M(II) effect on encapsulation of guests into a series of ML chiral cages: enantio-recognition.

Self-assembly of M(ClO) (M = Ni, Cu, and Zn) with (1,1',1'',2,2',2'')-(benzenetricarbonyltris(azanediyl))tris(2,3-dihydro-1-indene-2,1-diyl) trinicotinate (,-L) and the corresponding enantiomer (,-L) as a pair of chiral tridentate donors gives rise to the chiral cage pairs [M(,- and ,-L)](ClO). For the two pairs of [(MeCO)(HO)@M(,- and ,-L)](ClO) (M = Ni and Zn), the inner cavity is occupied by both an acetone and a single water molecule, whereas for the copper(II) pair of [MeCO@Cu(,- and ,-L)](ClO) under the same conditions, the cavity is filled by only one acetone molecule. Thus, the encapsulation of guest molecules into the cages during self-assembly shows significant metal(II) ion effects. These chiral cages are effective for the enantio-recognition of chiral ()-2-butanol and ()-2-butanol the shifts of the electrochemical oxidation potentials obtained by the linear sweep voltammetry (LSV) technique, density functional theory (DFT) calculations, and the chiral 2-butanol adsorption in the single-crystal-to-single-crystal (SCSC) mode.