Photoluminescence of pefloxacindi-ium manganese(II) and zinc(II) tetrahalides
Mn2+-based hybrid materials have become the hotspot of current research studies owing to their high photoluminescence quantum yield (PLQY), low-cost, environmental friendliness and stability. For the first time, we report the hydrothermal synthesis of two lead-free zero-dimensional luminescent organic-inorganic hybrid compounds, PefH2[MnBr4] (1) and PefH2[MnCl4] (2) (Pef = pefloxacin). They were characterized by elemental analysis, TG-DSC, single-crystal and powder XRD. Compounds 1–2 exhibit a distorted tetrahedral geometry around the manganese(II) metal center, which is isolated from the same centers by bulky pefloxacindi-ium (PefH22+) ions with a Mn···Mn distance of 7.3 Å. Their structures are stabilized by N—H···O, O—H···X (X = Br, Cl), C—H···O and C—H···X hydrogen bands and π–π stacking interaction. Thermal decomposition starts at T > 230°С for 1 and T > 210°С for 2 and proceeds for several stages. Upon UV excitation compounds exhibit a bright green emission with a moderate PLQY of 45% for 1 and 30% for 2. The influence of the halide ion and metal ion on the photoluminescence properties of isostructural compounds PefH2[MX4] (M = Mn, Zn and X = Br, Cl) is discussed.