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The reaction of select copper(II) monocarboxylates Cu(RCOO)2(H2O)x (R = C4H3O, C6H5, H; x = 2, 4) with pyrazole (Hpz), carried out in protic solvents, yields mono- or dinuclear species [Cu(RCOO)2(Hpz)n]m (n = 2, 4; m = 1, 2), always accompanied by tri- or hexanuclear derivatives based on the triangular [Cu3(μ3-OH)(μ-pz)3]2+ fragment. The molecular structures of all isolated compounds have been established through XRD determinations. In some cases, the mono-, or dinuclear species act as secondary building units, self-assembling into 1D or 3D coordination polymers. The hexanuclear benzoate cluster contains coordinated and crystallization MeOH molecules, whose removal generates a crystalline 1D coordination polymer that can be reconverted into the hexanuclear cluster by soaking in MeOH. The relatively high pKb values of carboxylate anions employed in the syntheses are responsible for the preferential formation of mono- or dinuclear species rather than tri- or hexanuclear ones.

A plausible path for the Cu-3(mu(3)-OH)(mu-Pz)(3) core formation is herein proposed by theoretically modelling the reaction in water between [Cu-2(RCOO)(4)](n), (R = CH3(CH2)(2)) and HPz, which yields the hexanuclear species [{Cu-3(mu(3)-OH)(mu-Pz)(3)(RCOO)(2)(CH3OH)(H2O)}(2)]. We focused on the A -> B reaction (A = [Cu-2(RCOO)(4)(H2O)(2)]; B = [Cu-3(mu(3)-OH)(mu-Pz)(3)(RCOO)(2)(CH3OH)(H2O)]) with the final goal of pinpointing stable intermediates, tightened by experimental conditions, by exploiting the outcomes of numerical experiments carried out in the habit of the density functional theory. (C) 2017 Elsevier B.V. All rights reserved.

A series of copper(II) pyrazolates were synthesized employing different synthetic approaches. By refluxing either [Cu3(μ3-OH)(μ-pz)3(CH3COO)2(pzH)] (pzH = pyrazole) or [Cu(μ-pz)2·H2O]n in water, [Cu(μ-pz)(μ-OH)]n (1) was unexpectedly obtained, whereas the reactions of copper(II) acetate hydrate with pzH or 4-XpzH (4-XpzH = 4-Xpyrazole, X = Cl, Br, I) in dimethylformamide (DMF) by microwave-assisted solvothermal syntheses yielded the compounds [Cu(μ-pz)2(μ-DMF)]n (2DMF) or [Cu(μ-4-Xpz)2(μ-DMF)]n (3DMF–5DMF). As unveiled by powder X-ray diffraction, all these compounds are 1-D coordination polymers showing square planar trans-CuN2O2 (1) or octahedral trans-CuN4O2 (2DMF–5DMF) metal centers, reasonably involved in through-bond antiferromagnetic interactions (magnetic susceptibility in the range 0.91–1.56 B.M.). Theoretical calculations carried out on these compounds at the B3LYP-D* level confirmed the structural aspects and IR spectroscopy features unveiled experimentally. Upon heating, 2DMF–5DMF reversibly lose DMF to give the corresponding low-crystallinity coordination polymers [Cu(μ-pz)2]n (2) and [Cu(μ-4-Xpz)2]n (3–5), of which only 3 was characterized in the past. In order to shed light on the local-level structural features of 2, 4 and 5, UV-Vis-NIR absorption and fluorescence emission spectroscopy measurements were performed, the results suggesting a tetrahedral stereochemistry for the metal centres.

The reaction of copper(II) chloroacetate (1d) with pyrazole (Hpz) mainly yielded the mononuclear compound [Cu(μ-ClCH2COO)2(Hpz)2] (2m), which self-assembled generating a one-dimensional coordination polymer. Moreover, the concomitant isolation of the tetranuclear [{Cu2(μ-pz)(μ-OCH2COO)(Hpz)(MeOH)}2(μ-ClCH2COO)2] (3t) and hexanuclear [{Cu3(μ3-OH)(μ-pz)3(Hpz)2}2(μ-ClCH2COO)2](Cl)2 (4h) species evidenced the occurrence of a peculiar, previously unreported, dehydrochlorination reaction and the formation of the trinuclear triangular moiety [Cu3(μ3-OH)(μ-pz)3]. Theoretical calculations based on density functional theory including solvation effects indicate a possible pathway for the formation of 3t. Interestingly, besides the energy minimum corresponding to 3t, a further relative energy minimum is found for a species which can be considered a possible reaction intermediate.

