化合物颜色成因简介

从过渡金属离子d-d电子跃迁和电荷转移及其影响因素出发,讨论了化合物呈色的本质,对影响化合物呈色的主要因素进行了论述,重点阐明了化合物颜色与其分子结构的关系,并列举了部分常见化合物的颜色及变化规律.通过分析,说明了化合物的颜色与其结构、环境因素和人的视觉等有着密切的关系.     

氢气燃烧火焰颜色影响因素的研究及演示方案再设计

基于对氢气燃烧火焰颜色的不同解释,从焰色反应、火焰温度、气体流速等3方面影响因素设计方案进行实验研究,得出影响氢气火焰颜色的主要因素是气流速度、火焰温度及药品的焰色反应。巧用球形干燥管既控制气流速度、又控制火焰温度的特点,设计出可以观察到氢气燃烧火焰呈明显蓝色的演示装置。用可现取的仪器药品、可执行的实验方案、可重现的实验现象、可检验的实验结果,验证了教材中关于氢气燃烧火焰颜色的论述,突破了实际操作中氢气燃烧颜色不易观察的局限。     

物质呈色机理探讨

一、物质的呈色世界上成千上万的物质,都有五彩缤纷、千变万化的颜色,为大自然增添了勃勃生机,给人们的生活带来了和谐与美感。     

宝玉石的呈色机理

通过对宝玉石化学组成与吸收光谱的分析,阐述了宝玉石的呈色机理。红宝石、蓝宝石、翡翠的呈色是过渡金属离子（如铬、铁、钛等）d-d电子跃迁和电荷转移跃迁等因素共同作用的结果。红宝石和蓝宝石的颜色并不简单取决于铬或/和铁的含量,而更多取决于铁、钛间Fe2+/Ti4+和Fe3+/Fe2+的比值。翡翠的呈色是铁、铬、钒等过渡金属离子共同作用的结果。宝玉石的颜色也可能起因于其他过渡金属离子、色心等,从而使其色彩更加美丽。     

真实感地图计算机设色模型(RMCDCM)研究

本文从RMCDCM研究其中的主要关键技术和技术难点出发,运用色度学原理,在实验分析的基础上,建立了一个CMY油墨印刷与RGB屏幕颜色转换的新模型及RMCDCM,对在色度学方面存在的RGB屏幕颜色范围大于印刷色的笼统概念。作出了确切解释。这不仅从理论上解释了CRT监视器、PAL和NTSC模型再现印刷色标时所产生的错误现象,而且为从方法上解决印刷色标的屏幕再现和印刷复原研究长期存在的技术难题,提供了理论根据。     

无机物的颜色与电子光谱——关于征答(18)的讨论

本文从物理和生理学角度讨论颜色的概念,介绍测量颜色的两种方法(国际制和光谱法)及两者的联系。结合“大学化学征答18”阐明无机物(溶液、固体、气态)产生颜色的原因及其电子光谱的峰位、峰数、强度、宽度等问题,从理论上说明影响物质颜色的因素。     

一种含氢燃料火焰降温观色筒的设计和应用*

针对酒精灯火焰呈黄色的解释争议进行研究,以降低环境温度和减少氧气浓度为方向,设计了可观察环境温度变化对含氢燃料火焰颜色影响的仪器。对乙醇、丁烷、蜡烛等燃烧火焰进行降温测试,发现含氢燃料正常燃烧火焰颜色一般为黄色、降低环境温度后变为极淡的蓝色(光亮条件下)的规律,证明了燃烧过程中水分子处于激发态是导致火焰颜色由蓝色变为黄色的重要原因,钠元素的焰色反应不是酒精灯火焰呈黄色的唯一原因。对丁烷喷枪火焰颜色的降温测试,意外观察到4种疑似氢原子光谱的可见光谱线,为今后寻找该谱线提供了可借鉴的方向。研究过程可作为基于真实情境的研究素材,通过问题的发现、仪器的改进和规律的总结,提高学生运用化学知识解决真实问题的能力,培养学生的核心素养。     

