Searching Organic Structure Directing Agents for the Synthesis of Specific Zeolitic Structures:  An Experimentally Tested Computational Study

Sastre, Germán; Cantı́n, Ángel; Díaz–Cabañas, María J.; Corma, Avelino

doi:10.1021/cm049912g

Cited by 58 publications

(58 citation statements)

References 32 publications

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“…[81] Latter on, Sastre et al suggested that there may exist direct covalent Ge-F bonds in D4R units, with expansion of the coordination of the involved Ge to 5. [82] The same authors calculated the chemical shifts of fluoride occluded in different configurations of D4R units containing 0, 1, 2 , 3, 4 or 8 Ge atoms (but they did not consider 5, 6 or 7, for undisclosed reasons) and concluded that, due to the displacement of fluoride out of the cage center and towards a corner, the main factor determining the chemical shift of fluoride was the nature of the 4 closest T, i.e., the n number of closest Si and m number of closest Ge, with n + m = 4. [37] Thus, the chemical shift of fluoride increased (values more positive) when the number m of Ge atoms closer to F increased.…”

Section: B Characterizationmentioning

confidence: 99%

The Si–Ge substitutional series in the chiral STW zeolite structure type

et al. 2018

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Section: B Characterizationmentioning

confidence: 99%

The Si–Ge substitutional series in the chiral STW zeolite structure type

et al. 2018

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“…Theoretical computations in recent years have made rapid progress in the accurate calculation of molecular structures, energetics, dynamics, and so forth, which provide deeper understanding of the synthesis processes. [5,[38][39] To further evaluate the role of the hybrid formed by the [bmim] + cation and Morp in the stabilization of the AFI structure, we optimized the ge-…”

Section: Resultsmentioning

confidence: 99%

New Insights into the Role of Amines in the Synthesis of Molecular Sieves in Ionic Liquids

Zhang

Guan

et al. 2009

Chemistry A European J

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A combination of state-of-the art in situ one- and two-dimensional NMR spectroscopy and density functional theory (DFT) calculations have been employed for the first time to investigate the role of amines in the synthesis of aluminophosphate molecular sieves in ionic liquids (ILs). In situ rotating-frame nuclear Overhauser effect spectroscopy (ROESY) was used to demonstrate that the hybrid of imidazolium ionic liquids with organic amines, such as morpholine, connected through a hydrogen bond can be formed in the gel during the crystallization of molecular sieves. By combining the characterizations of the final solid products obtained by using XRD analyses, solid-state NMR spectroscopy, thermogravimetric analysis, and DFT calculation results, it was verified that the hybrid between morpholine and the imidazolium cation in the initial preparation stage can act as the structure-directing agent (SDA) for the synthesis of AFI-structured aluminophosphate molecular sieves. Our findings may suggest a synthesis mechanism of molecular sieves in ionic liquids in which the IL-organic amine hybrid is required in the nucleation step, whereas the crystal growth occurs through the occlusion of ionic liquids in the zeolite channels.

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“…[12][13][14][15]18 The locations of the three monobenzylamines studied inside the AFI channels, known from the computational study, are presented in Figure 10. These three amines locate in very similar ways inside the AFI channels, forming dimers with the saturated ring perpendicular to the channel direction (Figure 10, right).…”

Section: Discussionmentioning

confidence: 99%

Structure-Directing Role of Molecules Containing Benzyl Rings in the Synthesis of a Large-Pore Aluminophosphate Molecular Sieve: An Experimental and Computational Study

et al. 2005

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We describe the synthesis of AlPO-5 and SAPO-5 materials (AFI topology) using five different tertiary amines or quaternary ammonium ions containing one or two benzyl rings as structure-directing agents (SDAs). All of the molecules successfully direct the crystallization of AlPO-5; however, only the most efficient templates are able to crystallize SAPO-5. The observed differences in template efficiency can be rationalized in terms of the interaction energy between these molecules and the AFI framework. In ranking the template molecules, we notice that a well-defined molecular shape enhances the templating ability, but molecules that are too rigid are not able to adapt to the AlPO framework, yielding an inferior templating ability. Results of atomic-level modeling show that templates with one benzyl ring self-assemble in the main AFI channel by forming dimers with the benzyl rings parallel to each other; templates with two benzyl rings assemble instead into longer chains in which the benzyl ring of one molecule faces the ring of the subsequent one. Both mono- and dibenzyl templates show a high space-filling ability in AFI. Kinetic and thermodynamic factors that might affect the structure-directing activity of the molecules are examined.

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Searching Organic Structure Directing Agents for the Synthesis of Specific Zeolitic Structures: An Experimentally Tested Computational Study

Cited by 58 publications

References 32 publications

The Si–Ge substitutional series in the chiral STW zeolite structure type

The Si–Ge substitutional series in the chiral STW zeolite structure type

New Insights into the Role of Amines in the Synthesis of Molecular Sieves in Ionic Liquids

Structure-Directing Role of Molecules Containing Benzyl Rings in the Synthesis of a Large-Pore Aluminophosphate Molecular Sieve: An Experimental and Computational Study

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