Anion-dependent ion-pairing assemblies of triazatriangulenium cation that interferes with stacking structures.

Area of Science:

• Supramolecular Chemistry
• Crystal Engineering
• Organic Synthesis

Background:

• Triazatriangulenium (TATA+) cations are bulky organic ions with potential applications in materials science.
• Understanding the solid-state behavior of ion pairs is crucial for designing functional molecular assemblies.
• The influence of counteranion size on the packing of large organic cations remains an area of active research.

Purpose of the Study:

• To synthesize and characterize ion pairs of a sterically demanding N-(2,6-dimethylphenyl)-substituted triazatriangulenium (TATA+) cation.
• To investigate the solid-state assembly behavior of these TATA+ ion pairs in relation to their counteranions.
• To elucidate the role of counteranion size and shape in directing the supramolecular architecture.

Main Methods:

• Synthesis of TATA+ cation derivatives.
• Preparation of ion pairs with various counteranions (e.g., halides, carboxylates, sulfonates).
• Single-crystal X-ray diffraction analysis to determine solid-state structures.

Main Results:

• Successful synthesis of TATA+ ion pairs with diverse counteranions.
• Single-crystal X-ray analysis revealed distinct ion-pairing assemblies in the solid state.
• No π-stacking interactions were observed between the cationic π-planes.
• The assembly structures were highly dependent on the counteranion: smaller anions occupied positions above the TATA+ plane, while bulkier anions were displaced to interact with adjacent cations.

Conclusions:

• The bulky TATA+ cation forms distinct solid-state ion-pairing assemblies dictated by counteranion characteristics.
• Counteranion size plays a critical role in controlling the supramolecular architecture, preventing π-stacking and influencing cation-anion interactions.
• These findings provide insights into the rational design of supramolecular structures based on sterically hindered organic cations.