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Origin of the structure-directing effect resulting in identical topological open-framework materials.

Xin L, Sun H, Xu R, Yan W - Sci Rep (2015)

Bottom Line: By analyzing the possible starting point of crystallization in several "one-structure/multiple-templates" systems and applying the molecular dynamics simulation to such systems, we found that the template-framework binding free energy level or charge transfer (exchange) degree was the key to the structure-directing effect of a template.This discovery explains why the structure-directing effect of a template can be affected by many variables, such as the nature of the source materials, molar composition of the initial reaction mixture (recipe), mineralizers, type of solvent, and heating temperature.In the synthesis of zeolites and related crystalline materials with open-frameworks, the template or organic additive played a topological structure-directing role instead of a structure-directing role.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, College of Chemistry, Jilin University, 2699 Qianjin Street, Changchun 130012, PR China.

ABSTRACT
In the synthesis of zeolites and related crystalline materials with open-frameworks, a single structure is obtained in the presence of many different templates, known as the "one-structure/multiple-templates" phenomenon. However, the reasons behind this phenomenon have yet to be elucidated. By analyzing the possible starting point of crystallization in several "one-structure/multiple-templates" systems and applying the molecular dynamics simulation to such systems, we found that the template-framework binding free energy level or charge transfer (exchange) degree was the key to the structure-directing effect of a template. This discovery explains why the structure-directing effect of a template can be affected by many variables, such as the nature of the source materials, molar composition of the initial reaction mixture (recipe), mineralizers, type of solvent, and heating temperature. In the synthesis of zeolites and related crystalline materials with open-frameworks, the template or organic additive played a topological structure-directing role instead of a structure-directing role.

No MeSH data available.


The repeat units and near non-framework species, as well as the highlighted core units of layered zinc phosphates with a close contact of 3.0 Å.The repeat units were placed in very similar orientations. The structure-directing agents were (a) 3-methylaminopropylamine (Left: above layer; Right: below layer) and (b) N,N’-dimethylethylenediamine (Left: above layer; Right: below layer). Phosphorus, zinc, oxygen, nitrogen, hydrogen, and carbon atoms are labeled with pink, dark cyan, red, blue, white, and grey colors, respectively.
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f2: The repeat units and near non-framework species, as well as the highlighted core units of layered zinc phosphates with a close contact of 3.0 Å.The repeat units were placed in very similar orientations. The structure-directing agents were (a) 3-methylaminopropylamine (Left: above layer; Right: below layer) and (b) N,N’-dimethylethylenediamine (Left: above layer; Right: below layer). Phosphorus, zinc, oxygen, nitrogen, hydrogen, and carbon atoms are labeled with pink, dark cyan, red, blue, white, and grey colors, respectively.

Mentions: Similar to other metal phosphates with open-frameworks, the synthesis of crystalline zinc phosphates with open-frameworks is typically performed in the presence of organic amines. In the presence of 3-methylaminopropylamine and N,N’-dimethylethylenediamine, two zinc phosphates with the same topology were obtained under hydrothermal conditions (Table 1 and Supplementary Table S1). Their repeat units, near non-framework species, and the highlighted core units are shown in Fig. 2. In these layered zinc phosphates, the protonated amines reside in the interlayer region and interact with the layers above and below through H-bonding and other non-bonding interactions. For clarity, the core units of the layers above and below are shown separately. Unlike AlPO4-CHAs and microporous gallophosphates with ULM-3 topology, these layered zinc phosphates crystallize in different space groups, but with similar unit cell parameters. In the core unit of the zinc phosphate directed by 3-methylaminopropylamine, two N atoms have strong H-bonding interaction with the P-centered tetrahedra located in the above layer (Fig. 2(a) left), while only one N atom has strong H-bonding to the P-centered tetrahedron located in the layer below (Fig. 2(a) right). However, in the core unit of another layered zinc phosphate directed by N,N’-dimethylethylenediamine, one N atom has strong H-bonding interaction with the P-centered tetrahedron located in the above layer (Fig. 2(b) left), while another N atom of this amine has the same strong H-bonding interaction with the P-centered tetrahedron located in the layer below (Fig. 2(b) right). Therefore, the core units of these two layered zinc phosphates are different even though they have the same topology (repeat unit). Again, these data suggest that the way amines direct these two zinc phosphates with same topology is distinct, and these amines have the same topological structure-directing ability instead of the same structure-directing ability.


