Academic literature on the topic 'Phenolic oxime ligands'

The use of the novel pro-ligand H₄L combining the complimentary phenolic oxime and diethanolamine moieties in one organic framework, results in the formation of the first example of a [Mn^III₁₂] truncated tetrahedron.

An unprecedented dinuclear CuII complex, [Cu2(L2)2], derived from a salamo-like chelating ligand H2L2, was produced by the cleavage of a newly synthesized, half-salamo-like ligand HL1 (2-[O-(1-ethyloxyamide)]oxime-3,5-dichloro-phenol). This was synthesized and characterized by elemental analyses, IR, UV–Vis and fluorescent spectra, single crystal X-ray diffraction analysis, and Hirshfeld surface analysis. X-ray crystallographic analysis indicated that the two CuII (Cu1 and Cu2) ions bore different (N2O3 and N2O2) coordination environments, the penta-coordinated Cu1 ion possessed a slightly twisted tetragonal pyramid geometry with the τ value τ = 0.004, and the tetra-coordinated Cu2 ion showed a slightly twisted square planar geometry. Interestingly, one oxime oxygen atom participated in the coordination reported previously. Moreover, an infinite two-dimensional layered supramolecular network was formed. Compared with HL1, the CuII complex possessed the characteristic of fluorescence quenching.

A new series of water soluble mixed ligand complexes [MII(L)(bpy)AcO].nH2O M = Cu, (n=1) (1); Co (2), Mn (3), Ni (4) (n=4) and Zn (5) (n=2) have been synthesized from 2-(2-Morpholinoethylimino)methyl)phenol Schiff base ligand (HL) and 2,2�-bipyridine in a 1:1:1 molar ratio. The resulting complexes were characterized by spectral techniques. The spectral data of these complexes suggest an octahedral geometry. In vitro antioxidant activity results of DPPH assay, hydroxyl radical, super oxide and nitric oxide for complexes (1-5) were compared with ligand (HL) and in vitro antimicrobial activities of all compounds were examined against selected bacterial and fungal strains which indicate that the complexes exhibit higher antimicrobial activity than free ligand (HL). Gel electrophoresis results indicated that, complexes (1) and (2) have exhibited more DNA cleavage efficiency than others. The intrinsic binding constant (Kb) values for the complexes (1-5) observed by electronic absorption technique were in the order of (1) ] (4) ] (5) ] (2) ] (3) and DNA binding affinity values for these complexes obtained by viscosity measurements were in the order of ethidium bromide ] (1) ] (2) ] (3) ] (4) ] (5).

Abstract Ground-contact stakes, made from defect-free southern yellow pine sapwood, were treated with water-borne copper(II) [ammoniacal copper carbonate, ACC, Cu(II)] alone, oil-borne oxine copper (Cu-8) alone, or a dual treatment of ACC followed by drying and then Cu-8. The treated stakes were installed at two locations in Mississippi (Dorman Lake and Saucier) in high- or severe-deterioration hazard zones and inspected after 69 months of exposure. Stakes treated with Cu(II) alone at the highest retention of 5.1 kg m−3 [copper retention is based on the copper oxide (CuO) weight, as is standard in the US] performed moderately well at the Saucier test site, with decay and termite ratings of 8.0 out of 10.0, but unsatisfactory at the Dorman Lake test plot, with decay and termite ratings both below 7.0. Samples treated with Cu-8 alone at the highest retention of 1.92 kg m−3 had poor termite protection, with ratings below 7 at both sites, and only fair decay ratings of 7.0 (Dorman Lake) and 7.6 (Saucier). In contrast, all stakes treated with Cu(II)/Cu-8 combinations, with at least 2.4 kg m−3 Cu(II) and 0.2 kg m−3 Cu-8, performed satisfactorily, with average decay and termite ratings all above 8.0 at both locations. The addition of Cu(II) to Cu-8 likely causes the di-ligand form [bis(8-hydroxyquinolinolate)Cu(II)] to equilibrate principally to the mono form. Thus, the combination of Cu(II) and Cu-8 appears to form a new compound with greater efficacy than either of the two starting “reagents” and, consequently, this mixture is not literally synergistic. Possible advantages of mono Cu-8 include: (1) the mono form may be easier to formulate in a water- or solvent-borne system than the commercial bis-Cu-8 biocide; (2) the preservative would have a relatively low metal content, which may make future disposal of treated wood easier; (3) this system would likely have much fewer metal corrosion problems than preservative systems formulated with uncomplexed copper(II); and (4) the two copper coordination sites that are not complexed with the ligand could bind to the carboxylic or phenolic groups in wood to make the mono form relatively leach-resistant.

