Basic auxochromes. Auxochrome vs chromophore. Auxochrome is a Greek word arising from two word roots; ‘auxo’ meaning “to increase” and. This lesson explains the parts of a molecule responsible for color: chromophores and auxochromes. Chromophores and auxochromes are. CHROMOPHORE IS THE ACTUAL PART RESPONSIBLE FOR IMPARTING COLOR TO A MOLECULE; AUXOCHROME IS A HELPER THAT.

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Auxochrome is a group of atoms which will impart a particular color when attached to a chromophore but when present alone, will fail to produce that color.

Chemical compounds Color Chemical reactions.

Auxochrome is a group of atoms which is functional and has the capability to alter the capacity of the chromophore to reflect colors. In the conjugated chromophorea, the electrons jump between energy levels that are extended pi orbitalscreated by a series of alternating single and double bondsoften in aromatic systems.

Chromophore – Wikipedia

For example, phenolphthalein is a pH indicator whose structure changes as pH changes as shown in the following table:. Color space Color model additive subtractive Color mixing Primary color Secondary color Tertiary color chromophorfs Quaternary color Quinary color Aggressive color warm Receding color cool Pastel colors Color gradient. Normally, auxochromes which intensify the colour are chosen. Examples of such compounds include bilirubin and urobilinwhich exhibit a yellow color. If these groups are in direct conjugation with the pi -system of the chromophore, they may increase the wavelength at which the light is absorbed and as a result intensify the absorption.


It increases the color of any organic compound.

Retrieved from ” https: Similar behavior is seen in azobenzene which has a red color, but p -hydroxyazobenzene is dark red in color. G—M List of colors: Light waves with frequency very close to their natural frequency are absorbed readily. Different auxochromes produce different effects in axuochromes chromophore which in turn causes absorption of light from other parts of the spectrum.

This is a property of pH indicatorswhose molecular structure changes upon certain changes in the surrounding pH.

This change in structure affects a chromophore in the pH indicator molecule. Examples are chlorophyllwhich is used by plants for photosynthesis and hemoglobinthe oxygen transporter in the blood of vertebrate anirnals. You agree that we have no liability for any damages.

Some of these are metal complex chromophores, which contain a metal in a coordination complex with ligands. This page was last edited on 30 Marchat Auxochromes are classified as either positively charged or negatively charged. Chromophores are constituents of molecules that absorb or reflect certain colors when light fall on them.

Chomophores, if an auxochrome is present in the meta position to the chromophore, it does not affect the color. Various factors in a chromophore’s structure go into determining at xhromophores wavelength region in a spectrum the chromophore will absorb. In order to prepare dyes, auxochromes are attached to chromophores so as to achieve the deep color intended for the product.


Auxochromex auxochromes are attached to the molecule, the natural frequency of the chromophore gets changed and thus the colour gets modified. This article needs additional citations for verification. To convert basic dyes to acidic dyes, the negatively charged sulphonic groups are often used. Academic Press, New York. Retrieved from ” https: Amino groups are examples of positively charged whereas carboxyl, hydroxyl and sulphonic groups are examples of negatively charged auxochromes.


Auxochrome – Wikipedia

They themselves fail to produce the colour; but when present along with the chromophores in an organic compound intensifies the colour of the chromogen. Chromophores with double covalent bond appear to be colored as a result of the heightened state of the electrons. The electromagnetic spectrum has a very wide variation in wavelengths but the human eye visualizes only short wavelength radiation. Woodward-Fieser rules can be used to approximate ultraviolet -visible maximum absorption wavelength in organic compounds with conjugated pi-bond systems.

Color model additive subtractive Color mixing Primary color Secondary color Tertiary color intermediate Quaternary color Chromophkres color Aggressive color warm Receding color cool Pastel colors Color gradient.

Chromaticity diagram Color solid Color wheel Color triangle Color analysis art Color realism art style. Unsourced material may be challenged and removed.

The highly conjugated pi-bonding system of the macrocycle ring absorbs visible light. An auxochrome is a functional group of atoms with one or more lone pairs of electrons when attached to a chromophore, alters both the wavelength and intensity of absorption.

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They are capable of absorbing and emitting light of various frequencies. Hence the molecule appears coloured.