Spectral Studies on the Supramolecular Assembly of 1H2NA: β-CD Complex and its Analytical Application as Chemosensor for the Selective Sensing of Cr³⁺

Abstract

The supramolecular assembly of 1-hydroxy-2-naphthoic acid (1H2NA) with β-CD has been investigated by UV-visible and fluorescence spectroscopy. The stoichiometry and binding constant of inclusion complex was estimated using the Benesi–Hildebrand plot derived from the excitation and emission spectral data at 303 K. The estimated ΔG indicated that the inclusion is an exergonic and spontaneous process. The mechanism of complexation was investigated and confirmed by FTIR spectroscopy, semiempirical, and molecular docking studies. During the investigation of complexation, significant increase in the fluorescence intensity for the variation of β-CD concentration was observed. Based on this phenomena the chemosensory power of 1H2NA: β-CD complex was investigated thoroughly for various metal ions and we found the emission of complex showed a drastic increase in the intensity for Cr³⁺ and the fluorescence intensity enhanced to >50 out of all the metal ions studied. The order of change of fluorescence intensities found to be, Cr³⁺ > Se⁴⁺ > Ni²⁺ > K⁺ > Th⁴⁺ > Ca²⁺, Ti⁴⁺ > Al³⁺ > Ce⁴⁺ > Mg²⁺ > Ag⁺ > Na⁺ > Fe³⁺. Selectivity and sensitivity analysis showed remarkable selectivity in sensing Cr³⁺ with the LOD of 0.3 × 10⁻⁴ M and LOQ of 0.9 × 10⁻⁴ M.

Key Words:

• 1-hydroxy-2-naphthoic acid
• β-cyclodextrin
• chemosensor
• fluorescence enhancement
• polycyclic aromatic compounds
• trivalent chromium

ACKNOWLEDGMENTS

K. Sivakumar is thankful to the SCSVMV University for the financial support through the University Funded Minor Research Project scheme. We thank the reviewers of this article for their valuable comments which helped to considerably improve the quality of the article.