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4-Chloro-2-nitro-benzoic acid-pyrazine (2/1).
Kazuma Gotoh1, Hiroyuki Ishida
1Department of Chemistry, Faculty of Science, Okayama University, Okayama 700-8530, Japan.
Acta Crystallographica. Section E, Structure Reports Online
|December 27, 2011
Summary
This study details the crystal structure of a co-crystal formed between 4-chloro-2-nitro-benzoic acid and pyrazine. Hydrogen bonds link these molecules into sheets, revealing specific molecular arrangements and interactions.
Area of Science:
- Crystallography
- Supramolecular Chemistry
- Organic Chemistry
Background:
- Co-crystals are crystalline solids composed of two or more different molecules in a defined stoichiometric ratio.
- Understanding co-crystal structures is crucial for designing materials with tailored physical and chemical properties.
- Hydrogen bonding plays a pivotal role in directing the self-assembly of molecular components in co-crystals.
Purpose of the Study:
- To elucidate the crystal structure of the co-crystal formed by 4-chloro-2-nitro-benzoic acid and pyrazine.
- To investigate the intermolecular interactions, particularly hydrogen bonding, governing the co-crystal assembly.
- To characterize the resulting supramolecular architecture.
Main Methods:
- Single-crystal X-ray diffraction was employed to determine the precise arrangement of molecules in the solid state.
- Analysis of hydrogen bonding networks (O-H···N and C-H···O) was performed.
- Geometric parameters, including dihedral angles and bond distances, were measured.
Main Results:
- The asymmetric unit contains one molecule of 4-chloro-2-nitro-benzoic acid and half a molecule of pyrazine, with pyrazine located on an inversion center.
- The co-crystal components form a 2:1 unit linked by O-H···N and C-H···O hydrogen bonds.
- A dihedral angle of 16.55° (4) was observed between the pyrazine and benzene rings.
- Intermolecular C-H···O hydrogen bonds link these units into a sheet structure parallel to the (040) plane.
- Further C-H···O interactions connect these sheets.
Conclusions:
- The study successfully determined the crystal structure of the 4-chloro-2-nitro-benzoic acid-pyrazine co-crystal.
- The hydrogen bonding network dictates the formation of a layered supramolecular structure.
- The findings provide insights into the rational design of co-crystals with specific structural motifs.
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