Molecularly Imprinted Polymers with Signaling Function Based on the UV–Vis Spectral Change by Diastereoselective Binding Events

Abstract

Abstract Signaling cinchonidine-imprinted polymers were prepared using a polymerizable iron(III) porphyrin and/or methacrylic acid as functional monomer(s), and evaluated by chromatographic tests, Scatchard analysis, and spectroscopic analysis. An imprinted polymer prepared with an equimolar amount of the iron(III) porphyrin monomer to cinchonidine and six equivalents of methacrylic acid gave the strongest binding (Ka = 5.7 × 105 M−1) and highest selectivity (α = 14.6) for cinchonidine against its diastereomer, cinchonine. Thus, it was concluded that the iron(III) porphyrin and methacrylic acid residues worked cooperatively at the imprinted binding site. There is also the added advantage that the porphyrin provides a signaling function proportional to the chiral binding event of cinchonidine. A linear relationship was observed between the UV–vis absorbance of the imprinted polymer and the logarithm of cinchonidine concentrations, indicating that the polymer may be used as a selective cinchonidine sensing material. Moreover, various metalloporphyrins can be used as functionalized monomers in order to prepare functional MIPs for a wide range of target compounds capable of coordination with such metalloporphyrins, even if the target compounds have no characteristic UV–vis absorption or fluorescence.