Efficient Intermolecular Charge Transport in π-Stacked Pyridinium Dimers Using Cucurbit[8]uril Supramolecular Complexes

Single molecule experiments show that π-stacked pyridinium dimers formed by a host-guest ternary complex have comparable charge transport properties to the single pyridinium molecules. Physical and chemical characterization reveals a high binding affinity and compact stacked structures of the host-guest complexes.

Scientific Achievement

In this work, we observe highly efficient intermolecular charge transport between stacked pyridinium dimers inside a synthetic host (cucurbit[8]uril, CB[8]) using single molecule techniques.

Significance and Impact

This work provides a new understanding of intermolecular charge transport in π-stacked dimeric structures with well-defined stacking geometries using supramolecular assembly.

Research Details

  • Extensive physical and chemical characterization shows that different types of pyridinium guest molecules dimerize into the cavity of CB[8] in a head-to-tail geometry with high binding affinity and compact π–π stacked structures.
  • Single-molecule conductance experiments directly show that intermolecular conductance through pyridinium dimers is comparable to the intramolecular conductive pathway.
  • Control experiments with a structural homolog of the host molecule (CB[7]) reveal that the host molecule does not directly participate in charge transport.
  • DFT simulations show that pyridinium molecules undergo planarization upon dimerization inside the host cavity with large electronic coupling, facilitating efficient charge transport.

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DOI: 10.1021/jacs.1c12741

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