Synthesis of chiral SalenZn(II) and its coordination with imidazole derivatives and amino acid ester derivatives

Abstract

A chiral complex, SalenZn(II) (S), was synthesized and characterized. Its coordination with imidazole derivatives and amino acid ester derivatives was studied by UV-vis spectrophotometric titrations and CD spectroscopy. The binding constants decreased in the order K (Im)>K (2-MeIm)>K (2-Et-4-MeIm)>K (N-MeIm) for imidazole derivatives, and K (AlaOMe)>K (PheOMe)>K (ValOMe) for amino acid ester derivatives with the same configuration and K _D >K _L for amino acid esters with different configuration. CD spectra can quantify the strength of SalenZn(II)-ligand interactions, giving results consistent with the magnitudes of the binding constants. Moreover the minimum energy conformations of the adducts were obtained by simulated annealing, and quantum chemical calculations were performed based on those conformations to explain experimental results at the molecular level.

Keywords:

• Chiral SalenZn(II)
• Coordination
• UV-vis spectrum
• CD spectrum
• Quantum chemical calculation

Acknowledgements

This work is supported by the National Nature Science Foundation (Nos. 20271030 and 20303009), the Tianjin Natural Science Foundation (No. 023604011).