基于颜色主波长与补色波长的比色法定量检测

利用sRGB(Standard RGB)颜色空间与国际照明委员会(CIE)色度系统的转化关系以及CIE 1931色品图的性质,编写MATLAB程序实现了颜色的RGB信息到颜色主波长或补色波长的转化,并将此程序用于分析面光源下采集到的显色产物的图片。利用颜色的主波长实现了对pH值的定量检测,利用颜色的补色波长完成了对亚硝酸根离子的定量检测。当pH值分别在4.0~7.0和7.5~10.0范围内,pH值均与其显色产物颜色的主波长呈线性变化;亚硝酸根离子浓度在10~40 mg/L范围内与其显色产物颜色的补色波长有良好的线性关系,通过结合图片的G值分析,扩大了传统吸收光谱法的检测范围。     

温度对铜和浓硫酸反应的影响探究

铜和浓硫酸反应在高中化学教学中是一个演示实验,但在实验中经常会出现黑色物质,导致溶液变浑浊,很难观察到蓝色的硫酸铜溶液。从温度对该反应产物、现象的影响角度进行探究,发现可以通过控制反应温度,使反应出现明显的“溶液变蓝色”现象,并且使黑色固体生成的量明显减少。     

微量元素对绿色翡翠的影响

应用电子探针对绿色翡翠样品进行了分析。结果表明,翡翠中的微量元素Cr和Fe是绿色翡翠致色的关键,当这些金属离子以类质同象进入硬玉晶格时,就会使硬玉呈现他色(由非主要化学成分引起的颜色);Ca、Mg等元素则对翡翠的质地有着重要的影响。     

Using a digital camera and computer data processing for the determination of organic substances with diazotized polyurethane foams

The possibility of using a digital camera and computer software for the estimation of the color intensity of polymeric azo compounds synthesized by the reaction of the azo coupling of diazotized polyurethane foams (PUFs) with different organic substances was studied. The method is based on photographing colored polyurethane foams with a digital camera followed by the computer processing of the color images. It was found that calibration equations are described by a descending exponent of the first order. The advantages of the proposed method are its high sensitivity due to the chemisorption concentration of substances, simplicity, and low cost. In combination with a high efficiency, compactness, and the availability of digital cameras, this allows us to recommend it for field analysis. It is shown by the example azo coupling reactions involving diazotized PUF that, using digital cameras as detectors and computer data processing, one can determine substances with a sensitivity equal to that of diffuse reflection spectroscopy.     

Chemisorption of vapors of organic substances on a modified silica gel

Experimental data on the equilibrium and dynamics of chemisorption of vapors of organic substances on a silica gel modified with color reagents are presented.     

Determining orthogonal and similar chromatographic systems from the injection of mixtures in liquid chromatography-diode array detection and the interpretation of correlation coefficients color maps

Generic orthogonal chromatographic systems might be helpful tools as potential starting points in the development of methods to separate impurities and the active substance in drugs with unknown impurity profiles. The orthogonality of 38 chromatographic systems was evaluated from weighted-average-linkage dendrograms and color maps, both based on the correlation coefficients between the retention factors on the different systems. On each chromatographic system, 68 drug substances were injected as mixtures of three or four components to increase the throughput. The (overlapping) peaks were identified and resolved with a peak purity algorithm, orthogonal projection approach (OPA). The visualization techniques applied allowed a simple evaluation of orthogonal and (groups of) similar systems.     

Use of a Scanner and Digital Image-Processing Software for the Quantification of Adsorbed Substances

The possibility of using a desktop scanner and digital image-processing software for the numerical evaluation of the color intensity of substances adsorbed on polyurethane foam is studied. The method is based on scanning colored samples of polyurethane foam using a desktop scanner, processing the color images using Adobe Photoshop as a graphics editor, and building calibration plots of the luminosity of the selected channel (R, G, or B) as a function of the concentration of the test compound using the Origin software. It has been found that the calibration plots are described by a first-order exponential decay function. The advantages of the method are its high performance, rapidity, and the possibility of mathematical processing of the results. It has been found that substances adsorbed on polyurethane foam can be determined with the use of a scanner and the corresponding image-processing software with the same sensitivity as with the use of diffuse-reflectance spectroscopy.     

