Ⅲ )。     

Sensitive and selective stripping voltammetric determination of copper(II) using a glassy carbon electrode modified with amino-reduced graphene oxide and β-cyclodextrin

We describe a square wave anodic stripping voltammetric (SWASV) platform for the determination of Cu(II). It is based on the use of amino-reduced graphene oxide (NH₂-rGO) and β-cyclodextrin (β-CD) that were self-assembled on the surface of a glassy carbon electrode (GCE). The hydrophilicity and electrochemical performance of the resulting modified GCE were investigated by measurement of static contact angles, cyclic voltammetry and electrochemical impedance spectroscopy. Cu(II) was reduced at −1.1 V and then reoxidized at −0.012 V. Under optimum experimental conditions, the modified GCE exhibited excellent SWASV response in that the stripping peak currents (when sweeping between −0.3 and +0.25 V) depends on the concentration of Cu(II) in the 30 nM to 100 μM range. The limit of detection is 2.8 nM (at 3σ/slope). The modified GCE displaying good reproducibility, is stable, highly sensitive and selective. It was successfully applied to the determination of Cu(II) in synthetic and real water samples. The fast electron transfer rate and simple preparation of the NH₂-rGO/β-CD composite makes it a promising electrode material for applications in sensing of heavy metal ions.

Amino-modified rGO and β-cyclodextrin form an attractive material for use in an electrochemical platform for highly sensitive and selective determination of Cu(II).

     

Very sensitive differential pulse adsorptive stripping voltammetric determination of 4-nitrophenol at poly (diphenylamine)/multi-walled carbon nanotube-β-cyclodextrin-modified glassy carbon electrode

In this work, a glassy carbon electrode (GCE) modified with poly (diphenylamine)/multi-walled carbon nanotubes-β-cyclodextrin (PDPA/MWCNT-β-CD) film was constructed and used for the determination of 4-nitrophenol (4-NP). Diphenylamine was successfully electropolymerised onto MWCNT-β-CD-modified GCE by cyclic voltammetry in monomer solution and 5 mol L^?1 H₂SO₄. The surface morphology of PDPA/MWCNT-β-CD film was characterised using scanning electron microscopy and electrochemical impedance spectroscopy. After adsorption of 4-NP on PDPA/MWCNT-β-CD at 0.2 V for 150 s, it showed a well-defined reduction peak in phosphate buffer solution at pH = 7. The PDPA/MWCNT-β-CD film enhanced the reduction peak current due to the complex formation between β-CD and 4-NP, presence of conductive polymer film as electron transfer mediator and also ability of MWCNTs for strong adsorptive and catalytic effect. Peak current increased linearly with 4-NP concentration in the range of 0.1 to 13.9 µg L^?1. The detection limit was obtained as 0.02 µg L^?1, which is better than other reported detection limits for the determination of 4-NP. The results showed that modified electrode has good sensitivity and selectivity. This sensor was used for the determination of 4-NP in water samples.     

2,2′,2″-(2,4,6-Trioxo-1,3,5-triazinane-1,3,5-triyl)triacetic Acid Derivatives. New Aspects of Reactivity

Russian Journal of Organic Chemistry - Reaction of 2,2′,2″-(2,4,6-trioxo-1,3,5-triazinane-1,3,5-triyl)triacetic acid derivatives with nucleophiles in aqueous medium involved opening of...     

Eletrochemical behaviour of pyridoxal 5′-phosphate in an acid medium on a mercury electrode

A study of the reduction of pyridoxal 5′-phosphate (PLP) in an acid medium on a d.m.e. was carried out. The effects of pH, PLP concentration, capillary characteristics and ethanol concentration on the d.c. and d.p. polarograms were studied. The data suggest that the process is not as simple as has been reported previously. Thus, under certain experimental conditions, the process consists of two one-electron steps with the formation of an intermediate radical which can dimerize, like the classical reduction mechanism of aromatic aldehydes and ketones. The results agree with no direct influence of the ionization equilibria on the reduction wave characteristics. Indirect evidence of the absence of phenolic group ionization was obtained.     

2,4,6-三(2′-吡啶基)-1,3,5-三嗪作显色剂分光光度法测定手面皮肤的铁含量

应用铁(Ⅱ)与2,4,6-三(2′-吡啶基)-1,3,5-三嗪(TPTZ)的显色反应,用分光光度法测定了手表面皮肤上沾染铁的含量。测定时,用在去离子水中浸湿的脱脂棉擦拭手皮肤上铁的印迹,将脱脂棉中的液体挤出并接盛于小烧杯中,重复操作一次。将两次擦拭所得液体移入25mL容量瓶中,加入30g·L-1抗坏血酸溶液2mL,1g·L-1 TPTZ溶液2mL及pH 4.2乙酸铵缓冲溶液3mL,加水至刻度,在室温下放置10min。测定波长为596nm,按此条件,铁(Ⅱ)的质量浓度在2.0mg·L-1以内遵守比耳定律。试验结果表明:手与铁器接触时间长,则沾染在手面的铁量多;手面的湿度越高,沾染的铁量也越多,其最大值和最小值之间相差可达12μg。     

A new efficient route for the synthesis of 4,4′,6,6′-tetra(azido) azo- 1,3,5-triazine

A new method for the synthesis of 4,4′,6,6′-tetra(azido)azo-1,3,5-triazine(TAAT)is described.The key intermediate 4,4′,6,6′- tetra(azido)hydrazo-1,3,5-triazine(TAHT)was synthesized by nucleophilic substitution in the case of sodium azide as nacleophile. N-Bromosuccinide(NBS)was used as oxidant to oxidize TAHT by a tractable operation under mild reaction condition.The target compound TAAT was obtained with a facile process and high overall yield of 81%.The structures of TAAT and its intermediates were identified by spectroscopic methods.