Mike S. Dadachov

A mesoporous germanium oxide with crystalline pore walls and its chiral derivative

Microporous oxides are inorganic materials with wide applications in separations, ion exchange and catalysis. In such materials, an important determinant of pore size is the number of M (where M = Si, Ge and so on) atoms in the rings delineating the channels. The important faujasite structure exhibits 12-ring structures while those of zeolites, germanates and other materials can be much larger. Recent attention has focused on mesoporous materials with larger pores of nanometre scale; however, with the exception of an inorganic–organic hybrid, these have amorphous pore walls, limiting many applications. Chiral porous oxides are particularly desirable for enantioselective sorption and catalysis. However, they are very rare in microporous and mesoporous materials. Here we describe a mesoporous germanium oxide, SU-M, with gyroidal channels separated by crystalline walls that lie about the G (gyroid) minimal surface as in the mesoporous MCM-48 (ref. 9). It has the largest primitive cell and lowest framework density of any inorganic material and channels that are defined by 30-rings. One of the two gyroidal channel systems of SU-M can be filled with additional oxide, resulting in a mesoporous crystal (SU-MB) with chiral channels.

Synthesis and structure of (Me3N)6[Ge32O64]·(H2O)4.5, a thermally stable novel zeotype with 3D interconnected 12-ring channels

Abstract A compound with a novel zeotype topology, (Me3N)6[Ge32O64] · (H2O)4.5 (Me3N=trimethylamine), was prepared from an aqueous solution containing germanium dioxide, pyridine, hydrofluoric acid and Dabco (Dabco=1,4-diazabicyclo-[2,2,2]-octane) as a template. Small needle-shaped crystals were obtained. The crystals were studied by scanning electron microscopy, X-ray powder diffraction and thermogravimetric analysis. The structure was determined by single crystal X-ray diffraction to be tetragonal, space group I41/amd, a=25.990(3) A and c=27.271(3) A, and Z=8, V=18420.88(391) A3, R=0.0604 for reflections with I>2σ (I) and wR=0.1696. The three-dimensional framework structure is built up by GeO4 tetrahedra, connected in such way that they form intersecting 12-ring channels along all three crystallographic axes. This is the first germanate zeotype with large intersecting channels. The free diameters of the apertures of the channels are 5.8 by 6.0 A along both the a- and the b-axes and 7.4 A along the c-axis. The porous structure is stable at temperatures sufficient for removing the organic template.

A three-dimensional open-framework germanate containing four-, five- and six-coordinated germanium

A new three-dimensional open-framework germanate, namely ethylenediamine bis(ethylenediammonium) tetrahydroxooctadecaoxononagermanate, (C(2)H(8)N(2))(C(2)H(10)N(2))(2)[Ge(9)O(18)(OH)(4)], has been synthesized hydrothermally and its structure determined by single-crystal X-ray diffraction. The framework is built of [Ge(9)O(22)(OH)(4)] units formed by four-, five- and six-oxygen-coordinated germanium and templated by ethylenediamine. Three types of intersecting channels are formed in the framework, one by eight-membered rings running along the b axis and the other two by ten-membered rings running parallel to the a and c axes, respectively.

Diammonium titanium pentafluoride, (NH4)2TiF5, containing Ti3+

Single crystals of the title compound have been synthesized by low-temperature hydrothermal treatment of titanium isopropoxide in the presence of hydrofluoric acid and ethylenediamine. The compound consists of parallel infinite chains of trans-corner-connected TiF 6 octahedra along the b axis, separated from each other by NH 4 + ions. The Ti atoms lie on inversion centres and the ammonium ions on mirror planes.

Design of three-dimensional open-framework structures from inorganic clusters

Abstract A series of open-framework germanates and silicogermanates were synthesized (denoted as SU-n) hydro-/solvo-thermally. Their structures were built from a single or two types of inorganic clusters containing a number of well-defined Ge-O coordination polyhedra. Different arrangements and combinations of these clusters resulted in different open-framework structures including some germanate/silicogermanates with extra-large pores (16–24 rings). Herein we present our recently discovered crystalline structures of SU-3, SU-8, SU-12, SU-44, SU-M and SU-MB. SU-M and SU-MB contain 30-ring channels and pores extending to the mesoporous range (> 20A).

