A systematic topological search for the framework of ZSM-10

Foster, Martin D.; Treacy, M.M.J.; Higgins, John B.; Rivin, Igor; Balkovsky, E.; Randall, Keith H.

doi:10.1107/s0021889805026038

Cited by 34 publications

(15 citation statements)

References 22 publications

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“…A major ambition for the field is the development of 'designer' zeolites with tailored geometry for new catalytic applications, by the appropriate choice of synthesis conditions and organic structure-directing agents (oSDAs) whose shape is intended to template the specific pore geometry of the desired framework (Dhainaut et al, 2013). Efforts to predict hypothetical tetrahedral frameworks as candidate structures have led to an embarrassment of riches; for example, the symmetry constrained inter-site bonding search (SCIBS) and energy minimization approach of Treacy and Foster has generated a database that now exceeds 5 million types (Foster et al, 2005;Treacy et al, 2004). The rate of synthesis of new zeolite structures experimentally, however, remains slow, thanks to two significant bottlenecks.…”

Section: The Flexibility Window In Zeolitesmentioning

confidence: 99%

Intrinsic flexibility of porous materials; theory, modelling and the flexibility window of the EMT zeolite framework

Fletcher

Wells

Leung

et al. 2015

Acta Crystallogr Sect B

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Framework materials have structures containing strongly bonded polyhedral groups of atoms connected through their vertices. Typically the energy cost for variations of the inter-polyhedral geometry is much less than the cost of distortions of the polyhedra themselves -as in the case of silicates, where the geometry of the SiO 4 tetrahedral group is much more strongly constrained than the Si-O-Si bridging angle. As a result, framework materials frequently display intrinsic flexibility, and their dynamic and static properties are strongly influenced by low-energy collective motions of the polyhedra. Insight into these motions can be obtained in reciprocal space through the 'rigid unit mode' (RUM) model, and in real-space through template-based geometric simulations. We briefly review the framework flexibility phenomena in energy-relevant materials, including ionic conductors, perovskites and zeolites. In particular we examine the 'flexibility window' phenomenon in zeolites and present novel results on the flexibility window of the EMT framework, which shed light on the role of structure-directing agents. Our key finding is that the crown ether, despite its steric bulk, does not limit the geometric flexibility of the framework.

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Section: The Flexibility Window In Zeolitesmentioning

confidence: 99%

Intrinsic flexibility of porous materials; theory, modelling and the flexibility window of the EMT zeolite framework

Fletcher

Wells

Leung

et al. 2015

Acta Crystallogr Sect B

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“…[4,5] Since the 1970s, millions of hypothetical zeolite frameworks have been predicted. [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] Considering the very limited number of zeolites discovered in real life, one might wonder if such a tremendous number of hypothetical zeolites are really chemically feasible synthetic targets. A prerequisite for evaluating the feasibility of hypothetical zeolites is to unravel the underlying distinguishing structural features shared by all existing zeolites.…”

