Insights into the Complexity of Weak Intermolecular Interactions Interfering in Host-Guest Systems

Area of Science:

• Supramolecular Chemistry
• Molecular Recognition
• Computational Chemistry

Background:

• Understanding molecular recognition is crucial for designing advanced materials and sensors.
• Heteroditopic hosts offer unique platforms for studying complex binding events.
• Weak intermolecular interactions, like cation-π and anion-π, govern many chemical processes.

Purpose of the Study:

• To investigate the recognition properties of heteroditopic hemicryptophane hosts.
• To probe the complexity of interfering weak intermolecular interactions in host-guest chemistry.
• To understand how chemical modifications influence anion, cation, and neutral pair binding.

Main Methods:

• Nuclear Magnetic Resonance (NMR) experiments were employed to study binding.
• Complete Active Space Self-Consistent Field (CASSCF) and CASPT2 calculations were used for theoretical support.
• Wavefunction calculations were utilized to analyze interaction mechanisms.

Main Results:

• Binding constants for anions were modulated up to 100-fold by varying fluorination sites.
• Subtle chemical modifications reversed the cooperativity in ion-pair recognition.
• Interference between short- and long-range interactions was observed, impacting anion-π interactions in the presence of cations.

Conclusions:

• Heteroditopic hemicryptophane hosts are effective models for studying complex recognition processes.
• Fluorination is a key strategy for tuning binding affinities and cooperativity.
• The interplay of cation-π and anion-π interactions significantly influences molecular recognition outcomes.