Intermolecular Interaction by Apical Oxygen in Titanyl Phthalocyanine

Local charge distribution around the titanium atom of amorphous and α-crystalline TiOPc films was investigated using Ti 2<I>p</I> X-ray absorption and emission spectroscopy. The X-ray emission spectra show two characteristic features that correspond to charge transfer states that result from in-plane Ti–N and apical Ti–O hybridizations. In the amorphous phase, the Ti–O charge transfer state has both localized and delocalized properties, whereas in the α-crystalline phase it has only the delocalized property. These different properties evidence the role of the oxygen atom in forming a network with a neighboring molecule and in balancing the total dipole moment in the α-crystalline phase.