1120-82-7Relevant academic research and scientific papers
X-ray crystal structures and MMA polymerization of cadmium(II) complexes with bidentate pyrazole ligands: The formation of monomers or dimers as a function of a methyl substituent on the pyrazole and aniline rings
Kim, Dongil,Kim, Sunghoon,Woo, Hyun Yul,Lee, Ha-Jin,Lee, Hyosun
, p. 445 - 453 (2014)
The reaction of CdBr2·4H2O with ancillary ligands, N,N-bis(1H-pyrazolyl-1-methyl)aniline (L1), N,N-bis(1H-pyrazolyl-1-methyl)-p-methylaniline (L2), N,N-bis(1H-pyrazolyl-1-methyl)-3,5-dimethylaniline (L3), N,N-bis(3,5-dimethyl-1H-pyrazolyl-1-methyl)aniline (L4) and N,N-bis(1H-pyrazolyl-1-methyl)-2,6-dimethylaniline (L5) in ethanol yields novel Cd(II) bromide complexes, [L1CdBr2] 2, [L2CdBr2]2, [L 3CdBr2]2, [L4CdBr2] and [L5CdBr2]. The X-ray crystal structures of [L 1CdBr2]2, [L2CdBr2] 2 and [L3CdBr2]2 reveal a bromo-bridged dimeric species with crystallographic inversion symmetry. Conversely, [L4CdBr2] and [L5CdBr2] exist as monomeric complexes, presumably due to the steric hindrance between the methyl substituents of the two pyrazole groups in the ligand and cadmium centre for [L4CdBr2], and crowding around the cadmium metal by methyl substituents on the aniline residue in the ligand for [L 5CdBr2]. The geometry at each Cd(II) centre for [L 1CdBr2]2, [L2CdBr2] 2 and [L3CdBr2]2 is best described as a distorted trigonal bipyramid. A distorted trigonal bipyramid is achieved in [L4CdBr2] by coordinative interaction of the nitrogen atom of the aniline unit and the cadmium atom with a σ plane of symmetry, based on the bond length of Cd-Naniline (2.759(7) A). [L 5CdBr2] exists with a distorted tetrahedral geometry involving non-coordination of the nitrogen atom of aniline and the Cd centre, resulting in the formation of an eight-membered chelate ring. The catalytic activity of monomeric, five-coordinated [L4CdBr2] in the polymerization of methyl methacrylate (MMA) in the presence of modified methylaluminoxane (MMAO) at 60°C resulted in a higher molecular weight and a narrower polydispersity index (PDI) than those obtained with dimeric [L nCdBr2]2 (Ln=L1, L 2, L3) or monomeric tetrahedral [L5CdBr 2]. Copyright
Synthesis, structural characterization, reactivity, and catalytic properties of copper(I) complexes with a series of tetradentate tripodal tris(pyrazolylmethyl)amine ligands
Haldon, Estela,Delgado-Rebollo, Manuela,Prieto, Auxiliadora,Alvarez, Eleuterio,Maya, Celia,Nicasio, M. Carmen,Perez, Pedro J.
, p. 4192 - 4201 (2014)
Novel tris(pyrazolylmethyl)amine ligands TpaMe3, Tpa*,Br, and TpaBr3 have been synthesized and structurally characterized. The coordination chemistries of these three new tetradentate tripodal ligands and the already known Tpa and Tpa* have been explored using different copper(I) salts as starting materials. Cationic copper(I) complexes [TpaxCu]PF6 (1-4) have been isolated from the reaction of [Cu(NCMe)4]PF6 and 1 equiv of the ligand. Complexes 2 (Tpax = Tpa*) and 3 (Tpax = TpaMe3) have been characterized by X-ray studies. The former is a 1D helical coordination polymer, and the latter is a tetranuclear helicate. In both structures, the Tpax ligand adopts a μ2: κ2:κ1-coordination mode. However, in solution, all of the four complexes form fluxional species. When CuI is used as the copper(I) source, neutral compounds 5-8 have been obtained. Complexes 6-8 exhibit a 1:1 metal-to-ligand ratio, whereas 5 presents 2:1 stoichiometry. Its solid-state structure has been determined by X-ray diffraction, revealing its 3D polymeric nature. The polymer is composed by the assembly of [Tpa 2Cu4I4] units, in which Cu4I 4 presents a step-stair structure. The Tpa ligands bridge the Cu 4I4 clusters, adopting also a μ2: κ2:κ1-coordination mode. As observed for the cationic derivatives, the NMR spectra of 5-8 show the equivalence of the three pyrazolyl arms of the ligands in these complexes. The reactivities of cationic copper(I) derivatives 1-4 with PPh3 and CO have been explored. In all cases, 1:1 adducts [TpaxCuL]PF6 [L = PPh3 (9-11), CO (12-15)] have been isolated. The crystal structure of [Tpa*Cu(PPh3)]PF6 (9) has been obtained, showing that the coordination geometry around copper(I) is trigonal-pyramidal with the apical position occupied by the tertiary amine N atom. The Tpa* ligand binds the Cu center to three of its four N atoms, with one pyrazolyl arm remaining uncoordinated. In solution, the carbonyl adducts 13-15 exist as a mixture of two isomers; the four- and five-coordinate species can be distinguished by means of their IR νCO stretching bands. Finally, the catalytic activities of complexes 1-4 have been demonstrated in carbene- and nitrene-transfer reactions.