The reactions of 4,4'-bipyridine with selected trinuclear triangular copper(II) complexes, [Cu-3(mu(3)-OH)(mu-pz)(3)(RCOO)(2)L-x], [pz = pyrazolate anion, R = CH3(CH2)(n) (2

[object Object]Different synthetic procedures lead to different coordination polymers (CPs) based either on the trinuclear triangular [Cu3(? 3-OH)(?-pz)3]2+ or on the mononuclear [Cu(Hpz)3]2+ (Hpz=pyrazole) secondary building units (SBUs), bridged by the flexible glutarate (Glu) dianion. The mononuclear complex [Cu(HGlu)2(Hpz)4] was also obtained as byproduct. One of the CPs based on the trinuclear SBU displays a relevant porosity due to three intersecting channels, accounting for about 40% of the solvent accessible void space.

By reacting 4,4′-bipyridine (bpy) with selected trinuclear triangular CuII complexes, [Cu3(μ3-OH)(μ-pz)3(RCOO)2(LL′)] [pz = pyrazolate anion; R = CH3, CH3CH2, CH2═CH, CH2═C(CH3); L, L′ = Hpz, H2O, MeOH] in MeOH, the substitution of monotopic ligands by ditopic bpy was observed. Depending on the stoichiometric reaction ratios, different compounds were isolated and structurally characterized. One- and two-dimensional coordination polymers (CPs), as well as two hexanuclear CuII clusters were identified. One of the hexanuclear clusters self-assembles into a supramolecular three-dimensional structure, and its crystal packing shows the presence of two intersecting channels, one of which is almost completely occupied by guest bpy, while in the second one guest water molecules are present. This compound also shows a reversible, thermally induced, single-crystal-to-single-crystal transition.

By reacting 4,4'-bipyridine (bpy) with selected trinuclear triangular Cu-II complexes, [Cu-3(mu(3)-OH)(mu-pz)(3)(RCOO)(2)(LL')] [pz = pyrazolate anion; R = CH3, CH3CH2, CH2=CH, CH2=C(CH3); L, L' = Hpz, H2O, MeOH] in MeOH, the substitution of monotopic ligands by ditopic bpy was observed. Depending on the stoichiometric reaction ratios, different compounds were isolated and structurally characterized. One- and two-dimensional coordination polymers (CPs), as well as two hexanuclear Cu-II clusters were identified. One of the hexanuclear clusters self-assembles into a supramolecular three-dimensional structure, and its crystal packing shows the presence of two intersecting channels, one of which is almost completely occupied by guest bpy, while in the second one guest water molecules are present. This compound also shows a reversible, thermally induced, single-crystal-to-single-crystal transition.

A quick, easy and green water-based synthesis protocol involving coprecipitation of oxalates combined with hydrothermal treatment resulted in the crystallisation of nanostructured manganites at a relatively low temperature (180 °C). The subcritical hydrothermal approach was shown to play a key role in stabilising phases which are generally achieved at much higher temperatures and under harsher conditions, thus disclosing an exciting alternative for their synthesis. Through this mild wet chemistry approach, the compounds CuMnO2, ZnMn2O4 and ZnMnO3 were synthesised as nanocrystalline powders. Noticeably, the optimised route proved to be effective in stabilising the exotic polymorph cubic spinel ZnMnO3 in pure form. This is particularly notable, as very few records concerning this compound are available in the literature. The compounds were fully characterised from compositional, structural, morphological and magnetic points of view.

none 9 The reaction of some saturated and unsaturated aliphatic copper(II) monocarboxylates, Cu(RCOO)2 [R = C6H5CH2 (phenylacetate, Phac), CH2[dbnd]CHCH2 (vinylacetate, Vnac), C6H5CH[dbnd]CH (3-trans-phenylacrylate, Phacr), C6H5(CH2)2 (3-phenylpropionate, Phpr), c-C6H11 (ciclo–hexylcarboxylate, c-Hexc), CH3(CH2)10 (laurate, Lau), CH3(CH2)12 (myristate, Myr), (CH3)3C (pivalate, Piv)] with pyrazole (Hpz) and water in protic solvents, yielded trinuclear triangular derivatives based on the [Cu3(μ3-OH)(μ-pz)3] fragment whose double positive charge is balanced by two coordinated carboxylate ions, actually [Cu3(μ3-OH)(μ-pz)3(Phac)2], 1, [Cu3(μ3-OH)(μ-pz)3(Vnac)2(Hpz)], 2, [Cu3(μ3-OH)(μ-pz)3(Phacr)2], 3, [Cu3(μ3-OH)(μ-pz)3(Phpr)2(Hpz)Cu3(μ3-OH)(μ-pz)3(Phpr)2(Hpz)(H2O)]·xH2O·yMeOH, 4, [Cu3(μ3-OH)(μ-pz)3(c-Hexc)2], 5, [Cu3(μ3-OH)(μ-pz)3(Lau)2], 6, [Cu3(μ3-OH)(μ-pz)3(Myr)2], 7, [Cu3(μ3-OH)(μ-pz)3(Piv)2(HPz)(HPiv)2], 8. This behavior is consistent with some previously observed features and evidences that the basicity of carboxylate ions is the key for the deprotonation of Hpz and water, leading to the formation of pz− and OH− ions, which are determinant for the self-assembly of the trinuclear triangular species. Single crystal XRD determinations evidenced that in compounds 1, 2 and 5 the trinuclear moieties further self-assemble generating monodimensional coordination polymers or, in one case (compound 4), a dodecanuclear discrete assembly. Massignani, Sara; Scatena, Rebecca; Lanza, Arianna; Monari, Magda; Condello, Francesca; Nestola, Fabrizio; Pettinari, Claudio; Zorzi, Federico; Pandolfo, Luciano Massignani, Sara; Scatena, Rebecca; Lanza, Arianna; Monari, Magda; Condello, Francesca; Nestola, Fabrizio; Pettinari, Claudio; Zorzi, Federico; Pandolfo, Luciano

