A Cu(II) MOF with laccase-like activity for colorimetric detection of 2,4-dichlorophenol and p-nitrophenol

Metal-organic framework (MOF) materials with aqueous stability have a good potential application in the field of mimetic enzymes. However, most of them have poor robustness in aqueous solution due to competitive coordination effects between water molecules and central metal ions. Herein, a copper-based MOF (Cu-SM MOF) was prepared using copper ions and 5-(sulfomethyl) isophthalic acid (5-SMIPA) by a hydrothermal process. Considering the similarity of coordination and morphology with HKUST-1, the aqueous stability and laccase-like activity of the Cu-SM MOF were investigated using HKUST-1 as the reference. The Cu-SM MOF shows superior aqueous stability to HKUST-1 after immersion in buffer solutions, especially under alkaline conditions. Moreover, the Cu-SM MOF possesses higher catalytic activity than HKUST-1 at a high salt concentration, high temperature, etc., because the Cu-SM MOF exhibits lower K_m and higher V_max values than those of laccase and reported mimetic enzymes. The mimetic enzyme behavior of the Cu-SM MOF is demonstrated in the oxidation of phenols, as well as in the detection of 2,4-dichlorophenol (2,4-DP) and p-nitrophenol with linear ranges of 1-100 μM and 2-250 μM, and limits of detection of 0.53 μM and 1.62 μM, respectively. Owing to the excellent aqueous stability and laccase-like activity of the Cu-SM MOF, it has great application prospects in many fields, such as the determination of phenols and the treatment of industrial wastewater.

Efficient photodegradation of dyes by a new 3D Cd(II) MOF with rare fsh topology

Metal–organic frameworks (MOFs) can be regarded as 3D coordination polymers that adopt ordered porous structures and possess abundant active sites, which make them promising photocatalysts for the degradation of organic...

Isomers of Terpyridine as Ligands in Coordination Polymers and Networks Containing Zinc(II) and Cadmium(II)

The use of divergent 4,2′:6′,4″- and 3,2′:6′,3″-terpyridine ligands as linkers and/or nodes in extended coordination assemblies has gained in popularity over the last decade. However, there is also a range of coordination polymers which feature 2,2′:6′,2″-terpyridine metal-binding domains. Of the remaining 45 isomers of terpyridine, few have been utilized in extended coordination arrays. Here, we provide an overview of coordination polymers and networks containing isomers of terpyridine and either zinc(II) and cadmium(II). Although the motivation for investigations of many of these systems is their luminescent behavior, we have chosen to focus mainly on structural details, and we assess to what extent assemblies are reproducible. We also consider cases where there is structural evidence for competitive product formation. A point that emerges is the lack of systematic investigations.

The terpyridine isomer game: from chelate to coordination network building block

The first 4,2':6',4''-terpyridine (4,2':6',4''-tpy) containing coordination polymer was reported over 20 years ago and in the last decade, there has been increased interest in the use of ditopic 4,2':6',4''-tpy ligands as linkers in coordination polymers and 2D-networks. Functionalization in the 4'-position of 4,2':6',4''-tpy is synthetically straightforward, giving access to a large suite of building blocks. Less well explored is the coordination chemistry of 3,2':6',3''-tpy ligands which exhibit greater conformational flexibility than 4,2':6',4''-tpy. One approach to making the transition from 2D- to 3D-networks is to utilize tetratopic bis(4,2':6',4''-tpy) and bis(3,2':6',3''-tpy) ligands which act as 4-connecting nodes. In this highlight, we survey recent progress towards a better understanding of the design principles associated with the use of ditopic and tetratopic 4,2':6',4''-tpy and 3,2':6',3''-tpy containing ligands and their roles both as linkers and nodes in coordination assemblies.

On the supramolecular properties of neutral, anionic and cationic cadmium complexes harvested from dithiolate–polyamine binary ligand systems

Three Cd(ii) complexes [Cd(i-mnt)(DMSO)₂]_n (1), {[Cd(i-mnt)pn]·2H₂O} (2), and [Cd(i-mnt)₃][Cd(tren)₂]₂ (3) harvested from 1,1-dicyanoethylene-2,2-dithiolate (i-mnt²⁻) and polyamine ligand systems have been designed, synthesized and structurally characterized.

A new copper(II) supramolecular coordination polymer and a dinuclear compound with multifunctional 2-amino-5-sulfobenzoic acid and flexible N-donor ligands: synthesis, structure and characterization

Multifunctional 2-amino-5-sulfobenzoic acid (H2afsb) can exhibit a variety of roles during the construction of supramolecular coordination polymers. The pendant carboxylic acid, sulfonic acid and amino groups could not only play a role in directing bonding but could also have the potential to act as hydrogen-bond donors and acceptors, resulting in extended high-dimensional supramolecular networks. Two new CuIIcoordination compounds, namelycatena-poly[[[diaquacopper(II)]-μ-1,6-bis(1H-1,2,4-triazol-1-yl)hexane-κ2N4:N4′] bis(3-amino-4-carboxybenzenesulfonate) dihydrate], {[Cu(C10H16N6)2(H2O)2](C7H6NO5S)2·2H2O}nor {[Cu(bth)2(H2O)2](Hafsb)2·2H2O}n, (1), and bis(μ-2-amino-5-sulfonatobenzoato-κ2O1:O1′)bis{μ-1,2-bis[(1H-imidazol-1-yl)methyl]benzene-κ2N3:N3′}bis[aquacopper(II)] trihydrate, [Cu2(C7H5NO5S)2(C14H14N4)2(H2O)2]·3H2O or [Cu2(afsb)2(obix)2(H2O)2]·3H2O, (2), have been obtained through the assembly between H2afsb and the CuIIion in the presence of the flexible N-donor ligands 1,6-bis(1H-1,2,4-triazol-1-yl)hexane (bth) and 1,2-bis[(1H-1,2,4-triazol-1-yl)methyl]benzene (obix), respectively. Compound (1) consists of a cationic coordination polymeric chain and 3-amino-4-carboxybenzenesulfonate (Hafsb−) anions. Compound (2) exhibits an asymmetric dinuclear structure. There are hydrogen-bonded networks within the lattices of (1) and (2). Interestingly, both (1) and (2) exhibit reversible dehydration–rehydration behaviour.

Constructing chiral MOFs by functionalizing 4,2′:6′,4′′-terpyridine with long-chain alkoxy domains: rare examples of neb nets

Three chiral 3D MOFs with uncommon neb topologies assemble from Co(NCS)₂ and 4′-(4-ⁿalkyloxyphenyl)-4,2′:6′,4′′-terpyridines (alkyl = hexyl or nonyl).