New binuclear copper(ii) coordination polymer based on mixed pyrazolic and oxalate ligands: Structural characterization and mechanical properties
López Marzo, Adaris M.,Guerrero, Miguel,Calvet, Teresa,Font-Bardia, Mercè,Pellicer, Eva,Baró, Maria Dolors,Pons, Josefina,Sort, Jordi
, p. 32369 - 32375 (2015)
A new inorganic-organic coordination polymer based on a copper(ii) binuclear complex coordinated with pyrazole (L1), 1-(hydroxymethyl)pyrazole) (L2) and oxalate (Ox) ligands has been unexpectedly obtained. The crystal structure of this coordination polymer has been unequivocally determined from single crystal X-ray diffraction. One copper(ii) center (Cu1) is four-coordinated with two nitrogens (N2, L1 and N3, L2), one oxygen (O1, L1) and one chlorine atom, while the other copper(ii) nucleus (Cu2) is five-coordinated with one nitrogen (N1, L1), three oxygens (O1, L2; O2 and O3, Ox) and one chlorine atom, giving slightly distorted square-planar and square-pyramidal geometries, respectively. To the best of our knowledge, such coordination environments have never been previously observed to coexist in the same structure. The terminal chlorine (Cl1) forms the connecting bridge between the planar binuclear [Cu2Cl(Ox)0.5(L1)(L2)]n units ending in an attractive structural framework. An extended layered structure staggered along the b-axis is observed in the supramolecular view. Nanoindentation experiments were carried out and relevant mechanical parameters such as hardness, Young's modulus, indentation energies and elastic recovery were determined. Additionally, a comparative analysis between the supramolecular structure and the mechanical properties is reported. This journal is
Coordination of new disulfide ligands to CuIand CuII: Does a CuII μ-thiolate complex form?
Ording-Wenker, Erica C. M.,Siegler, Maxime A.,Bouwman, Elisabeth
, p. 193 - 202 (2015)
Interest in dinuclear CuII μ-thiolate and CuI disulfide complexes is triggered by their similarity with the CuA site and the possibility to control this redox equilibrium. Three new disulfide ligands L1, L3 and L4 were synthesized and reacted with CuI salts to investigate whether thiolate or disulfide species would form. The nature of L1 precludes the formation of CuII μ-thiolate species, resulting in the formation of [Cu2I(L1)(CH3CN)](BF4)2 which was characterized via single crystal X-ray crystallography. Pyrazole-containing ligands L3 and L4 form CuI complexes that are stable in solution in air for hours with half-wave potentials of approximately +0.55 V versus Ag/AgCl, indicating high stability of the CuI state rather than the CuII state. The half-wave potentials of the CuI complexes with L1 and L2 are less positive, indicating that in order to allow formation of both CuII μ-thiolate and CuI disulfide species, a half-wave potential of roughly 0 V versus Ag/AgCl would be ideal. Furthermore, CuII crystal structures with L1, L2, L3 and L4 and different counterions were compared and analyzed. Pyrazolyl-containing ligands L3 and L4 form complexes that are very similar to the complexes with pyridyl-containing ligands L1 and L2.
Design, synthesis and evaluation of second generation MurF inhibitors based on a cyanothiophene scaffold
Hrast, Martina,Anderluh, Marko,Knez, Damijan,Randall, Christopher P.,Barreteau, Hélène,O'Neill, Alex J.,Blanot, Didier,Gobec, Stanislav
, p. 83 - 96 (2014)
MurF ligase is a crucial enzyme that catalyses the ultimate intracellular step of bacterial peptidoglycan biosynthesis, and thus represents an attractive target for antibacterial drug discovery. We designed, synthesized and evaluated a new series of cyanothiophene-based inhibitors of MurF enzymes from Streptococcus pneumoniae and Escherichia coli. The target compounds had increased polarity compared to the first generation of inhibitors, with demonstrated enzyme inhibitory potencies in the low micromolar range. Furthermore, the best inhibitors displayed promising antibacterial activities against selected Gram-positive and Gram-negative strains. These results represent an important step towards the development of new antibacterial agents targeting peptidoglycan biosynthesis.
