Novel Calixarene Benzo-15-crown-5 Derivatives: Synthesis and Complexation for Dyes

Three novel calix[4]arene, thiacalix[4]arene and calix[6]arene crown ether derivatives 6, 7 and 8 with integral crown ether rings were designed and synthesized in ideal yields by multiple procedures. The liquid-liquid extraction experiment showed that they possessed excellent extraction abilities towards three cationic and one anionic dyes [Orange I (OI), Methylene blue (MB), Neutral red (NR), Brilliant green (BG)]. The highest extraction percentage of compound 8 for Neutral red was 88.2%. Their complexation UV-Vis spectra with four dyes indicated 1:1 complexes between host and guest in DMSO solution. The complexation results and IR spectra suggested the crown ether ring, the bridging functional groups, and the cavity of calixarene unit participated in the complexation for dyes. The larger calixarene cavity was favorable for binding dyes. The association constant of compound 8 with BG was as high as 6.4×105 M−1.