Two Novel Lanthanide Metal–Organic Frameworks: Selective Luminescent Sensing for Nitrobenzene, Cu²⁺, and MnO₄^–

Abstract

Two novel lanthanide metal–organic frameworks (Ln-MOFs), formulated as {[Ln2(L2)2(H2O)5]·3H2O} n (Nd 1 and Eu 2) has been acquired under hydrothermal conditions, in which H3L2 ligand was derived from in situ decarboxylation reaction of H4L1 ligand (H3L2 = 5-(3′,5′-dicarboxylphenyl)­picolinic acid, H4L1 = 3-(3′,5′-dicarboxyphenyl)­pyridine-2,6-dicarboxylic acid). Both compounds possess (3,4,7)-connected 3,4,7T22 topology with a schläfli symbol of {43}­{45·6}­{48·69·84}. Compound 2 displays excellent luminescence properties and exhibits good stability in water and other common organic solvents. In particular, 2 can detect Cu2+ ion, MnO4 – anion, and nitrobenzene with a high sensitivity and selectivity through the fluorescence quenching effect. Thus, 2 can be dressed up as a prospective luminescent sensor for detecting Cu2+, MnO4 –, and nitrobenzene.

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

“…The experimental results show that the fluorescence intensity gradually decreased with the increase of concentration of copper(II) ion, and the degree of quenching was significant until the addition quantity is more than 100 μL, as seen in Figure 5. Based on the Stern-Volmer (SV) equation [8]: I 0 /I = 1 + K sv [C], we can obtain quenching constant K sv = 1.18 × 10 2 M À 1 which is in the range of valid values (K sv = 10 2~1 0 3 M À 1 ). I 0 and I represent fluorescence intensity of solutions without and with added Cu 2 + ion, respectively.…”

“…The mechanism of fluorescence quenching has been studied and discussed in many literatures. [5,8,[23][24][25] Hereby, the fluorescence quenching of CP after the addition of metal ions may be caused by the following factors: firstly, whether the structure of the substrate changes after the addition of the tested analyte. In this case, that has been ruled out (Figure S2).…”

“…After the sample of 1 was immersed in aqueous solution of Cu(NO 3 ) 2 for 24 hours, the test result of PXRD showed that the structure of the compound 1 was not damaged (see Supporting Information Figure S2). The mechanism of fluorescence quenching has been studied and discussed in many literatures [5, 8, 23–25] . Hereby, the fluorescence quenching of CP after the addition of metal ions may be caused by the following factors: firstly, whether the structure of the substrate changes after the addition of the tested analyte.…”

“…A novel lanthanide coordination polymer, {[Eu 2 (L) 2 (H 2 O) 5 ] ⋅ 3H 2 O} n (H 3 L=5‐(3′,5′‐dicarboxylphenyl)picolinic acid), designed by Z. Sun et al., which is highly sensitive to selective recognition of Cu 2+ and nitrobenzene by varying fluorescent effect [8] . Although fluorescent sensors have been reported for the identification of copper ions, [9,10] there are not many studies on the detection of copper ion using metal multicarboxylate coordination polymer (CP) modified by the N‐heterocyclic and phenyl groups as fluorescent sensor.…”

Triazine Based MOFs with Abundant N Sites for Selective Nitrobenzene Detection

“…The material is used for the adsorption of CO 2 and cationic dyes. And many interesting crystalline porous materials have yet to be synthesized and explored, [11][12][13] especially in the field of luminescent detection.…”