Vr. Thalladi et al., Steering non-centrosymmetry into the third dimension: crystal engineering of an octupolar nonlinear optical crystal, CHEM COMMUN, (17), 1999, pp. 1639-1640
The ability of CH3 groups to form helical chains of C-H ...pi interactions
with phenyl rings leads to polar stacking of trigonal octupolar networks in
a substituted triazine, and therefore to three-dimensional non-centrosymme
try.