Crystal structure of dipiperazine decafluorooxodititanate dihydrate, (C4H12N2)2[Ti2F10O)]·2H2O

Two types of novel framework materials, including six organically templated silicogermanates and five hybrid fluorotitanates, have been synthesized, and their structures have been determined by single crystal X-ray diffraction. Their structures and the interactions between the organic and inorganic species are discussed in some detail.The frameworks of the six silicogermanates, SU-9, SU-10, SU-11, SU-12, SU-14 and SU-21, are built up from either tetrahedra exclusively, or from mixed polyhedra. SU-9, SU-10 and SU-11 consist only of tetrahedra, and SU-12, SU-14 and SU-21 are built up from mixed polyhedra. In all silicogermanates, Si and Ge share the tetrahedrally coordinated positions, and only Ge occupies the 5- and 6-coordinated positions.The frameworks of SU-9, SU-10 and SU-11 belong to zeolite frameworks. SU-9 and SU-10 are built up from the same periodic building units (PBUs) that are formed by 4/4-4 units, and they adopt the known zeolite framework types AST and ASV, respectively. SU-11 is built up from 5-1 units and adopts the known zeolite framework type MFI. This is the first time that the frameworks of AST, ASV and MFI have been prepared in silicogermanate form.The 3-D frameworks of SU-12 and SU-14 contain (Ge,Si)7 composite building units that form one-dimensional 24-ring channels along the c axis. Their structures contain intersecting channels. SU-12 contains 8-, 10- 12- and 24-ring channels; while SU-14 has 9-, 10-, 12- and 24-ring channels. SU-21 is a two-dimensional framework structure containing 10-ring channels. It is the first silicogermanate with the template covalently bonded to Ge.All silicogermanates were synthesized by using organic amines as templates. The templates play a very important role in directing the structure of the inorganic framework.The obtained five hybrid fluorotitanates are SUF-1, SUF-2, SUF-3, SUF-4 and SUF-5. Their hybrid frameworks are built up from fluorotitanate anions, N-containing cations and crystal water/oxonium cations. Zero-dimensional fluorotitanate clusters are normally obtained when cyclic organic amines such as 1,4-diazabicyclo[2,2,2]octane (DABCO) and piperazine are used. Increasing the pH value of the starting solutions led to more condensed fluorotitanate anions, from isolated octahedra to pairs and eventually chains of octahedra. The formation of the hybrid frameworks of fluorotitanates is strongly dependent on hydrogen bonds between the fluorotitanate anions, N-containing organic cations and water molecules/oxonium ions.

09-P-12-Layered germanates with 9-membered rings

Publisher Summary This chapter discusses layered germanates with 9-membered rings. Two germanates–– (NH 4 ) 4 [(GeO 2 ) 3 (GeO 1.5 F 3 ) 2 ]·0.67H 2 O and (C 2 N 2 H 10 ) 2 [(GeO 2 ) 3 (BO 2.5 ) 2 ]––are prepared by hydrothermal synthesis. The framework layers are formed by 3- and 9-membered rings in both compounds and the structure topology within the layers is very similar. The 3-membered rings in both compounds are built by three GeO 4 tetrahedra. These 3-rings are connected by the pairs of GeO 3 F 3 octahedra in (NH 4 ) 4 [(GeO 2 ) 3 (GeO 1.5 F 3 ) 2 ]·0.67H 2 O and by the pairs of BO 4 tetrahedra in (C 2 N 2 H 10 ) 2 [(GeO 2 ) 3 (BO 2.5 ) 2 ] in such a way that 9-membered rings are formed. Ammonium cations and water molecules in the former compound and protonated ethylenediamine in the latter compound interrupt the framework layers. The two-dimensional frameworks of germanate and borogermanate are compared with other related structures.

Crystal structure of 1,4-diazabicyclo[2.2.2]octane hexafluorotitanium hydrate, (C6H14N2)[TiF6] · H2O

