A "molecular pivot-hinge" based on the pH-regulated intramolecular switching of Pt-Pt and pi-pi interactions.

The binuclear cycloplatinated complex {[Pt(L)]2(mu-dppm)}2+ (1), where HL is a new cyclometalating ligand 2-phenyl-6-(1H-pyrazol-3-yl)pyridine, is found to behave as a molecular pivot-hinge in which the closing and opening of the hinge is effected by the reversible formation and cleavage of the Pt-Pt d8-d8 interaction and the intramolecular pi-pi interaction mediated by the protonation/deprotonation of the 1-pyrazolyl-NH on the cyclometalating ligand L.