Synthesis, Crystal Structure, and Photoluminescence of a Lithium Perchlorate Complex with 18-Crown-6

The reaction of lithium perchlorate salt and 18-crown-6 (18C-6) in the commercial tetrahydrofuran (THF) solvent leads to a novel important intermediate Li(18C-6)(H2O)2(ClO4)⋅0.5((18C-6)⋅THF) (1). The crystal structure shows it as a mononuclear lithium complex, and the asymmetric unit contains a Li(H2O)2(18C-6) moiety, one half of the 18C-6 guest molecule, one half of the disordered THF solvent molecule, and a perchlorate anion. Solid-state photoluminescence experiments show that complex 1 emits violet luminescence, and its possible emission mechanism is investigated in detail based on theoretical calculations.