Chiral Sensing of Eu(III)-Containing Achiral Polymer Complex from Chiral Amino Acids Coordination Induction

摘要

The β-diketonate-based achiral polymer P-1 could be synthesized by the polymerization of 3,7-dibromo-2,8-dimethoxy-5,5-dioctyl-5H-dibenzo[b,d]silole (M1) with (Z)21,3-bis(4-ethynylphenyl)23-hydroxyprop-en-1-one (M2) via typical Sonogashira coupling reaction. The β-diketonate unit in the main chain backbone of P-1 can further coordinate with Eu(TTA)x [TTA~- = 4,4,4-trifluoro-1-(thiophen-2-yl)butane-1,3-dionate anion, X=1, 2, 3] to afford corresponding Eu(III)-containing polymer complexes. The resulting achiral polymer complex P-2 (X=2) can exhibit strong circular dichroism (CD) response toward both N-Boc-L and D-proline enantiomers. The CD signal was preliminarily attributed to coordination induction between chiral N-Boc-proline and the Eu(III) complex moiety. The linear regression analysis of CD sensing shows a good agreement between the magnitude of molar ellipticity and concentration of chiral N-Boc-l or d-proline, which indicates this kind Eu(III)-containing achiral polymer complex can be used as a chiral probe for enantioselective recognition of N-Boc-l or D-proline enantiomers based on Cotton effect of CD spectra.