Synthesis, spectral properties of cyanine dyes-β-cyclodextrin and their application as the supramolecular host with spectroscopic probe

Six new cyanine dye functionalised β-cyclodextrins were designed and synthesized to improve the drawback of the inadequate chromophore in β-cyclodextrin and to be suitable for the study of supramolecular interactions directly by visible spectroscopy. The dye structures were confirmed by 1H NMR, IR, UV–Vis and HRMS. The UV–Vis spectra of the new cyanine dyes in different solvents were investigated. The inclusion behaviour of a quinocyanine derived β-cyclodextrin dye which was used as the supramolecular host with 1-adamantanol or vitamin B6 was investigated. The results indicated that the stoichiometry for the inclusion complex of the quinocyanine derived β-cyclodextrin dye and both 1-adamantanol and vitamin B6 was 1:1, and their inclusion constants were 9.39 × 104 L/mol and 6.14 × 102 L/mol, respectively. The quinocyanine derived β-cyclodextrin dye was also used as the supramolecular host for the analysis of vitamin B6 in tablets with satisfactory results.

► β-cyclodextrin was modified with six cyanine dyes.
► λmax of dyes-β-cyclodextrin appeared in the range of 433–485 nm in different solvents.
►  The inclusion behaviour of dye-β-cyclodextrin with 1-adamantanol or vitamin B6 was studied.
► The results showed dye-β-cyclodextrin and 1-adamantanol could form inclusion complex (1:1).
► The dye-β-cyclodextrin could be applied to analyse vitamin B6 in tablets.