Teamwork: Structural characterization of the first dinuclear mercury(II) complex with a regular porphyrin reveals dissymmetry induced by binding of dimethyl sulfoxide molecules to the metal ions, which form two allosterically connected binding sites (see structure; gray C, orange Hg, blue N, red O, yellow S). The cooperativity of the metal insertion can be tuned, either positively or negatively, by the presence of a base or by the interaction with exogenous ligands.

A general method to synthesize various alphabeta alphabeta bis-strapped porphyrins, with a different functionalization on each side of the macrocycle, is described. The resulting new chelates may find applications as analogues of heme protein active sites, bifunctional chelates, or specific bis-chelating molecules with potential medical utility.