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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The presence of an auxochrome in the chromogen molecule is essential to make a dye. Woodward-Fieser rules can be used to approximate ultraviolet -visible maximum absorption wavelength in organic chromlphores with conjugated pi-bond systems. Chemical compounds Color Chemical reactions.

Chromophore – Wikipedia

A—F List of colors: For instance, benzene does not have any color of its own, but when it is combined with the -nitro group which acts as a chromophore; it imparts a pale yellow color. Hence the molecule appears coloured. Get New Comparisons in your inbox: This phenomenon, known as resonancemeans that the molecule can absorb radiation of a particular frequency which is same as the frequency of electron movement within the fhromophores.

There is no need to resubmit your comment. These are responsible for the absorption of different radiations with different wavelengths based on the energy of the electron.

Difference between auxochrome and chromophore

It increases the color of any organic compound. 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. This page was last edited on 30 Marchat Examples are chlorophyllwhich is used by chromopjores for photosynthesis and hemoglobinthe oxygen transporter in the blood of vertebrate anirnals. Chromaticity diagram Color solid Color wheel Color triangle Color analysis art Color realism art style.

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A chromophore gives the dye the property of absorbing different radiations whereas auxochrome imparts it with the property of being colored.

Views Read Edit View history. From Wikipedia, the free encyclopedia. Color space Color model additive subtractive Color mixing Primary color Secondary color Tertiary color intermediate Quaternary color Quinary color Aggressive color warm Receding color cool Pastel colors Color gradient.

Views Read Edit View history. A feature of these auxochromes is the presence of at least one lone pair of electrons which can be viewed as extending the conjugated system by resonance. Articles with short description. From Wikipedia, the free encyclopedia. Electrons present in the chromophore get excited from the ground level to the excited state when visible light falls on them.

Color tool Monochromatic colors Complementary colors Analogous colors Achromatic colors Neutral Polychromatic colors Impossible colors Light-on-dark Tinctures in heraldry.

Chromophores are represented as nitrogen, carbon, oxygen and sulphur which usually have single or double bonds. Auxochromes are classified as either positively charged or negatively charged. This makes the three rings conjugate together to form an extended chromophore absorbing longer wavelength visible light to show a fuchsia color.

Chromophore is that part of the molecule which when exposed to visible light will absorb and reflect a certain color.

Leave a Response Cancel Reply Name required. A chromophore is the part of chrompohores molecule responsible for its color. In these two examples, a metal is complexed at the center of a tetrapyrrole macrocycle ring: When auxochromes are attached to the molecule, the natural frequency of the chromophore gets changed and thus the colour gets modified.

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.

However, as auxcohromes pH increases beyond 8. Light waves with frequency very close to their natural frequency are absorbed readily. They are used together to make dyes.


This is a property of pH indicatorswhose molecular structure changes upon certain changes in the surrounding pH. If an auxochrome is present in the meta position of the chromophore, then there is no change in the color. They themselves fail to produce the auxochroms but when chromophpres along with the chromophores in an organic compound intensifies the colour of the chromogen.

Auxochrome is a group of atoms which is functional and has the capability to alter the capacity of the chromophore to reflect colors.

Auxochrome – Wikipedia

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. In the conjugated chromophores, the electrons jump between energy levels that are extended pi orbitalscreated by a series of alternating single and double bondsoften in aromatic systems. Similar behavior is seen in azobenzene which has a red color, but p -hydroxyazobenzene is dark red in color.

In order to prepare dyes, auxochromes are attached to chromophores so as to achieve the deep color intended for the product.


Azobenzene is an example of a dye which contains a chromophore. The highly conjugated pi-bonding system of the macrocycle ring absorbs visible light.

Linguistic relativity and the color naming debate Blue—green distinction in language Color history Color in Chinese culture Traditional colors of Japan Human skin color.