Turn-on fluorescent sensors based on post-modified Zr-MOF for enantioselective recognition of phenylalanine

Chiral enantiomers, particularly amino acids, frequently display distinct physiological activities and biological functions. Consequently, it is crucial to distinguish their absolute conformations. Herein, a pair of chiral sensors, UiO-L-Pro and UiO-D-Pro, were obtained by immobilizing the chiral center l-proline (L-Pro) and d-proline (D-Pro) into a Zr-based metal−organic framework (MOF) via a condensation reaction. Fluorescence analyses revealed a notable difference in the enhancement of fluorescence intensity between UiO-L-Pro and UiO-D-Pro when treated with l-phenylalanine (L-Phe) or d-phenylalanine (D-Phe), demonstrating enantioselective luminescence properties. Differences based on hydrogen bond interaction give them significant enantioselectivity factors α. The enantioselectivity factors α (α = K_BH(D-Phe)/K_BH(L-Phe)) for UiO-L-Pro and UiO-D-Pro were 4.15 and 0.47, respectively. Thus, the chiral material could be employed to identify different configurations of phenylalanine.