Preparation and structure of [iiii] tetraphosphonatocavitands bearing long chain functionality at the lower rim: Metal picrates extraction studies

The stereoselective synthesis of the iiii stereoisomer of novel tetraphosphonato-cavitands derived from resorc [4]arene is reported. o-Nitrophenyl-n-octyl ether and n-undecyl-n-decanyl thioether functionalities were introduced in the lower rim of 1 and 2, respectively, to develop new molecular devices. The crystal structure of the solvated cavitand 1.6CH(3)CN was elucidated by X-ray crystallography. C104H104O24N4P4.6CH(3)CN crystallizes in the monoclinic space group P2(1)/c, a = 20.574(4), b = 16.591(4), c = 33.973(7) Angstrom, beta = 92.09(2)degrees, V = 11589(4) Angstrom(3), Z = 4, R = 0.065. The host molecule has the iiii configuration with the four P=O bonds oriented towards the molecular cavity. The affinity of molecules 1 and 2 for metal cations was investigated by the liquid-liquid extraction method: among the investigated metal picrates, Ag+, Ba2+ and Eu3+ were the best-extracted cations.