Two isomeric redox- responsive azathiacrown ethers, based on p-phenylenediamine, have been synthesized in traditional crown (L-1) and crownophane (L-2) architectures. Each of these "Wurster's crowns" was designed to target the encapsulation of transition or heavy metal ions. The solid-state structures of these ligands show binding cavities defined by three exocyclic sulfur atoms and either a N donor atom (L-1) or the electron-rich T face of the phenylenediamine subunit (L-2). The ability of these ligands to form complexes with platinum(II) was investigated by various techniques including H-1 NMR spectroscopy, electrospray mass spectrometry, cyclic voltammetry, and single-crystal X-ray analysis. The traditional crown geometry proved to be better at forming stable endocyclic complexes with Pt(II) than the crownophane geometry, The square-planar Pt(II) crown complex includes direct bonding to the redox center (Pt1-N1 = 2.125 angstrom and Pt1-S-av = 2.278 angstrom) with concomitant polarization of the phenylenediamine moiety. This results in the crown complex oxidizing 916 mV more anodically than the free ligand. In contrast, modest shifts in the oxidation potential of the crownophane isomer indicate poor interaction between the redox center and complexed Pt(II) ion.