[((R)-C8H12N)4][Bi2Br10] and [((S)-C8H12N)4][Bi2Br10]: Chiral Hybrid Bismuth Bromides Templated by Chiral Organic Cations

Single crystals of organically templated chiral bromobismuthates(III), [((R/S)-C8H12N)4][Bi2Br10], have been grown for the first time via a slow evaporation method. Each of the chiral molecular compound consists of (R) or (S)-1-phenylethylammonium ([C8H12N]+) cations and [Bi2Br10]4– anions. Both the title compounds reveal thermal and moisture stabilities up to ca. 220 °C and over 1 month, respectively. The newly prepared Bi3+-based organic–inorganic hybrid materials show optical band gap of ca. 2.88 eV. The noncentrosymmetric [((R)-C8H12N)4][Bi2Br10] and [((S)-C8H12N)4][Bi2Br10] exhibit second harmonic generation efficiency of ca. 20 times that of α-SiO2 and are type I nonphase matchable. Uniformly deposited thin films of [((R)-C8H12N)4][Bi2Br10] and [((S)-C8H12N)4][Bi2Br10] have been also successfully obtained by a simple spin-coating method. The circular dichroism spectra for both reported thin films are symmetrical, attributable to the corresponding Cotton effect. The selectively deposited chiral thin films are expected to be used as a useful platform for various surface reactions and interface engineering.