Chiroptic response of ferroelectric liquid crystals triggered with localized surface plasmon resonance of achiral gold nanorods

Abstract

The chiroptic response of a multi-component molecular mixture [chiral smectic C (SmC*) liquid crystal] modified by achiral capped gold nanorods (GNRs) has been reported. The dispersion of the GNRs (radius rGNR = 5 × 10−9 m; length L = 4.5 × 10−8 m) with two concentrations (0.1 wt. % and 0.5 wt. %) resulted in the concentration dependent change in the circular dichroism (CD) spectrum of the SmC*-GNR complex. Three effects could be responsible for the change in the chiroptic properties of the SmC* liquid crystal. The first one is the stabilization of the helical superstructure due to the GNRs. The second one is the change in the angle between the transition electric and magnetic dipole moments near the absorption bands due to the influence of the longitudinal surface plasmon resonances (LSPRs) excited in nanorods. The third effect is the induction of chiral current in gold nanorods by the chiral component of the mixture. The latter phenomenon leads to the broad CD band at the wavelength of the LSPR.