Photochromism of Spiropyran

Spiropyran (colorless) → Merocyanine (colored)

Overview

UV light causes the C–O bond in spiropyran to break, opening the ring to form the planar, conjugated merocyanine isomer that absorbs visible light and appears colored. Visible light or heat reverses the reaction. This reversible photochromism is the basis for smart materials that change color in response to light.

Everyday Example

Photochromic sunglasses (Transitions lenses) that darken in sunlight use similar photochromic molecules that reversibly change structure.

Industrial Importance

Photochromic materials are used in self-tinting eyeglasses, smart windows, optical data storage, and molecular switches for nanotechnology.

Properties

Type: Photochemical
Reversible: Yes
Energy: Endothermic

Related Reactions

Chlorophyll Fluorescence Cis-Trans Isomerization of Retinal Dye-Sensitized Solar Cell (Grätzel Cell) Firefly Bioluminescence (Luciferin Oxidation) Luminol Chemiluminescence Ozone Decomposition by UV Ozone Formation by UV Light Photocatalytic NOx Removal Photocatalytic Water Splitting (TiO₂) Photochemical Cycloaddition ([2+2])

Frequently Asked Questions

What is the equation for Photochromism of Spiropyran?

The balanced equation is: Spiropyran (colorless) → Merocyanine (colored).

What type of reaction is Photochromism of Spiropyran?

Photochromism of Spiropyran is a photochemical reaction. It is reversible under certain conditions.

Is Photochromism of Spiropyran exothermic or endothermic?

Photochromism of Spiropyran is endothermic (absorbs energy).