Self‐assembly of a new class of amphiphilic poly(amidoamine) dendrimers and their electrochemical properties

Amphiphilic poly(amidoamine) (PAMAM) dendrimers consisting of a hydrophilic dendrimer core and hydrophobic aromatic dansyl or 1‐(naphthalenyl)‐2‐phenyldiazene (NPD) shells have been synthesized. These amphiphilic dendrimers from the zero generation to the third generation self‐assemble into vesicular aggregates in water. The self‐assembly behavior of these dendrimers strongly depends on their generations. The generation dependence has been further investigated by an exploration of their electrochemical properties. For the PAMAM–NPD aggregates, the photoisomerization process leads to a change in the aggregate size. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5512–5519, 2005     

5-(4-Carboxylphenylazo)-8-aminoquinoline as an analytical reagent for the spectrophotometric determination of gold

The synthesis and analytical application of 5-(4-carboxylphenylazo)-8-aminoquinoline (CPAQ) are described. A simple, rapid, selective, and sensitive spectrophotometric method for the determination of microgram amounts of gold is developed, based on the colour reaction between the metal ion and CPAQ in the presence of cetyltrimethyl ammonium bromide. Gold (III) reacts with the reagent in the ratio 1 3 (metal to ligand) in alkaline solution to form a blue-green complex with an absorption maximum at 608 nm. Beer's law is obeyed over the concentration range 0–1.8 g · ml^–1 (ppm) of gold. The molar absorptivity and Sandell's sensitivity of the method are 9.11 × 10⁴ l · mole^–1 · cm^–1 and 0.00216 g · cm^–2, respectively. The interference of various ions has been studied and conditions were developed for the determination of gold in an ore and anode slimes.     

Click‐Conjugation of Nanogold‐Functionalized PAMAM Dendrimer: Toward a Novel Electrochemical Detection Platform

This work reports a new electrochemical monitoring platform for sensitive detection of Cu²⁺ coupling click chemistry with nanogold‐functionalized PAMAM dendrimer (AuNP‐PAMAM). The system involved an alkyne‐modified carbon electrode and an azide‐functionalized AuNP‐PAMAM. Initially, the added Cu²⁺ was reduced to Cu⁺ by the ascorbate, and then the azide‐modified AuNP‐PAMAM was covalently conjugated to the electrode via Cu⁺‐catalyzed azide‐alkyne click reaction. The carried AuNPs accompanying PAMAM dendrimer could be directly monitored by stripping voltammetry after acidic pretreatment. By introduction of high‐loading PAMAM dendrimer with gold nanoparticles, as low as 2.8 pM Cu²⁺ (ppt) could be detected, which was 125‐fold lower than that of gold nanoparticle‐based labeling strategy. The method exhibited high specificity toward target Cu²⁺ against other potentially interfering ions, and was applicable for monitoring Cu²⁺ in drinking water with satisfactory results.     

4-AHBA为核的聚芳醚树枝状化合物的合成及其光学性能

合成了三个新的以2-(4-氨基-2-羟基苯基)苯并噻唑(4-AHBA)为核的聚芳醚树枝状化合物(1a～1c),其结构由1H NMR,13C NMR,IR,MS和元素分析表征.研究了1和4-AHBA在氯仿中的紫外吸收光谱和荧光发射光谱,结果表明,1与4-AHBA相比,紫外吸收强度大大提高,且最大吸收波长从349 nm红移...     

Spectrophotometric investigation of complexes with organic reagents for the optimization of spectrophotometric determinations (uv + vis) of inorganic analytes

Summary The knowledge of complex equilibria of elements with organic analytical reagents in solutions and that of thermodynamic and optical parameters of complexes and their distribution in the system is of considerable importance for the selection of optimal conditions for an exact spectrophotometric determination (uv + vis) of an element. All necessary parameters are available by means of a detailed graphical and numerical interpretation of spectrophotometric data. This approach is shown by example of some chromogenic reactions of 4-(2-pyridylazo)resorcin, 2-(2-thiazolylazo)-4-methoxyphenol and 2-(2-pyridylazo)-1-naphthol-4-sulphonic acid.

