Structural and antibacterial assessment of two distinct dihydroxy biphenyls encapsulated with β-cyclodextrin supramolecular complex.

• The 22-DHBP and 33-DHBP molecules are encapsulated in the β-CD inclusion complex by solvent, kneading and physical mixing method. • The prepared inclusion complexes' optical and structural properties are evaluated by UV, FL, FT-IR, NMR, TGA and SEM studies. • The binding constant value of 22-DHBP is 8.12 × 103 M-1 and 33-DHBP is 3.15 × 103 M-1. • General mechanism of DHBP/β-CD complex against bacteria cells is proposed. • The antibacterial activity of 22-DHBP/β-CD and 33-DHBP/β-CD inclusion complexes are studied. β-Cyclodextrin plays a vital role in biological application because it can enhance the stability and solubility of the guest molecules in the supramolecular inclusion complexes. Moreover, the β-Cyclodextrin inclusion complex has control-releasing behavior and lower toxicity than bare guest molecules. To improve the solubility and stability properties of two structurally different fluorescent guest molecules, namely 2,2′-dihydroxy biphenyl and 3,3′-dihydroxy biphenyls, they involve the β-Cyclodextrin inclusion complex process. Optical measurements clearly described the efficient binding through the changes in the absorbance and emission intensities of guest molecules in the presence of β-Cyclodextrin. The Job's plot from absorbance measurements reveals the 1:1 stochiometric ratio of binding of guests and the β-Cyclodextrin host. The FT-IR spectra of the solid complex show the characteristic stretching and bending vibrations from both the guests and the host molecule. The 1HNMR spectra of the inclusion complex promote downfield shifting of guest molecule protons upon binding with the β-Cyclodextrin host. The solid complex prepared using the solution method exhibits superior antibacterial activity against both gram-positive and gram-negative bacteria compared to the kneading and physical mixing methods. [ABSTRACT FROM AUTHOR]