Novel alkaline earth metal–organic frameworks with thiophene groups for selective detection of Fe3+

This work demonstrates that the alkaline earth ion radii play an important role in coordination numbers and topologies for constructing MOFs, and these MOFs can be used as fast-response fluorescence sensors for the detection of Fe³⁺.

Three water-stable luminescent two-dimensional CdII-based coordination polymers as sensors for highly sensitive and selective detection of Cr2O72− and CrO42− anions

Three 2D Cd^II-CPs with different topologies were prepared, in which 1 and 3 are rare examples which display excellent sensitivity, selectivity, recyclability and structural stabilities for the detection of Cr₂O₇²⁻/CrO₄²⁻.

Tunable photoluminescence in flexible carboxylate ligand-based coordination polymers with interesting topologies and Fe3+ sensitivity

Complexes 1–5, showing different interesting topological networks from 1D ladder to 3D frameworks, exhibit selective and sensitive fluorescence quenching of Fe³⁺ ion.

Dramatic luminescence signal from a Co(ii)-based metal–organic compound due to the construction of charge-transfer bands with Al3+ and Fe3+ ions in water: steady-state and time-resolved spectroscopic studies

A Co(ii)-based metal–organic compound exhibits luminescence turn-on by Al³⁺ and quenching by Fe³⁺ due to the formation of charge-transfer complexes/adducts.

Stable Ln-MOFs as multi-responsive photoluminescence sensors for the sensitive sensing of Fe3+, Cr2O72−, and nitrofuran

Stable Ln(iii)-MOFs with a versatile 2-(4-pyridyl)-terephthalic acid ligand can be used as a multifunctional sensing platform for Fe³⁺, Cr₂O₇²⁻, and nitrofuran detection.

2D lanthanide coordination polymers constructed from a semi-rigid tricarboxylic acid ligand: crystal structure, luminescence sensing and color tuning

Three lanthanide polymers {[Ln(TMCA)(DEF)(H₂O)]·(CH₃CN)}_n (Ln = Eu 1; Tb 2; Gd 3; H₃TMCA = 4′,4′,4′-[(trimethylamino)]-tris[(1,1′-biphenyl)-2-carboxylic acid]) were synthesized under solvothermal conditions.

Sensing organic analytes by metal–organic frameworks: a new way of considering the topic

In this review, our goal is comparison of advantageous and disadvantageous of MOFs about signal-transduction in different instrumental methods for detection of different categories of organic analytes.

An adjustable dual-emission fluorescent metal-organic framework: Effective detection of multiple metal ions, nitro-based molecules and DMA

A novel multifunctional Pb(II)-based MOF, [Pb_1.5(DBPT)]₂·(DMA)₃(H₂O)₄ (1), with excellent chemical stability, was successfully assembled by connecting {Pb₂O₁₀} unit with a multi-topic polycarboxylate ligand of 3-(3,5-dicarboxylphenyl)-5-(4-carboxylphenyl)-1-H-1,2,4-triazole (H₃DBPT). It exhibits dual fluorescence emissions at 380 nm (λ_ex = 280 nm) and 540 nm (λ_ex = 380 nm), respectively. Through the adjustable dual fluorescence emissions, it could act as a turn-off and turn-on switch for detecting N,N-dimethylacetamide (DMA) molecule. Moreover, Fe³⁺ ions exert luminescence quenching role on compound 1 at both excitation lengths in water, among which the quenching at λ_ex = 280 nm is of high sensitivity (K_SV = 1.2 × 10⁵), and the quenching at λ_ex = 380 nm is of wide-range. The sensing for metal ions of In³⁺, Zr⁴⁺, and Al³⁺ is also effective at λ_ex = 280 nm, with the K_SV constants of 1.6 × 10⁵, 1.6 × 10⁵, and 4.3 × 10⁴, respectively. More importantly, a series of nitroaromatic compounds (TNP, 2,4,6-trinitrophenol; 4-NA, 4-nitroaniline; NB, nitrobenzene) and nitro-based drugs (MNZ, metronidazole; DMZ, dimetridazole) could be detected at both excitation lengths, demonstrating the advantage of broad range response of fluorescence sensing. Thanks to the excellent chemical stability and unusual dual emission luminescence properties for chemical detection of various metal ions, nitro-based molecules and DMA solvent, the Pb-based MOF reported in this work is, therefore, a very promising multi-response sensor.

