Despite the interesting structure of the generic thiacalix[4]arene containing four coordinating sulfur atoms bridging four phenolic units, there are only a few reported examples of thiacalixarene-based coordination complexes that are used as electrocatalysts. Herein, we report electrocatalytic hydrogen evolution reaction (HER) by a thiacalix[4]arene-based copper(II) complex (1). As expected, two reduction waves were appeared (-0.48 V and -1.30 V vs Ag/AgCl) for Cu2+/Cu+ and Cu+/Cu reduction couples. The HER by proton reduction occurs at -1.03 V with a shift of 0.27 V compared to the second peak potential at -1.30 V. The increase in the number of acetic acid equivalents, from 0 to 17.5 with a frequency of 2.5 eq, was accompanied by an increase in the peak current that reached a maximum value of 183 µA for 15 equivalents of acetic acid.

Hani El Moll, Khalaf M. Alenezi, Abdallah O. Alshammari, Ashanul Haque, Jamal Humaidi Raoudha Soury, Eid M. S. Azzam, Fahad Abdulaziz, Salman Latif, Milan Vraneš