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confidence: 99%

Criteria for Zeolite Frameworks Realizable for Target Synthesis

2013

Angew Chem Int Ed

116

113

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Zeolites containing well-defined pores in molecular dimensions have important industrial applications in the fields of catalysis, adsorption, and ion exchange. [1,2] The primary building unit of a zeolite framework is the TO 4 tetrahedron (T is usually Si, Al, or P), which is linked to four neighbors by bridging O atoms to form various strictly four-connected frameworks. To date, over 200 distinct zeolite frameworks have been discovered or synthesized, [3] and the pursuit of novel zeolites will never stop because of their important industrial applications. In particular, the function-orientated synthesis of zeolites with desired structures has become a challenging goal. [4,5] Since the 1970s, millions of hypothetical zeolite frameworks have been predicted. [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] Considering the very limited number of zeolites discovered in real life, one might wonder if such a tremendous number of hypothetical zeolites are really chemically feasible synthetic targets. A prerequisite for evaluating the feasibility of hypothetical zeolites is to unravel the underlying distinguishing structural features shared by all existing zeolites. Considerable efforts have been made to this end. [12,19,20,[23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39] Low framework energy seemed to be the global feature that enabled the synthesis of most open-framework compounds. It explained very well the existence of conventional zeolites consisting of Al, Si, and P as the main T elements. Furthermore, a linear relationship between the framework energy (E, calculated as silica polymorphs) and the framework density (FD, defined as the number of T atoms per 1000 3 ) was discovered for conventional zeolites. [23,24,40,41] However, with the emergence of many high-energy zeolites, especially unconventional zeolites containing T elements other than Al, Si, and P, the energy criterion has been found to not always be reliable. [30,42] Figure S1 in the Supporting Information shows the plot of E versus FD for the 200 existing zeolite frameworks, which have been optimized as silica polymorphs (see the Experimental Section). Many unconventional zeolites significantly deviate from the regression line derived from the conventional zeolites. In 2006, Thorpe and co-workers found that many existing zeolite frameworks showed a "flexibility window" over a range of densities, [32] but soon afterwards they found that several zeolites that already existed violated this criterion. [36,38,39] Up to now, there is no criterion that could universally explain the feasibility of all existing zeolites without exception.In contrast to all previous attempts, we focused in this study on the local interatomic distances (LIDs) in fourconnected zeolite frameworks; these LIDs reflect the geometries of TO 4 tetrahedra and their local linkages. We discovered that the LIDs in all existing zeolites strictly obey several rules without exception, and thus represent certain intrinsic structural features of realizable zeoli...

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“…Diese Autoren testeten sämtliche 18.4 Million im Internet verfügbaren1 Graphen mit Vierfachkoordination und sechs unterschiedlichen tetraedrisch umgebenen (T) Atomen in der Raumgruppe P 6/ mmm . Aus den Beugungsmessungen war bekannt,2 dass a = b =31.575 und c =7.52 Å gilt. Praktisch konnte die ZSM‐10‐Struktur durch die Identifizierung derjenigen Topologie (in der Datenbank) gelöst werden, die mit den beobachteten Abmessungen der Elementarzelle und der Raumgruppensymmetrie übereinstimmte 3…”

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Molecular Heterogeneous Catalysis: A Single‐Site Zeolite‐Supported Rhodium Complex for Acetylene Cyclotrimerization

Kletnieks

Liang²,

Craciun

et al. 2007

Chemistry A European J

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By anchoring metal complexes to supports, researchers have attempted to combine the high activity and selectivity of molecular homogeneous catalysis with the ease of separation and lack of corrosion of heterogeneous catalysis. However, the intrinsic nonuniformity of supports has limited attempts to make supported catalysts truly uniform. We report the synthesis and performance of such a catalyst, made from [Rh(C(2)H(4))(2)(CH(3)COCHCOCH(3))] and a crystalline support, dealuminated Y zeolite, giving {Rh(C(2)H(4))(2)} groups anchored by bonds to two zeolite oxygen ions, with the structure determined by extended X-ray absorption fine structure (EXAFS) spectroscopy and the uniformity of the supported complex demonstrated by (13)C NMR spectroscopy. When the ethylene ligands are replaced by acetylene, catalytic cyclotrimerization to benzene ensues. Characterizing the working catalyst, we observed evidence of intermediates in the catalytic cycle by NMR spectroscopy. Calculations at the level of density functional theory confirmed the structure of the as-synthesized supported metal complex determined by EXAFS spectroscopy. With this structure as an anchor, we used the computational results to elucidate the catalytic cycle (including transition states), finding results in agreement with the NMR spectra.

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A systematic topological search for the framework of ZSM-10

Cited by 34 publications

References 22 publications

Intrinsic flexibility of porous materials; theory, modelling and the flexibility window of the EMT zeolite framework

Intrinsic flexibility of porous materials; theory, modelling and the flexibility window of the EMT zeolite framework

Criteria for Zeolite Frameworks Realizable for Target Synthesis

Molecular Heterogeneous Catalysis: A Single‐Site Zeolite‐Supported Rhodium Complex for Acetylene Cyclotrimerization

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