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.