3,3'-Diazenediyldiphthalic acid dihydrate.

Area of Science:

• Crystallography
• Molecular structure analysis
• Supramolecular chemistry

Background:

• Understanding the precise arrangement of atoms in crystalline solids is crucial for predicting material properties.
• Azo compounds are known for their diverse applications, and their structural characteristics influence their functionality.
• Hydrogen bonding plays a vital role in the self-assembly of molecules and the formation of extended networks.

Purpose of the Study:

• To elucidate the detailed three-dimensional crystal structure of the title compound, C(16)H(10)N(2)O(8)·2H(2)O.
• To analyze the molecular geometry, including the conformation of the azo group and the relative orientation of the benzene rings.
• To investigate the intermolecular interactions, specifically hydrogen bonding, that govern the crystal packing.

Main Methods:

• Single-crystal X-ray diffraction was employed to determine the atomic coordinates and unit cell parameters.
• Crystallographic data were analyzed to identify symmetry elements, bond lengths, bond angles, and torsion angles.
• Intermolecular interactions, such as hydrogen bonds, were characterized using geometric criteria.

Main Results:

• The crystal structure of C(16)H(10)N(2)O(8)·2H(2)O was successfully determined, with the organic molecule situated on a center of symmetry.
• The two benzene rings within the organic molecule are parallel but not coplanar, exhibiting specific N=N-C-C torsion angles of 12.1(5)° and -168.2(3)° around the azo group.
• A three-dimensional network is formed through O-H⋯O hydrogen bonds connecting the organic molecules and water molecules.

Conclusions:

• The study provides a precise structural description of C(16)H(10)N(2)O(8)·2H(2)O at the molecular level.
• The observed non-planar conformation of the benzene rings and the specific torsion angles offer insights into the electronic and steric factors governing the azo group.
• The formation of a 3D hydrogen-bonded network highlights the importance of water molecules in stabilizing the crystal structure and influencing potential solid-state properties.