Understanding behaviour of vitamin-C guest binding with the cucurbit[6]uril host

Abstract

The present study describes non-covalent interaction and complexation behaviour of sodium ascorbate (SA) with cucurbit[6]uril (CB[6]) at neutral pH in aqueous Na₂SO₄ solution. The interaction behaviour is investigated using various analytical techniques like NMR, UV–Vis, fluorescence, TGA and DRS. The substantial increase in the intensity of emission and absorption spectra of sodium ascorbate is observed. The Benesi–Hildebrand evaluation method is used to determine the stoichiometry and equilibrium constant of the cucurbit[6]uril–sodium ascorbate complex, which suggested the 1:1 complex. Time-dependent ¹H NMR, ¹³C CP MAS and CD studies also echoed non-covalent interaction between SA with CB[6].

Keywords:

• Sodium ascorbate
• cucurbit[6]uril
• 1:1 inclusion complex
• NMR studies

Acknowledgements

We would like to thank Indian Institute of Technology Jodhpur, India for the infrastructure and RKS is thankful to SERB for research grant SR/FT/CS-144/2011. PRS gratefully acknowledge DST Women Scientists Scheme-A (WOS-A)for the project SR/WOS-A/CS-91/2013. The authors acknowledge Dr Ritu Gupta for reading the manuscript.