Triphosphasumanene Trisulfide: High Out-of-Plane Anisotropy and Janus-Type π‑Surfaces

A triphosphasumanene
trisulfide was designed and synthesized as
an out-of-plane anisotropic π-conjugated molecule. Incorporating
three anisotropic phosphine sulfide moieties into a sumanene skeleton
induced a cumulative anisotropy with a large dipole moment (12.0 D),
which is aligned in perpendicular direction with respect to the π-framework
and more than twice as large as those of conventional out-of-plane
anisotropic molecules. In the crystal, the molecules align to form
columnar structures, in which electron-rich and electron-deficient
sides of the π-framework face each other. The interactions between
the electron-rich surfaces, which contain three sulfur atoms, and
Au(111) were examined by X-ray photoelectron spectroscopy.