Strong and directed association of porphyrins and iron(terpyridine)s using hydrogen bonding and ion pairing

The combination of cooperative hydrogen bonding and ion pairing between cationic iron(II)terpyridines and anionic porphyrins yielded remarkably stable neutral complexes even in the highly competitive solvent DMSO. Isothermal titration calorimetry (ITC) was used to compare association constants, enthalpies and entropies of binding between various combinations of the two molecular components that make up the complexes. Steady-state luminescence studies highlighted that, as expected, the fluorescence quenching of the porphyrin is maximized in the cases where the iron(terpyridine) is strapped the tightest across the macrocycle.