In this work, 1D Cd(II) halide chain (Cd(Bz)Br) and mononuclear Cd(II) halide complex (Cd(Bz)I) were obtained by regulating halide ions. Br- ions act as µ2-Br bridges, alternately connecting with Cd(II) ions to form the trunks of the 1D chains with repeating units of -Cd-Br2-. The outer edges of the branches contain anti-parallel N-methylbenzimidazole (Bz) planes, which are coordinated with the Cd(II) ions. Notably, the anti-parallel Bz planes between adjacent Cd(Bz)Br chains are tightly interlocked through π-π interactions, forming a "zipper"-like connection, which promotes the intersystem crossing process and stabilizes the excited triplet. These results in room-temperature ultralong afterglow from Cd(Bz)Br with a lifetime of 34.35 ms and a delay time of up to 0.7 s. Furthermore, the butterfly-shaped mononuclear complex Cd(Bz)I exhibits a room-temperature phosphorescence (RTP) lifetime of only 5.86 ms, with an afterglow duration of less than 0.1 s. By leveraging the significant differences in the RTP of these Cd(II) halide complexes, a complex anti-counterfeiting system with multiple encryption features was constructed. This work not only provides a vivid example of manipulating halide ions to expand the range of Cd(II) halide complexes in different dimensions but also opens new horizons for regulating the RTP of Cd(II) halide complexes.
Li et al. (Mon,) studied this question.