The chromogenic effect in molecular systems capable of existing in two isomeric forms, caused by the inversion of the thermodynamic stability of isomers during the transition from the condensed state to the gas phase at low residual pressure and defined as barochromism, was discovered in a series of benzothiazole spiropyrans. This, along with what was described earlier for indoline spiropyrans, allows us to assume the universal nature of the discovered phenomenon.
A.V. Metelitsa (Wed,) studied this question.