To crucially comprehend the relaying factors behind the growth mechanism of ZnO nanostructures, the needs to understand the cause of preferences in the enhancement of desired physicochemical properties are essential. The particular oriented attachment (OA) is believed to become the cause of the classical growth pattern of ZnO nanostructures which is mainly controlled by the Ostwald ripening (OR) process. In the present work, the concerns over the systematic changes in size and the morphological surface of ZnO nanostructures upon exposure to tannic acid (TA) prepared by drop-wise method turns the particles to different surface adjustment state. Here, we assessed the TA capping ability and its tendency to influence the OA process of the ZnO nanostructures. The detailed process of the growth-based TA system via transmission electron microscopy (TEM), scanning electron microscopy (SEM), and FFT autocorrelation revealed the pH effect on their physical properties which proved the transition surface properties state of the particles from rough to smooth states due to oriented attachment. For pure ZnO nanostructures, the surface is almost smooth owing to the strong bonding particles which are then changed to coarsened surface structures upon the introduction of TA. Strong surface adsorption of Zn cations and phenol ligands mediated the agglomerated nanocrystals, surprisingly with smaller nanostructures dimension.

Polynuclear metal clusters frequently feature geometric structural features not common in traditional coordination chemistry. These structures are of particular interest to bioinorganic chemists studying metallocluster enzymes, which frequently possess remarkably unusual inorganic structures. The structure of the manganese cluster μ5-oxido-di-μ3-phenoxido-hexa-μ-phenoxido-hexakis(pyridine-κN)hexamanganese(II) pyridine monosolvate, [Mn5(C6H5O)8O(C5H5N)6]·C5H5N or MnII 5(μ-OPh)6(μ3-OPh)2(μ5-O)(Py)6·Py, containing an unusual trigonal bipyramidal central oxide, is described. The compound was isolated from a reaction mixture containing bis(trimethylsilylamido)manganese(II) and phenol. The central O atom is presumed to have originated as adventitious water. The molecule crystalizes in a primitive monoclinic crystal system and is presented in the centrosymetric P2/n space group. The molecule possesses crystallographically imposed twofold symmetry, with the central O atom centred on the twofold axis and surrounded by a distorted trigonal bipyramidal arrangement of Mn atoms, which are further bridged by phenoxide ligands, and terminally ligated by pyridine. A pyridine solvent molecule resides nearby, also situated on a crystallographic twofold axis. The cluster is compared to three closely related previously reported structures.

