Two novel penetrating coordination polymers based on flexible S-containing dicarboxylate acid with sensing properties towards Fe3+ and Cr2O72- ions

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 hydrostable Zn2+ coordination polymer for multifunctional detection of inorganic and organic contaminants in water

From the perspective of human health and environmental safety, the development of hydrostable fluorescent sensors for the detection of heavy metal ions and nitroaromatics is an important but a challenging issue. To this end, a water-stable Zn²⁺ coordination polymer formulated as {[Zn(H₂L)]·2DMF·3H₂O}_n (ZnCP) was prepared elaborately by a solvothermal method using a multidentate ligand (H₄L) with 2,6-pyridine-dicarboxylic acid spaced by para-substituted benzene. Single-crystal analysis shows that the new ZnCP exhibits one-dimensional chain structural features, which further promoted to afford a wrinkled two-dimensional network structure via inter-chain hydrogen bonding. Powder X-ray diffraction and fluorescence measurements show that it can maintain crystallinity and structural integrity under harsh acidic and alkaline conditions with the pH ranging from 4 to 11. Notably, the bright blue-emissive ZnCP showed selective fluorescence quenching effects for Fe³⁺ and picric acid (PA), which makes it an excellent chemical sensor for Fe³⁺ and picric acid (PA) with low detection limits of 0.41 and 0.26 μM in water. The recognition mechanism of Fe³⁺ could be attributed to UV absorption competition and resonance energy transfer in the aid of weak electrostatic interactions, while the recognition mechanism of PA is considered to be a multi-quenching mechanism dominated by absorption competition and PET effects with the assistance of hydrogen bonding. In addition, poly(methyl methacrylate) (PMMA) films doped with ZnCP (ZnCP@PMMA) were developed to provide better sensing performance and portability for practical applications.

Stimuli-Responsive Zinc (II) Coordination Polymers: A Novel Platform for Supramolecular Chromic Smart Tools

The unique role of the zinc (II) cation prompted us to cut a cross-section of the large and complex topic of the stimuli-responsive coordination polymers (CPs). Due to its flexible coordination environment and geometries, easiness of coordination-decoordination equilibria, "optically innocent" ability to "clip" the ligands in emissive architectures, non-toxicity and sustainability, the zinc (II) cation is a good candidate for building supramolecular smart tools. The review summarizes the recent achievements of zinc-based CPs as stimuli-responsive materials able to provide a chromic response. An overview of the past five years has been organised, encompassing 1, 2 and 3D responsive zinc-based CPs; specifically zinc-based metallorganic frameworks and zinc-based nanosized polymeric probes. The most relevant examples were collected following a consequential and progressive approach, referring to the structure-responsiveness relationship, the sensing mechanisms, the analytes and/or parameters detected. Finally, applications of highly bioengineered Zn-CPs for advanced imaging technique have been discussed.

First Ln-MOF as a trifunctional luminescent probe for the efficient sensing of aspartic acid, Fe3+ and DMSO

The first Ln-MOF (Tb-MOF) as a trifunctional luminescent probe for the efficient sensing of aspartic acid, Fe³⁺ and DMSO was demonstrated.

Four novel Zn(ii)/Cu(ii) coordination polymers containing hydroxyl groups: synthesis, crystal structure, luminescence sensing and photocatalysis properties

CPs 1, 3 and 4 show a 2D network, while 2 possesses a 3D network. 1 is a highly selective and sensitive bifunctional luminescent sensor towards Cu²⁺ and Cr₂O₇²⁻ ions. 3 and 4 exhibit photocatalytic activities for degradation of dyes (MB/MO).

Cobalt(ii) and zinc(ii)-coordination polymers constructed from ether-linked tetracarboxylic acid and isomeric bis(imidazole) linkers: luminescence-based Fe(iii) detection in aqueous media

Four Co(ii) and Zn(ii)-coordination polymers were synthesized and characterized. Compound 3 exhibited sensitive and selective detection towards Fe³⁺ ions in the presence of other competing agents with a detection limit of 3.23 ppm.

