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Ionochromic
Ionochromism, similar to chromic methods such as photochromism, thermochromism and other chromism phenomena, is the reversible process of changing the color of a material by absorption or emission spectra of molecules using ions. Electrochromism is similar to ionochromism as it involves the use of electrons in order to change the color of materials. Both electrochromic and ionochromic materials undergo a change in color by the flow of charged particles, where electrochromic materials only involve an anionic species or negatively charged species such as electrons. An example of an ionochromic dye is a complexometric indicator. A complexometric indicator involves the presence of metal ions in order to facilitate color change and is often used in complexometric titration. Overview Ionochromism is the process of reacting an ionochromic material with a charged species, or a positively or negatively charged ion. Materials that have ionochromic properties exhibit reversible color c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chromism
In chemistry, chromism is a process that induces a change, often reversible, in the colors of compounds. In most cases, chromism is based on a change in the electron states of molecules, especially the π- or d-electron state, so this phenomenon is induced by various external stimuli which can alter the electron density of substances. It is known that there are many natural compounds that have chromism, and many artificial compounds with specific chromism have been synthesized to date. It is usually synonymous with chromotropism, the (reversible) change in color of a substance due to the physical and chemical properties of its ambient surrounding medium, such as temperature and pressure, light, solvent, and presence of ions and electrons. Chromism is classified by what kind of stimuli are used. Examples of the major kinds of chromism are as follows. * thermochromism is chromism that is induced by heat, that is, a change of temperature. This is the most common chromism of all. * pho ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chromism
In chemistry, chromism is a process that induces a change, often reversible, in the colors of compounds. In most cases, chromism is based on a change in the electron states of molecules, especially the π- or d-electron state, so this phenomenon is induced by various external stimuli which can alter the electron density of substances. It is known that there are many natural compounds that have chromism, and many artificial compounds with specific chromism have been synthesized to date. It is usually synonymous with chromotropism, the (reversible) change in color of a substance due to the physical and chemical properties of its ambient surrounding medium, such as temperature and pressure, light, solvent, and presence of ions and electrons. Chromism is classified by what kind of stimuli are used. Examples of the major kinds of chromism are as follows. * thermochromism is chromism that is induced by heat, that is, a change of temperature. This is the most common chromism of all. * pho ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Complexometric Indicator
A complexometric indicator is an ionochromic dye that undergoes a definite color change in presence of specific metal ions. It forms a weak complex with the ions present in the solution, which has a significantly different color from the form existing outside the complex. Complexometric indicators are also known as pM indicators. Complexometric titration In analytical chemistry, complexometric indicators are used in complexometric titration to indicate the exact moment when all the metal ions in the solution are sequestered by a chelating agent (most usually EDTA). Such indicators are also called metallochromic indicators. The indicator may be present in another liquid phase in equilibrium with the titrated phase, the indicator is described as extraction indicator. Some complexometric indicators are sensitive to air and are destroyed. When such solution loses color during titration, a drop or two of fresh indicator may have to be added. Examples Complexometric indicators are wat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phthalide
Phthalide is an organic chemical compound with the molecular formula C8H6O2. A white solid, it is the simplest benzo lactone. It is prepared from hydroxymethylbenzoic acid. Phthalides The phthalide core is found a variety of more complex chemical compounds including dyes (such as phenolphthalein), fungicides (such as tetrachlorophthalide, often referred to simply as "phthalide"), and natural oils (such as butylphthalide). Examples File:phenolphthalein.svg, Phenolphthalein File:tetrachlorophthalide.svg, Tetrachlorophthalide FIle:Butylphthalide.svg, Butylphthalide Butylphthalide (3-''n''-butylphthalide or NBP) is one of the chemical constituents in celery oil, along with sedanolide, which is primarily responsible for the aroma and taste of celery. Studies in animal models suggest that butylphthalide may b ... References {{reflist ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Methyl Red
Methyl red (2-(''N'',''N''-dimethyl-4-aminophenyl) azobenzenecarboxylic acid), also called C.I. Acid Red 2, is an indicator dye that turns red in acidic solutions. It is an azo dye, and is a dark red crystalline powder. Methyl red is a pH indicator; it is red in pH under 4.4, yellow in pH over 6.2, and orange in between, with a p''K''a of 5.1. Murexide and methyl red are investigated as promising enhancers of sonochemical destruction of chlorinated hydrocarbon pollutants. Methyl red is classed by the IARC in group 3 - unclassified as to carcinogenic potential in humans. Preparation As an azo dye, methyl red may be prepared by diazotization of anthranilic acid, followed by reaction with dimethylaniline: : Properties Methyl red displays pH dependent photochromism, with protonation causing it to adopt a hydrazone/quinone structure. : Methyl Red has a special use in histopathology for showing acidic nature of tissue and presence of organisms with acidic natured cell walls. Met ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Methyl Orange
