Removal, mechanistic and kinetic studies of Cr(VI), Cd(II), and Pb(II) cations using FeO functionalized Schiff base chelating ligands.

The Schiff base chelating ligands; (E)-2-(3,3-dimethoxy-2-oxa-7,10-diaza-3-silaundec-10-en-11-yl)phenol (L1), (E)-N-(2-((pyridine-2ylmethylene)amino)ethyl)-3-(trimethoxysilyl)propan-1-amine (L2) and (E)-N-(2-((thiophen-2-ylmethylene)amino)ethyl)-3-(trimethoxysilyl)propan-1-amine (L3) were immobilized on FeO magnetic nanoparticles (MNPs) and utilized in the extraction of Cr(VI), Cd(II) and Pb(II) metal cations from aqueous solutions. The compounds synthesized, denoted as L1@ FeO, L2@FeO, and L3@FeO, were characterized using FT-IR spectroscopy, TEM-SEM, VSM, and BET/BHJ techniques for analysis of functional groups, surface morphology, magnetic properties, and degree of porosity of the adsorbents, respectively. BET/BHJ technique confirmed the mesoporous nature of the compounds as their pore diameters ranged between 15 and 17 nm.

Introduction to the Young African Researchers collection.

Abisola O. Egbedina, Jairus L. Lamola, Mina Shawky Adly, and Stephen O.

Heterocyclic (pyrazine)carboxamide Ru(ii) complexes: structural, experimental and theoretical studies of interactions with biomolecules and cytotoxicity.

Treatments of -(1-benzo[]imidazol-2-yl)pyrazine-2-carboxamide (HL) and -(benzo[]thiazol-2-yl)pyrazine-2-carboxamide carboxamide ligands (HL) with [Ru(-cymene)Cl] and [Ru(PPh)Cl] precursors afforded the respective Ru(ii) complexes [Ru(L)(-cymene)Cl] (Ru1), [Ru(L)(-cymene)Cl] (Ru2), [Ru(L)(PPh)Cl] (Ru3), and [Ru(L)(PPh)Cl] (Ru4). These complexes were characterized by NMR, FT-IR spectroscopies, mass spectrometry, elemental analyses, and crystal X-ray crystallography for Ru2. The molecular structure of complex Ru2 contains one mono-anionic bidentate bound ligand and display pseudo-octahedral piano stool geometry around the Ru(ii) atom.

Electronic and ring size effects of N-heterocyclic carbenes on the kinetics of ligand substitution reactions and DNA/protein interactions of their palladium(II) complexes.

The synthesis, substitution kinetics and DNA/BSA interactions of four cationic Pd(II) complexes [Pd(1)Cl]BF (Pd1), [Pd(2)Cl]BF (Pd2), [Pd(3)Cl]BF (Pd3) and [Pd(4)Cl]BF (Pd4), derived from the reaction of [PdCl(NCCH)] with ligands 2,6-bis(3-methylimidazolium-1-yl)pyridine dibromide (1), 2,6-bis(3-ethylimidazolium-1-yl)pyridine dibromide (2), 2,6-bis(1-methylimidazole-2-thione)pyridine (3), and 2,6-bis(1-ethylimidazole-2-thione)pyridine (4), respectively are reported. The complexes were characterised by various spectroscopic techniques and single crystal X-ray diffraction for compound Pd2. Kinetic reactivity of the complexes with the biologically relevant nucleophiles thiourea (Tu), L-methionine (L-Met) and guanosine 5'-monophosphate sodium salt (5'-GMP) was in the order: Pd1 > Pd2 > Pd3 > Pd4, which was largely dependent on the electronic and ring size of the chelate ligands, consistent with Density functional theory (DFT) simulations.

Synthesis, substitution kinetics, DNA/BSA binding and cytotoxicity of tridentate N^E^N (E = NH, O, S) pyrazolyl palladium(II) complexes.

