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Multistate/Multifunctional Behaviour of 4′‐Hydroxy‐6‐nitroflavylium: A Write‐Lock/Read/Unlock/Enable‐Erase/Erase Cycle Driven by Light and pH Stimulation
Author(s) -
Moncada Margarida C.,
Parola A. Jorge,
Lodeiro Carlos,
Pina Fernando,
Maestri Mauro,
Balzani Vincenzo
Publication year - 2004
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200305348
Subject(s) - isomerization , photochromism , chemistry , lock (firearm) , photochemistry , combinatorial chemistry , organic chemistry , mechanical engineering , engineering , catalysis
Abstract We have investigated the network of reactions observed for the photochromic 4′‐hydroxy‐6‐nitroflavylium compound in aqueous solutions upon pH changes (including pH jump and stopped flow experiments) and light excitation. The changes observed in the NMR and UV/Vis spectra allowed identification of ten different forms in which this compound can be transformed depending on the experimental conditions. Equilibrium and kinetic constants have been determined. Compared with other members of the flavylium family, 4′‐hydroxy‐6‐nitroflavylium is characterized by a large cis → trans isomerization barrier, and a very efficient hydration reaction. These peculiar features allow writing, reading, storing and erasing photonic information on 4′‐hydroxy‐6‐nitroflavylium by a novel cyclic process that involves the following steps: write‐lock/read/unlock/enable‐erase/erase.