Crystal structures of tetrakis(4,4'-(2,2-diphenylvinyl)-1,1'-biphenyl)methane; transmission electron microscopy and X-ray diffraction

The crystal structures of tiny crystallites (micron to submicron in size) of tetrakis(4,4'-(2,2-diphenylvinyl)-1,1'-biphenyl)methane (C(DPVBi) 4 ) have been investigated by using a combination of transmission electron microscopy (TEM) and X-ray powder diffraction techniques. The crystal structure of as-synthesized C(DPVBi) 4 is hexagonal. The lattice parameters are a = 2.068 nm and c = 2.194 nm with possible space group P6. After C(DPVBi) 4 was annealed up to 280 °C, the crystal structure converted to a different hexagonal structure with lattice parameters: a = 2.102 nm and c = 3.370 nm. The possible space group is P6/m. The two hexagonal structures correspond to different packing of the individual molecules, which may result in different bulk optical and electronic properties.