Issue 11, 2012

Photochemistry of 2-(4-hydroxystyryl)-1-naphthopyrylium


A new photochromic system based on 2-(4-hydroxystyryl)-1-naphthopyrylium encompasses the properties of the previously described naphthoflavylium and styrylflavylium systems. The photoproduct exhibits a colour deep in hue and is red shifted in comparison with the equivalent flavylium system. Reaction of 2-hydroxy-1-naphthaldehyde with p-hydroxystyrylmethylketone in acetic acid in the presence of tetrafluoroboric acid and acetic anhydride as catalysts leads to a mixture of two compounds: the photochromic 2-(4-hydroxystyryl)-1-naphthopyrylium and a second product 2-(4-acetoxystyryl)-1-naphthopyrylium resulting from the acetylation by acetic anhydride of the former. In acidic medium and at room temperature the hydrolysis of the acetoxy derivative leads to the 2-(4-hydroxystyryl)-1-naphthopyrylium, in circa 2 days, [HCl] = 0.25 M. The pH dependent chemical reactions taking place with 2-(4-hydroxystyryl)-1-naphthopyrylium were determined by UV-Vis, stooped flow, flash photolysis and 1H NMR and follow the same general pattern of flavylium derivatives. In order to rationalize the photochromism, an energy level diagram summarizing all the equilibrium and rate constants of the network was drawn.

Graphical abstract: Photochemistry of 2-(4-hydroxystyryl)-1-naphthopyrylium

Supplementary files

Article information

Article type
13 Apr 2012
20 Jun 2012
First published
16 Jul 2012

Photochem. Photobiol. Sci., 2012,11, 1691-1699

Photochemistry of 2-(4-hydroxystyryl)-1-naphthopyrylium

R. Gavara, Y. Leydet, V. Petrov and F. Pina, Photochem. Photobiol. Sci., 2012, 11, 1691 DOI: 10.1039/C2PP25104C

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.