Investigation on inter molecular complexation between 4,4′-methylene-bis(N,N-dimethylaniline) and β-cyclodextrin: Preparation and characterization in aqueous medium and solid state

• The 1:1 stoichiometry of inclusion complex was confirmed by Benesi–Hildebrand double reciprocal plots.
• FT-IR, molecular docking studies strongly confirmed the formation of inclusion complex.
• In XRD analysis, reduction in crystallinity of inclusion complex was observed.
• Life time studies show that MBDA exhibit single and bi-exponential decay in water and β-CD respectively.

The purpose of this research was to investigate the inclusion complex formation between 4,4′-methylene-bis(N,N-dimethylaniline) (MBDA) and β-cyclodextrin (β-CD). The inclusion complex of MBDA and β-CD was characterized both in solution and solid state by UV–Visible spectroscopy, fluorescence spectroscopy, Differential Scanning Calorimetry (DSC), Fourier Transform Infra-red spectroscopy (FT-IR), Scanning Electron Microscopy (SEM), Powder X-ray diffractometry (XRD) and Atomic Force Microscopy (AFM). The solid inclusion complex was prepared by co-precipitation method. The 1:1 stoichiometry of inclusion complex and binding constant were determined by Benesi–Hildebrand plot and was confirmed by Jobs continuous variation method. The spectral shifts revealed that only a part of MBDA molecule is entrapped in the β-CD cavity. Nanosecond time resolved fluorescence study revealed that MBDA exhibits single exponential decay in aqueous medium and bi-exponential decay in β-CD medium indicating the formation of 1:1 inclusion complex. The Gibbs free energy change of the complexation process was determined and it was found that the inclusion complexation process was spontaneous. The most probable structure of the inclusion complex of MBDA and β-CD was proposed based on the molecular docking study.

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