1446174-99-7Relevant articles and documents
Grey colouring thermally reversible photochromic 1-vinylidene-naphthofurans
Sousa, Céu,Saraiva, Sofia,Macedo, Helena,Coelho, Paulo
, p. 269 - 276 (2017)
A set of new 1-vinylidene-naphthofurans substituted by styryl groups were synthetized. These compounds show photochromic properties when adsorbed in silica gel, or in acidified THF solutions, developing intense colours after exposure to the UV light and returning to the uncoloured state, in the dark, in several minutes. The introduction of the styryl chain extends the conjugation of the photoproducts and shifts their absorption bathochromically relative to the parent unsubstituted naphthofuran. For styryl-naphthofuran 5a, in an acidified THF solution, an intense grey colouration can be achieved after 1?min of UV exposure (or direct sunlight) and the decolouration, in the dark, occurs in less than 10?min?at room temperature.
Synthesis of 1-vinylidene-naphthofurans: A Thermally reversible photochromic system that colors only when adsorbed on silica gel
Sousa, Ceu M.,Berthet, Jerome,Delbaere, Stephanie,Coelho, Paulo J.
, p. 6956 - 6961 (2013/08/23)
A set of new 1-vinylidene-1,2-dihydro-naphtho[2,1-b]furans were unexpectedly obtained in the reaction of 2-naphthol with readily available 1,1,4,4-tetraarylbut-2-yne-1,4-diols. Surprisingly, when adsorbed in silica gel, these compounds exhibit photochromism at room temperature, whereas not in solution and in the solid state. UV or sunlight irradiation leads, in a few seconds, to the formation of intense pink/violet to green colors that bleach completely in a few minutes in the dark. These new compounds also exhibit reversible acidochromic properties in solution: addition of TFA leads to the opening of the furan ring and addition of a proton to the allene function, leading to a conjugated and violet tertiary carbocation that returned immediately to the uncolored allenic structure upon addition of a weak base.
