Langmuir–Blodgett Film of Amphiphilic 8-Aminoquinoline and its Sensitivity to Copper Ion

ABSTRACT

Two amphiphilic bis-amide tetradenate ligands based on 8-aminoquinoline, N,N′-bis(8-quinolinyl)alkylpropanediamide (H₂A) [alkyl: dodecyl (H₂A¹²) and hexadecyl (H₂A¹⁶)], were synthesized and characterized by Fourier transform infrared (FT-IR) ¹H-Nuclear magnetic resonance (¹H NMR), and Ultraviolet-visible (UV-vis) spectroscopy. H₂A can form stable monolayers. The interactions between the H₂A monolayer and metal ions such as the main group of metallic ions (Mg²⁺, Ca²⁺, Pb²⁺) and transitional metallic ions (Mn²⁺, Co²⁺, Ni²⁺, Cu²⁺, Zn²⁺, Cd²⁺, Hg²⁺, and La³⁺) were investigated. Only the Cu²⁺ ion has special coordination with H₂A monolayers. This coordination has been clearly proved by means of the π-A isotherms, X-ray photoelectron spectroscopy, and UV-vis spectroscopy. The selective copper binder of the Langmuir–Blodgett (LB) film of H₂A may be developed as a sensor of copper ion. H₂A¹⁶ LB film can detect the concentration of Cu(II) ion in the region of 1.0 × 10⁻⁷ ∼ 1.0 × 10⁻⁶ mol dm⁻³.

Keywords:

• 8-aminoquinoline
• copper ion
• Langmuir–Blodgett film
• sensor

ACKNOWLEDGMENTS

This research work was supported by the Natural Science Foundation of China, the Key Project of Natural Science Foundation of Guangdong Province (Grant Nos. 2001C31401 and 013202), and Foundation of State Key Laboratory of Materials Chemisrty and Applications of Peking University of China.