Investigation of adsorption mode of a novel group of N-benzylamino(boronphenyl)methylphosphonic acids using SERS

Here, we report a systematic surface-enhanced Raman spectroscopy (SERS) study of the structures of five N-benzylamino(boronphenyl)-methylphosphonic acids: N-benzylamino-(3-boronphenyl)-S-methylphosphonic acid (m-PhS), N-benzylamino-(4-boronphenyl)-S-methylphosphonic acid (p-PhS), N-benzylamino-(2-boronphenyl)-R-methylphosphonic acid (o-PhR), N-benzylamino-(3-boronphenyl)-R-methyl-phosphonic acid (m-PhR), and N-benzylamino-(4-boronphenyl)-R-methylphosphonic acid (p-PhR) adsorbed on nanometer-sized colloidal particles (20–25 nm). For example, we showed that all of these molecules interact with the colloidal surface through a boronophenyl ring, which plane remained vertical on the surface. For p-PhS, a preferential interaction between the PO bond and the colloidal silver surface is observed to be stronger than for the remaining compounds. The P(OH)2 and B(OH)2 fragments take part in the adsorption process. However, the BO bond of p-PhS and p-PhR seemed to be tilted with respect to the silver surface.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► SERS study of five analogs of N-benzylamino(boronphenyl)methylphosphonic acids. ► The effect of the absolute conformation on the molecules’ adsorption mechanism. ► The impact of the constitutional isomerism on the molecules’ adsorption geometry. ► The boronphenyl, CHP, B(OH)2, PO3H2 fragments crucial in the interaction.