Fast Color Change with Photochromic Fused Naphthopyrans.
Photochromic molecules can reversibly develop color upon irradiation with UV light. These smart molecules, mainly in the naphthopyran family, have been applied with success to ophthalmic lenses that darken quickly under sunlight and revert to the uncolored state after several minutes in the dark. This slow adaptation to the absence of light is one of the limitations and is due to the formation of an unwanted photoisomer. We have designed a new naphthopyran with a bridged structure which prohibits the formation of the undesirable, persistent photoisomer and thus shows a very fast switching between the uncolored and colored states. UV irradiation of a hybrid siloxane matrix doped with the new fused naphthopyran leads to the formation of a pink coloration bleaching in a few milliseconds, in the absence of light, at room temperature. This new fused naphthopyran is easily prepared in three steps from readily accessible precursors and is amenable to structural modifications to tailor color and lifetime of the colored photoisomer.
Centro de Química-Vila Real, Universidade de Trás-os-Montes e Alto Douro , 5000-801 Vila Real, Portugal.
Céu M
CM
Sousa
UDSL, CNRS UMR 8516, Faculté des Sciences Pharmaceutiques et Biologiques, Université Lille Nord de France , F-59006 Lille, France.
Jerome
J
Berthet
UDSL, CNRS UMR 8516, Faculté des Sciences Pharmaceutiques et Biologiques, Université Lille Nord de France , F-59006 Lille, France.
Stephanie
S
Delbaere
Centro de Química-Vila Real, Universidade de Trás-os-Montes e Alto Douro , 5000-801 Vila Real, Portugal.
André
A
Polónia
Centro de Química-Vila Real, Universidade de Trás-os-Montes e Alto Douro , 5000-801 Vila Real, Portugal.
Paulo J
PJ
Coelho