Two types of novel framework materials, including six organically templated silicogermanates and five hybrid fluorotitanates, have been synthesized, and their structures have been determined by single crystal X-ray diffraction. Their structures and the interactions between the organic and inorganic species are discussed in some detail.The frameworks of the six silicogermanates, SU-9, SU-10, SU-11, SU-12, SU-14 and SU-21, are built up from either tetrahedra exclusively, or from mixed polyhedra. SU-9, SU-10 and SU-11 consist only of tetrahedra, and SU-12, SU-14 and SU-21 are built up from mixed polyhedra. In all silicogermanates, Si and Ge share the tetrahedrally coordinated positions, and only Ge occupies the 5- and 6-coordinated positions.The frameworks of SU-9, SU-10 and SU-11 belong to zeolite frameworks. SU-9 and SU-10 are built up from the same periodic building units (PBUs) that are formed by 4/4-4 units, and they adopt the known zeolite framework types AST and ASV, respectively. SU-11 is built up from 5-1 units and adopts the known zeolite framework type MFI. This is the first time that the frameworks of AST, ASV and MFI have been prepared in silicogermanate form.The 3-D frameworks of SU-12 and SU-14 contain (Ge,Si)7 composite building units that form one-dimensional 24-ring channels along the c axis. Their structures contain intersecting channels. SU-12 contains 8-, 10- 12- and 24-ring channels; while SU-14 has 9-, 10-, 12- and 24-ring channels. SU-21 is a two-dimensional framework structure containing 10-ring channels. It is the first silicogermanate with the template covalently bonded to Ge.All silicogermanates were synthesized by using organic amines as templates. The templates play a very important role in directing the structure of the inorganic framework.The obtained five hybrid fluorotitanates are SUF-1, SUF-2, SUF-3, SUF-4 and SUF-5. Their hybrid frameworks are built up from fluorotitanate anions, N-containing cations and crystal water/oxonium cations. Zero-dimensional fluorotitanate clusters are normally obtained when cyclic organic amines such as 1,4-diazabicyclo[2,2,2]octane (DABCO) and piperazine are used. Increasing the pH value of the starting solutions led to more condensed fluorotitanate anions, from isolated octahedra to pairs and eventually chains of octahedra. The formation of the hybrid frameworks of fluorotitanates is strongly dependent on hydrogen bonds between the fluorotitanate anions, N-containing organic cations and water molecules/oxonium ions.

Crystal structure of dipiperazine decafluorodititanate dihydrate, (C4H12N2)2(Ti2F10] · 2H2O

Two types of novel framework materials, including six organically templated silicogermanates and five hybrid fluorotitanates, have been synthesized, and their structures have been determined by single crystal X-ray diffraction. Their structures and the interactions between the organic and inorganic species are discussed in some detail.The frameworks of the six silicogermanates, SU-9, SU-10, SU-11, SU-12, SU-14 and SU-21, are built up from either tetrahedra exclusively, or from mixed polyhedra. SU-9, SU-10 and SU-11 consist only of tetrahedra, and SU-12, SU-14 and SU-21 are built up from mixed polyhedra. In all silicogermanates, Si and Ge share the tetrahedrally coordinated positions, and only Ge occupies the 5- and 6-coordinated positions.The frameworks of SU-9, SU-10 and SU-11 belong to zeolite frameworks. SU-9 and SU-10 are built up from the same periodic building units (PBUs) that are formed by 4/4-4 units, and they adopt the known zeolite framework types AST and ASV, respectively. SU-11 is built up from 5-1 units and adopts the known zeolite framework type MFI. This is the first time that the frameworks of AST, ASV and MFI have been prepared in silicogermanate form.The 3-D frameworks of SU-12 and SU-14 contain (Ge,Si)7 composite building units that form one-dimensional 24-ring channels along the c axis. Their structures contain intersecting channels. SU-12 contains 8-, 10- 12- and 24-ring channels; while SU-14 has 9-, 10-, 12- and 24-ring channels. SU-21 is a two-dimensional framework structure containing 10-ring channels. It is the first silicogermanate with the template covalently bonded to Ge.All silicogermanates were synthesized by using organic amines as templates. The templates play a very important role in directing the structure of the inorganic framework.The obtained five hybrid fluorotitanates are SUF-1, SUF-2, SUF-3, SUF-4 and SUF-5. Their hybrid frameworks are built up from fluorotitanate anions, N-containing cations and crystal water/oxonium cations. Zero-dimensional fluorotitanate clusters are normally obtained when cyclic organic amines such as 1,4-diazabicyclo[2,2,2]octane (DABCO) and piperazine are used. Increasing the pH value of the starting solutions led to more condensed fluorotitanate anions, from isolated octahedra to pairs and eventually chains of octahedra. The formation of the hybrid frameworks of fluorotitanates is strongly dependent on hydrogen bonds between the fluorotitanate anions, N-containing organic cations and water molecules/oxonium ions.