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 1 × 10−5 to 1 × 10−1 mol L−1 with a detection limit of 7.2 × 10−6 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 (logKL,DPot) 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.