A third monoclinic polymorph of 3,4,5-trihy-droxy-benzoic acid monohydrate

Area of Science:

• Crystallography
• Materials Science
• Chemical Polymorphism

Background:

• Gallic acid monohydrate exists in multiple crystalline forms (polymorphs).
• Previous studies by Jiang et al. (2000) and Okabe et al. (2001) reported known polymorphs.
• Understanding polymorphism is crucial for material properties and applications.

Purpose of the Study:

• To characterize a newly identified polymorph of gallic acid monohydrate.
• To elucidate the crystal structure and hydrogen bonding network of this new form.
• To compare the structural features with previously reported gallic acid monohydrate polymorphs.

Main Methods:

• Single-crystal X-ray diffraction was used to determine the crystal structure.
• Analysis of molecular geometry, including planarity of the gallic acid molecule.
• Identification and analysis of intra- and inter-molecular hydrogen bonding interactions.

Main Results:

• A new polymorph of gallic acid monohydrate (C(7)H(6)O(5)·H(2)O) was successfully synthesized and characterized.
• The gallic acid molecule within this new polymorph is essentially planar.
• A distinct hydrogen bonding pattern, involving intra-molecular and inter-molecular O-H⋯O bonds, was observed and differs from prior polymorphs.

Conclusions:

• The discovery of a new polymorph expands the known structural diversity of gallic acid monohydrate.
• The unique hydrogen bonding network in this new form may influence its physical and chemical properties.
• Further investigation into the properties and formation of different gallic acid polymorphs is warranted.