Mononuclear nickel(II) complexes coordinated by polypyridyl ligands

Hadadzadeh, Hassan; Mansouri, Ghobad; Rezvani, Ali Reza; Khavasi, Hamid Reza; Skelton, Brian W.; Makha, Mohamed; Charati, Faramarz Rostami

doi:10.1016/j.poly.2011.06.037

Cited by 26 publications

(15 citation statements)

References 44 publications

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“…For instance, the ortho hydrogen atoms of the pyridine rings of the tptz ligand which are nearest to the to paramagnetic Ni(II) center, are again most affected by the contact shift and are shifted downfield. On the other hand, the meta and para hydrogen atoms are shifted upfield largely because of a pseudo-contact shift [61]. The contribution of contact shift for these protons is small because of their distance from Ni(II).…”

Section: Resultsmentioning

confidence: 98%

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Nickel(II) polypyridyl Complexes of 2,4,6-Tris(2-pyridyl)-1,3,5-triazine

et al. 2012

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The synthesis, purification, characterization, electrochemical properties, and fluorescence quenching of two new mononuclear Ni(II) complexes, [Ni(tptz) (CH 3 OH)Cl 2 ] (1) and [Ni(tptz) 2 ](PF 6 ) 2 ÁCH 3 CN (2), containing the ligand 2,4,6-tris(2-pyridyl)-1,3,5-triazine (tptz) are described. Solid state structures of both complexes have been determined by single crystal X-ray crystallography. In (1) and (2), the Ni(II) metal centers use the major coordination site of the tptz ligand and the coordination geometry around the Ni(II) is a distorted octahedron. The free tptz ligand has three emission bands that are assigned to the 1 (p-p * ) and 1 (n-p * ) states. The fluorescence spectra of (1) and (2) show that the fluorescence quenching of the tptz fluorophore proceeds via an energy transfer process. Magnetic susceptibility data derived from paramagnetic NMR revealed effective magnetic moments of 2.75 l B for (1), and 2.91 l B for (2) at room temperature. Cyclic voltammetry of (1) shows that the Ni(III/II) reduction couple is quasi-reversible whereas in complex (2), the Ni(II/I) couple indicates an electrochemical (EC) mechanism.

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Section: Resultsmentioning

confidence: 98%

“…and [Ni(phen) 3 ] 2? [61,63], the tptz 0/-couple occurs prior to the bpy 0/-and phen 0/-due to the larger p system of tptz ligand as a result of the one extra pyridyl ring on tptz as well as the extra electron accepting character of the triazine ring. Tptz has a substantially lower energy p * orbital than bpy and phen.…”

Section: Resultsmentioning

confidence: 99%

Nickel(II) polypyridyl Complexes of 2,4,6-Tris(2-pyridyl)-1,3,5-triazine

et al. 2012

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“…The Ni complexes 1 – 7 were characterized by high-resolution mass spectrometry (HRMS), cyclic voltammetry, elemental analysis, infrared spectroscopy (IR), and ultraviolet–visible (UV–vis) spectroscopy. 31 , 32 , 40 − 42 (see the Supporting Information ). Compound 7 was characterized by single-crystal X-ray diffraction (see the Supporting Information ).…”

Section: Results and Discussionmentioning

confidence: 99%

“…The Ni complex 7 exhibits a distorted octahedral geometry that is similar to those of previously reported [Ni(bipy) 3 ] 2+ , [Ni(phen) 3 ] 2+ , and [Ni(tpy) 2 ] 2+ structures possessing different counteranions. 40 , 43 , 44 …”

Section: Results and Discussionmentioning

confidence: 99%

Catalytic Hydroxylation of Polyethylenes

et al. 2017

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Polyolefins account for 60% of global plastic consumption, but many potential applications of polyolefins require that their properties, such as compatibility with polar polymers, adhesion, gas permeability, and surface wetting, be improved. A strategy to overcome these deficiencies would involve the introduction of polar functionalities onto the polymer chain. Here, we describe the Ni-catalyzed hydroxylation of polyethylenes (LDPE, HDPE, and LLDPE) in the presence of mCPBA as an oxidant. Studies with cycloalkanes and pure, long-chain alkanes were conducted to assess precisely the selectivity of the reaction and the degree to which potential C–C bond cleavage of a radical intermediate occurs. Among the nickel catalysts we tested, [Ni(Me4Phen)3](BPh4)2 (Me4Phen = 3,4,7,8,-tetramethyl-1,10-phenanthroline) reacted with the highest turnover number (TON) for hydroxylation of cyclohexane and the highest selectivity for the formation of cyclohexanol over cyclohexanone (TON, 5560; cyclohexanol/(cyclohexanone + ε-caprolactone) ratio, 10.5). The oxidation of n-octadecane occurred at the secondary C–H bonds with 15.5:1 selectivity for formation of an alcohol over a ketone and 660 TON. Consistent with these data, the hydroxylation of various polyethylene materials by the combination of [Ni(Me4Phen)3](BPh4)2 and mCPBA led to the introduction of 2.0 to 5.5 functional groups (alcohol, ketone, alkyl chloride) per 100 monomer units with up to 88% selectivity for formation of alcohols over ketones or chloride. In contrast to more classical radical functionalizations of polyethylene, this catalytic process occurred without significant modification of the molecular weight of the polymer that would result from chain cleavage or cross-linking. Thus, the resulting materials are new compositions in which hydroxyl groups are located along the main chain of commercial, high molecular weight LDPE, HDPE, and LLDPE materials. These hydroxylated polyethylenes have improved wetting properties and serve as macroinitiators to synthesize graft polycaprolactones that compatibilize polyethylene–polycaprolactone blends.