Origin of the structure-directing effect resulting in identical topological open-framework materials.

Xin L, Sun H, Xu R, Yan W - Sci Rep (2015)

The repeat units and near non-framework species, as well as the highlighted core units of layered zinc phosphates with a close contact of 3.0 Å.The repeat units were placed in very similar orientations. The structure-directing agents were (a) 3-methylaminopropylamine (Left: above layer; Right: below layer) and (b) N,N’-dimethylethylenediamine (Left: above layer; Right: below layer). Phosphorus, zinc, oxygen, nitrogen, hydrogen, and carbon atoms are labeled with pink, dark cyan, red, blue, white, and grey colors, respectively.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4597409&req=5

f2: The repeat units and near non-framework species, as well as the highlighted core units of layered zinc phosphates with a close contact of 3.0 Å.The repeat units were placed in very similar orientations. The structure-directing agents were (a) 3-methylaminopropylamine (Left: above layer; Right: below layer) and (b) N,N’-dimethylethylenediamine (Left: above layer; Right: below layer). Phosphorus, zinc, oxygen, nitrogen, hydrogen, and carbon atoms are labeled with pink, dark cyan, red, blue, white, and grey colors, respectively.
Mentions: Similar to other metal phosphates with open-frameworks, the synthesis of crystalline zinc phosphates with open-frameworks is typically performed in the presence of organic amines. In the presence of 3-methylaminopropylamine and N,N’-dimethylethylenediamine, two zinc phosphates with the same topology were obtained under hydrothermal conditions (Table 1 and Supplementary Table S1). Their repeat units, near non-framework species, and the highlighted core units are shown in Fig. 2. In these layered zinc phosphates, the protonated amines reside in the interlayer region and interact with the layers above and below through H-bonding and other non-bonding interactions. For clarity, the core units of the layers above and below are shown separately. Unlike AlPO4-CHAs and microporous gallophosphates with ULM-3 topology, these layered zinc phosphates crystallize in different space groups, but with similar unit cell parameters. In the core unit of the zinc phosphate directed by 3-methylaminopropylamine, two N atoms have strong H-bonding interaction with the P-centered tetrahedra located in the above layer (Fig. 2(a) left), while only one N atom has strong H-bonding to the P-centered tetrahedron located in the layer below (Fig. 2(a) right). However, in the core unit of another layered zinc phosphate directed by N,N’-dimethylethylenediamine, one N atom has strong H-bonding interaction with the P-centered tetrahedron located in the above layer (Fig. 2(b) left), while another N atom of this amine has the same strong H-bonding interaction with the P-centered tetrahedron located in the layer below (Fig. 2(b) right). Therefore, the core units of these two layered zinc phosphates are different even though they have the same topology (repeat unit). Again, these data suggest that the way amines direct these two zinc phosphates with same topology is distinct, and these amines have the same topological structure-directing ability instead of the same structure-directing ability.

Bottom Line: By analyzing the possible starting point of crystallization in several "one-structure/multiple-templates" systems and applying the molecular dynamics simulation to such systems, we found that the template-framework binding free energy level or charge transfer (exchange) degree was the key to the structure-directing effect of a template.This discovery explains why the structure-directing effect of a template can be affected by many variables, such as the nature of the source materials, molar composition of the initial reaction mixture (recipe), mineralizers, type of solvent, and heating temperature.In the synthesis of zeolites and related crystalline materials with open-frameworks, the template or organic additive played a topological structure-directing role instead of a structure-directing role.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, College of Chemistry, Jilin University, 2699 Qianjin Street, Changchun 130012, PR China.

ABSTRACT
In the synthesis of zeolites and related crystalline materials with open-frameworks, a single structure is obtained in the presence of many different templates, known as the "one-structure/multiple-templates" phenomenon. However, the reasons behind this phenomenon have yet to be elucidated. By analyzing the possible starting point of crystallization in several "one-structure/multiple-templates" systems and applying the molecular dynamics simulation to such systems, we found that the template-framework binding free energy level or charge transfer (exchange) degree was the key to the structure-directing effect of a template. This discovery explains why the structure-directing effect of a template can be affected by many variables, such as the nature of the source materials, molar composition of the initial reaction mixture (recipe), mineralizers, type of solvent, and heating temperature. In the synthesis of zeolites and related crystalline materials with open-frameworks, the template or organic additive played a topological structure-directing role instead of a structure-directing role.

No MeSH data available.