Synthesis and chirality control of bulk crystals and nanocrystals: from a right-handed nonpolar chain to a left-handed polar chain.

Both bulk crystals and nanocrystals of two helical complexes, [Cu(μ2-L)(H2O)]n (1) and {[Cu(μ2-L)(H2O)]·2H2O}n (2) (H2L = thiazolidine-2,4-dicarboxylic acid), have been synthesized with the chiralities of right-handedness (1) and left-handedness (2), respectively. 4-Cyanopyridine and poly(vinylpyrrolidone) (PVP) have been applied to control the synthesis of complexes with different helicities in bulk-crystal and nanocrystal forms, respectively. 2 can be irreversibly transformed to 1 under heating. Associated with the conformation changing, the symmetry alters between nonpolar and polar space groups.