The intramolecular capture of thermally generated merocyanine dyes derived from naphthopyrans: Photochromism of 5-(diarylhydroxymethyl)-2H-naphtho[1,2-b]pyrans |
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Authors: | Christopher D. GabbuttLucy V. Gibbons B. Mark Heron Suresh B. Kolla |
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Affiliation: | School of Chemistry, The University of Leeds, Leeds LS2 9JT, UK |
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Abstract: | A series of 2H-naphtho[1,2-b]pyrans bearing a diarylmethanol unit at C-5 have been synthesised by the addition of an excess of an aryllithium reagent to alkyl 2H-naphtho[1,2-b]pyran-5-carboxylate precursors. These naphthopyrans show photochromism when exposed to ultraviolet irradiation and also generate intense colours at low pH through triarylmethine cation generation. However, photochromism of the triarylmethine cation derived from the naphthopyran unit could not be detected. An irreversible cascade process initiated by the thermally-induced ring-opening of the diarylmethanol substituted 2H-naphtho[1,2-b]pyrans in the presence of an acid catalyst afforded novel benzopentalenonaphthalenone dyes. |
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Keywords: | Synthesis Photochromism Naphthopyran Benzo[5,6]pentaleno[1,2-b]naphthalene Triarylmethine cationic dye Absorption |
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