Antibacterial activity of aminals and hemiaminals of pyrazole and imidazole
Lupsor, Simona,Aonofriesei, Florin,Iovu, Mircea
, p. 3035 - 3042,8 (2012)
Antibacterial activity of 1,1'-methylenedipyrazole (AM1), 1-hydroxymethylpyrazole (SAM1), 1,1'-methylenediimidazole (AM2), and 1-hydroxymethylimidazole (SAM2) has been tested against reference and clinical strains by both difusimetric and broth dilution methods. Overall, the minimal inhibitory concentrations of tested compounds ranged from 180 to 270 μg/ml, while the minimal bactericidal concentrations were between 360 and 720 μg/ml. Comparative assessment with phenol and formaldehyde shows that AM1, AM2, SAM1, and SAM2 have moderate to good antibacterial activity.
New N,N,N',N'-tetradentate pyrazoly agents: Synthesis and evaluation of their antifungal and antibacterial activities
Abrigach, Farid,Bouchal, Btissam,Riant, Olivier,Macé, Yohan,Takfaoui, Abdelilah,Radi, Smaail,Oussaid, Abdelouahad,Bellaoui, Mohammed,Touzani, Rachid
, p. 83 - 89 (2016)
A new library of N,N,N',N'-tetradentate pyrazoly compounds containing a pyrazole moiety was synthesized by the condensation of (3,5-dimethyl-1H-pyrazol-1-yl)methanol 2a or (1H-pyrazol-1-yl)methanol 2b with a series of primary diamines in refluxed acetonitrile for 6h. The antifungal activity against the budding yeast Saccharomyces cerevisiae, as well as the antibacterial activity against Escherichia coli of these new tetradentate ligands were studied. We found that these tetradentate ligands act specifically as antifungal agents and lack antibacterial activity. Their biological activities depend on the nature of the structure of the compounds.
Tunable iridium catalyst designs with bidentate N-heterocyclic carbene ligands for SABRE hyperpolarization of sterically hindered substrates
Pham, Pierce,Hilty, Christian
supporting information, p. 15466 - 15469 (2020/12/25)
A series of bidentate N-heterocyclic carbene (NHC) iridium catalysts, [Ir(κC,N-NHC)H2L2]BPh4, are proposed for SABRE hyperpolarization. The steric and electronic properties of the NHCs are used to tune substrate affinity and thereby SABRE efficiency. The sterically hindered substrates 2,4-diaminopyrimidine and trimethoprim yielded maximum proton NMR signal enhancements of ～300-fold and ～150-fold, respectively.
New arylselanylpyrazole-copper catalysts: Highly efficient catalytic system for C–Se and C–S coupling reactions
Coelho, Felipe Lange,Dresch, Lucielle Codeim,Stieler, Rafael,Campo, Leandra Franciscato,Schneider, Paulo Henrique
, p. 19 - 26 (2019/01/04)
We describe herein the use of arylselanylpyrazole–copper complexes as versatile catalysts for C–Se and C–S coupling reactions. The performance of these complexes for C–Se reactions was investigated in chalcogenoacetylene synthesis. The reactions were carried out under mild and aerobic conditions and afforded selanylalkynes bearing a variety of electron-withdrawing and electron-donating groups. The performance of these catalysts for C–S coupling was investigated through the reaction of aryl halides with thiols and products were obtained in moderate to excellent yields. A plausible mechanism for selenoacetylene synthesis is also suggested, and the 77Se NMR results show that these arylselanylpyrazole ligands act as hemilabile ligands. High-resolution mass spectrometry was used to investigate the intermediates and also to corroborate the proposed catalytic cycle.
Nickel(II) complexes with tripodal NNN ligands as homogenous and supported catalysts for ethylene oligomerization
Tuskaev, Vladislav A.,Zubkevich, Sergei V.,Saracheno, Daniele,Gagieva, Svetlana Ch.,Dorovatovskii, Pavel V.,Kononova, Elena G.,Khrustalev, Victor N.,Zarubin, Dmitry N.,Bulychev, Boris M.,Kissin, Yury V.
, p. 29 - 38 (2019/01/04)
Four new coordination compounds of nickel (II) with derivatives of N,N-bis(pyrazol-1-ylmethyl)propylamine were synthesized; their composition and structure were confirmed with IR-spectroscopy and elemental analysis. The structures of products 13 and 15 were unambiguously established in an X-ray diffraction study. Compounds 13 and 15 crystallize in the orthorhombic space groups Pna21 and P212121 correspondingly and represent a monomeric octahedral nickel complexes, that are typical for tridentate scorpion-type ligands. New method for immobilization of nickel complexes with derivatives of N,N-bis(pyrazol-1-ylmethyl)propylamine on silica gel modified with aminopropyl groups was proposed. The EXAFS/XANES analysis indicated that Ni atom in the supported complexes adopt almost octahedral geometry, being partly surrounded by nitrogen atoms from organic ligand and partly grafted to silica surface through silanol groups, with Br? in outer coordination sphere. Both the original and the supported complexes, when activated with Et2AlCl or Et3Al2Cl3, catalyze ethylene oligomerization with the predominant formation of butene isomers. Generally, the immobilized complexes show higher activity and better selectivity towards 1-butene formation.
