Host-guest interaction of rotaxane assembly through selective detection of ferric ion: Insight into hemin sensing and switching with sodium ascorbate

• This rotaxane is selective and sensitive for Fe3+ and Hemin in semi-aq. media.
• The interaction of the synthesized rotaxane towards Hemin is superior to Fe3+ ion.
• Transformation of Hemin into Heme is also probed by their interactions with rotaxane.

A mechanically interlocked host rotaxane was synthesized by incorporation of tetraphenylethylene and phenanthroimidazole units in the axle to exhibit significant emission bands and demonstrate host-guest interactions via its topologically constrained cavity, and thus to induce a significant and selective fluorescence quenching of rotaxane towards ferric ion (Fe3+). The quenching efficiencies of rotaxane with both ferric ion (Fe3+) and bio-molecular Hemin (containing ferric ion) were investigated to compare the sensitivities of rotaxane for ferric ion and bio-molecular Hemin. The present study could probe host-guest interactions of rotaxane with ferric ion (Fe3+) and Hemin as well as monitoring the biological conversion of Hemin to Heme in presence of sodium ascorbate (as a reducing agent), where the reduced non-toxic Heme could be generated from the toxic form of Hemin.

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