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

Abstract

A novel barium(II) coordination polymer (CP), [Ba 3 (L) 2 (H 2 O) 4 ] n 1, has been firstly isolated based on organic ligand 1- [(2'carboxybiphenyl-4-yl)methyl]-2-propylimidazole-4,5-dicarboxylic acid (H 3 L=(HO 2 C) 2 (C 3 N 2 )(C 3 H 7 )CH 2 (C 6 H 4 )(C 6 H 3 )CO 2 H) 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 L 3À gives a variety of coordinated styles, nonadentate: μ 2 :(η 1 η 1 ), μ 2 :(η 1 η 1 ), μ 3 :(η 2 η 2 ) and decadentate: μ 1 :(η 1 η 1 ), μ 3 :(η 2 η 2 ), μ 3 :(η 1 η 2 ), μ 3 :(η 1 η 2 ), 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 K sv = 1.18 × 10 2 M À 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 À 65 .3 × 10 À 6 mol • L À 1 . The corresponding linear equation: y = 402.41897-0.70486x, and linear correlation coefficient: R 2 = 0.99866 (λ ex = 310 nm and λ em = 412 nm).