Synthesis and structure of a new fluorescent sensor based on Ba(II)‐multicarboxylate for detection of Cu2+ ion

Abstract

AbstractA novel barium(II) coordination polymer (CP), [Ba3(L)2(H2O)4]n 1, has been firstly isolated based on organic ligand 1‐[(2′‐carboxybiphenyl‐4‐yl)methyl]‐2‐propylimidazole‐4,5‐dicarboxylic acid (H3L=(HO2C)2(C3N2)(C3H7)CH2(C6H4)(C6H3)CO2H) by hydrothermal technique, and determined by single‐crystal X‐ray diffractions, elemental analysis, IR, powder X‐ray diffractions (PXRD). The Ba(II)‐CP 1 belongs to a novel 2‐D layer structure created from 1‐D serrated chain containing secondary building unit (SBU) [Ba(1)Ba(2)Ba(3)] via carboxylate group linkage. In 1, the ligand L3− gives a variety of coordinated styles, nonadentate: μ2:(η1η1), μ2:(η1η1), μ3:(η2η2) and decadentate: μ1:(η1η1), μ3:(η2η2), μ3:(η1η2), μ3:(η1η2), which is the first reported example. Moreover, the room‐temperature fluorescent measurements show that the Ba(II)‐CP 1 has specific ability to recognize copper(II) ion in aqueous solution by means of fluorescence quenching effect, corresponding obtained quenching constant Ksv=1.18×102 M−1 and the limit of detection LOD=0.274 μM. Fluorescence titration experiment reveals that there is a good linear relationship between copper ion concentration and fluorescence intensity in the concentration range of 2.0×10−6∼5.3×10−6 mol ⋅ L−1. The corresponding linear equation: y=402.41897–0.70486x, and linear correlation coefficient: R2=0.99866 (λex=310 nm and λem=412 nm).