Combinatorial-topological modeling of the cluster self-assembly of zeolite crystal structures: computer search for molecular templates for new zeolite ISC-2

摘要

The combinatorial-topological modeling of 3D periodic packings of layers composed of T-12 polyhedral clusters (t-hpr tiles in the form of hexagonal prisms) was carried out. The T12 clusters are among the most abundant units in the crystal structures of zeolites. The layers were produced by decoration of the vertices of the square and hexagonal (graphite-like) nets with T-12 clusters. All combinatorially possible patterns of 3D frameworks, which were constructed based on packings of decorated square nets, correspond to known zeolite structures: CHA (mineral chabazite, Ca-6(H2O)(40)Al12Si24O72), AEI (AlPO-18, Al24P24O96), SAV ((C18H42N6)(2)(H2O)(7)Mg5Al19P24O96), and KFI (Na-30(H2O)(98)Al30Si66O192). The modeling using the same scheme and a decorated hexagonal net gave rise to the frameworks of three known zeolites, GME (gmelinite, (Ca,Na)(4)(H2O)(24)A(l8)Si(16)O(48)), AFX (SAPO-56, H3Al23Si5P20O96), and AFT (AlPO-52, Al36P36O144), as well as of one previously unknown hypothetical zeolite ISC-2 with the unit cell parameters a = 13.90 , c = 30.00 , V = 5019.7 (3), sp. gr. . Zeolite ISC-2 contains a cavity with a new t-isc-2 topology [4(21).6(2).8(15)], which is responsible for its unique framework. An analysis of the specially created database of topological types of molecules (TTM collection) containing geometric and topological characteristics of more than 300000 different molecules suggested an organic structure-directing agent, which stabilizes the t-isc-2 cavity and which can be used for the synthesis of ISC-2.