title: Preventing the formation of the long-lived colored transoid-trans photoisomer in photochromic benzopyrans.
abstract: A new photochromic fused benzopyran presenting a bridge between the pyran double bond and the benzenic ring was prepared. While the UV irradiation of usual benzopyrans leads to the formation of two colored photoisomers with very different thermal stabilities, studies by laser flash photolysis showed that the presence of this particular bridge prevents the formation of the undesirable long-lived colored TT isomer and therefore after laser irradiation the colored solution fades following a fast monoexponential decay.
authors: Centro de Química - Vila Real, Universidade de Trás-os-Montes e Alto Douro, 5001-801 Vila Real, Portugal.
authors: Céu M
authors: CM
authors: Sousa
authors: João
authors: J
authors: Pina
authors: João Seixas
authors: JS
authors: de Melo
authors: Jérôme
authors: J
authors: Berthet
authors: Stéphanie
authors: S
authors: Delbaere
authors: Paulo J
authors: PJ
authors: Coelho
mesh_terms: D001578:Benzopyrans / Q000737:chemistry*; D003116:Color; D007536:Isomerism; D015394:Molecular Structure; D055668:Photochemical Processes
chemical_list: D001578:Benzopyrans