The role of sorbate in the determination of preferential adsorption sites in zeolite HY: A theoretical study

Jirapongphan, Siricharn S.; Warzywoda, Juliusz; Budil, David E.; Sacco, Albert

doi:10.1016/j.micromeso.2007.02.014

Cited by 11 publications

(10 citation statements)

References 15 publications

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“…1). 5 As shown in Figure 1, the cavity that is available for an enantioseparation in the modified zeolite is located inside the supercage. The models used for each phenylglycinol enantiomer (C 8 H 11 NO, Fig.…”

Section: Computational Methodologymentioning

confidence: 99%

“…1). [1][2][3][4][5] The supercages are the repeating sphere-like cavities (*12.6 Å in diameter) connected to each other in three dimensions in the zeolite HY structure. A separation mechanism has been proposed for this (i.e., valinol) enantioseparation system based on low energy configurations that were obtained from supercagebased docking simulations.…”

Section: Introductionmentioning

confidence: 99%

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Enantioseparation of phenylglycinol in chiral‐modified zeolite HY: A molecular simulation study

et al. 2007

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A mechanism has been proposed for the separation of valinol enantiomers using a chiral-modified zeolite HY (i.e., zeolite HY containing (+)-(1R;2R)-hydrobenzoin) Molecular modeling of chiral-modified zeolite HY employed in enantioselective separation. Jirapongphan SS, Warzywoda J, Budil DE, Sacco A Jr. Chirality 2007; in press, which accurately predicted the experimentally measured enantioseparation. This methodology has been applied to predict the separation of an enantiomeric pair of phenylglycinol molecules (a precursor in the synthesis of HIV-1 protease inhibitors) using the modified zeolite HY as a CSP. Phenylglycinol and valinol molecules are similar in terms of the presence of polar (i.e., amine and hydroxyl) groups. These functional groups are important in the proposed chiral discrimination. Supercage-based docking simulations yielded an enantioselectivity of 1.3 with (+)-(S)-phenylglycinol molecule better retained in the zeolite. Also, the simulations predicted two binding modes that were the same as those in the valinol system. This suggests that specific structural features (i.e., number and type of polar groups), which generate the hypothesized binding modes, are required in an enantioseparation utilizing the chiral-modified zeolite HY.

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Section: Computational Methodologymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Enantioseparation of phenylglycinol in chiral‐modified zeolite HY: A molecular simulation study

et al. 2007

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“…13 Also, the Compass force field has been successfully applied in simulations of the adsorption of benzene and hydrobenzoin in zeolite HY. 12,14 Periodic boundary conditions were applied on the zeolite unit cell that was examined. The van der Waals interactions were calculated using atom-based summation with a nonbonded cutoff of 12.0 Å (i.e., half of the cubic zeolite HY unit cell), while the Coulombic interactions were calculated using the Ewald summation.…”

Section: Force-field and Molecular Modelsmentioning

confidence: 99%

“…15,16 A representative model for the chiral-modified zeolite HY is illustrated in Figure 1. This model depicts the lowest energy configuration obtained from the supercage-based docking of (R,R)-hydrobenzoin (C 14 12 As shown in Figure 1, a 12-membered ring window of the zeolite frames the central portion of the chiral modifier molecule. Thus, the available space for the enantioseparation in the chiralmodified zeolite HY is located inside the supercages (Fig.…”

Section: Force-field and Molecular Modelsmentioning

confidence: 99%

“…As shown in Figure 1, a chiral modifier molecule (e.g., (+)-(1R;2R)-hydrobenzoin) is physically adsorbed inside the faujasite supercage of zeolite HY. [10][11][12] The role of zeolite matrix is analogous to that of the support material in CSPs. The confined-space supercages are the repeating sphere-like cavities (*12.6 Å in diameter) connected to each other in three dimensions in the zeolite HY structure.…”

Section: Introductionmentioning

confidence: 99%

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Molecular modeling of chiral‐modified zeolite HY employed in enantioselective separation

Jirapongphan¹,

Warzywoda²,

Budil³

et al. 2007

Chirality

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Insight into enantioselective separation utilizing chiral-modified zeolite HY could be useful in designing a chiral stationary phase for resolving pharmaceutical compounds. A model was employed to better understand the enantioseparation of valinol in zeolite HY that contains (+)-(1R;2R)-hydrobenzoin as a chiral modifier. This model incorporates the zeolite support and accounts for the flexible change. Results from grand canonical Monte Carlo and molecular dynamics simulations indicate that the associated diastereomeric complex consists of a single (+)-(1R;2R)-hydrobenzoin and a single valinol molecules located in the zeolite HY supercage. Supercage-based docking simulation predicted an enantioselectivity of 2.6 compared with that of 1.4 measured experimentally. Also, the supercage-based docking simulation demonstrated a single binding motif in the S complex, and two binding motifs in the R complex. The multiple binding modes in the R complex resulted in its lower stability. This is hypothesized to be the origin of the weaker binding between (-)-(R)-valinol and the chiral modifier, and explains why (+)-(R)-valinol is retained more in the chiral-modified zeolite system studied.

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Molecular origin of decreased diffusivity with loading for benzene/HY

Zheng

Zhao

et al. 2016

AIChE Journal

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On the basis of our recently proposed "ideal" and "insertion" adsorption mechanisms of aromatics in HY zeolites, changes in energetic and dynamic properties with loading were investigated through Monte Carlo and molecular dynamic (MD) calculations. Loading-dependent isosteric heat could be divided into three linear ranges. The two inflection points were attributed to adsorbate interactions and inherent adsorption mechanism changes. With regard to the loading dependence of diffusivity, diffusivity decreased faster at high loadings than at low and medium loadings, separated by an inflection point. This result confirmed a two-stage diffusion mechanism based on the distribution of adsorbate from MD simulations which was able to qualitatively predict the further restriction of the mobility. This study provided insights into the modeling of mobility at high loadings on the basis of site-hopping mechanism.

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The role of sorbate in the determination of preferential adsorption sites in zeolite HY: A theoretical study

Cited by 11 publications

References 15 publications

Enantioseparation of phenylglycinol in chiral‐modified zeolite HY: A molecular simulation study

Enantioseparation of phenylglycinol in chiral‐modified zeolite HY: A molecular simulation study

Molecular modeling of chiral‐modified zeolite HY employed in enantioselective separation

Molecular origin of decreased diffusivity with loading for benzene/HY

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