Synthesis and evaluation of some pyridyl-substituted pyrimidines as copper-specific chromogenic reagents

Preparation and metal-ion chromogenic properties of five new 2,4,6-trisubstituted pyrimidines containing pyridyl and methyl or phenyl groups are described. All five exhibit specific chromogenic reactions with copper(I), and two possess suitable characteristics for use as sensitive spectrophotometric copper reagents. The results obtained are also of interest in designing related chromogenic reagents.     

Synthesis, structure, anion binding, and sensing by calix[4]pyrrole isomers

The synthesis, structure, and anion binding properties of chromogenic octamethylcalix[4]pyrroles (OMCPs) and their N-confused octamethylcalix[4]pyrrole isomers (NC-OMCPs) containing an inverted pyrrole ring connected via alpha'- and beta-positions are described. X-ray diffraction analyses proved the structures of two synthesized isomeric pairs of OMCPs and NC-OMCPs. The addition of anions to solutions of chromogenic OMCPs and NC-OMCPs resulted in different colors suggesting different anion-binding behaviors. The chromogenic NC-OMCPs showed significantly stronger anion-induced color changes compared to the corresponding chromogenic OMCP, and the absorption spectroscopy titrations indicated that chromogenic OMCPs and NC-OMCPs also possess different anion binding selectivity. Detailed NMR studies revealed that this rather unusual feature stems from a different anion-binding mode in OMCPs and NC-OMCPs, one where the beta-pyrrole C-H of the inverted pyrrole moiety participates in the hydrogen-bonded anion-NC-OMCP complex. Preliminary colorimetric microassays using synthesized chromogenic calixpyrroles embedded in partially hydrophilic polyurethane matrices allow for observation of analyte-specific changes in color when the anions are administered in the form of their aqueous solutions and in the presence of weakly competing anions.     

TMB目视比色法检测水中余氯的改进

为解决GB/T 5750.11-2006生活饮用水标准检验方法中的3,3',5,5'-四甲基联苯胺(TMB)目视比色法检测余氯时出现的评价方法准确性欠佳、TMB显色剂发黄、显色体系偏绿等问题,对TMB目视比色法的评价方法、TMB显色剂的配制条件和水样的检测条件进行了研究。结果表明,次氯酸钠不宜作为余氯标准物质来评价TMB目视比色法的改进效果,而通过检测显色体系的A450和目视比色值相结合的方法来判断方法改进效果更为准确。采用优级纯浓盐酸和无氯纯水室温搅拌溶解,可使显色剂无色透明,从而解决TMB显色剂发黄的问题,符合国标要求。将显色剂配制用酸(盐酸)的浓度由国标中0.1mol/L变更为0.6 mol/L,可解决余氯显色体系偏绿的问题。显色体系pH变化后,显色时间、显色温度、显色剂用量可仍按照国标方法的要求进行操作。通过以上改进措施,进一步提高了余氯检测结果的准确度。     

Synthesis and metal ion complexing properties of novel chromogenic cryptands

Four novel chromogenic benzocryptands and one side-armed chromogenic cryptand have been synthesized and their complexing abilities for alkali metal cations are described.     

三氮烯类试剂在镉光度分析中的应用

介绍了1985年以来三氮烯类显色剂在光度分析中的应用,着重介绍了灵敏度高,选择性好的显色剂。     

Colorimetric detection of cyanide with a chromogenic oxazine

[reaction: see text] We have designed a chromogenic oxazine for the colorimetric detection of cyanide. Indeed, the [1,3]oxazine ring of our compound opens to form a 4-nitrophenylazophenolate chromophore in response to cyanide. This quantitative chromogenic transformation permits the detection of micromolar concentrations of cyanide in water. Furthermore, our chromogenic oxazine is insensitive to the presence of large concentrations of fluoride, chloride, bromide, or iodide anions, which are generally the principal interferents in the colorimetric detection of cyanide.     

Chromogenic Polymers and Their Packaging Applications: A Review

Abstract

This review paper provides an overview of chromogenic polymers and their classifications, mechanisms, chemistry, synthesis procedures, and potential applications with a focus on packaging. Commonly and academically accepted classifications derived from chemical engineering, material science, and packaging science are used. Furthermore, recent progress and outputs aligned with chromogenic polymers for overcoming the common challenges are discussed. Finally, future prospects, market trends and academic investigations are described, including challenges related to chromogenic polymers.     

Selective lithium ion extraction with chromogenic monoaza crown ethers

Two chromogenic monoaza crown ethers were synthesized and investigated for their lithium extraction capabilities. The chromogenic monoaza 14-crown-4 compound exhibited the best selectivity for lithium over sodium; ca. 2800, with a detection limit of 0.08 ppm.     

Chromogenic anion sensors

Chromogenic sensors for anions generally consist of two parts: anion receptors and chromophores. In this review, 6 types of chromogenic anion sensors are described, namely, NH-based hydrogen bonding, Lewis acid, metal-ion template, transition metal complexes, chromogenic guest displacement and chromoreactands. The first 4 types possess anion receptors attached directly to the chromophores while the guest displacement techniques employ indicators as the ones that were replaced by specific anions. The last type has emerged recently and uses specific reactions between chromogenic hosts or indicators and particular anions to cause dramatic colour changes.     

