Robert W. Broach

Synthesis and structure of microporous layered tin(IV) sulfide materials

Synthetic methods have been developed which yield large single crystals and highly crystalline phase-pure microporous layered SnS-n materials. This allows study of the structure–property–function relations of these materials. The tin sulfide layer of the SnS-1 structure type contains hexagonally shaped 24-atom rings which are constituted by six Sn3S4 broken-cube cluster building units, linked together by double bridge Sn(µ-S)2Sn sulfur bonds. The SnS-3 structure type contains elliptically shaped 32-atom rings which are also constructed from six Sn3S4 broken-cube clusters. However, they are linked by double bridge Sn(µ-S)2Sn sulfur bonds as well as tetrahedral edge-bridging Sn(µ-S2SnS2)Sn spacer units. The SnS-1 structure type [A2Sn3S7 ] was obtained in the presence of A+=Et4N+ , DABCOH+ (protonated 1,8-diazabicyclooctane), and a mixed template system of NH4+ /Et4N+ , while the SnS-3 structure type [A2Sn4S9 ] emerged in the presence of A+=Prn4N+ and Bun4N+ . Various SnS-1 and SnS-3 structures are examined and compared in relation to the size/shape of constituent template cations. A particular kind of structure-directing function was observed, that is, larger template molecules create larger void spaces within and between the tin sulfide sheets. Unique framework flexibility was discovered for both structure types. In order to accommodate the size/shape changes of templates, the flexible porous tin(iv) sulfide layers are able to undergo a certain degree of elastic deformation to alter the architecture of void spaces within and between the layers, rather than forming a completely new porous structure type. This is believed to be responsible for the relatively small number of structure types so far discovered for tin(iv) sulfide-based microporous layered materials compared to the myriad of three-dimensional open-framework structure types found for the zeolites and aluminophosphates. The observed differences among the various SnS-1 or SnS-3 structures is significant and has resulted in distinct adsorption behavior towards guest molecules. The TPA-SnS-3 framework is also found to be pressure sensitive. This all bodes well for envisaged chemical sensor applications for this class of porous materials.

Synthesis, characterization and structure of SAPO-56, a member of the ABC double-six-ring family of materials with stacking sequence AABBCCBB

Summary Three small pore (8-ring) structures have been synthesized using N,N,N′,N′-tetramethyl-1,6-hexanediamine (TMHD) as the structure-directing agent, AIPO-17 or SAPO-17 (ERI), MAPSO-34 (CHA) and a new structure, designated SAPO-56. Synthesis conditions and gel composition influence the structure-type formed. SAPO-56 adsorbs oxygen, nitrogen, and normal paraffins but not isoparaffins, and has a pore volume comparable to SAPO-34 (CHA). Synchrotron x-ray powder diffraction, electron diffraction, and MAS-NMR were used in conjunction with model building to solve the structure. The SAPO-56 structure, a member of the ABC six-ring family, contains only D6R units (like CHA and AFT), arranged to give gmelinite cages (GME) and large cages (AFT) previously observed in AIPO-52.

Combinatorial chemistry – The emperor's new clothes?

Considering the increasing pressures and constraints on research and development towards focussed innovation, the prospects of new fast and cost-effective approaches addressing the many challenges faced in more rapidly developing next generation products are expected to be very significant. The application of the new methodologies of combinatorial chemistry to materials discovery and development, though facing special challenges, has now been demonstrated in the hydrothermal synthesis of a series of aluminophosphate materials. Using this approach an extensive study of complex multi-component systems was easily achieved, demonstrating the highly reproducible experimental conditions that allows efficient screening of phase composition based on X-ray diffraction analysis.