This thesis describes the synthesis of a host of polynuclear iron complexes synthesised with phenolic oxime ligands, fundamentally developing the coordination chemistry of iron with these ligands. The metallic cores that occur within iron phenolic oxime clusters were found to contain almost exclusively oxo-centred triangles and oxo-centred tetrahedra. We found that we could alter the reaction conditions or derivatise the ligands and develop these basic building blocks into more elaborate arrays, exerting a degree of control over creating larger or smaller clusters. Chapter one describes the syntheses, structures and magnetic properties of new iron complexes alongside previously synthesised related complexes (4, 5, 8, 9 and 15) containing salicylaldoxime (saoH2) or derivatised salicylaldoximes (RsaoH2). These are [Fe3O(OMe)(Ph-sao)2Cl2(py)3]·2MeOH (1·2MeOH), [Fe3O(OMe)(Ph-sao)2Br2(py)3]·Et2O (2·Et2O), [Fe4(Ph-sao)4F4(py)4]·1.5MeOH (3·1.5MeOH), [Fe6O2(OH)2(Et-sao)2(Et-saoH)2(O2CPh)6] (4), [HNEt3]2[Fe6O2(OH)2(Et-sao)4(O2CPh(Me)2)6]·2MeCN (5·2MeCN), [Fe6O2(O2CPh)10(3-tBut-5-NO2-sao)2(H2O)2]·2MeCN (6·2MeCN), [Fe6O2(O2CCH2Ph)10(3-tBut-sao)2(H2O)2]·5MeCN (7·5MeCN), {[Fe6Na3O(OH)4(Me-sao)6(OMe)3(H2O)3(MeOH)6]·MeOH}n (8·MeOH) and [HNEt3]2[Fe12Na4O2(OH)8(sao)12(OMe)6(MeOH)10] (9). The predominant building block appears to be the triangular [Fe3O(R-sao)3]+ species which can self-assemble into more elaborate arrays depending on reaction conditions. The four hexanuclear and two octanuclear complexes of formulae [Fe8O2(OMe)4(Mesao) 6Br4(py)4]·2Et2O·MeOH (10·2Et2O·MeOH), [Fe8O2(OMe)3.85(N3)4.15(Mesao) 6(py)2] (11), [Fe6O2(O2CPh-4-NO2)4(Me-sao)2(OMe)4Cl2(py)2] (12), [Fe6O2(O2CPh-4-NO2)4(Et-sao)2(OMe)4Cl2(py)2]·2Et2O·MeOH (13·2Et2O·MeOH), [HNEt3]2[Fe6O2(Me-sao)4(SO4)2(OMe)4(MeOH)2] (14) and [HNEt3]2[Fe6O2(Etsao) 4(SO4)2(OMe)4(MeOH)2] (15) all are built from series of edge-sharing [Fe4( μ4- O)]10+ tetrahedra. Complexes 10 and 11 display a new μ4-coordination mode of the oxime ligand and join a small group of Fe-phenolic oxime complexes with nuclearity greater than six. Chapter three then introduces co-ligands to the reaction scheme to compete with the salicylaldoxime ligands for metal coordination sites. Five tetranuclear and two nononuclear complexes are stabilised with salicylaldoxime (saoH2) or derivatised salicylaldoximes (R-saoH2) in conjunction with either 1,4,7- triazocyclononane (tacn), 2-hydroxymethyl pyridine (hmpH) or 2,6-pyridine dimethanol (pdmH2), [Fe4O2(sao)4(tacn)2]·2MeOH (16·MeOH), [Fe4O2(Mesao) 4(tacn)2]·2MeCN (17·2MeCN), [Fe4O2(Et-sao)4(tacn)2]·MeOH (18·MeOH), [Fe9NaO4(Et-sao)6(hmp)8]·3MeCN·Et2O (19·3MeCN·Et2O), [Fe4 (Etsao) 4(hmp)4]·Et-saoH2 (20·Et-saoH2), [Fe4(Ph-sao)4(hmp)4]·2MeCN (21·2MeCN) [Fe9O3(sao)(pdm)6(N3)7(H2O)] (22). Chapter four straps two salicylaldoxime units together in the 3-position, using ligands with aliphatic a,W-aminomethyl links, allowing the assembly of the polynuclear complexes [Fe7O2(OH)6(H2L1)3(py)6](BF4)5·6H2O·14MeOH (23·6H2O·14MeOH), [Fe6O(OH)7(H2L2)3][(BF4)3]·4H2O·9MeOH (24·4H2O·9MeOH) and [Mn6O2(OH)2(H2L1)3(py)4(MeCN)2](BF4)5(NO3)·3MeCN·H2O·5py (25·3MeCN·H2O·5py). In each case the metallic skeleton of the cluster is based on a trigonal prism in which two [MIII 3O] triangles are tethered together via three helically twisted double-headed oximes. The latter are present as H2L2- in which the oximic and phenolic O-atoms are deprotonated and the amino N-atoms protonated, with the oxime moieties bridging across the edges of the metal triangles. Both the identity of the metal ion and the length of the straps connecting the salicylaldoxime units have a major impact on the nuclearity and topology of the resultant cage, with, perhaps counter-intuitively, the longer straps producing the “smallest” clusters.