Crystal Structure and Thermophosphorochromic Property of One-Dimensional Hybrid Haloplumbates with Alkylated Benzothiazole Counter Cations

Low-dimensional hybrid haloplumbates have shown unique optical properties, e.g., solid state emission and temperature-dependent photoluminescence (PL). Herein, by introducing alkylated benzothiazole (btz) as counter cations into the inorganic lead halide system, five hybrid haloplumbates were afforded, namely, (Mebtz) PbI3 (1a, Me = methyl), (Mebtz) PbBr3 (1b), (Etbtz) PbI3 (2, Et = ethyl), (Isbtz) PbI3 (3, Is = isopropyl), and (Bubtz)(2)Pb3I8 (4, Bu = n-butyl). The structures, optical absorptions, and PL properties of the five hybrids are regulated by changing the alkylation group on the btz molecule. Compounds 1a-3 are composed of (PbX3)(-) (X = I or Br) single chains with methylated, ethylated, or isopropylated btz as counter cations. However, 4 contains a (Pb3I8)(2-) ribbon-like structure charge compensated by an n-butylated btz cation. The detailed crystal structure analyses reveal that the inorganic haloplumbate moieties in 1a and 3 interact with btz derivative cations mainly through Coulomb interaction, while they interact mainly through hydrogen bonds in 1b, 2, and 4. Importantly, 3 and 4 show thermophosphorochromic behaviors, which involve multiple color changes when temperature changes, namely, from white through reddish orange to orange for 3 and from greenish yellow through yellow to white for 4. Theoretical calculations and physical property measurements suggest that the thermophosphorochromic behaviors arise from two emission peaks in the visible light region. The high energy emission corresponds to the organic cation-centered charge transitions, while the lower energy emission arises from the charge transition between the inorganic and organic moieties. Different alkylated benzothiazole derivative cations were employed to modulate the crystal structures and thermophosphorochromic properties of inorganic organic hybrid haloplumbates.