Long-lived excited state of spiroanthroxazine after its matrix isolation in halogenated polyolefins by supercritical fluid impregnation

Supercritical fluid impregnation was used to perform matrix isolation of spiroanthroxazine (SAO) photochromic molecules in halogenated polymer films (polyvinylchloride and tetrafluoroethylene copolymer with vinylidene fluoride). An excited (colored) SAO form not relaxing to the ground (colorless) state was stabilized in polymers. Such a long-lived excited SAO form could exist as an isomer of the B form (B535 with an absorption band at λmax = 535 nm) in the fluorinated polymer matrix, for which the absorption maximum was shifted by more than 75 nm to the blue, and as the B form with a small admixture of the B535-form (in polyvinylchloride).