A zeolite family with expanding structural complexity and embedded isoreticular structures

Abstract

The prediction and synthesis of new crystal structures enable the targeted preparation of materials with desired properties. Among porous solids, this has been achieved for metal-organic frameworks, but not for the more widely applicable zeolites, where new materials are usually discovered using exploratory synthesis. Although millions of hypothetical zeolite structures have been proposed, not enough is known about their synthesis mechanism to allow any given structure to be prepared. Here we present an approach that combines structure solution with structure prediction, and inspires the targeted synthesis of new super-complex zeolites. We used electron diffraction to identify a family of related structures and to discover the structural 'coding' within them. This allowed us to determine the complex, and previously unknown, structure of zeolite ZSM-25 (ref. 8), which has the largest unit-cell volume of all known zeolites (91,554 cubic ångströms) and demonstrates selective CO2 adsorption. By extending our method, we were able to predict other members of a family of increasingly complex, but structurally related, zeolites and to synthesize two more-complex zeolites in the family, PST-20 and PST-25, with much larger cell volumes (166,988 and 275,178 cubic ångströms, respectively) and similar selective adsorption properties. Members of this family have the same symmetry, but an expanding unit cell, and are related by hitherto unrecognized structural principles; we call these family members embedded isoreticular zeolite structures.

Cation Control of Molecular Sieving by Flexible Li-Containing Zeolite Rho

“…Zeolites A 18,19 and chabazite 20,21 with particular cation compositions have been suggested to demonstrate such behaviour, as have certain forms of zeolite Rho [22][23][24] and structures related to Rho. 25,26 In zeolite Rho, 27 large lta cages are linked by double 8-ring structural units, which act as windows and are also the favoured sites for large univalent cations such as Na + , K + and Cs + (8-ring refers to a ring of 8 framework metal atoms and 8 oxygen atoms). These cations adopt sites in either single 8-rings or double eight-rings (represented as 8R or D8R sites in this work) depending on their ionic radius ( Figure 1).…”

FELIX: an algorithm for indexing multiple crystallites in X-ray free-electron laser snapshot diffraction images

“…RHO-G6, one of the largest recently solved zeolite structures (Guo et al, 2015); hen egg white lysozyme, a protein standard solved to high resolution via serial crystallography (Boutet, 2013); and AT 1 R, a G-protein coupled receptor structure recently solved by serial femtosecond X-ray diffraction (Zhang et al, 2015). The crystal structures of these molecules have cubic, tetragonal and monoclinic lattice symmetries, respectively.…”

Protein structure determination by electron diffraction using a single three-dimensional nanocrystal

“…Originally, the method concentrated on diffracting and imaging twodimensional crystals (Raunser & Walz, 2009;Stahlberg et al, 2015), and resulted in important structures of membrane proteins (Unwin & Henderson, 1975;Gonen et al, 2005). Electron diffraction of three-dimensional crystals allowed the structure solution of organic and inorganic samples (Vainshtein, 1964;Dorset, 1995;Weirich et al, 1996;Mugnaioli et al, 2009;Kolb et al, 2010;Gorelik et al, 2012;Zou et al, 2011;Guo et al, 2015). Crystallographic data are most efficiently collected by continuously rotating the crystal (Dauter, 1999).…”