Luminescent coordination polymers constructed using a mixed-ligand strategy for highly selective luminescence sensing of nitrobenzene, Fe3+ and Cr2O72− ions and photodegradation of rhodamine B

Using a mixed ligand strategy, ten new LCPs were constructed. They all display highly sensitive and selective luminescence sensing for NB, Cr₂O₇²⁻and Fe³⁺ ions. Moreover, 3–10 also exhibit high photocatalytic activities toward the degradation of RhB.

A novel (3,6)-connected CdII coordination polymer based on an ether-linked tricarboxylate ligand: synthesis, topology and luminescence sensing properties in aqueous solution

A novel three-dimensional coordination polymer, namely, poly[[diaquabis(μ-4,4'-bipyridine)bis{μ₃-5-[(2-carboxyphenoxy)methyl]isophthalato}tricadmium(III)] dimethylformamide monosolvate 2.5-hydrate], {[Cd₃(C₁₆H₉O₇)₂(C₁₀H₈N₂)₂(H₂O)₂]·2C₃H₇NO·5H₂O}_n, was obtained by the reaction of ether-linked 5-[(2-carboxyphenoxy)methyl]isophthalic acid (H₃L) with Cd^II salts in the presence of 4,4'-bipyridine (bpy) under solvothermal conditions. In this complex, the Cd^II centres are connected by the carboxylate ligands to form two-dimensional wave-like layers, which are pillared by bpy ligands and extended into a rare three-dimensional (3,6)-connected sqc27 framework. The complex demonstrated good water stability and strong luminescence emissions. It not only possesses excellent luminescence sensing activities toward Fe³⁺ and Cr₂O₇^2- in aqueous solution, but can also distinguish between Cr₂O₇^2- and CrO₄^2- by luminescence. Furthermore, it could be simply and quickly regenerated at least five times. A study of the sensing mechanism indicated that luminescence quenching may be related to the energy competition between the complex and sensing analytes.

A New 3D 10-Connected Cd(II) Based MOF With Mixed Ligands: A Dual Photoluminescent Sensor for Nitroaroamatics and Ferric Ion

The precise unification of functional groups and photoluminescence properties can give rise to MOFs that can offer diverse applications like selective detection of nitroaromatic compounds (NACs) which are considered to be an important ingredient of explosive as well as cation and anion sensing. Hence, a new 3D metal-organic framework (MOF) [Cd2(btc)(bib)(HCOO)(H2O)·H2O]n (1) has been synthesized using mixed ligand strategy by solvothermal reaction of cadmium acetate with two ligands viz. 1,3,5-benzenetricarboxylic acid (H3btc) and 1,4-bis(2-methyl-imidazol-1-yl)butane (bib). The MOF 1 possesses highly 10-connected network which is based on {Cd4(btc)2(bib)4} molecular building block. The studies showed that 1 could be taken as the fluorescent sensor for sensitive recognition of NACs, in particular 2,4,6-trinitrophenol (TNP) with notable quenching (K sv = 5.42 × 104 M-1) and LOD of 1.77 ppm. Additionally, 1 also displayed selective sensing for Fe3+ ions with K sv = 6.05 × 103 M- 1 and LOD = 1.56 ppm. Also, this dual sensor displayed excellent reusability toward the detection of TNP and Fe3+ ion. Theoretical calculations have been performed to propose the probable mechanism for the sensing luminescence intensity. Calculations indicated that because of the charge transfer and weak interaction that is operating between NACs and MOF, the weakening in the photoluminescence intensity resulted.

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.

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.

Metal–organic frameworks with 5,5′-(1,4-xylylenediamino) diisophthalic acid and various nitrogen-containing ligands for selectively sensing Fe(iii)/Cr(vi) and nitroaromatic compounds

Four Zn(ii) complexes are applied in selectively sensing Fe(iii)/Cr(vi) and nitroaromatic compounds.