Two temperature-induced 1D Cu II chain enantiomeric pairs showing different magnetic properties and nonlinear optical responses.

At different reaction temperatures, using Cu(NO 3 ) 2 ·3H 2 O to react with enantiomerically pure N-donor ligands (L S /L R ), respectively, two pairs of chiral one-dimensional (1D) Cu II chain enantiomers formulated as [Cu(μ 2 -NO 3 )(NO 3 )(L S )] n /[Cu(μ 2 -NO 3 )(NO 3 )(L R )] n (S-1-Cu/R-1-Cu, formed at 40 °C with an NO 3 - group as a sole bridging ligand) and [Cu(μ 2 -L S )(NO 3 ) 2 ] n /[Cu(μ 2 -L R )(NO 3 ) 2 ] n (S-2-Cu/R-2-Cu, formed at 25 °C with L S or L R as a bridging ligand) were prepared, where L S /L R = (+)/(-)-4,5-pinenepyridyl-2-pyrazine. Interestingly, such a disparity in bridging ligands leads not only to their distinct structural features but also to their completely different magnetic couplings together with a large difference in their nonlinear optical responses. S-1-Cu with a 1D helical structure shows weak ferromagnetic coupling between Cu II ions, while S-2-Cu with a 1D stairway-like structure presents weak antiferromagnetic coupling. In particular, they simultaneously possess both second- and third-harmonic generation (SHG and THG) responses in one molecule with large strength differences. More remarkably, S-1-Cu exhibits a very large THG response (162 × α-SiO 2 ), which is 22.5 times that of S-2-Cu, and the SHG strength of S-1-Cu is more than 3 times that of S-2-Cu. This work demonstrates that reaction temperature has a great impact on the self-assembled structures of coordination polymers and subsequently results in their large performance differences.