CdII -Organic Frameworks Fabricated with a N-Rich Ligand and Flexible Dicarboxylates: Structural Diversity and Multi-Responsive Luminescent Sensing for Toxic Anions and Ethylenediamine

Three metal-organic frameworks {[Cd(L)(glu)]⋅3 H₂ O}_∞ (1), {[Cd₂ (L)₂ (adi)₂ ]⋅5 H₂ O}_∞ (2) and {[Cd(L)(sub)]⋅3 H₂ O⋅DMA }_∞ (3) (L=pyridine-3,5-bis(5-azabenzimidazole), H₂ glu=glutaric acid, H₂ adi=adipic acid and H₂ sub=suberic acid) were obtained under solvothermal conditions. Complex 1 shows a 2D (4,4) network constructing of Cd₂ -glu and Cd-L chains. Complex 2 presents a 2-fold interpenetrating 3D framework with pcu topology. Complex 3 is a 3D framework with cds topology. Three complexes with versatile structures were obtained by changing aliphatic dicarboxylate ligands with different lengths based on a N-rich ligand. Moreover, the fluorescence measurements indicate that complex 1 is a good multifunctional chemosensor for the detection of Cr₂ O₇ ^2- and MnO₄ ^- anions by fluorescence quenching effect, and ethylenediamine by fluorescence enhancement effect, with detection limits of 1.196 ppm, 0.551 ppm and 64.572 ppm, respectively. Both complexes 2 and 3 can selectively sense Cr₂ O₇ ^2- anion with detection limits of 1.126 ppm for 2 and 0.831 ppm for 3 by a fluorescence quenching effect.

Three-in-one is really better: exploring the sensing and adsorption properties in a newly designed metal-organic system incorporating a copper(ii) ion

A 2-D copper(ii)-based coordination polymer, [Cu(SCN)(hmp)]_n CP (1), was crystallized via the slow evaporation method after the reaction of CuSO₄·5H₂O, 2-pyridinemethanol (hmpH), sodium thiocyanate and sodium hydroxide in water for functional applications. CP (1) was characterized via elemental analysis, FTIR, PXRD, magnetic, EPR, crystallographic and TGA studies. The crystal structure and EPR data confirmed a square pyramidal geometry around the Cu(ii) ions. The topological analysis revealed that CP 1 has a {6^{^}3} point symbol with a [6.6.6] extended point symbol and 3-c net, uninodal net having hcb and Shubnikov hexagonal plane net/(6,3) type of uncommon topology. The magnetic studies suggested the strong antiferromagnetic nature of CP (1). The fluorescence sensing property of CP (1) was investigated with different nitro aromatic compounds and hazardous metal ions. CP (1) demonstrated high selectivity and sensitivity towards nitrobenzene, even in the presence of other competitive nitro aromatics. In addition, CP (1) showed excellent selectivity and sensitivity toward Fe³⁺ over other metal ions. The possible detection mechanisms were proposed employing UV-visible and fluorescence spectroscopy and DFT calculations. CP (1) also showed excellent recyclability towards both analytes, and its initial intensity was almost regained after several washings. Moreover, CP (1) acted as an excellent adsorbent material for natural dyes with different charges and sizes, i.e., methylene blue (MB), methyl orange (MO) and Rhodamine-B. Furthermore, CP (1) was utilized repeatedly for the effective adsorption of MB from wastewater without significant loss in its adsorption capacity. Hence, the present CP (1) was designed to relate coordination chemistry with various functional applications of interest.

