Abstract

Thermochromism is a reversible change in spectral and physico-chemical properties as a result of heating and cooling.

Usually the response lies in the visible region. It is observed in complexed metals, in both organic and inorganic materials generally, and in all phases of matter, although predominately in solids and solutions for which the transition temperature is important for applications under heating or cooling.

The main examples given here are selected through metal complexes involving Co²⁺, Cu²⁺, or Ni²⁺ with different ligands or anions, metal oxides such as VO₂, Fe₃O₄ and metal sulfides, organic and polymer compounds involving spiroheterocyclic systems, Schiff bases and related nitrogen-containing compounds, bianthrones, and overcrowded ethenes. The breadth of the subject is very large taking into account the bibliography issued from different sources: inorganic and organic chemistry and physical investigations of the systems often associated with supports like polymer binders.