The pincer complexes, [Pd(L)Cl]BF (PdL), [Pd(L)Cl]BF (PdL), [Pd(L)Cl]BF (PdL), [Pd(L)Cl]BF (PdL) were prepared by reacting the corresponding ligands, 2,6-bis[(1H-pyrazol-1-yl)methyl]pyridine (L), bis[2-(1H-pyrazol-1-yl)ethyl]amine (L), bis[2-(1H-pyrazol-1-yl)ethyl]ether (L), and bis[2-(1H-prazol-1-yl)ethyl]sulphide (L) with [PdCl(NCMe)] in the presence NaBF. The solid-state structures of complexes PdL-PdL confirmed a tridentate coordination mode, with one chloro ligand completing the coordination sphere to afford square-planar complexes. Chemical behaviour of the complexes in solution confirms their stability in both aqueous and DMSO stock media.

Liquid-liquid extraction of copper(II), zinc(II), cadmium(II), and lead(II) from aqueous solution and sewage effluent using phenoxy-amino ligands.

The phenoxy-amino ligands 2-(((2-(diethylamino)ethyl)amino)methyl)phenol (L1) and 2-(((2-mercaptoethyl)amino)methyl)-phenol (L2) were studied as model chelating agents for liquid-liquid extraction of copper(II), zinc(II), cadmium(II), and lead(II) cations from water using dichloromethane-water biphasic system. The relative affinities of these chelating ligands for copper(II), zinc(II), cadmium(II), and lead(II) by liquid-liquid extraction were found to be in the order copper(II)> zinc(II) > cadmium(II) > lead(II). The ligands L1 and L2 showed binding efficiencies ranging from 78%-97% for copper(II), 75%-91% for zinc(II), 76%-92% for cadmium(II), and 59%-67% for lead(II).

Role of π-conjugation on the coordination behaviour, substitution kinetics, DNA/BSA interactions, and cytotoxicity of carboxamide palladium(II) complexes.

Treatments of N-(pyridin-2-ylmethyl)pyrazine-2-carboxamide (L1), N-(quinolin-8-yl)pyrazine-2-carboxamide (L2), N-(quinolin-8-yl)picolinamide (L3) and N-(quinolin-8-yl)quinoline-2-carboxamide (L4) with [PdCl2(NCMe)]2 afforded the corresponding Pd(ii) complexes, [Pd(L1)Cl] (PdL1); [Pd(L2)Cl] (PdL2); [Pd(L3)Cl] (PdL3); and [Pd(L4)Cl] (PdL4) in moderate yields. Structural characterisation of the compounds was achieved by NMR and FT-IR spectroscopies, elemental analyses and single crystal X-ray crystallography. The solid-state structures of complexes PdL2-PdL4 established the presence of one tridentate carboxamide and Cl ligands around the Pd(ii) coordination sphere, to give distorted square planar complexes.

Synthesis and characterization of FSB@FeO composites and application in removal of indigo carmine dye from industrial wastewaters.

The syntheses and characterization of fish scale biochar magnetic composites (FSB@FeO) and their applications in the removal of indigo carmine dye from effluents are described. Preparation of the fish scale biochar magnetic composites, FSB@400 °C-FeO, FSB@600 °C-FeO, and FSB@800 °C-FeO, was done following the chemical co-precipitation method. The adsorbents were characterized using peak optical absorbance, functional groups, magnetic strength, surface morphology, particle size, elemental compositions, surface charge, surface area, thermal stability, and crystalline phase, using ultraviolet-visible spectroscopy (UV-vis spec), Fourier transform infrared (FTIR) spectroscopy, vibrating sample magnetometry (VSM), transmission electron microscopy/scanning electron microscopy (TEM/SEM), energy dispersive X-ray (EDX), point of zero charge pH (pH), Brunauer-Emmett-Teller (BET), thermo-gravimetric analysis (TGA), and powder x-ray diffraction (PXRD) techniques, correspondingly.

Palladium(II) complexes of tridentate bis(benzazole) ligands: Structural, substitution kinetics, DNA interactions and cytotoxicity studies.

