text: Photochromic, thermochromic, solvatochromic and electrochromic characteristics of spiropyrans make them especially important in the technology area. Most of their applications are based on their photochromic properties.
  Photochromic compounds based on spiropyrans, spirooxazines, and [2H]chromenes are being investigated because of their silver-free light-sensitive properties that could be used for optical recording data, including thin films,  photoswitches (sensors that discern light of certain wavelength), light filters with modulated transmission and miniature hybrid multifunctional materials.
  Thanks to the creation of novel media sensitive to IR radiation and the potential of spiropyrans for optical recording data, semiconductor lasers as activating source of radiation are possible.
  Spiropyrans with ion complexes and spiropyran copolymers which are part of powdered and film materials have been used too to record optical data and increase the length of time of its storage.
  Another group of spiropyrans which contain indoline or nitrogen heterocycles and the indolinospirothiapyrans found their application in film forms of photochromic materials using polyester resins. Those resins with a high refractive index were used to make photochromic lenses. Moreover, spiropyrans are being used in cosmetics.
  New types of modified spiropyrans polymers contained in photochromic compounds found their use in the creation of photoreceptors. The ones with rhodopsin as a compound are adopted to raise the level of the photosignal.
  Another collection of spiropyrans characterized for their sensitivity to UV radiation are detectors for the protection of organs, for the production of light filters with modulated transmission, or photochromic lenses.
  The determination of peroxidase activity and NO levels in the atmosphere are applications of carboxylated spiropyrans.
  Today, spiropyrans are most used as molecular logic devices, photochromic and electrooptical devices, molecular and supramolecular logic switches, photoswitches and multifunctional artificial receptors.
  Spiropyrans can be used to probe the conformational state of DNA, as certain derivatives can intercalate into DNA when in the open form.
  Spiropyrans are used in photo controlled transfer of amino acids across bilayers and membranes because of nucleophilic interaction between zwitterionic merocyanine and polar amino acids. Certain types of spiropyrans display ring opening upon recognition of an analyte, for example zinc ions.