L-cysteinium semioxalate

Area of Science:

• Crystallography
• Chemical Physics
• Materials Science

Background:

• Amino acids and their derivatives are fundamental biological molecules with diverse chemical properties.
• Cocrystals and salts of amino acids offer unique structural and functional characteristics.
• Understanding the solid-state structures of L-cysteine salts provides insights into molecular interactions.

Purpose of the Study:

• To elucidate the crystal structure of the salt formed between L-cysteine and oxalic acid.
• To compare the structural features of this salt with related compounds, including pure L-cysteine and other cysteine-oxalate salts.
• To investigate the hydrogen bonding network and conformational properties within the crystal lattice.

Main Methods:

• Single-crystal X-ray diffraction was employed to determine the three-dimensional structure.
• Analysis of hydrogen bonding interactions (O-H...O, N-H...O, S-H...O) was performed.
• Conformational analysis of the L-cysteinium cation and semioxalate anion was conducted.

Main Results:

• The asymmetric unit comprises an L-cysteinium cation and a singly deprotonated semioxalate anion.
• The oxalate anion is non-planar, and the L-cysteinium cation conformation differs from neutral L-cysteine zwitterions.
• A 3D framework structure is formed via hydrogen bonds, with channels along the a-axis accommodating side chains.

Conclusions:

• The L-cysteine-oxalic acid salt exhibits a distinct crystal structure compared to bis(DL-cysteinium) oxalate.
• Hydrogen bonding plays a crucial role in stabilizing the 3D framework, with specific interactions dictating cation arrangement.
• The study highlights the structural diversity achievable in amino acid salts and cocrystals.