Structural characterisation of β-cyclodextrin crosslinked by adipic acid

This study was conducted to investigate the structural characterisation of β-cyclodextrin (β-CD) crosslinked by adipic acid. β-CD was treated with different concentrations (0%, 5%, 10% and 15%, w/v) of adipic acid. Different instruments, such as scanning electron microsope (SEM), Fourier-transform infrared (FT-IR) spectroscopy and ¹H and ¹³C nuclear magnetic resonance (NMR) spectra were used to find out chemical structure in the crosslinked β-CD. SEM analysis suggested that crosslinking β-CD with 15% adipic acid changed the original morphology and considerably increased the particle size of the raw material. FT-IR spectroscopy data showed that an intensive absorption band at 1706cm ^-1 was present in the β-CD samples treated with 10% and 15% adipic acid, indicating a crosslinking between hydroxyl groups of β-CD and carboxyl groups of adipic acid. NMR spectra revealed that the ester linkages between hydroxyl groups of β-CD and carboxyl groups of adipic acid were formed after crosslinking of β-CD with adipic acid.