Fig. 2

Crystal structures and calculated hole mobilities for ellipticine. a, b Crystal structures of a polymorph I and b polymorph II viewed from the π−π stacking and the H-bonding directions. The corresponding calculated charge transfer integrals and the measured stacking distances were labeled. The blue dash lines denote H-bonds (NH to N). The yellow dash lines enclose one unit cell of the crystal lattice. c, d Calculated hole mobilities (in cm² V⁻¹ s⁻¹) of ellipticine c polymorph I and d polymorph II. In both cases, 0° corresponds the H-bonding direction, and 90° the π−π stacking direction