The structures of as-synthesized AlPO4-53(A), calcined dehydrated AlPO4-53(B), and AlPO4-53(C), a new phase determined by the FOCUS method

Abstract AlPO 4 -53 was synthesized hydrothermally with methylamine as a structure-directing agent. The structure of as-synthesized AlPO-53(A) was solved using AlPO-EN3 as a starting model. The Rietveld refinement converged ( R P = 0.140) in space group P2 1 2 1 2 1 ( a =10.3212(1) A, b =13.6308(1) A and c =17.4539(1) A) for unit cell composition: Al 24 P 24 O 96 ·8.5CH 3 NH 2 ·14H 2 O. AlPO-53(A) is isotypic with as-synthesized AlPO-EN3, JDF-2, UiO-12-as, and presumably CFSAPO-1(A). The structure of calcined dehydrated AlPO-53(B) was solved by direct methods, and refined to R P =0.084 in Pbca ( a =18.0241(1) A, b =13.9174(1) A and c =9.6554(1) A). The topology of AlPO-53(B), the tetrahedral equivalent of AlPO-EN3, is iso-structural with MCS-1 and UiO-12-500. This topology (structure type code AEN) has two 8-ring channels that intersect to form a 2D system. Heating AlPO 4 -53 to 700°C yields a new condensed phase, AlPO-53(C). The structure of AlPO-53(C) was solved with the FOCUS program and refined to R P =0.124 in C121 with a =16.4440(4) A, b =5.1075(1) A, c =13.4846(4) A, and β =88.259(1)°. AlPO-53(C) has a new topology described as brw nets in the ac plane, linked by single and double zigzag chains, parallel to b . The elliptical 8-ring pores, parallel to b , produce a 1D channel system. The highly distorted 4-, 6-, and 8-rings in AlPO-53(B) become more regular in AlPO-53(C). The thermal transformation of AlPO-53(B) to AlPO-53(C) is illustrated.

UZM-13, UZM-17, UZM-19 and UZM-25: synthesis and structure of new layered precursors and a zeolite discovered via combinatorial chemistry techniques

Abstract A combinatorial chemistry investigation screening the abilities of the diethyldimethylammonium (DEDMA), ethyltrimethylammonium (ETMA), and [Me 3 N(CH 2 ) 4 NMe 3 ] 2+ (diquat-4, DQ-4) cations to form zeolites over a range of conditions was carried out. Each of the templates formed a layered precursor; UZM-13, UZM-17, and UZM-19 forming in the DEDMA, ETMA, and DQ-4 systems, respectively. The layered materials are distinct from, but similar to MCM-47 by XRD. The structure of UZM-13 was solved from powder data and was confirmed to contain MCM-47-like aluminosilicate layers. Calcination of these layered materials led to condensation along the b-axis, forming similar 3-dimensional zeolitic species designated UZM-25. However, the UZM-25 derived from the UZM-13 material was superior in crystallinity and had the only XRD pattern that could be indexed. The structure of UZM-25 was determined to be of the CDO structure type, which contains 2-dimensional intersecting 8-ring pores, from both powder and single crystal data.

Direct methods structure determination from synchrotron powder diffraction data of a new clathrasil, TMA silicate

Abstract The structure of as-synthesized TMA Silicate, an aluminosilicate synthesized with the tetramethyl ammonium (TMA) structure directing agent, was solved using intensities extracted from high-resolution synchrotron powder diffraction data and ab initio direct methods. The trial topology was improved by DLS refinement, and the structure was confirmed by successful Rietveld refinement. The space group is C2/m, and lattice parameters are a = 13.35211(14) A ; b = 13.05531(12) A ; c = 12.53013(13) A ; β = 113.285(1) °. The framework topology of as-synthesized TMA Silicate consists of 4-connected T-atoms in 4-, 5-, 6- and 8-rings. Two types of cages are interconnected by pores no larger than 6-rings. The larger cage is a peanut-shaped 30-hedron [485126108] that is the fundamental polyhedral building unit. The three-dimensional structure results from sharing the 4-, 5- and 6-ring faces between adjoining large cages. The three-dimensional structure also contains a smaller 10-hedron cage [445462]. Both cages have crystallographic 2/m site symmetry. Tetramethyl ammonium cations are located in each lobe of the peanut-shaped cages. Because the largest opening to any cage is through 6-ring pores, which are too small to let the TMA pass, as-synthesized TMA Silicate can be classified as a clathrasil.