---

Spektralphotometrische Untersuchung von Komplexverbindungen mit organischen Reagentien für die Optimierung spektralphotometrischer Bestimmungen (uv + vis) eines anorganischen Analyts

Zusammenfassung Die Kenntnis von Komplexbildungsgleichgewichten der Elemente mit organischen Reagentien in Lösung, der thermodynamischen und optischen Parameter der Komplexe und deren Verteilung im System ist für die Auswahl optimaler Bedingungen für eine spektralphotometrische Elementbestimmung (uv + vis) wichtig. Alle notwendigen Parameter sind auf Grund einer eingehenden graphischen und mathematischen Interpretation spektralphotometrischer Daten zugänglich. Dieser Weg wird als Beispiel an drei ausgewählten spektralphotometrischen Reagentien, 4-(2-Pyridylazo)resorcin, 2-(2-Thiazolylazo)-4-methoxyphenol und 2-(2-Pyridylazo)-1-naphthol-4-sulfonsäure, gezeigt.

Dedicated to Prof. Dr. Fritz Umland on the occasion of his 60th birthday     

4-(H酸偶氮)-1-苯基-3-甲基吡唑啉酮与钍的显色反应及其应用

研究了新试剂4-(H酸偶氮)-1-苯基-3-甲基吡唑啉酮(HAPMP)与钍的显色反应.在pH=5.0的HAc-NaAc缓冲介质中,阳离子表面活性剂CFMAB存在下,HAPMP与Th(Ⅳ)反应生成2:1红色络合物,λ_(mas)=55nm,ε=2.24×10~5 L·mol~(-1)·cm~(-1).钍(Ⅳ)含量在0～640μg/L内符合比定律,方法用于合金中钍的测定,结果令人满意.     

The Colour Reaction of Mercury with 1-(6-Ethoxyl-2-benzothiazolyl)-3-(4-Nitrophenyl)-Triazene and its Application

Thetfiazenereagentswereusedforthedeterminationofcadmium,mercuryandzinc.Wehavesynthesizedthetriazenereagentscontainingheterocyclicring'-'.Recently,annewreagentEtOBTNPTwassynthesized.Becausethereagentcontainsanelectronpropellinggroup(-OCH,CH,)inoneendandanelectronwithdrawinggroup(-NO,)intheotherend,sotheconjugatesystemisenlargedinthemolecularstructure,thisresultinginadvantageofmigrationofelectroniccloud.ThesensitivityofthecolourreactionofEtOBTNPTwithmercuryissuperiortoothertfiazenereage…     

Second generation phenylene dendrimer, 1,3,5-tris[4-(3,5-diphenylphenyl)phenyl]benzene,as a precursor of a new carbon material

1. Download : Download high-res image (59KB)
2. Download : Download full-size image

     

Flotation and spectrophotometric determination of silver with 4-(p-nitrophenylazo)-2-amino-3-pyridinol

A sensitive flotation-spectrophotometric method, based on the complex formed between Ag(I) and 4-(p-nitrophenylazo)-2-amino-3-pyridinol is described. The complex precipitates when the aqueous solution is shaken with benzene, and the solid formed is then dissolved in dimethylformamide. The molar absorptivity of the resulting solution is 10.7×10⁴l·mole^–1·cm^–1 at 605 nm. Beer's law is obeyed between 0.08 and 1 ppm of silver. The molar ratio of Agreagent in the separated complex is 12. The effect of foreign ions has been determined and the proposed method can be applied to determination of silver in an exhausted photographic developing solution.     

A new polymeric chromogenic reagent for dual-wavelength spectrophotometric determination of iron(III)

By condensing chitosan with 7-(4-formyl-phenylazo)-8-quinolinol-5-sulfonic acid (FPAQS), a new polymeric chromogenic reagent C-FPAQS has been synthesized and its properties investigated. In acidic media (pH 2.7), C-FPAQS reacts with iron(III) to yield an orange complex with a molar absorptivity of 2.8 × 10⁴ lmol^–1 cm^–1 at 420 nm, and in the meantime a negative peak at 524 nm. The apparent molar absorptivity (420–524 nm) obtained by dual-wavelength measurements is 7.9 × 10⁴lmol^–1cm^–1 which is about two times higher than that by single-wavelength measurements at 420 nm Beer's law is obeyed in the range of 0–0.8 g ml^–1 for iron(III). The developed method has been satisfactorily used to determine iron at the 0.03 to 3% (ww) level in a nylon-6 and in a soil sample. Compared to the corresponding low-molecular weight FPAQS and other chromogenic reagents, C-FPAQS has not only good sensitivity but also largely increased acid solubility and improved selectivity for iron, which may be explained by the incorporation of FPAQS into an acid-soluble polymer.     