Series of Cadmium(II) Coordination Polymers Based on a Versatile Multi-N-Donor Tecton or Mixed Carboxylate Ligands: Synthesis, Structure, and Selectively Sensing Property

Five Cd(II) metal-organic frameworks (MOFs), [Cd(HL)₂] (1), [Cd(HL)₂(H₂O)₂] (2), [Cd₃(HL)₂(obda)₂] (3), [Cd₂(HL)₂(ohmbda)(DMA)(H₂O)] (4), and [Cd₂(HL)(btc)(H₂O)₂]·3H₂O (5), were prepared by reactions of Cd(NO₃)₂·4H₂O with 1-(1H-imidazol-4-yl)-4-(4H-tetrazol-5-yl)benzene (H₂L) or mixed carboxylate ancillary ligands of 1,2-benzenedicarboxylic acid (H₂obda), 5-hydroxy-1,3-benzenedicarboxylic acid (H₂ohmbda), and 1,3,5-benzenetricarboxylic acid (H₃btc), respectively. Their structures have been characterized by single-crystal X-ray diffraction, elemental analysis, infrared spectroscopy (IR), thermogravimetric analysis, and powder X-ray diffraction. Compounds 1 and 2 are supramolecular isomeric frameworks without consideration of the solvent molecules. Complex 1 exhibits a binodal (3, 5)-connected two-dimensional (2D) layer structure with the point (Schläfli) symbol of (5²·6)(5⁵·6⁴·7), while complex 2 shows a 2D + 2D → 3D (three-dimensional) framework. Complex 3 is a (3, 5, 6)-connected tetranodal 3D net with the point (Schläfli) symbol of (4·8²)₂(4⁵·6·8⁴)₂(4⁵·6⁵)₂(4⁸·6⁶·8). Compound 4 is a (3, 3, 8)-connected trinodal 3D net with the point (Schläfli) symbol based on a binuclear [Cd₂N₂O] subunit, while 5 is a 2-nodal (3, 4)-connected 2D V₂O₅-type network based on [Cd₂N₂(COO)₂] SBU. The studies of molecular sensing properties show that the luminescent MOFs can be employed as fluorescent sensors for the detection of Fe³⁺ and nitro compounds. Compound 1 and 3 exhibit quenching responses for Fe³⁺ in dimethylformamide solution with detection limits of 2.3 × 10^-6 and 8.6 × 10^-7 M, respectively. Meanwhile, compound 5 can sense 4-nitrophenol with a detection limit as low as 5.75 × 10^-7 M.

A new two-dimensional ZnII coordination polymer based on 1,3-bis(2-methyl-1H-imidazol-1-yl)benzene and 5-nitrobenzene-1,3-dicarboxylic acid: synthesis, crystal structure and physical properties

A novel two-dimensional (2D) Zn^II coordination framework, poly[[μ-1,3-bis(2-methyl-1H-imidazol-1-yl)benzene](μ-5-nitrobenzene-1,3-dicarboxylato)zinc(II)], [Zn(C₈H₃NO₆)(C₁₄H₁₄N₄)]_n or [Zn(NO₂-BDC)(1,3-BMIB)]_n [1,3-BMIB is 1,3-bis(2-methyl-1H-imidazol-1-yl)benzene and NO₂-H₂BDC is 5-nitrobenzene-1,3-dicarboxylic acid], has been prepared and characterized by IR, elemental analysis, thermal analysis and single-crystal X-ray diffraction. Single-crystal X-ray diffraction analysis revealed that the compound is a new 2D polymer with a 6³ topology parallel to the (10-2) crystal planes based on left-handed helices, right-handed helical NO₂-BDC-Zn chains and [Zn₂(1,3-BMIB)₂]_n clusters. In the crystal, adjacent layers are further connected by C-H...O hydrogen bonds, C-H...π interactions, C-O...π interactions and N-O...π interactions to form a three-dimensional structure in the solid state. In addition, the compound exhibits strong fluorescence emissions in the solid state at room temperature.

Rational design, crystal structures and sensing properties of a series of luminescent MOFs based on a flexible tetracarboxylate ligand and N-donor ligands

Six Zn/Cd MOFs were synthesized and characterized. 1–3 are 1D ring chains. 4–5 show 2D bilayer network. 6 possesses a 3D network structure. In particular, 2 demonstrates highly selective and sensitive luminescent sensor towards acetone and Fe³⁺ ion.

Selective CO2 adsorption and theoretical simulation of a stable Co(ii)-based metal–organic framework with tunable crystal size

A stable Co(ii)-MOF shows selective CO₂ adsorption and high H₂ uptake. The simulations of sorption confirm this reasonable design approach.

