Solvent-induced polymorphism in dipodal N-donor ligands containing a biphenyl core

Area of Science:

• Materials Science
• Crystallography
• Supramolecular Chemistry

Background:

• Dipodal N-donor ligands with biphenyl cores are crucial in coordination chemistry.
• Understanding ligand polymorphism is essential for controlling material properties.
• Solvent effects on crystal phase formation are complex and require detailed investigation.

Purpose of the Study:

• To perform polymorph screening for two related biphenyl-based N-donor ligands.
• To isolate and analyze the crystal structures of new polymorphic phases.
• To investigate the influence of solvents on ligand crystallization and phase stability.

Main Methods:

• Powder X-ray diffraction (PXRD) for phase identification and structural analysis.
• Thermal analysis (e.g., DSC, TGA) to study phase transitions.
• Hirshfeld surface analysis and crystal lattice energy calculations to understand intermolecular forces.

Main Results:

• New crystalline phases of the N-donor ligands were isolated and structurally characterized.
• Solvent-induced polymorphism was identified, with specific solvents favoring metastable phases (e.g., THF, EtOH).
• Heating induced transformations from metastable to more stable crystalline forms, monitored by PXRD.

Conclusions:

• The study successfully identified and characterized new polymorphic forms of the investigated ligands.
• Solvent choice significantly impacts the resulting crystal phase, highlighting the importance of crystallization conditions.
• Understanding these polymorphic behaviors is key for designing and synthesizing functional materials based on these ligands.