Utilization of a Crown Ether/Amine‐Type Rotaxane as a Probe for the Versatile Detection of Anions and Acids by Thin‐Layer Chromatography

Abstract

A crown ether/amine-type [2]rotaxane was synthesized and utilized as a probe for the detection of acids and anions. The addition of acids to the amine-type [2]rotaxane solution generated corresponding crown ether/ammoniumtype [2]rotaxanes, which were purified by silica gel column chromatography as ammonium salts. The isolated yields of the [2]rotaxanes, possessing a variety of anions, depended on the acidity and polarity of the counter anions. The behaviours of the ammonium-type [2]rotaxanes on thin-layer chromatography (TLC) silica gel reflected the properties of the counter anions. The treatment of the amine-type [2]rotaxane with acids afforded the corresponding ammonium-type [2]rotaxanes bearing several different anions. The ammonium-type [2]rotaxanes behaved similarly to the purified [2]rotaxanes on the TLC silica gel. Furthermore, we succeeded in the analysis of anions using mixtures of the amine-type [2]rotaxane and salts in an appropriate solvent. We demonstrated the detection of anions by the combination of TLC and the utilization of the [2]rotaxane probe.

Rhodium‐Catalyzed ON‐OFF Switchable Hydrogenation Using a Molecular Shuttle Based on a [2]Rotaxane with a Phosphine Ligand

“…In a variable‐temperature (VT) NMR study of the neutral [2]Rotaxane‐Phos , a translational movement of DB24C8 along the axle with the DB24C8 predominately located at the benzylaniline site (ca. 94 %) was observed (Figure S9a in the Supporting Information), which is in agreement with the published results [10d] . These observations indicated that the introduction of a phosphine functionality at the terminus of the axle did not affect the supramolecular properties of the [2]rotaxane.…”

“…In addition to the main signals, similar to those of the neutral [2]Rotaxane‐Phos , small single signals around 6.6, 4.6, 4.5, 4.3, and 2.1 ppm characteristic of DB24C8 located at the dibenzylamine site were observed. This observation suggests the existence of a translational isomer (12 %) with DB24C8 located at the dibenzylamine region [10d] . In the 31 P NMR spectra recorded at lower temperatures, the doublet signal remained unchanged (Figure S20 in the Supporting Information), which indicates that the translational isomers were not distinguishable.…”

Dual-stimuli pseudorotaxane switches under kinetic control

“…Finally, no sign of threading is observed for PA3 neither with DB24C8 nor TTFC8 within 14 days. These results are in good agreement with a recent study by Credi et al 19 which also showed the 3,5dimethyl phenyl moiety to be an efficient stopper in DB24C8 containing rotaxanes [37][38][39][40] and identified the 2,6-dimethyl phenyl moiety as kinetically inert to threading of DB24C8. 19 Consequently, out of these candidates we chose PA11 (1-naphthyl) as the most suitable pseudostopper for dualstimuli-induced switching experiments, because threading occurs at time intervals that are conveniently observable by NMR spectroscopy.…”