- Synthesis and characterization of polydentate schiff-base ligands and their complexes
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In this study, we synthesized the amine compounds 2-{(E)-[(2-aminoethyl) imino]methyl}phenol (H3A) and 2-{(E)-[(3-aminopropyl)imino]methyl}-6- methoxyphenol (H3B) as the starting materials. From reactions of the starting materials with 2-hydroxy-5-methylisophthalaldehyde, phthalaldehyde, and 2-hydroxy-5-t-butylisophthalaldehyde, we prepared the new ligands H 3L1-H3L3 and H2L. The Cu(II) and Cd(II) complexes of the ligands have been obtained. Microanalytical data, magnetic moment, 1H(13C) NMR, mass spectra, FT-IR, and conductivity measurements have been used to explain the structures of the ligands and their complexes. The protonation constants of the ligands H 3L1-H3L3 have been studied in a 1:1 molar ratio (M:L). Protonation and stability constants of the Schiff bases and their Cu(II) and Cd(II) complexes have been determined by the potentiometric titration method in 50% dioxane-water media at 25.00 ± 0.02°C under a nitrogen atmosphere and ionic strength of 0.1M NaClO4. The ligands H3L1-H3L3 have seven protonation constants. In other words, the ligand H2L has six protonation constants. The variation of protonation constants of these compounds were interpreted on the basis of structural effects exposed by the substituents.
- Demirelli, Havva,Tuemer, Mehmet,Goelcue, Ayseguel
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- Synthesis, characterization and properties of some divalent metal(II) complexes: Their electrochemical, catalytic, thermal and antimicrobial activity studies
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In this study, we synthesized the amine compound 2-(2-aminoethyliminomethyl)phenol (H3A) as the starting material, and then we prepared the polydentate Schiff base ligands from the reactions of the amine compound (H3A) with phtaldialdehyde (H2L), 4-methyl-2,6-di-formlyphenol (H3L1) and 4-t-butyl-2,6-di-formylphenol (H3L2) in the ethanol solution. Moreover, the complexes Cd(II), Cu(II), Co(II), Ni(II), Zn(II) and Sn(II) of the ligands H2L, H3L1 and H3L2 have been prepared. All compounds have been characterized by the analytical and spectroscopic methods. In addition, the magnetic susceptibility and molar conductance measurements have been made. The catalytic properties of the mono- and binuclear Co(II) and Cu(II) complexes have been studied on the 3,5-di-tert-butylcatechol (3,5-DTBC) and ascorbic acid (aa) as a substrate. The oxidative C-C coupling properties of the Co(II) and Cu(II) complexes have been investigated on the sterically hindered 2,6-di-tert-butylphenol (dtbp). The antimicrobial activity properties of the ligands and their mono- and binuclear complexes have been studied against the bacteria and fungi. The results have been compared to the antibacterial and fungi drugs. The TGA curves show that the decomposition takes place in three steps for all complexes. Electrochemical properties of the complexes Cu(II) and Ni(II) have been investigated for the first time in acetonitrile by cyclic voltammetry.
- Tuemer, Mehmet,Ekinci, Duygu,Tuemer, Ferhan,Bulut, Akif
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- Preparation of monosodium 2-sulfoterephthalate to make a MIL-101(Cr)-SO3H catalyst
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MIL-101(Cr)-SO3H has excellent thermal and chemical stabilities, making it an ideal porous acid catalyst for many organic reactions and petrochemical industries. However, there are some disadvantages such as the fact that it is not easy to mass produce crystalline MIL-101(Cr)-SO3H and it is time-consuming to purchase the starting organic ligand of 2-sulfoterephthalate monosodium (sTA-Na). In this study, readily available p-xylene (1,4-dimethylbenzene) was used as the raw material for the lab-synthesis of sTA-Na. Some optimal conditions were studied and established to obtain a maximum sTA-Na yield of ~75%. The prepared sTA-Na was characterized by FT-IR, PXRD, FE-SEM, NMR and MS spectroscopies, showing that its functional groups, molecular structure, and molecular weight are the same as those of the commercial counterpart from TCI company; however, their particle shapes and crystal phases are different. Then, the MIL-101(Cr)-SO3H powder was prepared from the lab-synthesized sTA-Na and used as a catalyst in ethylene dichloride (EDC) cracking to produce a vinyl chloride monomer (VCM). The catalytic activity test in the EDC cracking showed that the reaction temperature can be lowered to 255 °C from 550 °C, while the percentage conversion (~75%) and the selectivity (99.8%) remain unchanged or even better than those in current industrial processes, indicating that MIL-101(Cr)-SO3H is a promising catalyst applied as an energy efficiency technology in the EDC cracking to produce VCM.
