Four super water-stable lanthanide–organic frameworks with active uncoordinated carboxylic and pyridyl groups for selective luminescence sensing of Fe³⁺

Abstract

Four super water-stable isostructural lanthanide-organic frameworks, [Ln(HL)(H2O)2]n·2H2O (1-Ln) (Ln = Eu, Tb, Nd and Sm), have been successfully synthesized under hydrothermal conditions with 3,5-di(2,4-dicarboxylphenyl)pyridine (H4L) and Ln(NO3)3·6H2O. 1-Ln shows a novel 2D layered structure with uncoordinated carboxylic and pyridyl groups pointing to the interior of interlayer channels. The luminescent properties of 1-Eu in the solid state and one steeped in aqueous solution have been measured, which show excellent luminescence and good luminescent stability in water. Next 1-Eu was chosen as a probe for sensing different metal ions. Consequently, 1-Eu exhibits a highly selective response to Fe(3+) through the luminescence quenching effect in aqueous solutions. The probable mechanisms of the quenching effects have been investigated in detail.

A microporous metal–organic framework with open metal sites for selective sensing Fe3+, CrO42- and nitrobenzene

“…The luminescent intensity of 1 is almost completely quenched at a CrO 4 2-concentration of 500 mg/L. Furthermore, a nonlinear correlation for (I 0 -I)/I 0 and the concentration of CrO 4 2-ions was obtained, the S-V curves deviate from the straight line ( Figure 4c-d), and this phenomenon suggests that more than one quenching mechanism appear in the process, including dynamic quenching and static quenching [23]. However, the Stern-Volmer plots for CrO 4 2-are nearly linear at low concentrations (R 2 = 0.9755) with the K sv value of 3.2…”

“…Firstly, to investigate this potential application of 1 for heavy metal ions, 1 were ground and immersed in DMF solutions of M(NO 3 , respectively) for 24 h, and then oscillated for 30 min using ultrasonic waves to form uniform dispersion suspensions. The luminescent intensities of 1 are decreased sharply by Fe 3+ ion, indicating its highly selective sensor [22][23][24][25]. To evaluate the sensing behavior for Fe 3+ of 1, the titration experiments were applied and the results showed that luminescent intensities were gradually weakened by increasing the concentrations of Fe 3+ ions (Figure 2b-d).…”

A Highly Sensitive and Recyclable Ln‐MOF Luminescent Sensor for the Efficient Detection of Fe3+ and CrVI Anions

“…For Cr VI anions, it can be observed that the absorption spectrum of Cr 2 O 7 2− shows extensive overlap with the excitation spectrum of 1 or 2 (Figure S10). Thus, the energy of the excitation light will be strongly absorbed by Cr 2 O 7 2− , reducing the efficiency of energy transfer from the ligand to the lanthanide ions, ultimately leading to luminescence quenching . Therefore, we considered the above mentioned “antenna effect” as the reason for the luminescence quenching for Cr VI anions.…”

A Terbium‐Organic Framework Material for Highly Sensitive Sensing of Fe3+ in Aqueous and Biological Systems: Experimental Studies and Theoretical Analysis

“…Since Liu and co‐workersfirstly reported the lanthanide MOF, Na[EuL(H 2 O) 4 ]⋅2H 2 O for sensing cations, Ln–MOFs have been widely employed for the detection of small molecule or ion in solutions, harmful organic vapor in air, and biomedicine, which have been discussed in several excellent works . Among them, a lot of luminescent Ln–MOFs‐based materials for sensing Fe 3+ have been reported and summarized in Table . So far, however, Ln–MOF probes with the capacity to detect Fe 3+ with ultralow concentration are rare.…”