Effects of coronands on ionic conductivities of complexes of poly[2-(4-vinylphenoxy)-2,4,4,6,6-penta(methoxyethoxyethoxyethoxy)cyclotriphosphazene] with LiClO4

The effects of coronands such as crown ether and azacrown on the conductivity of complexes of LiClO₄ with poly[2-(4-vinylphenoxy)-penta(methoxyethoxyethoxyethoxy)cyclotriphosphazene] [poly(STEP)] were investigated. The extent of T_g elevation of poly(STEP)-LiClO₄ with 18-crown-6 was comparable to that of the poly(STEP)-LiClO₄ system. A similar behavior was observed for the system containing 12-crown-4. However, the increase in T_g values is considerably suppressed when tetraazacyclotetradecane with methoxyethoxy group as a side arm (MTAC) is used. All of the additives are effective to improve the conductivity, and the maximum conductivities of 10⁻⁴ S/cm at 30°C and 10⁻³ S/cm at 90°C have been achieved for the complex of the poly(STEP)-LiClO₄-MTAC system with Li⁺/O = 0.06, which are 3.5–7 times higher than those of poly(STEP)-LiClO₄ complexes. From the behaviors of T_g elevation and the conductivity, the role of the coronands for the conduction of the multi-armed poly(STEP)-LiClO₄ system is discussed. © 1996 John Wiley & Sons, Inc.     

荧光试剂3-(4-氨基苯基)中氮茚-1-羧酸甲酯用于亚硝酸根测定

介绍了一种新的测定亚硝酸根的荧光探针分子———3-(4-氨基苯基)中氮茚-1-羧酸甲酯(API)。API在酸性介质中与亚硝酸根生成重氮盐化合物,进一步在碱性介质中生成相应的羟基二氮烯,使荧光强度明显增强。基于该反应,提出了一种操作简便、灵敏度高、选择性好的亚硝酸根荧光测定方法。该方法对亚硝酸根检测的线性范围为4.5×10-8~7.5×10-6mol/L,检出限为8.3×10-9mol/L(0.38μg/L,S/N=3)。用于检测水体中亚硝酸根浓度,取得了满意的结果。     

季胺盐型表面活性剂与镉试剂显色反应的研究及应用

在三乙醇胺存在下，季铵盐型表面活性剂溴化十六烷基三甲铵，溴化十二烷基二甲基苄铵和溴化十六烷基吡啶分别与１－（４－硝基苯基）－３－「４－苯基偶氮）苯基」－三氮烯形成离子缔合物显色，吸收光谱红移，离子缔合物；ＮＰ－ＰＡＰＴ与ＤＤＭＢＡＢ来１：２与ＣＴＭＡＢ，ＣＰＢ均为１：３；测定了显色体系的ＣＴＭＡＢ，ＤＤＭＢＡＭ，ＣＰＢ的临界胶束浓度，符合比尔定律的范围，表观摩尔吸光系数δｍａｘ，探讨了微量ＣＴＭＡ     

7-(对甲酰基苯偶氮)-8-羟基喹啉-5-磺酸的合成及其双波长分光光度法测定镓

7－（对甲酰基苯偶氮）－8－羟基喹啉－5－磺酸是一新显色剂。该试剂在微碱性介质中（pH＝7．5）与镓形成黄色络合物。络合物λmax＝392nm，摩尔吸光系数ε392＝2．24×104L·mol-1·cm-1。同时在500nm呈现负峰，用双峰观波长法测定镓ε392～500＝6．89×104L·mol-1·cm－1，灵敏度是单波长法的三倍多．线性范围0～2．0×10－5mol／L。用拟定的方法测定了掺硅的GaAS材料及岩石中的镓，加入回收率为106％～110％；方法的相对标准偏差小于1．6％。     

