Luminescent Coordination Polymer with Conjugated Lewis Acid Sites for the Detection of Organic Amines

Abstract

A stable three-dimensional coordination polymer, [Eu3(bcbp)3(NO3)7(OH)2]n (1) (H2bcbp·2Cl = 1,1′-bis(4-carboxyphenyl)-(4,4′-bipyridinium) dichloride), was prepared by the solvothermal reaction of Eu(NO3)3·6H2O and H2bcbp·2Cl in methanol, which was characterized by infrared spectroscopy, single-crystal X-ray diffraction, powder X-ray diffraction, and thermogravimetric analyses. In the solid state, 1 consists of an unusual trinuclear Eu(III) unit (Eu3(CO2)6(NO3)7(OH), Eu3–SBU), which further connects to six neighboring ones through six bcbp ligands to form a three-dimensional network. As expected, 1 exhibits a strong red-light emission at ambient temperature. Due to the presence of the electron-deficient bipyridinium moiety in the conjugation, this emission is selectively quenched by electron-rich organic amine compounds with high sensitivity and exhibits a prominent visual color change.