4,4'-Bipyridine-2-hydroxy-propane-1,2,3-tricarboxylic acid (3/2)

Area of Science:

• Crystal Engineering
• Supramolecular Chemistry
• Materials Science

Background:

• Citric acid (H(3)hypta) is a versatile organic acid.
• 4,4'-bipyridine (4,4'-bipy) is a common bidentate ligand used in coordination chemistry and crystal engineering.

Purpose of the Study:

• To synthesize and characterize a novel molecular cocrystal formed from citric acid and 4,4'-bipyridine.
• To investigate the intermolecular interactions and structural features of the resulting cocrystal.

Main Methods:

• Cocrystallization of citric acid and 4,4'-bipyridine in a 1:1.5 molar ratio.
• Single-crystal X-ray diffraction analysis to determine the crystal structure.
• Analysis of bond distances, intermolecular interactions (π-π stacking, C-H⋯π, hydrogen bonding).

Main Results:

• Formation of the molecular cocrystal 1.5C(10)H(8)N(2)·C(6)H(8)O(7).
• Confirmation of the un-ionized citric acid molecule through C-O bond distance analysis.
• Identification of significant π-π and C-H⋯π stacking interactions between aromatic rings.
• Observation of intermolecular O-H⋯N hydrogen bonds and an intramolecular O-H⋯O hydrogen bond within the citric acid moiety.

Conclusions:

• The study successfully synthesized and characterized a new molecular cocrystal of citric acid and 4,4'-bipyridine.
• The crystal structure is stabilized by a combination of π-π stacking, C-H⋯π interactions, and hydrogen bonding.
• The findings contribute to the understanding of cocrystal formation and supramolecular assembly involving organic acids and N-heterocycles.