Technique integration applied to structure solution: The case of UZM-5. Details of the structure, faulting and templating

Abstract The structure solution of the new zeolite framework UZM-5 is reviewed. It is shown how the structure solution emerges from integration of a number of zeolite characterization techniques such as powder X-ray diffraction, transmission electron microscopy, infrared spectroscopy and McBain adsorption. In addition to the ideal structure, faulting is evident in both powder X-ray diffraction and transmission electron microscopy. Details of the surface structure and faulting on the (001) planes are described.

Structures of the K[superscript +] and NH[subscript 4 superscript +] forms of Linde J

The aluminosilicate zeolite Linde J has a unique topology. The structures of the K{sup +} and NH{sub 4}{sup +} forms of Linde J ([X{sub 2}(H{sub 2}O)][Si{sub 2}Al{sub 2}O{sub 8}] where X = K or NH{sub 4}) are identical except for slight cell size and positional differences due to NH{sub 4}{sup +} being larger than K{sup +} cations. The space group is P2{sub 1}2{sub 1}2{sub 1}. Cell dimensions are: K{sup +} Linde J, a = 9.4577(2) {angstrom}, b = 9.5573(2) {angstrom}, c = 9.9429(2) {angstrom}; NH{sub 4}{sup +} Linde J, a = 9.6324(4) {angstrom}, b = 9.6423(3) {angstrom}, c = 10.0230(3) {angstrom}. Zigzag 8-ring channels intersect giving a 2-D pore system.The aluminosilicate zeolite Linde J has a unique topology. The structures of the K{sup +} and NH{sub 4}{sup +} forms of Linde J ([X{sub 2}(H{sub 2}O)][Si{sub 2}Al{sub 2}O{sub 8}] where X = K or NH{sub 4}) are identical except for slight cell size and positional differences due to NH{sub 4}{sup +} being larger than K{sup +} cations. The space group is P2{sub 1}2{sub 1}2{sub 1}. Cell dimensions are: K{sup +} Linde J, a = 9.4577(2) {angstrom}, b = 9.5573(2) {angstrom}, c = 9.9429(2) {angstrom}; NH{sub 4}{sup +} Linde J, a = 9.6324(4) {angstrom}, b = 9.6423(3) {angstrom}, c = 10.0230(3) {angstrom}. Zigzag 8-ring channels intersect giving a 2-D pore system.

Diffusion pathway for propylene adsorption in AlPO-14 characterized by molecular modeling and in situ synchrotron powder diffraction

Abstract The detailed structures of AlPO-14 in N 2 , propane and propylene were determined under various pressures and temperatures using an in situ reactor and synchrotron radiation. N 2 and propane did not significantly modify the AlPO-14 structure, whereas complex changes were observed on adsorption of propylene. For samples with high propylene loading, the locations of the propylene molecules in the pores were found by difference Fourier analyses and refined by Rietveld methods. Theoretical modeling using the determined structures showed that is the most likely diffusion path for propylene in AlPO-14. The adsorption of propylene appeared to modify the pore openings and retard desorption.

05-P-16 - Synthesis, characterization and structural aspects of novel microporous indium

Publisher Summary This chapter discusses the synthesis, characterization, and structural aspects of a novel family of indium silicate microporous materials, designated InSi-n. The InSi-n phases have been synthesized with 11 novel framework topologies and contain In/Si ratios of 0.25–1. Most InSi-n phases are stable to calcination to at least 500°C and show adsorption behavior that is zeolitic in character. Ion-exchange behavior similar to zeolites has also been observed in InSi-n materials. Preliminary structural details include a crystal structure determination of a new topology with 8-ring channels and high-resolution electron microscopy (HREM) evidence for large pores in the members of the InSi-n family.