Investigation of metal ion detection ability and antibacterial activity of PNHQ/β-CD inclusion complex through experimental and computational approaches for environmental and biological applications

A versatile 4-(2-nitrophenyl)-3,4-dihydro-2H-[1,3]oxazino[5,6-h]quinolin-2-one(PNHQ) heterocyclic compound was synthesized through reflux method. For improving the solubility and stability of PNHQ involving inclusion complex process in β-cyclodextrin as a host and PNHQ as a guest (PNHQ/β–CD). Binding behaviour and DFT calculation of inclusion complexes were carried out by the PM3 Gaussian software. The orientations of β-CD with PNHQ reveal the binding site of the inclusion complex. Further, properties of the inclusion complex were studied using FT-IR, ¹H NMR, 2D ¹H-ROESY NMR, XRD, SEM, and TGA analysis. Then, the binding energy and 1:1 stoichiometry of the inclusion complex were determined with the help of the Benesi-Hildebrand equation. Inclusion complexes provide more beneficial impacts in various applications, including environmental monitoring, biological studies, and industrial processes. Here, fluorescent cation sensors studies on β-CD with PNHQ were conducted which selectively detect Fe²⁺ and Pb²⁺ ions in β-CD aqueous medium. The fluorescent quenching ‘turn off’ CHEQ mechanism has been observed. The sensitivity analysis exhibits a better sensing LOD value for β-CD with PNHQ inclusion complex than PNHQ. This result may be due to the interaction of hydroxy groups in cyclodextrin, with cytotoxicity behaviour of ICs being enhanced, affirming the effective complexation of host and guest molecules. In this work, the antibacterial efficiency of PNHQ/β-CD was evaluated. Moreover, the results suggest that the prepared inclusion complex (PNHQ/β-CD) is a promising material for biological and environmental applications.