Lithium and sodium 3-(3,4-di-hydroxy-phen-yl)propenoate hydrate

Area of Science:

• Coordination Chemistry
• Materials Science
• Crystallography

Background:

• Caffeic acid (3-(3,4-di-hydroxy-phenyl)propenoic acid) is a naturally occurring phenolic compound with diverse biological activities.
• Alkali metal complexes of organic acids are of interest for their structural diversity and potential applications.
• Understanding the coordination behavior of caffeic acid with alkali metals can lead to new functional materials.

Purpose of the Study:

• To synthesize and characterize new coordination polymers of caffeic acid with lithium and sodium.
• To elucidate the crystal structures of the resulting lithium and sodium complexes.
• To investigate the coordination modes and network formation in these metal-organic compounds.

Main Methods:

• Reaction of caffeic acid with lithium hydroxide (LiOH) and sodium hydroxide (NaOH) in aqueous solution.
• Single-crystal X-ray diffraction analysis to determine the crystal structures of the synthesized compounds.
• Analysis of coordination environments, bonding modes, and hydrogen-bonding interactions.

Main Results:

• Formation of poly[aqua-[μ-3-(3,4-di-hydroxy-phen-yl)propenoato]lithium] (1) and poly[aqua-[μ-3-(3,4-di-hydroxy-phen-yl)propenoato]sodium] (2).
• Crystal structure of 1 features a tetrahedral lithium cation and μ3-κ3 coordination of caffeate, forming chain-like structures.
• Crystal structure of 2 shows a seven-coordinate sodium cation, forming linked coordination polyhedra and a tri-periodic network.

Conclusions:

• The reaction of caffeic acid with LiOH and NaOH yields distinct coordination polymer structures.
• Lithium complex (1) forms 1D chains through carboxylate bridging and hydrogen bonding.
• Sodium complex (2) exhibits a more complex 3D network structure due to higher coordination number and bridging modes.