Photoinduced pitch changes in chiral nematic liquid crystals formed by doping with chiral diarylethene

Chiral binaphthyl derivatives having two photochromic diarylethene units we re synthesized in an attempt to use them as dopants for photoresponsive liq uid crystals. These compounds showed thermally irreversible photochromic re actions. The circular dichroism (CD) spectra and the optical rotation value s of the derivatives reversibly changed in methanol upon alternate irradiat ion with ultraviolet and visible light. Large photostimulated pitch changes of chiral nematic K-15 liquid crystals were observed on addition of the de rivatives as dopants. The relation between the optical rotation and the twi sting power force was discussed.