A new Hg(2+)-selective chromoionophore based on calix[4]arenediazacrown ether

A new azophenol type chromogenic ionophore based on the p-tert-butylcalix[4]arenediazacrown ether was prepared: the ionophore exhibited a pronouncedly selective chromogenic behaviour toward Hg2+ ions among the surveyed guests of alkali, alkaline earth, transition and heavy metal ions in liquid-liquid extraction experiments.     

光学分析试剂

光学分析试剂是建立有关光学分析方法的物质基础,在许多领域中具有极强的应用背景。本文介绍若干种光学分析试剂尤其是高分子显色剂的研究进展。     

A Simple Method Involving Aqueous Two-Phase Separation-Systems for Activity Determination of Enzymes Hydrolyzing Macromolecular Substrates

Abstract

A new general procedure for quantitation of enzymes degrading macromolecular substrates is described. With the use of chromogenic substrates combined with separation of substrate and product by aqueous two-phase systems, rapid separation and accurate measurements can be achieved.

Furthermore, in competitive substrate assays using constant amounts of enzyme and chromogenic substrate in combination with a varying amount of native substrate, unknown concentrations of native substrate can easily be determined.

The principle is illustrated here by a system consisting of the enzyme, dextranase; the chromogenic substrate, blue dextran; and the native substrate, dextran.     

Chromogenic and fluorescent ‘‘turn-on' chemodosimeter for fluoride based on F~–-sensitive self-immolative linker

A new chromogenic and fluorescent ‘‘turn-on" chemodosimeter 3 was designed and synthesized by using a fluoride-sensitive self-immolative linker, in combination with the fluorescent dyes 7-hydroxy-4-trifluoromethyl coumarin. The chemodosimeter exhibited high selectivity and sensitivity toward fluoride anions through ‘‘turn-on" chromogenic and fluorogenic dual modes.     

冠硫醚化学Ⅵ: 生色冠硫醚的合成及其配合机理的研究

本文报道了四个新的含7-氮杂-1,4,10,13-四硫杂环十六烷单元的生色冠硫醚的合成, 测定了其中3,4的电离常数分别为: pK~α=8.63(3); pK~a~1=8.49,pK~a~2=12.12(4)。通过光谱方法研究了它们与过渡金属离子的配合机理。     

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     

A precise spectrophotometric determination of a major constituent in pure materials: Application to pure magnesium metal

A spectrophotometric method is proposed for the direct assay of pure materials. The bulk of the metal to be determined is reacted with an accurately measured amount of a chelating agent, and the small excess of metal ion is determined spectrophotometrically with a chromogenic reagent. The optimal conditions can be predicted by drawing the theoretical spectrophotometric titration curves near the equivalent point of a supposed titration with the chelating agent as titrant and the chromogenic reagent as indicator. The method was applied to pure magnesium metal with EDTA as the chelating agent and calmagite as the chromogenic reagent, and the relative standard deviation was found to be 0.014%. The accuracy and precision appear to be much better than those attainable by titrimetry or differential spectrophotometry.     

Chemical approach to ill-conditioned calculation problems in spectrophotometry

Multiple-component determinations present difficulties which cannot be resolved mathematically when there is severe spectral overlap, as in the determination of rare-earth elements with chromogenic reagents. The interdependence of absorptivities is greatly decreased when absorbance data from procedures based on several chromogenic reagents are used together in the calculations of calibration factors and concentrations. Various features of the method are discussed.     

Novel Ca-selective merocyanine-type chromoionophore derived from calix[4]arene-diamide

The synthesis and calcium-selective chromogenic ion binding properties of benzothiazolium derivative of calix[4]arene are described. The merocyanine-type ionophore derived from calix[4]arene-diamide showed selective chromogenic properties toward Ca²⁺ ions in aqueous methanol. The compound showed significant Ca²⁺ ion dependent changes in UV-vis spectral properties in the presence of other physiologically important metal ions (Na⁺, K⁺, and Mg²⁺). The pH sensitive chromogenic behavior also suggests that the compound can be used as a sensitive pH indicator around pH 6.5.     

新的不对称变色酸双偶氮衍生物的合成及其结构对稀土、钍、铋显色反应的影响

新的不对称变色酸双偶氮衍生物的合成及其结构对稀土、钍、铋显色反应的影响张华山,张军锋,黎心懿（武汉大学化学系,武汉,４３００７２）关键词变色酸双芳基偶氮衍生物,稀土,钍,铋,分光光度法变色酸双偶氮衍生物是光度法测定稀土、钍等金属的重要显色剂。其中多卤...     

Sensing of aqueous phosphates by polymers with dual modes of signal transduction

A new approach to sensing of aqueous phosphate-related anions based on chromogenic conductive polymers is demonstrated. This method utilizes synergy between low-level p-doping in a polythiophene polymer and hydrogen bonding to increase anion-sensor affinity. These chromogenic conductive polymers show anion-specific changes both in color and in conductivity upon increasing concentration of anions, thus providing two independent modes of signal transduction.