Inorganic-organic hybrid double sulfates as catalysts of the diastereoselective nitroaldol reaction

International audienceBis(1-phenylethanaminium) disulfatotetraaquazincate(II) dihydrate (C8H12N)2[Zn(H2O)4(SO4)2]*2H2O (1), bis(1H-benzo[d]imidazolium) hexaaquazinc(II) bis(sulfate) tetrahydrate (C7H7N2)2[Zn(H2O)6](SO4)2*4H2O (2) and bis(2-methyl-1H-imidazolium) hexaaquazinc(II) bis(sulfate) dihydrate (C4H7N2)2[Zn(H2O)6](SO4)2*2H2O (3) have been synthesized and fully structurally characterized including single-crystal X-ray diffraction analysis. 1-3 are organically templated hybrid layered materials comprising aquazinc(II) and aminium cations and sulfate anions. 1-3 are effective catalysts in the asymmetric Henry reaction; 1 being the most efficient one (yields up to 85% and threo/erythro diastereoselectivity up to 89:11)

Synthesis, structure and electrochemical behaviour of Na, Mg-II, Mn-II, Cd-II and Ni-II complexes of 3-(2-carboxyphenylhydrazone)pentane-2,4-dione

Mononuclear manganese(II) [Mn(kappa O-HL)(2)(CH3OH)(4)] (4), nickel(II) [Ni(kappa O-2, kappa N-L)(H2O)(3)] (5), cadmium(II) [Cd(kappa O-2-HL)(2)(CH3OH)(3)] (7), tetranuclear zinc(II) [Zn-4(mu-OH)(2)(1 kappa O:2 kappa O-HL)(4)(kappa O-HL)(2)(H2O)(4)] (6) and polynuclear aqua sodium(I) [Na(H2O)(2)(mu-H2O)(2)](n)(HL)(n) (2) and magnesium(II) [Mg(OH)(H2O)(mu-H2O)(2)](n)(-HL)(n) (3) complexes were synthesized using 3-(2-carboxyphenyl-hydrazone)pentane-2,4-dione (H2L, 1) as a ligand precursor. The complexes were characterized by single crystal X-ray diffraction, elemental analysis, IR, H-1 and C-13 NMR (for 2, 3, 6 and 7) spectroscopies. Mono- or dianionic deprotonated derivatives of H2L display different coordination modes and lead to topologies and nuclearities of the complexes depending on metal ions and conditions used for the syntheses. Extensive intermolecular H-bonds form supramolecular arrangements in 1D chains (4 and 6), 1D chains of the organic anion and 2D networks of the metal-aqua aggregates (2 and 3), 2D networks (7) or even 3D frameworks (5). Electrochemical studies, by cyclic voltammetry and controlled potential electrolysis, show ligand centred redox processes as corroborated by theoretical DFT calculations in terms of LUMO and HOMO compositions. (C) 2012 Elsevier Ltd. All rights reserved

Microwave-assisted and solvent-free peroxidative oxidation of 1-phenylethanol to acetophenone with a CuII–TEMPO catalytic system

Abstract The water-soluble copper(II) complex [Cu(H2R)(HL)]∙H2O (1) was prepared by reaction of copper(II) nitrate hydrate with (E)-2-(((1-hydroxynaphthalen-2-yl)methylene)amino) benzenesulfonic acid (H2L) and diethanolamine (H3R). It was characterized by IR and ESI-MS spectroscopies, elemental and X-ray crystal structural analyses. 1 shows a high catalytic activity for the solvent-free microwave (MW) assisted oxidation of 1-phenylethanol with tert-butylhydroperoxide, leading, in the presence of TEMPO, to yields up to 85% (TON = 850) in a remarkably short reaction time (15 min, with the corresponding TOF value of 3.40 × 103 h− 1) under low power (25 W) MW irradiation

Complexes of copper(II) with 3-(ortho-substituted phenylhydrazo)pentane-2,4-diones: syntheses,properties and catalytic activity for cyclohexane oxidation

