Synthesis, crystal structure and remote allosteric binding properties of cone thiacalix[4]pseudocrown receptors bearing anthraquinone function and different arms

Herein, three novel cone thiacalix[4] pseudocrown receptors 1-3, bearing anthraquinone and triazole functions as well as different side arms, were successfully synthesized via a double click reaction as the key step. Their recognition properties have been fully evaluated using optical, electrochemical, and theoretical methods. Receptor 1 features high selectivity for Pb2+, whereas receptor 2 can optically recognize Zn2+ in the presence of Cd2+. This difference of binding specificity to metal ions may be ascribed to the remote tuning effect from the side arms connected to the lower rim of thiacalix[4] arene that realizes the accommodation of binding specificity. Moreover, the plausible coordination modes have been presented.