A Zn(II) Coordination Polymer for Fluorescent Turn-Off Selective Sensing of Heavy Metal Cation and Toxic Inorganic Anions

A novel coordination polymer [Zn(atyha)2]n (1) (Hatyha = 2-(2-aminothiazole-4-yl)-2- hydroxyiminoacetic acid) was constructed by hydrothermal reaction of Zn2+ with Hatyha ligand. CP 1 exhibits a 2D (4,4)-connected topological framework with Schläfli symbol of {44·62}, where atyha- anions serve as tridentate ligands, bridging with Zn2+ through carboxylate, thiazole and oxime groups. CP 1 displays a strong ligand-based photoluminescence at 390 nm in the solid state, and remains significantly structurally stable in water. Interestingly, it can be utilized as a fluorescent probe for selective and sensitive sensing of Fe3+, Cr2O72- and MnO4- through the fluorescent turn-off effect with limit of detection (LOD) of 3.66 × 10-6, 2.38 × 10-5 and 2.94 × 10-6 M, respectively. Moreover, the efficient recyclability for detection of Fe3+ and Cr2O72- is better than that for MnO4-. The mechanisms of fluorescent quenching involve reversible overlap of UV-Vis absorption bands of the analytes (Fe3+, Cr2O72- and MnO4-) with fluorescence excitation and emission bands for CP 1, respectively.

Metal and Ligand Effect on the Structural Diversity of Divalent Coordination Polymers with Mixed Ligands: Evaluation for Photodegradation

Eight coordination polymers constructed from divalent metal salts, N,N^'-bis(pyridin-3-ylmethyl)terephthalamide (L), and various dicarboxylic acids are reported, affording [Co(L)(5-ter-IPA)(H₂O)₂]_n (5-tert-H₂IPA = 5-tert-butylisophthalic acid), 1, {[Co(L)(5-NO₂-IPA)]⋅2H₂O}_n (5-NO₂-H₂IPA = 5-nitroisophthalic acid), 2, {[Co(L)_0.5(5-NH₂-IPA)]⋅MeOH}_n (5-NH₂-H₂IPA = 5-aminoisophthalic acid), 3, {[Co(L)(MBA)]⋅2H₂O}_n (H₂MBA = diphenylmethane-4,4'-dicarboxylic acid), 4, {[Co(L)(SDA)]⋅H₂O}_n (H₂SDA = 4,4-sulfonyldibenzoic acid), 5, {[Co₂(L)₂(1,4-NDC)₂(H₂O)₂]⋅5H₂O}_n (1,4-H₂NDC = naphthalene-1,4-dicarboxylic acid), 6, {[Cd(L)(1,4-NDC)(H₂O)]⋅2H₂O}_n, 7, and {[Zn₂(L)₂(1,4-NDC)₂]⋅2H₂O}_n, 8, which were structurally characterized by using single-crystal X-ray diffraction. The structural types of 1-8 are subject to the metal and ligand identities, showing a 2D layer with the hcb, a 3D framework with the pcu, a 2D layer with the sql, a polycatenation of 2-fold interpenetrated 2D layer with the sql, a 2-fold interpenetrated 2D layer with the 2,6L1, a 3D framework with the cds, a 2D layer with the 2,4L1, and a 2D layer with the (10²⋅12)(10)₂(4⋅10⋅12⁴)(4) topologies, respectively. The investigation on the photodegradation of methylene blue (MB) by using complexes 1-3 reveals that the degradation efficiency may increase with increasing surface areas.

Zinc(II) Carboxylate Coordination Polymers with Versatile Applications

This review considers the applications of Zn(II) carboxylate-based coordination polymers (Zn-CBCPs), such as sensors, catalysts, species with potential in infections and cancers treatment, as well as storage and drug-carrier materials. The nature of organic luminophores, especially both the rigid carboxylate and the ancillary N-donor bridging ligand, together with the alignment in Zn-CBCPs and their intermolecular interaction modulate the luminescence properties and allow the sensing of a variety of inorganic and organic pollutants. The ability of Zn(II) to act as a good Lewis acid allowed the involvement of Zn-CBCPs either in dye elimination from wastewater through photocatalysis or in pathogenic microorganism or tumor inhibition. In addition, the pores developed inside of the network provided the possibility for some species to store gaseous or liquid molecules, as well as to deliver some drugs for improved treatment.

