Circularly Polarized Luminescence from Achiral Single Crystals of Hybrid Manganese Halides

[K­(dibenzo-18-crown-6)]+ (KC) cations are
used for cocrystallization with manganese halides, producing isostructural
single crystals of organic–inorganic hybrid complexes, [K­(dibenzo-18-crown-6)]2MnX4 (abbreviated (KC)2MnX4) (X = Cl, Br), which
feature one-dimensional morphology and green phosphorescence with
considerable photoluminescence quantum yields accompanied by excellent
optical waveguide behavior with a low loss coefficient. More interestingly, (KC)2MnX4 crystallizes in the monoclinic space group Cc belonging to the achiral point group m (Cs), where the non-centrosymmetric
arrangement of racemic units, with right- and left-handed rotating
optical axes, endows these achiral single crystals with circularly
polarized luminescence, observed for the first time.