Ultrasound-Assisted Synthesis of Luminescent Micro- and Nanocrystalline Eu-Based MOFs as Luminescent Probes for Heavy Metal Ions

Abstract

The luminescent coarse-, micro- and nanocrystalline europium(III) terephthalate tetrahydrate (Eu2bdc3‧4H2O) metal-organic frameworks were synthesized by the ultrasound-assisted wet-chemical method. Electron micrographs show that the europium(III) terephthalate microparticles are 7 μm long leaf-like plates. According to the dynamic light scattering technique, the average size of the Eu2bdc3‧4H2O nanoparticles is equal to about 8 ± 2 nm. Thereby, the reported Eu2bdc3‧4H2O nanoparticles are the smallest nanosized rare-earth-based MOF crystals, to the best of our knowledge. The synthesized materials demonstrate red emission due to the 5D0–7FJ transitions of Eu3+ upon 250 nm excitation into 1ππ* state of the terephthalate ion. Size reduction results in broadened emission bands, an increase in the non-radiative rate constants and a decrease in both the quantum efficiency of the 5D0 level and Eu3+ and the luminescence quantum yields. Cu2+, Cr3+, and Fe3+ ions efficiently and selectively quench the luminescence of nanocrystalline europium(III) terephthalate, which makes it a prospective material for luminescent probes to monitor these ions in waste and drinking water.

A red luminescent europium metal organic framework (Eu-MOF) integrated with a paper strip using smartphone visual detection for determination of folic acid in pharmaceutical formulations

“…66,67 This indicated that both DMF and water molecules simultaneously work as reactants and solvents. The XRD patterns of the synthesized Eu-MOF (Eu 2 bdc 3 ·4H 2 O), which are highly consistent with the corresponding Eu-MOF crystal material in simulated XRD patterns Tb 2 bdc 3 ·4H 2 O and some of the Eu-MOF crystals reported in the literature, 68–70 are shown in Fig. 2B.…”

Merging Dual Antenna Effect with Target-Insensitive Behavior in Bimetal Biligand MOFs to Form Efficient Internal Reference Signal: Color Tonality-Ratiometric Designs

“…Figure I shows a consistent peak position and characteristic peaks of the Eu-TPA and Zn-TPA MOFs. It can be seen that the MOF exhibited the main diffraction peaks at 2 theta values of 14.74°, 15.59°, 21.81°, 24.59°, 28.49°, and 30.44° which are well consisted with the results in the literature that suggested a successful synthesis of the MOF by a one-step synthesis strategy confirming its crystalline nature. − …”

Recent progress of metal–organic frameworks as sensors in (bio)analytical fields: towards real-world applications

“…For example, the electrochemical method can produce MOFs under mild reaction conditions. Ultrasonic-assisted and microwave-assisted methods [ 95 – 97 ] can produce uniformly seeded MOFs with better size control [ 98 , 99 ]. This is the case of a recent study for the preparation of Co-MOFs (TMU-51) by an ultrasound-assisted technique, in which, by tuning the power of ultrasound, smaller particles with controlled morphology were achieved, which finally resulted in an improved sensing performance for nitrophenol detection [ 100 ].…”