The 6-OH group of b-cyclodextrin (b-CD) was modified by triethylene tetramine. The modified host molecule successfully complexes 1,5-naphthalenediamine and 1,8-naphthalenediamine, respectively, in the presence of lanthanide metal ions (Y3+, Yb3+, Nd3+, Sm3+). As a result, eight ternary inclusion complexes (host-guest-metal) were formed, which were characterized via 1H nuclear magnetic resonance (NMR) technique. The chemical shift variations of host and guest molecules were studied. The stoichiometric proportion of host and guest molecules is 2:1 for all the eight complexes. Signal degeneration still exists for the guest molecules after the inclusion, which verifies the symmetrical conformation of the guest molecules inside the cavities of the two host molecules. After the inclusion process, we found that the fluorescent strength of guest molecules was increased in a remarkable degree in this series, meanwhile, the fluorescent strength of 1,5-naphthalenediamine was higher than that of 1,8-naphthalenediamine by 3 to 4 times, which verifies that 1,8-naphthalenediamine coordinates with lanthanide metal ions, however, similar coordination does not occur in the case of 1,5-naphthalenediamine.
Key words: b-Cyclodextrin (b-CD), modification, naphthalenediamine, lanthanide metal, nuclear magnetic resonance (NMR), fluorescence, complexation.
CD, Cyclodextrin; NMR, nuclear magnetic resonance; TSPP, tetrasodium pyrophosphate; DMSO, dimethyl sulfoxide.