Mono/bimetallic water-stable lanthanide coordination polymers as luminescent probes for detecting cations, anions and organic solvent molecules

Abstract

Eleven water-stable isostructural mono/bimetallic lanthanide coordination polymers (Ln-CPs) {[Eu_xTb_1−x (HL)(H₂O)₃]·H₂O}_n (x = 1.0 (1), 0.9 (3), 0.8 (4), 0.7 (5), 0.6 (6), 0.4 (7), 0.3 (8), 0.2 (9), 0.1 (10), 0.05 (11), 0 (2), H₄L = 5,5′-(1H-2,3,5-triazole-1,4-diyl)diisophthalic acid) with uncoordinated Lewis basic triazole sites within the pores were prepared. The Ln-CPs represented by 1 showed a rapid and drastic emission quenching induced by external Fe³⁺ and Cr³⁺ cations and CrO₄²⁻ and CO₃²⁻ anions in aqueous solution. In addition, because of the comparable emission intensities of Eu³⁺ and Tb³⁺ ions, bimetallic CP 8 can be used as a ratiometric luminescent sensor for organic solvent molecules. Moreover, the luminescent color of the 8 sensor in pyridine and in other guest solvents undergoes obvious changes that can be clearly distinguished by the naked eye.