Spectral investigation and characterization of host–guest inclusion complex of 4,4′-methylene-bis(2-chloroaniline) with beta-cyclodextrin

Abstract

The host–guest inclusion complex of 4,4′-methylene-bis(2-chloroaniline) (MBCA) with beta-cyclodextrin (β-CD) was prepared by co-precipitation method and characterized using absorption, fluorescence, fourier transform infrared, differential scanning calorimetry, scanning electron microscopy, atomic force microscopy and X-ray diffraction. The spectral shifts revealed that the aniline ring of 4,4′-methylene-bis(2-chloroaniline) was entrapped in the beta-cyclodextrin cavity. Nano second time resolved fluorescence studies revealed that 4,4′-methylene-bis(2-chloroaniline) exhibits single exponential decay in aqueous medium and bi-exponential in beta-cyclodextrin medium confirmed the formation of 1:1 inclusion complex. The Gibbs free energy change of the complexation process was determined and the complexation process was spontaneous. The differential scanning calorimetry analysis showed that the thermal stability of 4,4′-methylene-bis(2-chloroaniline) was altered in the presence of beta-cyclodextrin. The implementation of molecular docking test confirmed that the complexation could reduce the energy of the system. A mechanism was proposed to explain the mode of inclusion in the inclusion process.