Sequential Formation of Heteroternary Cucurbit[10]uril (CB[10]) Complexes

Area of Science:

• Supramolecular Chemistry
• Host-Guest Chemistry
• Macrocyclic Chemistry

Background:

• Verkade custom superbases are highly reactive organic compounds.
• Cucurbiturils (CBs) are macrocyclic hosts known for their ability to encapsulate guest molecules.
• Protonated Verkade superbases present unique challenges and opportunities in host-guest complexation due to their size and charge.

Purpose of the Study:

• To investigate the complexation of trimethyl-azaphosphatrane (AZAP) with cucurbit[10]uril (CB[10]) in an aqueous environment.
• To explore the structural dynamics of the CB[10] host upon guest binding.
• To determine the feasibility of co-encapsulating additional guest molecules within the formed complex.

Main Methods:

• Synthesis and characterization of the host:guest complex.
• Molecular dynamics (MD) simulations to analyze complex structure and dynamics.
• Spectroscopic techniques to confirm co-encapsulation.

Main Results:

• A 1:1 host:guest complex was successfully formed between CB[10] and AZAP in water.
• MD simulations revealed an 8-shaped conformation of CB[10] around AZAP, with partial cavity occupancy.
• The unoccupied space within the CB[10]⋅AZAP complex was utilized for the co-inclusion of planar, monocationic co-guest (CG) molecules.

Conclusions:

• Heteroternary complexes of the type CB[10]⋅AZAP⋅CG can be formed, demonstrating a novel supramolecular assembly.
• The conformational flexibility of CB[10] allows for accommodating bulky guests like AZAP and facilitating co-complexation.
• This work opens new avenues for designing sophisticated supramolecular architectures with tailored functionalities.