Iron(II) clathrochelates as electrocatalysts of hydrogen evolution reaction at low pH

The iron(II) clathrochelate complexes containing pyridinyl substituents showed high electrocatalytic activity of hydrogen evolution reaction (HER) at low pH. The influence of the ribbed substituents nature upon the efficiency of the process in hydrogen evolution reaction was studied by the cyclic voltammetry (CV) method. It was demonstrated that the presence of terminal 4-pyridinyl moieties in this type of iron(II) clathrochelate complexes allowed to use them as a homogeneous electrocatalyst for the molecular hydrogen formation in aqueous solutions due to the emergence of ion associates from the corresponding mono - and diproteinated macrobicyclic clathrochelate particles. Electrolysis with a controlled potential along with analysis of gas chromatography confirmed the production of H2 in high Faraday yields in all cases at a pH range from 1 to 4. The use of clathrochelate iron complexes in the reaction of a molecular hydrogen production from aqueous solutions at a low pH is the first example of the cage complexes using for this process.