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Exploring Calixarene-Based Pseudorotaxane Architectures: Threading Ammonium Axles With an Exo-Rim π-Functionalized
Veronica Iuliano1, Paolo Della Sala1, Placido Neri1
1Dipartimento di Chimica e Biologia, Università di Salerno, Salerno, Italy.
Chemistry (Weinheim an Der Bergstrasse, Germany)
|June 23, 2026
Summary
Researchers synthesized a novel calixarene derivative with a deep cavity, enhancing host-guest interactions for molecular machines. This functionalized macrocycle shows improved binding and selectivity, advancing the design of new molecular components.
Area of Science:
- Supramolecular Chemistry
- Organic Synthesis
- Materials Science
Background:
- Calixarenes are versatile macrocyclic hosts with tunable cavities.
- Designing macrocycles with enhanced host-guest interactions is crucial for molecular recognition and self-assembly.
- Functionalization of the calixarene rim can significantly alter binding properties and selectivity.
Purpose of the Study:
- To synthesize and characterize a novel 1,4-π-functionalized calix[6]arene derivative (2).
- To investigate the host-guest complexation behavior of the new derivative with dialkylammonium axles.
- To evaluate the impact of exo-rim π-functionalization on binding affinity, orientational selectivity, and noncovalent interactions.
Main Methods:
- Synthesis and characterization of the calix[6]arene derivative.
- Nuclear Magnetic Resonance (NMR) spectroscopy to confirm pseudorotaxane formation and study binding.
- Density Functional Theory (DFT) and Noncovalent Interaction (NCI) calculations to support experimental findings.
Main Results:
- Successful synthesis of the 1,4-π-functionalized calix[6]arene (2) with an extended and deep aromatic cavity.
- Demonstrated threading of dialkylammonium axles, even with bulky exo-rim groups, forming stable pseudorotaxane complexes.
- Exo-rim π-functionalization was found to influence binding affinity and orientational selectivity.
- Enhanced stability (4.4 times) of pseudorotaxanes formed with the new derivative compared to a tert-butyl functionalized analog.
- Evidence of enhanced C─H···π interactions due to the enlarged cavity of derivative 2, promoting specific host-guest interactions.
Conclusions:
- The novel π-functionalized calix[6]arene (2) effectively forms stable pseudorotaxanes with dialkylammonium guests.
- The extended and deep aromatic cavity of derivative 2 significantly enhances host-guest interactions, particularly C─H···π interactions.
- Exo-rim functionalization plays a key role in modulating binding affinity and selectivity in these supramolecular systems.
- These findings provide valuable insights for the rational design of advanced molecular components and machines.
![Solid-phase Synthesis of [4.4] Spirocyclic Oximes](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2FCDNSource%2Fteasers%2F58508.jpg&w=3840&q=50)
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