chromophoric

Chromophoric is an adjective used in chemistry to describe a molecule, functional group, or structural unit that contains a chromophore, the part responsible for color by absorbing light in the visible or near-visible range. The presence of a chromophore often dictates the color of the substance.

A chromophore is typically a conjugated system of pi electrons or a specific functional group capable of electronic transitions. Common chromophores include extended carbon–carbon double bond systems, aromatic rings, carbonyl groups, azo groups, and nitro groups. In transition metal complexes, metal-to-ligand or ligand-to-metal charge transfer can also create chromophoric behavior. Absorption of photons promotes electrons between molecular orbitals (such as π to π* or n to π* transitions). The wavelengths absorbed determine the observed color, with the printed color corresponding to the complementary wavelengths.

Chromophoric content is widespread in dyes, pigments, photoactive materials, and biological pigments. Examples of natural chromophores include chlorophyll, carotenoids, and the heme group. Often, several chromophores or overlapping transitions contribute to a compound’s overall color.

In UV–visible spectroscopy, chromophores are responsible for characteristic absorption bands, enabling qualitative and quantitative analyses. The term chromophoric is used to describe substances that contain such color-imparting groups, whereas non-chromophoric substances lack significant absorbance in the visible region and typically appear colorless.