Self-assembly and Langmuir–Blodgett (LB) film of a novel hydrogen-bonded complex: a surface enhanced Raman scattering (SERS) study

Hydrogen-bonded complexes composed of a 1,2-bis(4-pyridyl)ethylene and two fatty acids were employed for the fabrication of organized monolayers. Surface enhanced Raman scattering (SERS) spectra demonstrated that monolayer Langmuir–Blodgett (LB) film could be directly obtained at surface pressure 5 mN m−1 by depositing the complex with one of its hexadecoic acid molecules lost due to decomposition of hydrogen bond. For the self-assembled monolayer, SERS spectra indicated that during self-assembling process, only one part of the complex was adsorbed on silver substrate, just similar to that occurring at air/water interface due to the same reason. Increasing the molar ratio of the hexadecoic acid to the mole of 1,2-bis(4-pyridyl)ethylene in the complex solution up to 16-fold, we successfully prepared a monolayer of the complex without decomposition. Under this condition the 1,2-bis(4-pyridyl)-ethylene was inferred to adopt the adsorption flat on the substrate.