Methyl orange is a pH indicator frequently used in titration because of its clear and distinct color variance at different pH values. Methyl orange shows red color in acidic medium and yellow color in basic medium. Because it changes color at the p''K''a of a mid strength acid, it is usually used in titration of strong acids in weak bases that reach the equivalence point at a pH of 3.1-4.4. Unlike a universal indicator, methyl orange does not have a full spectrum of color change, but it has a sharp end point. In a solution becoming less acidic, methyl orange changes from red to orange and, finally, to yellow—with the reverse process occurring in a solution of increasing acidity. Indicator colors In a solution that decreases in acidity, methyl orange moves from the color red to orange and finally to yellow with the opposite occurring for a solution increasing in acidity. This color change from yellow to red occurs because the protons in the acidic solution react with the N=N bo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thymol Blue
Thymol blue (thymolsulfonephthalein) is a brownish-green or reddish-brown crystalline powder that is used as a pH indicator. It is insoluble in water but soluble in alcohol and dilute alkali solutions. It transitions from red to yellow at pH 1.2–2.8 and from yellow to blue at pH 8.0–9.6. It is usually a component of Universal indicator __FORCETOC__ A universal indicator is a pH indicator made of a solution of several compounds that exhibits several smooth colour changes over a wide range pH values to indicate the acidity or alkalinity of solutions. Although there are several .... At wavelength (378 - 382) nm, extinction coefficient > 8000 and at wavelength (298 - 302) nm , the extinction coefficient > 12000. Structures Thymol blue has different structures at different pH. :thymol blue. Safety It may cause irritation. Its toxicological properties have not been fully investigated. Harmful if swallowed, Acute Toxicity. Only Hazardous when percent values are above 1 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cresol Red
Cresol red (full name: ''o''-cresolsulfonephthalein) is a triarylmethane dye frequently used for monitoring the pH in aquaria. Molecular biology Cresol red can be used in many common molecular biology reactions in place of other loading dyes. Cresol Red does not inhibit ''Taq'' polymerase to the same degree as other common loading dyes. Color marker Cresol red can also be used as an electrophoretic color marker to monitor the process of agarose gel electrophoresis and polyacrylamide gel electrophoresis. In a 1% agarose gel, it runs approximately at the size of a 125 base pair (bp) DNA molecule (it depends on the concentration of buffer and other component). Bromophenol blue and xylene cyanol Xylene cyanol can be used as an electrophoretic color marker, or tracking dye, to monitor the process of agarose gel electrophoresis and polyacrylamide gel electrophoresis. Bromophenol blue and orange G Orange G also called C.I. 16230, Acid ... can also be used for this purpose. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phenol Red
Phenol red (also known as phenolsulfonphthalein or PSP) is a pH indicator frequently used in cell biology laboratories. Chemical structure and properties Phenol red exists as a red crystal that is stable in air. Its solubility is 0.77 grams per liter (g/L) in water and 2.9 g/L in ethanol.''Merck Index'', 11th ed., 7213 Phenolsulfonphtalein It is a weak acid with p''K''a = 8.00 at . A solution of phenol red is used as a pH indicator, often in cell culture. Its color exhibits a gradual transition from yellow ( λmax = 443 nm) to red (λmax = 570 nm) over the pH range 6.8 to 8.2. Above pH 8.2, phenol red turns a bright pink (fuchsia) color.''Merck Index'', 13th ed., 7329 PhenolsulfonphthaleinBeilstein 5-19-03-00457 In crystalline form, and in solution under very acidic conditions (low pH), the compound exists as a zwitterion as in the structure shown above, with the sulfate group negatively charged, and the ketone group carrying an additional proton. This form is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thymolphthalein
Thymolphthalein is a phthalein dye used as an acid– base ( pH) indicator. Its transition range is around pH 9.3–10.5. Below this pH, it is colorless; above, it is blue. The molar extinction coefficient for the blue thymolphthalein dianion is 38,000 M−1 cm−1 at 595 nm. Thymolphthalein is also known to have use as a laxative and for disappearing ink. Preparation Thymolphthalein can be synthesized from thymol and phthalic anhydride Phthalic anhydride is the organic compound with the formula C6H4(CO)2O. It is the anhydride of phthalic acid. Phthalic anhydride is a principal commercial form of phthalic acid. It was the first anhydride of a dicarboxylic acid to be used commer .... : References {{reflist PH indicators Triarylmethane dyes Phthalides Phenols Isopropyl compounds ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cresolphthalein
''o''-Cresolphthalein is a phthalein dye used as a pH indicator in titrations. It is insoluble in water but soluble in ethanol. Its solution is colourless below pH 8.2, and purple above 9.8. Its molecular formula is C22H18O4. It is used medically to determine calcium levels in the human body, or to synthesize polyamides or polyimides. Production o-Cresolphthalein is not produced industrially, rather, it is commercially available. To be produced, the method generally used to synthesize phthalein dyes is effective. This method is used to synthesize phenolphthalein and thymolphthalein. To begin, a 2M equivalent of a phenol or a substituted phenol should be combined with a 1M equivalent of a phthalic anhydride. However, if the phenol is substituted, the carbon para to the hydroxyl carbon must not be substituted. Anhydrous methanesulfonic acid should be present as a condensing agent and a solvent that will dehydrate. The combined compounds should be mixed at 90 °C for 5 hours. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phenolphthalein
Phenolphthalein ( ) is a chemical compound with the chemical formula, formula carbon, C20hydrogen, H14oxygen, O4 and is often written as "HIn", "HPh", "phph" or simply "Ph" in shorthand notation. Phenolphthalein is often used as an indicator in acid–base titrations. For this application, it turns colorless in acidic solutions and pink in base (chemistry), basic solutions. It belongs to the class of dyes known as phthalein dyes. Phenolphthalein is slightly soluble in water and usually is dissolved in Alcohol (chemistry), alcohols for use in experiments. It is a weak acid, which can lose H+ ions in solution. The nonionized phenolphthalein molecule is colorless and the double deprotonated phenolphthalein ion is Fuchsia (color), fuchsia. Further loss of proton in higher pH occurs slowly and leads to a colorless form. Phenolphthalein ion in concentrated sulfuric acid is orange red due to sulfonation. Uses pH indicator Phenolphthalein's common use is as an indicator in acid-base t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
