Study on inclusion complexation between plant growth regulator 6-benzylaminopurine and β-cyclodextrin: Preparation, characterization and molecular modeling

An inclusion complex between the plant growth regulator 6-benzylaminopurine (6-BA) and β-cyclodextrin (β-CD) was prepared. A 1:1 host–guest stoichiometry was conformed by elemental analysis and Job’s plot. From phase solubility diagram, a calculated apparent stability constant was 259.49 L/mol. The obtained complex was found to significantly improve the water solubility of 6-BA, and there was a 4.1-fold increase in the presence of 12 mmol/L β-CD as compared with the free 6-BA. Thermoanalysis, NMR and IR spectra were applied to characterize the complex. 1H NMR and ROESY results indicated that the benzene ring of 6-BA was included into the β-CD cavity, which was in agreement with the most predominant configuration optimized by molecular modeling.