New microporous and mesoporous materials: elucidation of their structures by electron microscopy

We have recently published three papers (P. Wagner et al., Phys. Chem. 103 (1999) 8245; S. Inagaki et al., J. Am. Chem. Sec. 121 (1999) 9611; A. Carls son et al, J. Electron Microscopy 48 (1999) 795) that herald a new approach to structural solutions in micro- and mesoporous solid state materials, Am ong these materials are the first hybrid inorganic-organic mesoporous mater ials, synthesized using the organosilane compound 1,2-bis(trimethoxysilyl) ethane (BTME). Both organic and inorganic fragments are distributed complet ely uniformly at the molecular scale in the mesoporous walls. Two distinct phases with two- and three-dimensional (2d- and 3d-) hexagonal periodic por e-arrangements have been detected. We have also recently reported another n ew cubic hybrid phase with a "decaoctahedral" crystal morphology. Two new a pproaches for solving the structures of porous materials from either electr on diffraction (ED) or high-resolution electron microscope (HREM) observati ons have also been developed. The former was successfully applied by combin ing "direct methods" for structural analysis of the new microporous crystal SSZ-48, which crystallizes only in very small crystals. The latter techniq ue was applied to 3d-structural analysis of the mesoporous material MCM-48. The structure solutions, in the latter case, are obtained uniquely without preassumed models or parameterization, unlike previous reports,