Investigation of inclusion complexes of sulfamerazine with α- and β-cyclodextrins: An experimental and theoretical study

• Aniline part of SMRZ included into the CD cavity.
• Different types of inclusion complexes are formed in both α-CD and β-CD.
• SMRZ exhibit biexponential decay in water and triexponential decay in CD solutions.
• SMRZ form a nanochain like agglomerated inclusion complexes with α-CD and β-CD.
• Intermolecular interactions present in the SMRZ/CDs inclusion complexes.

Inclusion complexation behavior and binding ability of sulfamerazine (SMRZ) with α- and β-cyclodextrins (α-CD and β-CD) were investigated. The formation of inclusion complexes are studied by UV–visible, fluorescence, time-resolved fluorescence, 1H NMR, FT-IR, DSC, XRD, SEM, TEM and molecular modeling methods. Both experimental and PM3 results indicated that the SMRZ is partially encapsulated in the CD cavity. The different spectral shifts observed in both the CDs indicate that different types of inclusion complexes are formed. Nanosecond time-resolved fluorescence studies demonstrated that SMRZ exhibit biexponential decay in water and triexponential decay in CD solutions. The resonance of the aromatic protons of SMRZ showed remarkably upfield shift in the complexes suggested that the aniline ring deeply encapsulated in the CD cavity. The amino and amido stretching vibrations at 3483 cm−1 and 3379 cm−1 respectively are strongly affected in the inclusion complexes. DSC curves for the inclusion complexes exhibited a broad endothermic effect from 106.4 °C, 123.8 °C and 234.5 6 °C for α-CD and 118.2 °C and 231.4 °C for β-CD. TEM images of both inclusion complexes are forms a nanochain like agglomerated structures with a width ranging from 40 nm to 100 nm. Thermodynamic parameters and binding affinity of the inclusion complex formation were determined and discussed.

TEM photographs of SMRZ/β-CD inclusion complex.Figure optionsDownload as PowerPoint slide