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Updated: May 24, 2026

Construction and Systematical Symmetric Studies of a Series of Supramolecular Clusters with Binary or Ternary Ammonium Triphenylacetates
Published on: February 15, 2016
Complexation between pillar[5]arenes and a secondary ammonium salt
Chengyou Han1, Guocan Yu, Bo Zheng
1Department of Chemistry, Zhejiang University, Hangzhou 310027, P. R. China.
We formed a [2]pseudorotaxane using n-octylethyl ammonium hexafluorophosphate threaded through 1,4-dimethoxypillar[5]arene. This supramolecular assembly, confirmed by NMR and mass spectrometry, can be reversibly switched off with chloride ions.
Area of Science:
- Supramolecular Chemistry
- Host-Guest Chemistry
- Organic Chemistry
Background:
- Pillar[5]arenes are macrocyclic hosts with tunable cavities.
- Rotaxanes and pseudorotaxanes are mechanically interlocked molecular architectures.
- Controlling molecular recognition and assembly is crucial in supramolecular chemistry.
Purpose of the Study:
- To synthesize and characterize a novel [2]pseudorotaxane complex.
- To investigate the host-guest complexation between 1,4-dimethoxypillar[5]arene and n-octylethyl ammonium hexafluorophosphate.
- To explore the stimuli-responsive behavior of the formed complex.
Main Methods:
- Proton Nuclear Magnetic Resonance (1H NMR) spectroscopy
- Electrospray Ionization Mass Spectrometry (ESI-MS)
- X-ray single crystal analysis
- Binding constant determination in chloroform
Main Results:
- Successful formation of a [2]pseudorotaxane between 1,4-dimethoxypillar[5]arene and n-octylethyl ammonium hexafluorophosphate (G).
- Binding constant for the complexation was determined to be 1.09 (±0.31) × 10^3 M^-1 in chloroform.
- Complexation was confirmed by 1H NMR, ESI-MS, and X-ray crystallography.
- The complexation was found to be reversible and could be switched off by the addition of chloride ions (Cl-).
- Comparative studies with 1,4-bis(n-propoxy)pillar[5]arene were also conducted.
Conclusions:
- 1,4-dimethoxypillar[5]arene effectively forms pseudorotaxane structures with specific ammonium guests.
- The binding affinity and structural integrity of the pseudorotaxane were quantitatively assessed.
- Chloride ions serve as an effective external trigger to disassemble the supramolecular complex.
- This work contributes to the understanding of pillararene-based host-guest chemistry and the design of switchable molecular systems.
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