A remarkable solvent effect on the nuclearity of neutral titanium(IV)-based helicate assemblies

Area of Science:

• Coordination Chemistry
• Supramolecular Chemistry
• Materials Science

Background:

• Self-assembly of metal-organic complexes is crucial for developing novel materials.
• Titanium(IV)-based helicates represent a class of compounds with potential applications.
• Understanding solvent effects on complex stability is key for synthesis and application.

Purpose of the Study:

• To synthesize and characterize a neutral circular trinuclear titanium(IV)-based helicate.
• To investigate the stability and transformation of the helicate in different solvents.
• To elucidate the thermodynamic driving forces behind the observed structural changes.

Main Methods:

• Synthesis via reaction of titanium(IV) isopropoxide with a tetraphenolic ligand.
• Characterization using single-crystal X-ray diffraction, NMR spectroscopy (13C CP-MAS, 1H NMR DOSY), and mass spectrometry.
• Thermodynamic analysis using PACHA software to determine enthalpy and entropy changes.

Main Results:

• A neutral circular trinuclear Ti(IV)-based helicate was successfully synthesized and characterized.
• The circular helicate is unstable in dichloromethane, converting to a double-stranded helicate.
• Thermodynamic data indicate the transformation is endothermic, influenced by dichloromethane's high dielectric constant and dipole moment.

Conclusions:

• The solvent properties of dichloromethane destabilize the circular trinuclear helicate.
• The transformation to a double-stranded helicate is entropically driven in dichloromethane.
• Strategies to enhance the stability of the circular helicate can be developed based on solvent choice.