Hydrogen-Bonded Networks Based on Cobalt(II), Nickel(II), and Zinc(II) Complexes of N,N'-Diethylurea

N,N'-diethylurea (DEU) was employed as a ligand to form the octahedral complexes [M(DEU)6]2+ (M=Co, Ni and Zn). Compounds [Co(DEU)6](BF4)2 (1), [Co(DEU)6](CIO4)2 (2), [Ni(DEU)6](CIO4)2 (3), and [Zn(DMU)6](CIO4)2 (4) have been prepared from the reactions of DEU and the appropriate hydrated metal(II) salts in EtOH in the presence of 2,2-dimethoxypropane. Crystal structure determinations demonstrate the existence of [M(DEU)6]2+ cations and CIO4− (in 2–4) or BF4− (in 1) counterions. The [M(DEU)6]2+ cations in the solid state are stabilized by a pseudochelate effect due to the existence of six strong intracationic N-H ⋯ O(DEU) hydrogen bonds. The [M(DEU)6]2+ cations and counterions self-assemble to form hydrogen-bonded 2D architectures in 2–4 that conform to the kgd (kagome dual) network, and a 3D hydrogen-bonded rtl (rutile) network in 1. The nature of the resulting supramolecular structures is influenced by the nature of the counter-ion. The complexes were also characterized by vibrational spectroscopy (IR)

A Mononuclear and a Mixed-Valence Chain Polymer Arising from Copper(II) Halide Chemistry and the Use of 2,2′-Pyridil

Reactions of 2,2′-pyridil (pyCOCOpy) with CuCl2 · 2H2O and CuBr2 in EtOH yielded the mononuclear complex [Cu(pyCOOEt)2Cl2] · H2O (1) and the one-dimensional, mixed-valence complex [Cu2ICuII(pyCOOEt)2Br4]n (2), respectively. Both complexes crystallize in the triclinic space group P 1¯. The lattice constants are a = 8.382(2), b = 9.778(2), c = 7.814(2), α = 101.17(1), β = 114.55(1), γ = 94.14(1)° for 1 and a = 8.738(1), b = 9.375(2), c = 7.966(1), α = 79.09(1), β = 64.25(1), γ = 81.78(1)° for 2. 2,2′-pyridil undergoes a metal-assisted alcoholysis and oxidation leading to decomposition and yielding the ethyl picolinate (pyCOOEt) ligand. The autoredox process associated with the reduction of copper(II) to copper(I) in the case of complex 2 is discussed in terms of the increased redox activity of the copper(II) bromide system relative to the copper(II) chloride system

Chemically modified electrodes with MOFs for the determination of inorganic and organic analytes via voltammetric techniques: a critical review

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

A Mononuclear and a Mixed-Valence Chain Polymer Arising from Copper(II) Halide Chemistry and the Use of 2,2'-Pyridil

Reactions of 2, 2 -pyridil (pyCOCOpy) with (2) , respectively. Both complexes crystallize in the triclinic space group P 1. The lattice constants are a = 8.382(2), b = 9.778(2), c = 7.814(2), α = 101.17(1), β = 114.55(1), γ = 94.14(1) • for 1 and a = 8.738(1), b = 9.375(2), c = 7.966(1), α = 79.09(1), β = 64.25(1), γ = 81.7

Synthesis, Structure, and Antiproliferative Activity of Three Gallium(III) Azole Complexes

As part of our interest into the bioinorganic chemistry of gallium, gallium(III) complexes of the azole ligands 2,1,3-benzothiadiazole (btd), 1,2,3-benzotriazole (btaH), and 1-methyl-4,5-diphenylimidazole (L) have been isolated. Reaction of btaH or btd with GaBr3 or GaCl3 resulted in the mononuclear complexes [GaBr3(btaH)2] (1) and [GaCl3(btd)2] (2), respectively, while treatment of GaCl3 with L resulted in the anionic complex (LH)2[GaCl4] (3). All three complexes were characterized by single-crystal X-ray crystallography and IR spectroscopy, while their antiproliferative activities were investigated against a series of human and mouse cancer cell lines

Unravelling the mechanism of water sensing by the Mg2+ dihydroxy-terephthalate MOF (AEMOF-1 ‘)

In this contribution we build upon our previous work on the MOF [Mg(H(2)dhtp)(H2O)(2)]center dot DMAc (AEMOF-1 center dot DMAc) and its activated dry version AEMOF-1 ‘ which has been shown to exhibit excellent luminescence sensing properties towards water in organic solvents. We demonstrate through combined structural and photophysical studies that the observed changes in the fluorescence properties of AEMOF-1 ‘ upon hydration arise from a structural transformation to the mononuclear complex [Mg(H(2)dhtp)(H2O)(5)]center dot H2O (H(4)dhtp = 2,5-dihydroxyterepthalic acid) (1). In the latter complex, excited state intramolecular proton transfer (ESIPT) is strongly favoured thereby leading to enhanced and red shifted emission in comparison to AEMOF-1 center dot DMAc. Powder X-ray diffraction measurements confirmed that complex 1 is identical to the hydrated form of AEMOF-1 center dot DMAc. As in the case of AEMOF-1 ‘, the dry form of complex 1 (1 ‘) is also an effective sensor for the determination of traces of water in tetrahydrofuran (THF). This work demonstrates that the same chromophore may exhibit very different emission properties when it exists in different chemical environments and that these transformations may be controlled and utilized in water sensing applications

A general synthetic route for the preparation of high-spin molecules: Replacement of bridging hydroxo ligands in molecular clusters by end-on azido ligands

Abstract A general method of increasing the ground-state total spin value of a polynuclear 3d-metal complex is illustrated through selected examples from cobalt(II) and nickel(II) cluster chemistry that involves the dianion of the gem-diol form of di-2-pyridyl ketone and carboxylate ions as organic ligands. The approach is based on the replacement of hydroxo bridges, that most often propagate antiferromagnetic exchange interactions, by the end-on azido ligand, which is a ferromagnetic coupler