Circularly Polarized Luminescence from Inorganic Materials: Encapsulating Guest Lanthanide Oxides in Chiral Silica Hosts

Recently, circularly polarized luminescence (CPL)-active systems have become a very hot and interesting subject in chirality- and optics-related areas. The CPL-active systems are usually available by two approaches: covalently combining a luminescent centre to chiral motif or associating the guest of luminescent probe to a chiral host. However, all the chiral components in CPL materials were organic, although the luminescent components were alternatively organics or inorganics. Herein, the first totally inorganic CPL-active system by "luminescent guest-chiral host" strategy is proposed. Luminescent sub-10 nm lanthanide oxides (Eu2O3 or Tb2O3) nanoparticles (guests) were encapsulated into chiral non-helical SiO2 nanofibres (host) through calcination of chiral SiO2 hybrid nanofibres, trapping Eu3+ (or Tb3+). These lanthanide oxides display circular dichroism (CD) optical activity in the ultraviolet wavelength and CPL signals around at 615 nm for Eu3+ and 545 nm for Tb3+. This work has implications for inorganic-based CPL-active systems by incorporation of various luminescent guests within chiral inorganic hosts.