Chiral salen Mn(III) complex-based enantioselective potentiometric sensor for L-mandelic acid.

A new enantioselective potentiometric sensor containing chiral salen Mn(III) as the chiral selector was designed for the assay of L-mandelic acid (L-MA). Optimized membrane electrodes displayed linear dynamic range from 1x10(-5) to 1x10(-1) mol L(-1) with a detection limit of 7.2x10(-6) mol L(-1) and a Nernstian response of -58.1+/-0.5 mV decade(-1) towards L-MA within pH range 7.0-10.2. The potentiometric enantioselectivity coefficient (logK(L,D)(Pot)) of this sensor was -4.0, indicating that the chiral salen Mn(III) complex-based electrode exhibited fairly good discrimination toward L-MA over counter isomer D-MA. The mechanism of chiral recognition for L-MA is discussed by using HF/STO-3G calculation method simulation.