Enumeration of Subperiodic Zeolitic Tetrahedral Frameworks. III. Layers, Rods, Tubes, and Clusters

Abstract

We describe a new database of 4-coordinated hypothetical “subperiodic” zeolitic frameworks, comprising 0-periodic (clusters), 1-periodic (rods and tubes), and 2-periodic (layers) structures. The structures are found by a combinatorial search over 4-coordinated directed graphs, given the space group and the number of unique tetrahedral vertices, as in our earlier database. However, the filters are now reversed to reject the 3-periodic zeolites. Being fully 4-coordinated, these subperiodic structures require no hydroxyl terminations at their free surfaces when realized as SiO2 silicates. The layers closely resemble thin zeolites and are particularly interesting candidates for synthesis. The layer structures offer a rich library of structural possibilities for low-energy termination of the free surfaces of the known zeolites while maintaining full tetrahedral coordination. We present two examples of possible (001)-surface reconstructions for the LTL framework.