ELECTRON-MICROSCOPY AND DIFFRACTION OF CRYSTALLINE DENDRIMERS AND MACROCYCLES

The precisely defined geometry of phenylacetylene dendrimers and macrocycles makes it possible to investigate systematic variations in chemical architecture on the nature of microstructural organization. Here we report on transmission electron microscopy, selected-area electron diffraction and high-resolution electron microscopy studies of crystalline phases of these synthetic materials. Since the molecules are sensitive to electron beam damage, low-dose techniques were used to capture images and diffraction patterns dynamically. The data show increased crystal misorientation with increasing side-group length and molecular complexity. As the size increases, the number of conformations available to the molecule also increases, making it difficult to pack the molecules with fewer defects.