Solvatochromism

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Solvatochromism is the ability of a chemical substance to change color due to a change in solvent polarity. Negative solvatochromism corresponds to hypsochromic shift, positive solvatochromism corresponds to bathochromic shift with increasing solvent polarity. The sign of the solvatochromism depends on the difference in dipole moment of the molecule of the dye between its ground state and excited state.

An example of positive solvatochromism is the 4,4'-bis(dimethylamino)fuchsone, which is orange in nonpolar toluene, red in slightly polar acetone, and red-violet in more polar methanol.

Examples of negative solvatochromism are 2-(4'-hydroxystyryl)-N-methyl-quinolinium betaine, which is ink-blue in nonpolar chloroform and blood-red in polar water, and 4-(4'-hydroxystyryl)-N-methyl-pyridinium iodide, which is violet in n-butanol, red in 1-propanol, orange in methanol, and yellow in water.

[edit] Uses

Solvatochromism can be used in environmental sensors, and in molecular electronics for construction of molecular switches.

[edit] See also

• Bathochromic shift
• Hypsochromic shift

[edit] External links

• Negative solvatochromism experiment
• Positive solvatochromism experiment

 

Chromism  photochromism (light) | thermochromism (heat) | electrochromism (electricity) | solvatochromism (solvent) | ionochromism (ions) | halochromism (pH) | tribochromism (friction) | piezochromism (pressure)