Calix[4]benzocrown-[60]fullerene dyads: synthesis and complexation properties for dyes

Two novel calix[4]benzocrown-[60]fullerene dyads were obtained by refluxing calix[4]benzocrown derivative containing formacyl group with sarcosine or glycine and C-60 in toluene at reflux via 1,3-dipolar cycloaddition of azomethine ylides tied to C60 in the yields of 30 and 28 %, respectively. Their structures and conformations were characterized by UV-Vis, H-1 NMR, ESI-MS, elemental analysis. Their complexation properties for four dyes were studied by liquid-liquid extraction experiments, complexation UV-Vis spectroscopy and complexation ESI-MS spectroscopy. The results of liquid-liquid extraction suggested that they exhibited excellent extraction abilities towards the four test dyes with the extraction percentages fluctuating in the scope of 75-90 %. The complexation UV-Vis spectra showed the 1:1 complexes between hosts and guests in DMSO solution. The association constants were as high as 5.40 x 10(4) - 1.05 x 10(6) M-1. The formation of 1: 1 complex was further confirmed by the complexation ESI-MS spectrum of compound 4a for Neutral red in DMSO solution. These complexation experiments implied that the novel calix[4]benzocrown-[60]fullerene dyads possess excellent complexation abilities for organic dyes.