Reactions of copper(II) with 3-phenylhydrazopentane-2,4-diones X-2-C6H4-NHN = C{C(= O)CH3}(2) bearing a substituent in the ortho-position [X = OH (H2L1) 1, AsO3H2 (H3L2) 2, Cl (HL3) 3, SO3H (H2L4) 4, COOCH3 (HL5) 5, COOH (H2L6) 6, NO2 (HL7) 7 or H (HL8) 8] lead to a variety of complexes including the monomeric [CuL4(H2O)(2)]center dot H2O 10, [CuL4(H2O)(2)] 11 and [Cu(HL4)(2)(H2O)(4)] 12, the dimeric [Cu-2(H2O)(2)(mu-HL2)(2)] 9 and the polymeric [Cu(mu-L-6)](n)] 13 ones, often bearing two fused six-membered metallacycles. Complexes 10-12 can interconvert, depending on pH and temperature, whereas the Cu(II) reactions with 4 in the presence of cyanoguanidine or imidazole (im) afford the monomeric compound [Cu(H2O)(4){NCNC(NH2)(2)}(2)](HL4)(2)center dot 6H(2)O 14 and the heteroligand polymer [Cu(mu-L-4)(im)](n) 15, respectively. The compounds were characterized by single crystal X-ray diffraction (complexes), electrochemical and thermogravimetric studies, as well as elemental analysis, IR, H-1 and C-13 NMR spectroscopies (diones) and ESI-MS. The effects of the substituents in 1-8 on the HOMO-LUMO gap and the relative stability of the model compounds [Cu(OH)(L-8)(H2O)]center dot H2O, [Cu(L-1)(H2O)(2)]center dot H2O and [Cu(L-4)(H2O)(2)]center dot H2O are discussed on the basis of DFT calculations that show the stabilization follows the order: two fused 6-membered > two fused 6-membered/5-membered > one 6-membered metallacycles. Complexes 9, 10, 12 and 13 act as catalyst precursors for the peroxidative oxidation (with H2O2) of cyclohexane to cyclohexanol and cyclohexanone, in MeCN/H2O (total yields of ca. 20% with TONs up to 566), under mild conditions

Trends in properties of para-substituted 3-(phenylhydrazo)pentane-2,4-diones

Trends between the Hammett's sigma(p) and related normal sigma(n)(p), inductive sigma(I), resonance sigma(R), negative sigma(-)(p) and positive sigma(+)(p) polar conjugation and Taft's sigma(o)(p) substituent constants and the N-H center dot center dot center dot O distance, delta(N-H) NMR chemical shift, oxidation potential (E-p/2(ox), measured in this study by cyclic voltammetry (CV)) and thermodynamic parameters (pK, Delta G(0), Delta H-0 and Delta S-0) of the dissociation process of unsubstituted 3-(phenylhydrazo)pentane-2,4-dione (HL1) and its para-substituted chloro (HL2), carboxy (HL3), fluoro (HL4) and nitro (HL5) derivatives were recognized. The best fits were found for sigma(p) and/or sigma(-)(p) in the cases of d(N center dot center dot center dot O), delta(N-H) and E-p/2(ox), showing the importance of resonance and conjugation effects in such properties, whereas for the above thermodynamic properties the inductive effects (sigma(I)) are dominant. HL2 exists in the hydrazo form in DMSO solution and in the solid state and contains an intramolecular H-bond with the N center dot center dot center dot O distance of 2.588(3)angstrom. It was also established that the dissociation process of HL1-5 is non-spontaneous, endothermic and entropically unfavourable, and that the increase in the inductive effect (sigma(I)) of para-substitutents (-H < -Cl < -COOH < -F < -NO2) leads to the corresponding growth of the N center dot center dot center dot O distance and decrease of the pK and of the changes of Gibbs free energy, of enthalpy and of entropy for the HL1-5 acid dissociation process. The electrochemical behaviour of HL1-5 was interpreted using theoretical calculations at the DFT/HF hybrid level, namely in terms of HOMO and LUMO compositions, and of reactivities induced by anodic and cathodic electron-transfers. Copyright (C) 2010 John Wiley & Sons, Ltd

A bio-based alginate aerogel as an ionic liquid support for the efficient synthesis of cyclic carbonates from co2 and epoxides

Funding Information: This work was supported by Ministerio de Ciencia y Universidades (project RTI2018-097456-B-I00) and Funda??o para a Ci?ncia e Tecnologia FCT/MCTES (project PTDC/EQU-EPQ/31926/2017), UIDB/50006/2020 of the Associate Laboratory for Green Chemistry?LAQV and UIDB/00100/2020 of Centro de Qu?mica Estrutural. This work was also supported by a Short Term Scientific Mission of the CMST COST Action CM1206. A.B. Paninho is thankful to FCT for the doctoral fellowship PD/BD/52497/2014 and pos-doctoral fellowship PTDC/EQU-EPQ/31926/2017. The authors also thanks to the project ?SunStorage-Harvesting and storage of solar energy?, with reference POCI-01-0145-FEDER-016387, funded by European Regional Development Fund (ERDF), through COMPETE 2020-Operational Program. The NMR spectrometers at FCT NOVA are part of Rede Nacional de RMN (PTNMR), supported by FCT/MCTES through ROTEIRO/0031/2013? PINFRA/22161/2016 and co-financed by FEDER through COMPETE 2020, POCI, and PORL and FCT/MCTES through PIDDAC.In this work, the ionic liquid [Aliquat][Cl] was supported into alginate and silica aerogel matrices and applied as a catalyst in the cycloaddition reaction between CO2 and a bio-based epoxide (limonene oxide). The efficiency of the alginate aerogel system is much higher than that of the silica one. The method of wet impregnation was used for the impregnation of the aerogel with [Aliquat][Cl] and a zinc complex. The procedure originated a well-defined thin solvent film on the surface of support materials. Final materials were characterised by Fourier Transform Infrared Spectroscopy, N2 Adsorption–Desorption Analysis, X-ray diffraction, atomic absorption and Field Emission Scanning Microscopy. Several catalytic tests were performed in a high-pressure apparatus at 353.2 K and 4 MPa of CO2.publishersversionpublishe

