Bis(DL-cysteinium) oxalate

Area of Science:

• Crystallography
• Structural Chemistry
• Biochemistry

Background:

• Cysteine is a crucial amino acid involved in various biological processes.
• Understanding the solid-state structure of cysteine derivatives provides insights into molecular interactions and conformations.
• Oxalate is a common metabolite and can form salts with biological molecules.

Purpose of the Study:

• To elucidate the crystal structure of the 2:1 cysteine-oxalate compound.
• To investigate the hydrogen bonding network and intermolecular interactions within the crystal.
• To compare the conformation of cysteine in this salt with theoretical calculations and other crystalline forms.

Main Methods:

• Single-crystal X-ray diffraction analysis was employed to determine the crystal structure.
• Hydrogen bond analysis was performed to identify and characterize O-H...O, N-H...O, and S-H...O interactions.
• Conformational analysis was conducted and compared with theoretical data.

Main Results:

• The crystal structure of 2C3H8NO2S+.C2O4(2-) was determined, showing a 2:1 stoichiometry of cysteine to oxalate.
• A triple-layer structure was observed, with an oxalate layer sandwiched between L- and D-cysteine layers, connected by extensive hydrogen bonds.
• Short S...S contacts were identified, forming S-H...O intermolecular hydrogen bonds, and the cysteine cation conformation differed from theoretical predictions.

Conclusions:

• The crystal packing and hydrogen bonding significantly influence the conformation of the cysteine cation.
• The study reveals a novel arrangement of chiral cysteine molecules with oxalate, highlighting the role of intermolecular forces in dictating solid-state structures.
• This work provides valuable structural data for cysteine-oxalate interactions and their conformational consequences.