Synthesis,X-ray crystal structure and cation binding properties of a tetrahomodioxacalix[4]arene tetraester

Treatment ofp-t-butyltetrahomodioxacalix4]arene with ethyl bromoacetate yields a tetraester derivative (4) whose crystal and molecular structure have been determined and whose ion binding properties have been assessed by phase transfer and stability constant measurements. Colorless transparent triclinic crystals (obtained from methoxyethanol) C₆₂H₈₄O₁₄,a = 10.347(2),b = 11.583(2),c = 13.448(3) Å, = 72.04(2), = 86.50(2)°, = 81.23(2)°, space group ,Z = 1, MoK radiation = 0.70930 Å. Refinement was carried out using 2221 reflections withI > 1.5(I). The complexation properties resemble those of calix6]arene hexaester (6), although weaker, with a preference for the larger alkali cations. Ca²⁺ and Ba²⁺; though not extracted, are more strongly complexed than alkali cations. Eu³⁺ is better complexed than Na⁺.Supplementary Data relating to this article are deposited with the British Library as Supplementary Publication No. SUP 82106 (22 pages) and at the Cambridge Crystallographic Data Centre, University Chemical Laboratory, Lensfield Road, Cambridge CB2 9EW, U.K.