Amide−Ligand Hydrogen Bonding in Reverse Micelles

One approach to modeling the second coordination shell of
metalloproteins is to pair amide-containing counterions with metal
complexes to form hydrogen bonds in the solid state. In a more
general approach, we have designed a surfactant counterion that
can sustain hydrogen bonding interactions with metal complexes
in solution. The surfactant is cationic and incorporates an amide
as part of its headgroup to form hydrogen. The surfactant forms
hydrogen bonding reverse micelles that accommodate anionic metal
complexes in their polar core. In reverse micelles containing an
iron(III) hexacyanide complex, spectroscopic evidence suggests
that the anion is confined to the polar core region in solution. Single-crystal X-ray diffraction data on the surfactant ferricyanide system
reveals a layered structure with interdigitated alkyl chains and an
extensive network of hydrogen bonds that link amide groups to
the cyanide ligands and to neighboring headgroups.