- Lee, Kuo-Tong,Pien, Chien-Yi
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p. 868 - 876
(2022/01/22)
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- Cross-Linked Artificial Enzyme Crystals as Heterogeneous Catalysts for Oxidation Reactions
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Designing systems that merge the advantages of heterogeneous catalysis, enzymology, and molecular catalysis represents the next major goal for sustainable chemistry. Cross-linked enzyme crystals display most of these essential assets (well-designed mesoporous support, protein selectivity, and molecular recognition of substrates). Nevertheless, a lack of reaction diversity, particularly in the field of oxidation, remains a constraint for their increased use in the field. Here, thanks to the design of cross-linked artificial nonheme iron oxygenase crystals, we filled this gap by developing biobased heterogeneous catalysts capable of oxidizing carbon-carbon double bonds. First, reductive O2 activation induces selective oxidative cleavage, revealing the indestructible character of the solid catalyst (at least 30 000 turnover numbers without any loss of activity). Second, the use of 2-electron oxidants allows selective and high-efficiency hydroxychlorination with thousands of turnover numbers. This new technology by far outperforms catalysis using the inorganic complexes alone, or even the artificial enzymes in solution. The combination of easy catalyst synthesis, the improvement of "omic" technologies, and automation of protein crystallization makes this strategy a real opportunity for the future of (bio)catalysis.
- Lopez, Sarah,Rondot, Laurianne,Leprêtre, Chloé,Marchi-Delapierre, Caroline,Ménage, Stéphane,Cavazza, Christine
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supporting information
p. 17994 - 18002
(2017/12/26)
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- Syntheses and evaluation of drug-like properties of CO-releasing molecules containing ruthenium and group 6 metal
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In this paper, drug-like properties of two series of carbonyl metal CO-releasing molecules, Ru(CO)3ClnL (n = 1, L = amino acid or its derivatives 1-7, L = acetylacetone 8 or 2,2′-bipyridyl 9; n = 2, L = aminopyridine derivatives 10-13; n = 0, L = salicylaldehyde Schiff base 14-15) and M(CO)5L(M = Cr, Mo, W; L = glycine methyl ester 16-18; L = N-methyl imidazole 19-21), were preliminarily evaluated from four aspects involving in cytotoxicity, in vivo toxicity, bio-distribution and metabolism. Cytotoxic effects of all complexes were assayed by MTT. IC50 values of complexes 1-15 were 39.55-240.16 mg/l, and those of complexes 16 and 18 were 21.36-22.21 mg/l. Toxicity tests of mice used oral acute toxic class method and got LD50 values of some complexes; among them, LD50 of complex 1 was in 800-1000 mg/kg, complex 7 in 1100-1500 mg/kg and complex 18 in 75-125 mg/kg. After several consecutive administrations, tested complexes severely damaged liver and kidney in both functional and morphological aspects. And by metal ions measurements using ICP-AES, we found that the tested complexes were unevenly distributed in tissues and organs. In vivo, RuII in complexes was oxidized to RuIII by P450 enzymes, and for Mo 0 and W0 in complexes, part of them transformed into higher oxidation state, the others kept original state.
