Anion-induced assembly of different mercury coordination complexes and DFT calculations to evaluate weak interactions between similar double-helical chains

Self-assembly of the flexible ligand 3,6-di-(1,2,4-triazole-1-yl)-N- alkylcarbazole with HgX₂ (X = I, Br, Cl, SCN) yielded a short series of new coordination polymer complexes (1, 3-6) with double-helical, "W" , and single molecular structure of complex 2. Weak interactions, including hydrogen bonds, π-π interactions, M· · ·X bonds, and counteranions play significant roles in the final crystal structures. Three different DFT calculations are performed on the weak interaction between the two helical chains from the four different coordination polymers (complexes 1, 4, 5 and 6). The outcomes show a similar trend, the larger the halogen anion, the weaker the interaction between the infinite chains, which provides useful information on the thermal stable properties of the infinite double-helical polymer chains.