DNA and BSA binding, anticancer and antimicrobial properties of Co(II), Co(II/III), Cu(II) and Ag(I) complexes of arylhydrazones of barbituric acid

Two new cocrystalline compounds, (Hen)(H2L2)$2/3H2O (2) and (Him)(H3L3)$2H2O (8), were prepared by the reaction of 5-(2-(4-chlorophenyl)hydrazono)pyrimidine-2,4,6(1H,3H,5H)-trione (H3L2) and the sodium salt of 2-(2-(2,4,6-trioxotetrahydropyrimidin-5(2H)-ylidene)hydrazinyl)benzenesulfonic acid (H4L3), [Na(H3L3)(m-H2O)(H2O)2]2 (1) with protonated ethylenediamine (Hen) and imidazole (Him), respectively. By using 5-(2-(2-hydroxyphenyl)hydrazono)pyrimidine-2,4,6(1H,3H,5H)-trione (H4L1) and 1, several known CuII, CoII, CoII/III and new AgI complexes, [Cu(H2L1)(H2O)(im)]$3H2O (3), [Co(H2O)6]- [Co(H2L1)2]2$8H2O (4), [Co(H2L3)(im)3] (5), [Cu(H2L3)(im)2]$H2O (6), [Ag(H2O)(m-H3L3)]n (7) and [Co(H2O)6]- [H3L3]2$8H2O (9), were also prepared in order to study their DNA and BSA binding, anticancer and antimicrobial properties. The complexes are able to interact with DNA and BSA with high binding constant values. In particular, complex 4 strongly intercalates DNA and binds BSA. The antimicrobial activity of all compounds, determined against a panel of reference bacterial and fungal strains, indicates that only 2 and 7 possess antimicrobial activity. The same compounds 2 and 7 show a pronounced antiproliferative activity against the human tumor cell lines A375, MDA-MB 231 and HCT116

A Computational Fluid Dynamics Approach for Dissolved Oxygen Modelling with Application to Wind-powered Aeration Systems

Dissolved oxygen is one of the most critical parameters of water quality in aquaculture. Aeration systems are generally used to improve oxygen levels and yields. However, these systems have high capital and operating cost, require electricity and, thus, are out of reach for farmers in developing countries. There is a need for affordable and sustainable aeration technologies. This thesis presents the development of a computational dissolved oxygen model which evaluates the spatial and temporal distribution of dissolved oxygen to enable evaluation and optimization of new aeration approaches. The three-dimensional model was developed based on Finite Volume Method and validated by bench-scale and field experiments. Results showed that the model was capable of predicting the dissolved oxygen concentration with an average prediction error of 7.2%.M.A.S

Iron(III) and cobalt(III) complexes with both tautomeric (keto and enol) forms of aroylhydrazone ligands: catalysts for the microwave assisted oxidation of alcohols

Two Schiff bases derived from the condensation of 2-hydroxybenzohydrazide with 3,5-di-tert-butyl-2-hydroxybenzaldehyde (H2L1) or with 2,3-dihydroxy benzaldehyde (H2L2) were used to synthesize the Fe(III) and Co(III) complexes [Fe(L-1)(HL1)] (1) and [Co(L-2)(HL2)] (2), respectively. The compounds were characterized by elemental analysis, IR, ESI-MS and single crystal X-ray analysis. Structural studies indicated the presence of both keto and enol tautomeric forms of the ligand in 1 and 2. The complexes (mainly 1) act as catalysts in the microwave-assisted solvent-free peroxidative oxidation (by tert-butylhydroperoxide, TBHP) of primary and secondary alcohols. A facile, efficient and selective synthesis of ketones was achieved with a yield up to 96% and a TON up to 500, after 30 min under low power (15 W) microwave irradiation (complex 1 as catalyst). 2-Pyrazinecarboxylic acid (Hpca) shows a promoting effect.info:eu-repo/semantics/publishedVersio