RESUMO
The self-assembly of NiCl2 with a chiral bidentate ligand pair, (1R,2S)-(+)- and (1S,2R)-(-)-1-(nicotinamido)-2,3-dihydro-1H-inden-2-yl nicotinate (r,s-L and s,r-L) in a mixture of ethanol and dioxane, gives rise to stable crystals consisting of [2Cl@Ni2Cl2(s,r-L)4(H2O)2]·4C4H8O2·EtOH and [2Cl@Ni2Cl2(r,s-L)4(H2O)2]·4C4H8O2·EtOH chiral cages, respectively, with two encapsulated chloride anions in the cavities. The most interesting feature is that the self-assembly of NiCl2 with the mixture of r,s-L and s,r-L (1 : 1-1 : 4) produces crystals of thermodynamically stable achiral cages, [2Cl·2H2O@Ni2Cl2(s,r-L)2(r,s-L)2(H2O)2]·7C4H8O2, in the molar ratio range. Furthermore, the [2Cl@Ni2Cl2(s,r-L)4(H2O)2]·4C4H8O2·EtOH and [2Cl@Ni2Cl2(r,s-L)4(H2O)2]·4C4H8O2·EtOH chiral crystals can recognize the pairs of L-,D-tryptophan and L-,D-cysteine via cyclic voltammetry (CV) signals, in contrast to the [2Cl·2H2O@Ni2Cl2(s,r-L)2(r,s-L)2(H2O)2]·7C4H8O2 achiral crystal.
RESUMO
Self-assembly of CuX2 (X- = BF4-, PF6-, and SbF6-) with a pair of chiral bidentate ligands, (1R,2S)-(+)- and (1S,2R)-(-)-1-(nicotinamido)-2,3-dihydro-1H-inden-2-yl-nicotinate (r,s-L or s,r-L), in a mixture solvent including ethanol in a glass vessel gives rise to SiF62--encapsulated Cu2L4 chiral cage products. The SiF62- anion from the reaction of X- with SiO2 of the glass-vessel surface acts as a cage template or cage bridge. One of the products, [SiF6@Cu2(SiF6)(s,r-L)4]·3CHCl3·4EtOH, is one of the most effective heterogeneous catalysts for the oxidation of 3,5-di-tert-butylcatechol. Furthermore, an l-DOPA/d-DOPA pair is recognizable by the cyclic voltammetry (CV) signals of its combination with chiral cages [SiF6@Cu2(BF4)2(s,r- or r,s-L)4]·4CHCl3·2EtOH pair and [SiF6@Cu2(SiF6)(s,r- or r,s-L)4]·3CHCl3·4EtOH pair.
