Rewinding of Helical Systems by Use of the Cr(III) Complex as a Photoresponsive Chiral Dopant

Abstract

Vibrational circular dichroism (VCD) spectroscopy has been applied for monitoring in situ the photoinduced rewind of supramolecular helices in a liquid crystal. The monitored system was a room-temperature liquid crystal, ZLI-1132, doped with a novel chiral Cr(III) complex. Under the illumination of UV light (365 nm), the photoracemization of the Cr(III) complex led to the rewind of helices in the chiral nematic phase. In response to this, the VCD spectrum of the system exhibited the transient change, confirming the elongation of helical pitch length. The possibility of using the VCD spectrum as a memory of photoresponsive events is discussed.