Self-Assembly of Extended Head-to-Tail Triangular Pt3 Macrocycles into Nanotubes.

New pyridylsalicylaldimine-based ligands with extended conjugation have been synthesized. The reaction of these ligands with K2PtCl4 yielded triangular Pt3 macrocycles rather than the anticipated Pt4 macrocycles. The macrocycles have been analyzed in solution by variable-temperature and variable-concentration 1H NMR, NOESY, and DOSY spectroscopy studies. These investigations show that the macrocycles aggregate at room temperature in solution by an entropy-driven process. In the solid state, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and transmission electron microscopy studies show that the macrocycles aggregate into nanotubular structures. Triangular platinum-containing macrocycles with the expanded pyridylsalicylaldimine ligands are promising for constructing nanotubes and discotic liquid crystals.