The two-dimensional Ca-MOF shows a dual function as a sorbent and an electrochemical sensor for heavy metal ions, which is reported for the first time for a MOF material.
Voltammetric analytical techniques combine exceptional sensitivity, low cost, portability and capability for simultaneous determination of multiple analytes. The sensitivity of voltammetric analysis is largely determined by the efficiency of the working electrode. Electrodes modified with metal organic frameworks (MOFs) seem particularly promising for use in the analysis of a series of important inorganic and organic analytes. Nevertheless, research on chemically modified electrodes with MOFs is still in its infancy. In this critical review, we present the current status of research related to MOF-modified electrodes highlighting the respective MOF-modified electrodes which are based on MOFs that show exceptional chemical stability or/and sorption capability towards the targeted analytes. We also provide perspectives for future research aiming at motivating additional scientists to be involved in this exciting field of MOF-based electroanalytical sensors. † These authors contributed equally.
Employment of N,N′‐bis(2‐hydroxy‐4‐carboxyphenyl)oxalamide (H6L) in Cu2+ chemistry afforded the mononuclear complex (Et4N)4[CuL] ⋅ 13H2O (A) which comprises a square planar [CuL]4− complex with several O donor atoms in its periphery. The 1 : 1 reaction between complex A and Ln(NO3)3 ⋅ xH2O (Ln=La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er and Yb, x=6 or 9) in 1 : 4 mixture of ethanol/water in the presence of excess of KCl yielded two families of isomorphous 3d/4f coordination polymers, namely (Et4N)0.5[K0.5(H2O)Ln(H2O)4(CuL)] ⋅ 3H2O [Ln=La(1), Ce(2), Pr(3), Nd(4), Sm(5), Eu(6) and Gd(7)] and [K(H2O)Ln(H2O)4(CuL)] ⋅ ⋅6H2O [Ln=Tb(8), Dy(9), Ho(10), Er(11) and Yb(12)]. The crystal structures of 2–4 revealed the presence of 3D coordination polymers while the crystal structure of 9 the presence of a 2D coordination polymer. In both 3d/4f families, complex A retains its original structure and serves as a “metallo‐ligand”. The magnetic properties of 2–4, 7–9, 11 and 12 are discussed.
The use of 4,4′‐[oxalylbis(azanediyl)]bis(2‐hydroxybenzoic acid) (H6L1) in the Ba2+ chemistry has afforded a 3D polymer, namely [Ba(H2L2)(H2O)]n (1), which is based on H2L22– anions derived by the in‐situ metal‐assisted transformation of H6L1. The neutral H4L2 [4‐(carboxyformamido)‐2‐hydroxybenzoic acid] ligand was isolated from 1 and characterized by spectroscopic methods. Polymer 1 is based on edge and face‐sharing BaO10 polyhedra which create an inorganic layer pillared to the third dimension by the organic ligands and has been classified as an I2O1 framework. The topological analysis of 1 provided an opportunity to introduce a method for the deconstruction of I2O1 frameworks by adopting principles applied in the deconstruction of Metal‐Organic‐Frameworks (MOFs) with rod Secondary Building Units (SBUs). A detailed discussion and insights for the proper use of the ImOn notation which finds application in describing the dimensionality in MOFs, is also provided.
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