Structural characterization of HPM-7, a more ordered than expected germanosilicate zeolite

[EN] HPM-7, a germanosilicate synthesized using long imidazolium-based dications with two different linkers, is shown to possess the POS topology, although disorder may exist but it is very difficult to discern. First, three simple ordered polymorphs (POS-A to POS-C) with very similar energies and structural motifs could give rise to intergrowths that would be very difficult to recognize by powder X-ray diffraction, according to DIFFaX simulations. Another four structures (POS-D to POS-G) can be derived from POS by changing the orientation of two single four rings within the structure, possibly providing an additional source of disorder. While 3D EDT strongly suggests that HPM-7 basically possesses the POS-A (i.e.POS) topology, a detailed HR-STEM study demonstrates the rare existence of some disorder compatible with the polymorph POS-D. The general avoidance of polymorphs with very similar structural motifs and comparable energies points to a rather specific structure-direction by the organic dications used.The authors acknowledge the financial support by the Spanish Ministerio de Economía y Competitividad, the Spanish Agencia Estatal de Investigación and the EU’s Fondo Europeo de Desarrollo Regional under projects MAT2016-77496-R (AEI/FEDER, UE) and MAT2015-71117-R (MINECO/FEDER, UE). We are indebted to the ERSF (Grenoble) and the BM25 Spline staff, particularly to G. Castro and A. Serrano as well as to L. A. Villaescusa (Valencia) for help in collecting the SPXRD data and for helpful comments and suggestions. P. L. is grateful to the China Scholarship Council (CSC) for a fellowship and to the Dalian Institute of Chemical Physics for permission to leave. AM acknowledges the Natural National Science Foundation of China (NFSC) through the grants NFSC-21850410448 & NSFC-21835002. AM and YZ acknowledge the Centre for Highresolution Electron Microscopy (CħEM), supported by SPST of ShanghaiTech University under contract no. EM02161943. We acknowledge the support of the publication fee by the CSIC Open Access Publication Support Initiative through its Unit of Information Resources for Research (URICI)