Construction of three high-dimensional supramolecular networks from temperature-driven conformational isomers

Under different temperatures, the reaction mixture of the multidentate organic ligand usy-L-4 and Zn(NO3)(2) + NaN3 crystallized to give three conformational isomers, namely Zn(usy-L-4)(eta(1)-N-3)(2)(alpha-1, beta-2 and gamma-3) (usy-L-4 = N,N-dimethyl-2-(pyridin-2-ylmethylimino) ethanamine). Single-crystal X-ray diffraction analyses reveal that the conformational isomerism of three compounds 1-3 stems from the different orientations of two azide groups with eta(1)-terminal nitrogen atom coordinating to central zinc ion in reference to the basal chelating plane of ligand usy-L-4, and further resulting in different supramolecular networks with two-dimensional 4(4) rhombic-grid for alpha-1, a three-dimensional 3(6)center dot 4(18)center dot 5(3)center dot 6 compressed-NbO framework for beta-2, and a three-dimensional "dense" 4(24)center dot 6(4) topology for gamma-3. Meanwhile, three isomers may be also irreversibly converted from 1 to 2, to 3 through SC-to-SC transformation driven by temperature.