Rational synthesis, crystal structure, and sensing and adsorption properties of luminescent metal–organic frameworks

Five novel Cd(ii) metal–organic frameworks (Cd-MOFs) were synthesized employing a rational design approach under solvothermal conditions. The luminescence sensing and the targeted dye adsorption properties of the MOFs 1–5 are investigated.

NH2-MIL-53(Al) nanocrystals: a fluorescent probe for the fast detection of aromatic nitro-compounds and ions in aqueous systems

Fluorescent NH₂-MIL-53(Al) nanocrystals used for the fast detection of ANCs and ions in aqueous systems were fabricated by a solvothermal route.

Selectively detecting toluene and benzaldehyde by two stable lanthanide–organic frameworks as luminescent probes

Two stable lanthanide–organic frameworks as luminescent probes to sensitively detect for toluene and benzaldehyde through luminescent quenching.

Five new coordination polymers with a Y-shaped N-heterocyclic carboxylic acid: structural diversity, bifunctional luminescence sensing and magnetic properties

Five novel CPs have been synthesized under solvothermal conditions. The results show that 1 and 2 present high sensing ability for NACs and Fe³⁺ ions, and there exist ferromagnetic interaction in 3/4 and antiferromagnetic interaction in 5.

Luminescent metal–organic frameworks with a 2-(4-pyridyl)-terephthalic acid ligand for detection of acetone

Employing an unsymmetrical pyridyl-dicarboxylate ligand, three MOFs with diverse structures were obtained. The Cd-MOF shows excellent selective sensing towards acetone molecules.

Multi-responsive luminescent sensor based on three dimensional lanthanide metal–organic framework

A novel multi-functional luminescent MOF was synthesized, which shows excellent recyclable luminescent sensing for acetone, Fe³⁺, Cr₂O₇²⁻ and 4-NP.

Different photochromic properties induced by lone pair–π interactions with varying strengths in two stereocontrolled self-assembly isomeric coordination polymers

The different photochromic properties of two naphthalenediimide-based isometric compounds are derived from two lone pair–π interactions with varying strengths.

Dicarboxylate-induced structural diversity of luminescent ZnII/CdII coordination polymers derived from V-shaped bis-benzimidazole

Six Zn^II/Cd^II CPs (1–6), derived from V-shaped bbib and dicarboxylates, have been synthesized; complex 2 is a good bifunctional chemosensor for the detection of Fe³⁺ and MnO₄⁻.

Two azo-functionalized luminescent 3D Cd(ii) MOFs for highly selective detection of Fe3+ and Al3+

Two 3D luminescent Cd(ii) MOFs (Cd-MOF-1 and Cd-MOF-2) exposing azo functional sites displayed selective detection of Fe³⁺ and Al³⁺ metal ions with high sensitivities.

A multifunctional MOF as a recyclable catalyst for the fixation of CO2 with aziridines or epoxides and as a luminescent probe of Cr(vi)

A multifunctional metal-organic framework (1) can serve as an efficient and recyclable catalysts for the conversion of CO₂ with aziridines or epoxides. Furthermore, the material can also act as a recyclable luminescent probe for Cr(vi) species among twenty anions.

From 2D → 3D interpenetration to packing: N coligand-driven structural assembly and tuning of luminescent sensing activities towards Fe3+ and Cr2O72− ions

Three complexes were hydrothermally synthesized and exhibited excellent selectivity towards Fe³⁺ and Cr₂O₇²⁻.

3D LnIII-MOFs: slow magnetic relaxation and highly sensitive luminescence detection of Fe3+ and ketones

Five Ln-MOFs were obtained: the Dy-MOF shows slow magnetic relaxation, and the Eu-MOF and Tb-MOF show selective and sensitive sensing towards Fe³⁺ ions and ketones in a water system.

Construction of metal–organic frameworks (MOFs) and highly luminescent Eu(iii)-MOF for the detection of inorganic ions and antibiotics in aqueous medium

A series of Ln(iii) complexes were synthesized. The highly luminescent chemically stable Eu-MOF shows multi-responsive luminescence sensing functions.

A novel luminescent hybrid material based on zinc complexes and graphene oxides for detection of Fe3+ in aqueous media

A novel GOS-modified zinc complex probe with water dispersibility is designed to detect Fe³⁺ in aqueous media (Stern–Volmer constant K_SV = 4 × 10⁶ L mol⁻¹).