Structural transformation of copper coordination complexes accompanied with chiral transformation

Four copper coordination complexes [CuL(CH3OH)](n) (1), [CuL(C2H5OH)](n) (2), [(CuL)center dot 0.5H(2)O](n) (3), and [CuL(H2O)center dot 0.5H(2)O](n) (4) with a tridentate Schiff base ligand (NaHL = sodium (E)-2-((4-fluoro-2-hydroxybenzylidene)amino)acetate) were obtained in different solvents and reaction times. Structural analysis reveals that 1 and 2 are isomorphic 2D honeycomb network coordination polymers, while 3 and 4 are 1D polymers with helical chains and zigzag chains, respectively. Both metal ions and ligands show multiple coordination modes due to the influence of the solvent, resulting in huge differences in the crystal structure. Interestingly, as time passes, achiral 1 and 2 undergo recrystallization and are transformed into the chiral M-helix structure 3. Moreover, 1, 2, and 3 can transform into 4 just by soaking in water. The mechanism of structural transformation as well as the optical and chiral properties were studied based on single-crystal structure analysis. The results indicate that the tridentate Schiff base ligand can provide flexible coordination environments to construct versatile structures and help with structural transformation.

Automated summary

In this study, four copper coordination complexes were synthesized under different solvent and reaction time conditions. The structural analysis revealed that these complexes exhibited diverse crystal structures and chirality properties, and could undergo structural transformations under specific conditions.