Multichromia - od nauki do sztuki

In this paper we shortly describe multichromism. This phenomenon is the ability of some organic and inorganic compounds to reversibly change their colour due to exposure to some external stimuli. Colour change could be induced, for example, magnetically, electrically, by light, temperature or humidity. Photochromism and thermochromism, which are types of multichromism, have drawn attention of artists as they see in them the potential for creating some spectacular and breathtaking artworks. These two phenomena have been described herein, thermochromism shortly and photochromism in a more elaborated way. Examples of compounds exhibiting thermochromic and photochromic properties are mentioned along with their chemical structures, mechanisms of the colour change process and potential or already available applications. In case of photochromism, families of spiropyrans and spiroxazines, as they are extensively investigated since the previous century, are described in a more detailed way. The discussion about the chemical structure of compounds and polarity of the solvent and their influence on the colour of the merocyanine form of spiro compounds is provided. A thorough analysis of the composition and the role of each component in commercially available photochromic pigment is also discussed. Moreover, examples of paintings already painted in the multichromic (thermo- and photochromic) technique, as well their pictures and interpretation are also included in this paper.