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“…For instance, the ortho hydrogen atoms (Ha) of the tptz ligand pyridine rings which are nearest to the paramagnetic Co(II) center, are again most affected by the contact shift and are shifted downfield. On the other hand, the meta and para hydrogen atoms are shifted upfield largely because of the pseudo-contact shift [43]. The contribution of contact shift for these protons is small because of their distance from Co(II).…”

Section: H Nmr Spectrummentioning

confidence: 98%

Synthesis, crystal structure, antibacterial activity and theoretical studies on a novel mononuclear cobalt(II) complex based on 2,4,6-tris(2-pyridyl)-1,3,5-triazine ligand

Maghami

Farzaneh

Ghiasi

et al. 2015

Journal of Molecular Structure

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Synthesis, crystal structure, antibacterial activity and theoretical studies on a novel mononuclear cobalt(II) complex based on 2,4,6-tris(2-pyridyl)-1,3,5-triazine ligand h i g h l i g h t s A new Co(II) complex with formula [Co(tptz)(CH 3 OH)Cl 2 ]ÁCH 3 OHÁ0.5H 2 O has been prepared. Using tptz = 2,4,6-tris(2-pyridyl)-1,3,5-triazine as ligand. The antibacterial activity of Co(II), Ni(II), Cu(II), Mn(II) and Rh(III) with tptz have been evaluated. The DFT studies consistent with experimental results. g r a p h i c a l a b s t r a c tThe crystal structure of Co(II) with formula [Co(tptz)(CH 3 OH)Cl 2 ]ÁCH 3 OHÁ0.5H 2 O, (tptz = 2,4,6-tris(2-pyridyl)-1,3,5-triazine) was determined by single-crystal X-ray diffraction. The DFT studies consistent with experimental results. Then, the in vitro antibacterial activity of ligand and tptz complexes of Co(II), Ni(II), Cu(II), Mn(II) and Rh(III) have been evaluated. a b s t r a c t A cobalt complex was prepared from CoCl 2 Á6H 2 O and 2,4,6-tris(2-pyridyl)-1,3,5-triazine (tptz) in methanol and designated as [Co(tptz)(CH 3 OH)Cl 2 ]ÁCH 3 OHÁ0.5H 2 O (1). It was characterized by several techniques including TGA analysis and FT-IR, UV-Vis and 1 H NMR spectral studies. The crystal structure of 1 was determined by single-crystal X-ray diffraction. The Co(II) metal center in 1 is six coordinated with a distorted octahedral geometry. The tptz ligand is tridentate and coordinates to the cobalt through coplanar nitrogen atoms from the triazine and two pyridyl rings. Two chloride anions and a methanol molecule complete the inner coordination sphere of the metal ion. The optimized geometrical parameters obtained by DFT calculation are in good agreement with single XRD data. The in vitro antibacterial activity of various tptz complexes of Co(II), Ni(II), Cu(II), Mn(II) and Rh(III) were evaluated against Gram-positive (Bacillus subtilis, Staphylococcus aureus and Gram-negative (Escherichia coli and Pseudomonas aeruginosa) bacteria. Whereas all complexes exhibited good activity in comparison to standard antibacterial drugs, the inhibitory effects of complexes were found to be more than that of the parent ligand. Overall, the obtained results strongly suggest that the cobalt(II) complex is a suitable candidate for counteracting antibiotic resistant microorganisms.

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Mononuclear nickel(II) complexes coordinated by polypyridyl ligands

Cited by 26 publications

References 44 publications

Nickel(II) polypyridyl Complexes of 2,4,6-Tris(2-pyridyl)-1,3,5-triazine

Nickel(II) polypyridyl Complexes of 2,4,6-Tris(2-pyridyl)-1,3,5-triazine

Catalytic Hydroxylation of Polyethylenes

Synthesis, crystal structure, antibacterial activity and theoretical studies on a novel mononuclear cobalt(II) complex based on 2,4,6-tris(2-pyridyl)-1,3,5-triazine ligand

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