2-[3-(1

Area of Science:

• Crystal Engineering
• Supramolecular Chemistry
• Materials Science

Background:

• 1,3-bis-(benzimidazol-2-yl)propane (L) is a versatile ligand.
• Gallic acid (HGal) is a natural phenolic acid with hydrogen bonding capabilities.
• Co-crystallization is a key strategy in materials design.

Purpose of the Study:

• To synthesize and characterize a novel co-crystal of L and HGal.
• To elucidate the crystal structure and intermolecular interactions.
• To investigate the formation of voids and solvent inclusion within the crystal lattice.

Main Methods:

• Single-crystal X-ray diffraction was employed to determine the molecular and crystal structure.
• Structure refinement included the use of a solvent mask to quantify included solvent molecules.
• Analysis of hydrogen bonding and supramolecular motifs (R and D) was performed.

Main Results:

• A co-crystal with the formula (HL +·Gal-)2·L·(C4H8O2)2.94 was successfully synthesized and characterized.
• The crystal structure consists of a salt [(HL)+(Gal)-] co-crystallized with a molecule of L in a 2:1 ratio.
• Significant void spaces (approx. 28% of unit-cell volume) were observed, containing disordered ethyl acetate solvent molecules.
• The crystal packing is primarily governed by O-H⋯O, N-H⋯O, and O-H⋯N hydrogen bonds.

Conclusions:

• The study successfully determined the crystal structure of a novel co-crystal formed between 1,3-bis-(benzimidazol-2-yl)propane and gallic acid.
• Hydrogen bonding plays a crucial role in organizing the supramolecular architecture, leading to the formation of cylindrical tunnels.
• The presence of significant solvent-filled voids highlights the potential for host-guest chemistry and materials design.