A Keggin-type polyoxometalate-based metal-organic complex as a highly efficient heterogeneous catalyst for the selective oxidation of alkylbenzenes

The direct oxidation of C-H bonds in organic materials into necessary oxygen-containing compounds under mild conditions has attracted increasing attention. A Keggin-type polyoxometalate-based metal-organic complex (MOC), [CuII4Cu^I(H₂trz)₄(C₂O₄)(H₂O)₄(H₃PW_11.18CuII0.82O₄₀)]·8H₂O (1) (H₃trz = 1,2,4-triazole), was designed and synthesized under hydrothermal conditions, and was structurally characterized by single crystal X-ray diffraction, PXRD, IR spectroscopy, TGA, and XPS. Complex 1 is a 3D 4,6,8-connected architecture derived from [Cu₅(H₂trz)₄(C₂O₄)₂(H₂O)₂]_n units and [PW_11.18Cu_0.82O₄₀]^6- anions, which can catalytically oxidize various types of alkylbenzenes. Gas chromatographic analysis showed that complex 1 as a heterogeneous catalyst could effectively catalyze the oxidation of diphenylmethane with 93% conversion and 99% selectivity within 6 h. In addition, the conversion for the catalytic oxidation of ethylbenzene was 96% with 99% selectivity. Compared with some reported catalysts, complex 1 exhibited a better catalytic effect and lower reaction time. Meanwhile, the catalytic oxidation of other benzyl derivatives with complex 1 was also investigated, which indicated that complex 1 possessed excellent catalytic performance.

Ultrasensitive fluorescence detection of norfloxacin in aqueous medium employing a 2D Zn(ii)-based coordination polymer

A 2D fluorescent coordination polymer, {[Zn(L)0.5(mip)] 1.75H2O}n (1), was successfully assembled. 1 was developed as an ultrasensitive fluorescent probe for the sensing of norfloxacin (NOR) in water.

A layered Mn-based coordination polymer as an efficient heterogeneous catalyst for CO2 cycloaddition under mild conditions

A layered coordination polymer has been constructed by using a semi-rigid ligand, exhibiting a robust catalytic activity toward the cycloaddition of CO2 with epoxides.

Ten polytorsional-amide-induced helical-based coordination polymers with difunctional electrochemical activities

Ten polytorsional-naphthalene-amide-based CPs constructed from different carboxylates and metal ions were obtained and exhibited difunctional electrochemical activities.

Polytorsional-amide/carboxylates-directed Cd(ii) coordination polymers exhibiting multi-functional sensing behaviors

By rational assembly of polytorsional-amide [N,N′-bis(4-methylenepyridin-4-yl)-1,4-naphthalene dicarboxamide (L)] and polytorsional-carboxylates [H₂ADI = adipic acid, H₂PIM = pimelic acid, H₂SUB = suberic acid], three new Cd-based coordination polymers (CPs) C₃₀H₃₀CdN₄O₇ (1), C₃₁H₃₂CdN₄O₇ (2) and C_31.03H_30.55CdCl_0.24N₄O_5.52 (3) were successfully synthesized. CPs 1–2 and 3 are 2D networks and a 3D framework, which all display 3,5-connected topologies with different structural details. The effects of carboxylates with different carbon chains on the structure of the complexes were studied. Fluorescence experiments show that CPs 1–3 have good multi-functional sensing ability for metal cations (Fe³⁺), anions (MnO₄⁻, CrO₄²⁻, Cr₂O₇²⁻) and organochlorine pesticides (2,6-dichloro-4-nitroamine) with good anti-interference and recyclable characteristics. The possible sensing mechanism is also investigated in detail.

