Inorganic Chemistry, Vol.46, No.7, 2637-2644, 2007
Interchain-solvent-induced chirality change of 1D helical chains: From achiral to chiral crystallization
Three helical supramolecular stereoisomers of meso-2, Delta-2, and Delta-3 with the formula of cis-[Ni(f-rac-L)][Ni(CN)(4)] were successfully constructed based on the [Ni(f-rac-L)(2+) and [Ni(CN)(4)](2-) building blocks (L = 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane). In all three supramolecular stereoisomers, cis-[Ni(f-rac-L)](2+) cations are alternately bridged by [Ni(CN)(4)](2-) anions through two cis (in meso-2 and Delta-2) or trans (in Delta-3) cyano groups to form one-dimensional (1D) helical chains of cis-[Ni(f-rac-L)][Ni(CN)(4)]. In meso-2, the right/left-handed chirality of the originally formed chain is transferred oppositely to adjacent chains through the interchain hydrogen-bonding interactions of hexameric water clusters, leading to the formation of meso-2 with a central symmetrical space group, P2(1)/n, in which the 1D helical chains are packed in an alternating right- and left-handed chirality. In Delta-2 and Delta-3, the right/left-handed chirality of the original chain is transferred uniformly to adjacent chains through the zipper-like interchain hydrophobic interactions, resulting in the formation of Delta-2 and Delta-3 with chiral space groups of P2(1)2(1)2(1) and P3(1)21, respectively, in which all of the 1D helical chains are arranged in the same right/left-handed chirality.