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Five N'-benzylidene-N-methylpyrazine-2-carbohydrazides
Ligia R Gomes1, John Nicolson Low, Ana S M C Rodrigues
1REQUIMTE, Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre 687, P-4169-007 Porto, Portugal.
This study investigates methylated pyrazine-2-carbohydrazides, revealing significant dihedral angles and supramolecular structures formed by hydrogen bonds and π-π stacking. Comparisons highlight differences from nonmethylated analogs.
Area of Science:
- Organic Chemistry
- Crystallography
- Supramolecular Chemistry
Background:
- Pyrazine-2-carbohydrazides are a class of compounds with potential applications in various fields.
- Understanding the structural and intermolecular properties of these compounds is crucial for their development.
Purpose of the Study:
- To synthesize and characterize five novel methylated pyrazine-2-carbohydrazide derivatives.
- To investigate the dihedral angles, supramolecular structures, and intermolecular interactions (hydrogen bonding and π-π stacking) of these compounds.
- To compare the structural features of methylated derivatives with their nonmethylated counterparts.
Main Methods:
- Synthesis of five N'-benzylidene-N-methylpyrazine-2-carbohydrazide derivatives.
- X-ray crystallography to determine the solid-state structures.
- Analysis of dihedral angles between pyrazine and benzene rings.
- Identification of hydrogen bonding and π-π stacking interactions.
Main Results:
- The synthesized compounds exhibited dihedral angles between pyrazine and benzene rings ranging from 55° to 78°.
- Supramolecular structures were predominantly formed by weak C-H···O/N hydrogen bonds, with one compound existing as a hydrate.
- All five compounds displayed π-π stacking interactions.
- Comparison with nonmethylated analogs showed significantly smaller dihedral angles (0-6°).
Conclusions:
- Methylation significantly influences the dihedral angles and overall molecular conformation of pyrazine-2-carbohydrazides.
- The identified hydrogen bonding and π-π stacking interactions play a key role in the self-assembly of these supramolecular structures.
- Structural differences between methylated and nonmethylated compounds provide insights into structure-property relationships.
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