In the past decade great effort has been put into the development of synthetic strategies to produce trinuclear triangular CuII (TTC) arrays, which may be synthetic analogues of the trinuclear site in ascorbate oxidase and blue oxidase. A large number of scientific contributions have been dedicated to the synthesis and spectroscopic characterization of TTC arrays. In contrast, only a small number of studies deal with their possible applications. As a consequence, systematic studies describing their reactivity are very rare and the few existing models can only partially explain how structural and molecular parameters influence their reactivity and their possible uses and applications. This contribution reports a summary of all experimental results related to the Cu3(μ3-OH)(μ-pz)3 core (pz = unsubstituted pyrazolate). We describe here all species, distinguishing them according to whether they are neutral, cationic or anionic, as well as their main structural features, the synthetic procedures employed for their production, their reactivity toward nucleophiles and strong acids and, finally, their possible and perspective applications.

Hydrated zinc(II) formate reacts with 2,2′-bipyridine (2,2′-bpy) to form a novel zig-zag mono-dimensional coordination polymer (1D CP) [{Zn(μ-OCHO)(OCHO)(2,2′-bpy)(HO)}·HO], 1, which was structurally characterized by a single-crystal X-ray diffraction study. Title compound crystallizes in the orthorhombic system, Pbca space group, [a = 6.7651(8), b = 17.4876(19), c = 23.180(3)]. Each zinc ion displays a distorted octahedral geometry due to the coordination of a monotopic formate, one molecule of water and the two nitrogen atoms of 2,2′-bpy, while the octahedral scheme is completed by the coordination of a ditopic formate connecting two zinc ions according to a syn-anti configuration, thus generating the polymeric structure. Moreover, a crystallization water molecule acts as a supramolecular bridge connecting formate ions belonging to neighboring, symmetry equivalent, 1D CPs through quite strong H-bonds, thus leading to an overall waved 2D open framework. Thermal analyses show significant weight losses corresponding to the elimination of water molecules followed by the decomposition of both formate groups and 2,2′-bipyridine., Financial support from the University of Camerino, the Junta de Andalucía (Grant 2009/FQM-4826) and CSIC (Grant PIF/2008-017-1) is gratefully acknowledged.

The controlled, room-temperature synthesis of M-doped (M = CuII, MnII, SmIII, GdIII, or TbII) ZnS nanostructures (with an average crystallite size of 5-10 nm) in the confined space of miniemulsion droplets is reported herein and discussed. The adopted synthetic route is a colloidal method, ideally suited to easily achieve small particle size and narrow size distribution. The synthesized functional nanostructures crystallize in the sphalerite lattice, as determined by powder X-ray diffraction. In addition to structural characterization, several complementary techniques, such as X-ray photoelectron spectroscopy, thermogravimetric analysis, differential scanning calorimetry, micro-Raman spectroscopy, inductively coupled plasma mass spectrometry, and Fourier transform infrared spectroscopy were used to determine chemical and physical properties as well as the microstructural features of our products. As far as the morphological aspects of the obtained samples are concerned, they were studied by means of scanning and transmission electron microscopies. Finally, the local structure around dopant ions was unravelled by means of X-ray absorption spectroscopy, in particular through extended X-ray absorption fine structure measurements carried out at the Zn, S, and dopant K or L3 edges. This information has been complemented with the investigation of the photoluminescence properties.

The low-lying empty orbitals of bis(acetylacetonato)copper have been probed by near-edge X-ray absorption fine structure (NEXAFS) spectroscopy at the Cu L2,3 edges and time-dependent density functional theory (TDDFT) calculations within the Tamm-Dancoff approximation (TDA) coupled to the relativistic zeroth-order regular approximation including spin-orbit effects (SO-ZORA TDDFT-TDA). Both the relative positions of NEXAFS features and their linear dichroism are satisfactorily reproduced. Moreover, a comparison with literature data pertaining to two other square-planar CuII complexes ([CuCl4]2- and copper phthalocyanine) provided information about how metal-to-ligand charge-transfer transitions associated with excitations from CuII 2p orbitals to low-lying, ligand-based ?* molecular orbitals in a simplified one-electron picture may contribute to the CuII L2,3 edge intensity and, thus, weaken its believed relationship with the CuII-ligand symmetry-restricted covalency.