Photophysical and self‐assembly behavior of poly(amidoamine) dendrons with chromophore as scaffold: The effect of dendritic architecture

Two series of amphiphiles composed of hydrophilic poly(amidoamine) dendrons (from the first to the third generation) as the shell and hydrophobic aromatic chromophores (3,6‐di(maleimidyl)‐9‐phenyl carbazole and 9‐(4′‐maleimidyl phenyl)‐3‐maleimidyl carbazole) as the central scaffold were synthesized. The effect of dendritic architecture on the photophysical properties and the self‐assembly behavior of these amphiphiles were studied by UV–vis absorption spectroscopy, fluorescence spectroscopy, and transmission electron microscopy (TEM) measurements. Both the generation of dendritic shell and the location of dendrons at the chromophoric scaffold had great effect on the photophysical properties of these amphiphiles. In addition, different spherical aggregates were formed from these amphiphiles in the aqueous solution at different concentrations. Because of the combined effects of steric hindrance and architecture of dendritic shells, the amphiphiles from G2 dendron with central chromophore self‐organized into ordered aggregates more readily than that from G1 and G3. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4584–4593, 2008     

Determination of stability constants of some substituted 4-pyrazolone dyes containingo-methoxy,o-carboxy,ando-nitro groups with trivalent lanthanide ions

The relative stabilities of the metal derivatives of hydrazo pyrazolone dyes containingortho -OCH₃, -COOH, and -NO₂ groups have been measured potentiometrically in 75% (v/v) dioxane—water mixture at 30 °C and <0.1 ionic strength. The stability constant of their 1:1 and 1:2 chelates with twelve trivalent lanthanide ionsLn(III) have also been determined. The effects of substituents on the hydrazo-moiety of the ligand on the equilibria are discussed. The affinity of different ligands for complexation with lanthanide ions reaches its highest value withortho-carboxyphenylhydrazopyrazolone. The data were correlated and the results were used to explain the stabilization of such chelates by dative -bonding betweenLn(III) and the ligand.

---

Bestimmung der Stabilitätskonstanten einigero-Methoxy-,o-Carboxy undo-Nitro-substituierter 4-Pyrazolon-Farbstoffe mit trivalenten Lanthanidenionen

Zusammenfassung Es wurden die relativen Stabilitäten der Metallderivate von Hydrazopyrazolon-Farbstoffen mitortho-OMe, -COOH und -NO₂ potentiometrisch in 75% (v/v) Dioxan—Wasser bei 30 °C und einer Ionenstärke <0.1 bestimmt. Die Stabilitätskonstanten der 1:1 und 1:2 Chelate mit zwölf trivalenten LanthanidenionenLn(III) wurden ebenfalls gemessen. Die Substituenteneffekte werden diskutiert. Dabei zeigeno-Carboxyphenylhydrazopyrazolone die höchste Affinität zu Lanthanidenionen. Die Daten werden miteinander korreliert und die Resultate auf der Basis einer dativen -Bindung zwischenLn(III)-Ion und dem Liganden diskutiert.

     

A Novel and Simple Synthesis of 2-(Trifluoromethyl)-4H-thiochromen-4-ones

Abstract

Alkyl 2-mercaptophenyl ketones react with trifluoroacetic anhydride in the presence of triethylamine to give 2-(trifluoromethyl)-4H-thiochromen-4-ones, which are transformed into the corresponding pyrazoles by treatment with hydrazine hydrate and into 1,1-dioxides by oxidation with H₂O₂ in AcOH.     

Boron chelate complexes with some enaminones and diketones containing the pyridine fragment and their mutual transformations in solutions

The interaction of Ph₂BOBu with 4-amino-4-(2-pyridyl)-3-buten-2-one, 3-amino-1-(2-pyridyl)-2-buten-I-one, and 1-(2-pyridyl)butan-1,3-dione was investigated. The 5- or 6-membered chelates withN,O- orN,N-coordination of boron are formed depending on the pyridine-containing ligand structure. These complexes are capable of mutual transformation in solutions.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 710–714, March, 1996.