The synergistic effect of electron lone pairs and aromaticity on the binding affinity towards metal surfaces

Non-covalent binding interactions of organic molecules through their electron lone pairs and aromatic functional groups towards metal surface are understood. Four isoxazole derivatives containing different sequential aromatic groups and lone pair of electrons are designed and synthesized along with cobalt nanoparticles as a representative of metal surface and titrated against each other. Multiple characterization techniques including UV-Vis absorption spectroscopy, fluorescence emission spectroscopy, hydrodynamic size, and zeta potential are used to study binding and results are compared to each other. We are able to differentiate and understand binding interactions of these functionalities towards metal surface, where the binding mechanism is different based on variations in these molecules. The binding ability of lone pair of electrons (1.48 x 10(8)) is slightly stronger than the p-bond electronic cloud of aromatic benzene group (1.46 x 10(8)), however presence of both functionalities tends to enhance the binding more than twice (3.24 x 10(8)), a synergistic effect that is very strongly observed. These results are also verified by DFT calculations. This work will certainly be helpful to design molecules for their specific interaction required for various applications.