Reaction of n-butyllithium with poly(vinyl chloride)

The reactions of poly(vinyl chloride) and butyllithium in tetrahydrofuran were investigated. A deep purple color developed at first with addition of butyllithium to the THF–PVC solution, and a spontaneous color change of the misture occurred successively to blue, green, and finally pale vellow. In these reaction stages, the PVC might be butylated, dehydrochlorinated, and partially lithiated by BuLi. These facts were substantiated by the results of successive reactions with various substances such as Michler's ketone, carbon dioxide, and styrene.     

Recent development in nanomaterials fabricated paper-based colorimetric and fluorescent sensors: A review

The paper-based sensing devices have drawn a broad interest in analytical chemistry for colorimetric and fluorescent-based analysis of biological, environmental, clinical, and food samples. It is due to the simple, rapid, biodegradable, user-friendly, less expensive, and low waste generation into the environment. Here, the recent development of paper-based sensors fabricated with different noble metal nanoparticles (NPs) and semiconductor and carbon quantum dots (QDs) is demonstrated to analyze several chemical substances from various samples. User-friendly and portable recording devices such as digital cameras, smartphones, scanners, etc. along with color detecting softwares are employed to measure the color intensity of nanomaterials fabricated paper devices after the deposition of a sample solution containing various chemical substances. The advantages and disadvantages of incorporating nanomaterials in the paper substrate (direct deposition, inkjet printing, screen printing and wax printing) are illustrated. The mechanism for colorimetric, fluorescence, phosphorescence, and chemiluminescence sensing using noble metal NPs (Ag, Cu, and Au), semiconductors, and carbon QDs for the determination of metal ions, anions, pesticides, biomolecules, and other toxic chemical substances are discussed. Thus, this review article would be highly useful for scientists and researchers to design colorimetric sensors to monitor chemical toxicants in clinical, environment, foods, and many other related samples.     

Validation of the Delvotest SP NT DA. Performance Tested Method 011101

Delvotest SP NT DA is designed to test milk for the presence of antibacterial substances, such as antibiotics. The test is made of an agar gel containing bacterial spores and a color indicator. The milk sample is added onto the agar gel, and the test is incubated at 64 degrees C. The principle of the test is based on the diffusion of possible inhibitory substances that may be present in the milk sample into agar. This reduces growth and acid production by the test organism, and delays or prevents the agar from changing color from purple to yellow. The Delvotest Accelerator is an automated system in which the plates containing the milk to be analyzed are placed for incubation. The Accelerator automatically detects the end of the incubation and reads the results. A sample containing antibiotic will be noted as "positive." A sample without antibiotics or with antibiotics at concentrations below detection level will be noted as "negative." The present report includes all technical details about the Delvotest SP NT DA, and the results of the validation study. The validation study demonstrates that the Delvotest SP NT DA conforms to the product performance claims and confirms the robustness of the test. The Delvotest SP NT DA is, therefore, granted Performance Tested Method certification.     

Preparation of double nickel(II) cobalt(II) phosphates with controlled cationic composition

The possibility of the heterogeneous synthesis of crystalline nickel(II) cobalt(II) aqua ammine orthophosphates with a specified ratio of cations was studied. The substances were studied by IR spectroscopy, X-ray phase analysis, and thermal analysis. Owing to a wide color spectrum, they show promise as pigments for ceramic industry.     

Zinc-supported azobenzene derivative-based colorimetric fluorescent ‘turn-on’ sensing of bovine serum albumin

Fluorescence sensing with small molecular chemosensors is a versatile technique for elucidation of function of various substances. Herein, a new zinc ion supported fluorescent turn-on system for bovine serum albumin (BSA) has been demonstrated. The fluorescence intensity increases 15.4-fold and visual color changes from light reddish orange to yellow can be detected after adding BSA.