A robust Zn(ii)/Na(i)-MOF decorated with [(OAc)₂(H₂O)₂]_n²ⁿ⁻ anions for the luminescence sensing of copper ions based on the inner filter effect

Abstract

Based on the inner filter effect, a luminescent Zn(ii)/Na(i) metal-organic framework (MOF) {[Zn2Na(L)(HL)2(H2O)2][OAc]·2H2O}n (1, H2L = 5-methyl-1,3-benzenedicarboxylic acid) with excellent stability was constructed for the fluorescence detection of Cu2+ ions. MOF 1 holds a 3D cationic framework in which [(OAc)2(H2O)2]n2n- anions are embedded into its 1D channels. Abundant hydrogen-bonding and π-π interactions in the MOF facilitate electron transfer from ligand-to-metal, resulting in a good luminescence peak at 412 nm and an efficient fluorescence quenching of MOF 1 in the presence of Cu2+ ions, due to the inner filter effect. The interactions between the Cu2+ ions and the OAc- anion in the channel endowed the Cu2+ ions with facile access to be adsorbed, and afforded the selective quenching of fluorescence. The MOF particles are well dispersed in water and the Cu2+ ions are pre-concentrated by adsorption, thus facilitating the determination of Cu2+ ions with a detection limit down to 0.65 μM. Our work thus paves a way for developing MOFs as an appealing platform to construct materials for environmental applications.

Efficient Detection of Fe3+ and Cr2O72− Ions in Water by Zn-Tetrazolate-Based Two-Dimensional Metal-Organic Framework: A Comparative Study

“…The PXRD patterns of BUT-25 before and after the fluorescence experiments were in accordance with each other, excluding the possibility of structural damage (Figure S1) [12]. The intense color change visible to the naked eye after the fluorescence tests indicates a strong interaction between the MOF and the target ions, as shown in Figures S5b,c, which might be responsible for detecting Cr 2 O 7 2− and Fe 3+ ions [13]. The UV-Vis absorption spectra of selected anions clearly shows that the absorption spectrum of Cr 2 O 7 2− consists of two bands in the 200-600 nm range, which covered the excitation wavelength (290 nm) and emission spectrum of BUT-25, while absorption spectrum of Fe 3+ ion covered the excitation wavelength of BUT-25, as shown in Figures S6 and S7, pointing towards fluorescence quenching of BUT-25 due to the inner filter effect and resonance energy transfer mechanism [14].…”

Ultrasensitive Fluorescent miRNA Biosensor Based on a “Sandwich” Oligonucleotide Hybridization and Fluorescence Resonance Energy Transfer Process Using an Ln(III)-MOF and Ag Nanoparticles for Early Cancer Diagnosis: Application of Central Composite Design

“…Based on the interaction between probe-1 and probe-2, fluorescence quenching may occur because of the FRET or inner filter effect (IFE) mechanism . When the absorption spectrum of quencher species overlapped with both excitation and emission fluorophore spectra, the IFE mechanism may be responsible for the fluorescence quenching.…”

“…Based on the interaction between probe-1 and probe-2, fluorescence quenching may occur because of the FRET or inner filter effect (IFE) mechanism. 65 When the absorption spectrum of quencher species overlapped with both excitation and emission fluorophore spectra, the IFE mechanism may be responsible for the fluorescence quenching. It has been usually observed because of the shielding of the excitation beam, which highly depends on the concentration of quencher or fluorophore species in solution.…”

Metal-Organic Frameworks for Bioimaging: Strategies and Challenges

“…Over the next two decades, as an independent branch of coordination chemistry, MOF families grew at an astonishing rate. Recently, MOFs have been widely exploited in various aspects, such as storage of materials [3], separation [4][5][6], purification [7], catalysis [8][9][10][11][12][13], sensing [14][15][16][17][18][19], bio-imaging [20,21], energy storage [22][23][24][25][26][27], drug delivery [28,29], etc. MOFs are particularly promising for biomedical candidates in biological sensing and imaging due to their quenching performance and luminescence properties [30].…”