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

We presenta database of subperiodic zeolitic structurescomprising clusters, tubes/rods, and layers. All structures are fully4-coordinated. We demonstrate how the 3-periodic zeolite L can beterminated on a 001 plane, while maintaining full 4-connectivity withno hydroxyl terminations. 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 structuresare 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 reversedto reject the 3-periodic zeolites. Being fully 4-coordinated, thesesubperiodic structures require no hydroxyl terminations at their freesurfaces when realized as SiO2 silicates. The layers closelyresemble thin zeolites and are particularly interesting candidatesfor synthesis. The layer structures offer a rich library of structuralpossibilities for low-energy termination of the free surfaces of theknown zeolites while maintaining full tetrahedral coordination. Wepresent two examples of possible (001)-surface reconstructions forthe LTL framework.