Deschenaux, Robert

1996, Di Blasio, Benedetto, Galdiero, Stefania, Saviano, Michele, De Simone, Giuseppina, Benedetti, Ettore, Pedone, Carlo, Gibbons, William A., Deschenaux, Robert, Rizzarelli, Enrico, Vecchio, Graziella

The synthesis and crystal structure of the title ?-cyclodextrin (?-CD) are reported. It crystallizes in the orthorhombic space group P212121 [a 17.250(9), b 19.45(1), c 23.24(1) Å, dcalc 1.304 g/cm3, Z 4]. The structure was refined to final indexes R1 = 0.083 and wR2 = 0.24 for the 4843 obsd. reflections with I ? 2?(I). At the end of the refinement the presence of 12 H2O mols. per ?-CD mol. distributed over 16 sites was detected. In the solid state the monofunctionalized ?-CD shows a "sleeping swan"-like shape with the covalently bound (Boc-aminoethyl)imidazolyl moiety forming a folded structure with its terminal part inserted inside the hydrophobic cavity of the ?-CD ring. The ?-CD macrocycle presents only small differences with respect to the conformation obsd. in hydrated uncomplexed or methylated ?-CDs. The macrocycle structure maintains an approx. 7-fold symmetry. The substituted ?-CD mols. pack in layers parallel to the bc plane. The layers are stacked in an head-to-tail arrangement of the monomeric units, with formation of columns of mols. along the a axis. The layers are connected to each other by H-bonds through H2O mols. Channels generated in the crystal by the packing of the macrocycles are filled with H2O mols. [on SciFinder(R)]