Structure-Directing Agent Location and Non-Centrosymmetric Structure of Fluoride-Containing Zeolite SSZ-55

Single crystals of pure silica zeolite SSZ-55 were prepared using the fluoride route. Single-crystal X-ray
diffraction at a synchrotron source revealed the framework structure of the material, but the unit cell
(orthorhombic a = 12.905(2) Å, b = 21.344(4) Å, c = 5.1279(10)) is too small to accommodate ordered
arrays of the organic structure-directing agent. Molecular modeling was used to simulate the docking of the
structure-directing agent in the channels of the material, and this revealed a strong space-filling interaction
with a number of possible orientations of the organic cation. The overall non-centrosymmetric structure of
the solid (spacegroup C2221) was confirmed using second harmonic generation experiments.