Crystal structure and hydrogen-bonding patterns in 5-fluoro-cytosinium picrate

Area of Science:

• Crystallography
• Supramolecular Chemistry
• Materials Science

Background:

• 5-Fluorocytosine (5FC) is a fluorinated analog of the DNA/RNA base cytosine.
• Picrate (PA-) is a common counterion used in crystal engineering.

Purpose of the Study:

• To elucidate the crystal structure of 5-fluorocytosinium picrate.
• To investigate the intermolecular interactions governing the crystal packing.

Main Methods:

• Single-crystal X-ray diffraction analysis.
• Analysis of hydrogen bonding and other non-covalent interactions.

Main Results:

• The crystal structure shows a protonated 5-fluorocytosine (5FC+) cation and a picrate (PA-) anion.
• The 5FC+ and PA- interact via three-center N-H⋯O hydrogen bonds, forming R2^1(6) and R1^2(6) motifs.
• These interactions extend into a 2D sheet structure with additional N-H⋯O and C-H⋯O interactions.
• Weak C-F⋯π interactions are also observed.

Conclusions:

• The crystal packing of 5-fluorocytosinium picrate is dominated by hydrogen bonding.
• The observed interactions lead to the formation of a stable 2D supramolecular architecture.
• The study provides insights into the self-assembly of fluorinated nucleobase analogs.