Surface plasmon resonance spectroscopic chiral discrimination using self-assembled leucine derivative monolayer

Pirkle-type chiral stationary phases (CSPs) showed excellent enantiomeric separation for amino acid derivatives by forming energetically different two transient diastereomeric pi-pi donor-acceptor complexes with two enantiomers. A CSP derived from N-(3,5-dinitrobenzoyl) leucine with a thiol ending group for immobilization on Au was synthesized and self-assembled on Au surface as chiral sensing layer. The monolayer characterized by spectroscopic and microscopic methods such as AFM, FTIR reflection absorption spectroscopy (FTIR-RAS) and cyclic voltammetry (CV). The enantiospecific detection onto CSP of the leucine derivative was studied by surface plasmon resonance (SPR). (S)-CSP SAM showed high chiral differential detection for (S)-analyte in a range of 1.0x10(-9) to 1.0x10(-4) M. In combination with the SPR method, the leucine derivative monolayer provided a reliable and simple experimental platform for enantiospecific detection.