Three (3,5)-connected Cd(ii) coordination polymers induced by polytorsional-amide/carboxylates exhibiting controllable multifunctional fluorescent sensing activities.

Two Co(ii) complexes containing pyridylbenzimidazole ligands as chemosensors for the sensing of levofloxacin, acetylacetone, and Ni2+ with high selectivity and sensitivity

Based on the organic ligand 1,1′-(1,6-hexanediyl)bis[2-(2-pyridyl)benzimidazole], two new Co(ii)-based complexes were successfully synthesized hydrothermally, and they are promising sensors for detecting acac, LEV, and Ni2+ ions.

An exceptionally stable luminescent cadmium(ii) metal–organic framework as a dual-functional chemosensor for detecting Cr(vi) anions and nitro-containing antibiotics in aqueous media

Based on four kinds of SBUs, a robust Cd(ii) LMOF was fabricated that possessed highly sensitive detectability as a dual-response chemosensor for Cr(vi) anions and broad-spectrum nitro-containing antibiotics in aqueous media.

Four dual-functional luminescent Zn(ii)-MOFs based on 1,2,4,5-benzenetetracarboxylic acid with pyridylbenzimidazole ligands for detection of iron(iii) ions and acetylacetone

Four Zn-MOFs with different topological types were synthesized and characterized, MOFs 1–4 have excellent sensitivity, selectivity, recyclability and structural stabilities for detecting acac/Fe³⁺ in the naked eye range.

Six CoII coordination polymers exhibiting UV-light-driven photocatalysis for the degradation of organic dyes

Six different Co^II coordination polymers based on a new bis-pyridyl-bis-amide and polycarboxylates were obtained, showing photocatalytic activity for organic dyes.

Self-photoreduced Ag0-doped Ag(i)–organic frameworks with efficient visible-light-driven photocatalytic performance

A series of Ag0-doped Ag(i)organic frameworks have been constructed via a facile self-photoreduction strategy and can be applied as efficient photocatalysts for the photocatalytic degradation of methyl orange.

Various carboxylates induced eight Zn(ii)/Cd(ii) coordination polymers with fluorescence sensing activities for Fe(iii), Cr(vi) and oxytetracycline

Eight new Zn(ii)/Cd(ii) coordination polymers constructed from a naphthalene-amide-pyridyl ligand and various carboxylates were synthesized and characterized, which show multifunctional fluorescence responses for cations, anions and antibiotics.

A pH-stable Ag(i) multifunctional luminescent sensor for the efficient detection of organic solvents, organochlorine pesticides and heavy metal ions

Developing novel luminescent materials for sensitive and rapid detection of heavy metal ions, organic solvents and organochlorine pesticides is vital for environmental monitoring. Herein, a new Ag(i) luminescent coordination polymer [Ag(3-dpyb)(H₃odpa)]·H₂O (LCP 1) (3-dpyb = N,N′-bis(3-pyridinecarboxamide)-1,4-butane, H₄odpa = 4,4′-oxydiphthalic acid) was obtained by a hydrothermal reaction and characterized by single crystal, powder X-ray diffraction, infrared spectroscopy, thermogravimetric analysis and luminescence spectroscopy. LCP 1 is a three-dimensional (3D) supramolecular framework formed from 1D [Ag-3-dpyb-H₃odpa]_n chains and H-bond interactions. The luminescence sensing study of LCP 1 for recognizing organic solvents, organochlorine pesticides and heavy metal ions was performed, which demonstrated it to be a potential luminescent sensor for Hacac, NB, 2,6-DCN, Fe²⁺, Hg²⁺, and Fe³⁺. Fe²⁺, Hg²⁺, and Fe³⁺ in river water were determined using LCP 1 with satisfying recovery.

3D supramolecular LCP 1 can detect Hacac, NB, 2,6-DCN, Fe²⁺, Hg²⁺, and Fe³⁺ with a low detection limit and pH stability.