- Wang, Pengpeng,Liu, Huapeng,Zhao, Quanyi,Chen, Yonglin,Liu, Bin,Zhang, Baoping,Zheng, Qian
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p. 199 - 215
(2014/02/14)
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- Synthesis, spectral characterization and X-ray crystal structure of Fe(III) and Co(III) complexes with an acyclic Schiff base ligand
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Two complexes of composition [Co(HL)2]'ClO4·CH 3OH (1) and [Fe2L3]·0.38H2O (2) (H2L = 2-((2-(2-hydrox-ybenzylamino)ethylamino)methyl)phenol) have been synthesized and their structures have been characterized. The mononuclear cobalt complex 1 shows the metal ion Co(III) in an octahedral environment, being coordinated to two ligand molecules in a N4O2 core, remaining one of the two hydroxyl phenol groups of each ligand not deprotonated and uncoordinated. Instead, complex 2 is dinuclear, and each of the two metal centers is coordinated by one molecule ligand and other ligand molecule acts as bridge between the two metal centers, resulting a distorted N4O2 octahedral environment for each Fe(III) ion. In this case the two hydroxyl phenol groups of the ligand molecules are deprotonated and coordinated. Variable-temperature solid-state magnetic studies have been performed for compound 2.
- Sow, Mouhamadou Moustapha,Diouf, Ousmane,Gaye, Mohamed,Sall, Abdou Salam,Pérez-Lourido, Paulo,Valencia-Matarranz, Laura,Castro, Goretti,Caneschi, Andrea,Sorace, Lorenzo
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p. 171 - 175
(2013/10/22)
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- Ruthenium(II) unsymmetrical N2O2 tetradentate Schiff-base complexes: Synthesis, characterization, and catalytic studies
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A series of six-coordinate ruthenium(II) complexes [Ru(CO)(Lx)(B)] (B= PPh3, AsPh3 or Py; Lx = unsymmetrical tetradentate Schiff base, x= 5-8; L5=salen-2-hyna, L6=Cl-salen-2-hyna, L7=valen-2-hyna, L8=o-hyac-2-hyna) have been prepared by reacting [RuHCl(CO) (EPh3)2(B)] (E=P or As) with unsymmetrical Schiff bases in benzene under reflux. The new complexes have been characterized by analytical and spectroscopic (infrared, electronic, 1H, 31P, and 13C NMR) data. An octahedral structure has been assigned for all the complexes. The new complexes are efficient catalysts for the transfer hydrogenation of ketones and also exhibit catalytic activity for the carbon-carbon coupling reactions.
- Gowri,Muthukumar,Krishnaraj,Viswanathamurthi,Prabhakaran,Natarajan
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experimental part
p. 524 - 533
(2010/11/05)
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- A convenient synthesis of nickel(II) and cobalt(II) complexes of unsymmetrical salen-type ligands and their application as catalysts for the oxidation of 2,6-dimethylphenol and 1,5-dihydroxynaphthalene by molecular oxygen
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Salen-type ligands 1-4 have been synthesized in high yields, from which the nickel(II) complexes 9-11 and the cobalt(II) complexes 12 and 13 have been prepared and characterized. The complexes have been assessed for their ability to activate molecular oxygen in the catalytic oxidation of phenols, namely, 2,6-dimethylphenol and 1,5-dihydroxynaphthalene. The nickel complexes 9-11 are inactive in the oxidation of the phenols but the cobalt complexes 12 and 13 show high catalytic activity.
- Adam, Waldemar,Saha-Moeller, Chantu R.,Ganeshpure, Pralhad A.
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- Equilibria and Absorption Spectra of Schiff Bases
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Equilibria in the formation of Schiff bases between eight aromatic aldehydes including salicylaldehyde and pyridoxal 5'-phosphate with a variety of different amines, diamines, and amino acids have been investigated.The formation constants, the acid dissociation constants of the Schiff bases, and the absorption spectra of the various ionic species of the Schiff bases have been evaluated.The spectra have been resolved into components with log normal curves to provide a precise description of the band shapes and to permit estimation of tautomerisation constants.Constants for ring closure in the Schiff bases of diamines have also been estimated.In addition to the major tautomer, which has an ortho quinonoid structure, smaller amounts of both a phenolic tautomer and a tautomer with a dipolar ionic pyridine ring are present in small amounts.Results of this study are correlated with those of previous investigation on related systems and with spectra of two enzymes.
- Metzler, Carol M.,Cahill, Allen,Metzler, David E.
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p. 6075 - 6082
(2007/10/02)
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