Two New Polymorphs of the Organic Semiconductor 9,10-Diphenylanthracene: Raman and X‑ray Analysis

Raman
microscopy in the lattice phonon region coupled with X-ray
diffraction have been used to study the polymorphism in crystals and
microcrystals of the organic semiconductor 9,10-diphenylanthracene
(DPA) obtained by various methods. While solution grown specimens
all display the well-known monoclinic structure widely reported in
the literature, by varying the growth conditions two more polymorphs
have been obtained, either from the melt or by sublimation. By injecting
water as a nonsolvent in a DPA solution, one of the two new polymorphs
was predominantly obtained in the shape of microribbons. Lattice energy
calculations allow us to assess the relative thermodynamic stability
of the polymorphs and verify that the energies of the different phases
are very sensitive to the details of the molecular geometry adopted
in the solid state. The mobility channels of DPA polymorphs are shortly
investigated.