Zeolite and zeolite-like molecular sieves are being used in a large number of applications such as adsorption and catalysis. Achievement of the long-standing goal of creating a chiral, polycrystalline molecular sieve with bulk enantioenrichment would enable these materials to perform enantioselective functions. Here, we report the synthesis of enantiomerically enriched samples of a molecular sieve. Enantiopure organic structure directing agents are designed with the assistance of computational methods and used to synthesize enantioenriched, polycrystalline molecular sieve samples of either enantiomer. Computational results correctly predicted which enantiomer is obtained, and enantiomeric enrichment is proven by high-resolution transmission electron microscopy. The enantioenriched and racemic samples of the molecular sieves are tested as adsorbents and heterogeneous catalysts. The enantioenriched molecular sieves show enantioselectivity for the ring opening reaction of epoxides and enantioselective adsorption of 2-butanol (the R enantiomer of the molecular sieve shows opposite and approximately equal enantioselectivity compared with the S enantiomer of the molecular sieve, whereas the racemic sample of the molecular sieve shows no enantioselectivity). chirality | zeolite | asymmetric catalysis | chiral adsorption

Zeolite A (LTA) has many large-scale uses in separations and ion exchange applications. Because of the high aluminum content and lack of high-temperature stability, applications in catalysis, while highly desired, have been extremely limited. Herein, we report a robust method to prepare pure-silica, aluminosilicate (product Si/Al = 12–42), and titanosilicate LTA in fluoride media using a simple, imidazolium-based organic structure-directing agent. The aluminosilicate material is an active catalyst for the methanol-to-olefins reaction with higher product selectivities to butenes as well as C5 and C6 products than the commercialized silicoalumniophosphate or zeolite analogue that both have the chabazite framework (SAPO-34 and SSZ-13, respectively). The crystal structures of the as-made and calcined pure-silica materials were solved using single-crystal X-ray diffraction, providing information about the occluded organics and fluoride as well as structural information.

The use of biomass as a resource to produce value‐added products has garnered significant interest as a means of reducing reliance on fossil fuels. This task is complicated by the complex, highly functionalized nature of abundant biomass derivatives, such as glucose. Tin‐containing zeolite Beta (Sn‐Beta) can selectively isomerize glucose to fructose through a 1,2‐intramolecular hydride shift (1,2‐HS) or selectively produce mannose through a 1,2‐intramolecular carbon shift (1,2‐CS) by titration of the silanol groups with sodium (Na‐Sn‐Beta). To understand the structure–activity relationships between the conditions of the active sites in the zeolite, two molecular models (tin silsesquioxanes) of the tin sites in the zeolite were synthesized. Tin silsesquioxanes that contain an octahedral tin site with and without an adjacent silanol group selectively form fructose through a 1,2‐HS and mannose through a 1,2‐CS, respectively, and provide further evidence for the nature of the active sites in Sn‐Beta.

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Large‐pore microporous materials are of great interest to process bulky hydrocarbon and biomass‐derived molecules. ITQ‐27 (IWV) has a two‐dimensional pore system bounded by 12‐membered rings (MRs) that lead to internal cross‐sections containing 14 MRs. Investigations into the catalytic behavior of aluminosilicate (zeolite) materials with this framework structure have been limited until now due to barriers in synthesis. The facile synthesis of aluminosilicate IWV in both hydroxide and fluoride media is reported herein using simple, diquaternary organic structure‐directing agents (OSDAs) that are based on tetramethylimidazole. In hydroxide media, a zeolite product with Si/Al=14.8–23.2 is obtained, while in fluoride media an aluminosilicate product with Si/Al up to 82 is synthesized. The material produced in hydroxide media is tested for the hydroisomerization of n‐hexane, and results from this test reaction suggest that the effective pore size of zeolites with the IWV framework structure is similar to but slightly larger than that of ZSM‐12 (MTW), in fairly good agreement with crystallographic data.

Tin-containing zeolite Beta (Sn-Beta) has been investigated as a catalyst for isomerizing aldohexoses into ketohexoses through a Lewis acid mediated hydride shift. Recent studies on the reactivities of Lewis base-doped and alkali-exchanged Sn-Beta samples have conclusively demonstrated that the "open" tin site performs the glucose isomerization reaction. With Lewis base doped Sn-Beta, glucose conversion is almost completely eliminated and product selectivity is shifted predominantly to mannose. These data suggest that glucose reactions may occur through pathways that do not involve the "open" site in Sn-Beta; albeit at significantly lower rates. To examine this possibility, reactions of glucose catalyzed by a homogeneous model of Sn-Beta that does not contain "open" sites, methylligated tin silsesquioxane 1a, is experimentally and theoretically examined. 1a is an active glucose conversion catalyst selectively producing mannose, although the rates of reaction are far below those obtained from Sn-Beta. A hybrid quantum mechanical/molecular mechanics model is constructed, and the complete catalytic cycle is computationally examined, considering ring-opening, three distinct pathways for each hydride-and carbonshift reaction, and ring-closing. The combined experimental and computational results

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