Molecular Crystals and Liquid Crystals, Vol.501, 62-71, 2009
Photochromic Properties of Naphthopyrans - PMMA Thin Film
A class of naphthopyran derivatives (3a-10a) with electron-donating and electron-acceptor substituent is prepared by condensation of 1,2-diaryl-2-propyn-1-ol with beta-naphthol in the presence of pyridinium para-toluenesulfonate (PPTS) as catalyst. All compounds go ring-opening isomerization in polymethylmethacrylate (PMMA) matrix with UV light irradiation (30 watt) and the maximum absorption of ring-opening isomers is at the range of 426-556 nm. Ring-opening isomers are completely back to ring-closing isomers when samples are kept in darkness, the bleach rate of ring-opening isomers in PMMA film increased significantly when temperature is more than 45 degrees C. Fatigue testing showed that no significant change of optical density was detected after 10 cycles.