Various synthesized Pillararene macrocycles were allowed to form complexes with the ionic liquid; 1-Butyl-3-methyl-imidazolium tetrafluoroborate (IL). The pillararenes used in the study were synthesized by the established pioneering method of Ogoshi that involves treatment of 1,4-disubstituted benzenes with paraformaldehyde in the presence of BF3.OEt2. Selected synthesized pillararenes; DMpillararene (4a), DPpillararene (4b), DPGpillararene (4c) were allowed to form complexes with the ionic liquid, and complexations were confirmed by MALDI-TOF, ESI-MS, 1H NMR, and DOSY spectroscopy. ESI-MS reveals highly intense ion peaks that correspond to [pillararene+IL]+ for the complexes of the three pillararenes with the ionic liquid. Changes in characteristic peaks in hosts and guests, as a result of complexation, were studied by 1H NMR. Results obtained suggest a formation of 1 : 1 complexes between the pillararene host and the IL guest. Host-guest interactions in such complexes have also been studied using 1H-1H 2D ROESY NMR spectroscopy. Obtained through-space correlations revealed interactions between certain parts of the pillararene hosts and the ionic liquid. The complexation between the three pillararenes and the IL was studied by molecular dynamics (MD) simulations. The obtained results suggest the insertion of the IL inside the nanocavities of the hosts.
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