Properties of liquid crystals and Cu²⁺ recognition based on Schiff bases

ABSTRACT

Two series of new Schiff base compounds were synthesized. For Schiff base compounds with a pyridine nitrogen atom in 4-position (7a–e), their supramolecular hydrogen bonding complexes show good liquid crystal properties. However, no liquid crystal property is observed for 8a–e. Results of theoretical calculations demonstrate that it is the intermolecular hydrogen bond of Schiff base compounds (8a–e) that prevents the formation of supramolecular hydrogen bonding. The Schiff base compounds, with terminal alkoxy chains, can recognize Cu²⁺ selectively with a color change. Nevertheless, others cannot recognize Cu²⁺.

Keywords:

• Fluorine
• Schiff base
• liquid crystals
• recognition
• Cu²⁺

Acknowledgments

The authors gratefully acknowledge the support of the Shandong excellent Young Scientist Research Award Fund (Project No. BS2011CL007).