Photochromism of 4'-Methoxyflavylium Perchlorate. A 'Write-Lock-Read-Unlock-Erase' Molecular Switching System

摘要

In aqueous solution (2H<8) the thermodynamically stable form of the 4'-methoxyflavylium ion (AH~+) is its hydrated derivative trans-4'-methoxychalocone, Ct. The Ct compound shows a broad absorption band with λ_max=350 nm. In acid medium, irradiation of Ct with near-UV light causes strong spectral changes with five isosbestic points and appearance of a very intense band in the visible region with maximum at 435 nm, corresponding to the AH~+ form.