Reactions of 2,6-bis(benzimidazol-2-yl)pyridine (L), 2,6-bis(benzoxazol-2-yl)pyridine (L), and 2,6-bis(benzothiazol-2-yl)pyridine (L) with [Pd(NCMe)Cl] in the presence of NaBF afforded the corresponding Pd(II) complexes, [Pd(L)Cl]BF, PdL; [Pd(L)Cl]BF, PdL; [Pd(L)Cl]BF, PdL; respectively, while reaction of bis[(1H-benzimidazol-2-yl)methyl]amine (L) with [Pd(NCMe)Cl] afforded complex [Pd(L)Cl]Cl, PdL. Characterisation of the complexes was accomplished using NMR, IR, MS, elemental analyses and single crystal X-ray crystallography. Ligand substitution kinetics of these complexes by biological nucleophiles thiourea (Tu), L-methionine (L-Met) and guanosine 5'-diphosphate disodium salt (5-GMP) were examined under pseudo-first order conditions.

Erratum: Di-chlorido-bis-[2-(pyridin-2-yl-κ)-1-benzimidazole-κ ]nickel(II) monohydrate. Corrigendum.

[This corrects the article DOI: 10.1107/S2414314620000401.].

Fischer Carbene Complexes of Iridium(I) for Application in Catalytic Transfer Hydrogenation.

New examples of the very rare class of iridium(I) Fischer carbene complexes (FCCs) are reported from the facile transmetalation from group 6 FCCs. Postcomplexation modification of either the carbene ligand or the ancillary coligands results in a tunable Ir metal center, for unprecedented application as a (pre)catalyst in a benchmark transfer hydrogenation reaction. The introduction of an aminocarbene ligand with a pendant N-donor moiety capable of hemilabile coordination yielded the best catalytic results with turnover frequencies reaching 445 h and requiring 0.

Preparation, characterization of fish scales biochar and their applications in the removal of anionic indigo carmine dye from aqueous solutions.

The preparation and applications of Tilapia (Oreochromis niloticus) fish scale biochars (FSB) as an adsorbent in the removal of indigo carmine dye (ICD) from aqueous solutions is described. The biochars were prepared through pyrolysis over a temperature range of 200 °C-800 °C and characterized for surface charge, functional groups, thermal stability, particle size and morphology, elemental composition, crystallinity, and surface area by using pH, Fourier transform infrared (FTIR) spectroscopy, thermo-gravimetric analysis (TGA), transmission electron microscopy/scanning electron microscopy (TEM/SEM), energy dispersive X-ray (EDX) spectroscopy, powder X-ray diffraction (PXRD) and Brunauer-Emmett-Teller (BET) techniques, respectively. Batch experiments were carried out to determine the variation of adsorption process with initial dye concentration, contact time, initial solution pH, adsorbent load, temperature and adsorbent pyrolysis temperature on the removal of the dye.

Di-chlorido-bis-[2-(pyridin-2-yl-κ)-1-benzimidazole-κ ]nickel(II) monohydrate.

In the title complex, [NiCl(CHN)]·HO, a divalent nickel atom is coordinated by two 2-(pyridin-2-yl)-1-benzimidazole ligands in a slightly distorted octa-hedral environment defined by four N donors of two ,'-chelating ligands, along with two -oriented anionic chloride donors. The title complex crystallized with a water mol-ecule disordered over two positions. In the crystal, a combination of O-H⋯Cl, O-H.

Structural, kinetics and mechanistic studies of transfer hydrogenation of ketones catalyzed by chiral (pyridyl)imine nickel(ii) complexes.

The chiral synthons (S-)-1-phenyl-N-(pyridine-2-yl)ethylidine)ethanamine (L1), (R-)-1phenyl-N-(pyridine-2-yl)ethylidine))ethanamine (L2) (S)-1-phenyl-N-(pyridine-2-yl methylene) ethanamine (L3), and (R)-1-phenyl-N-(pyridine-2-yl methylene) ethanamine (L4) were synthesized in good yields. Treatments of L1-L4 with NiBr(DME) and NiCl precursor afforded dinuclear complexes [Ni(L1)-μ-Br]NiBr (Ni1), [Ni(L2)-μ-Br]NiBr (Ni2), [Ni(L3)-μBr]Br (Ni3), [Ni(L4)-μ-Br]NiBr (Ni4) and [Ni(L4)Cl] (Ni5). The identities of the compounds were established using NMR, FT-IR and EPR spectroscopy, mass spectrometry, magnetic moments, elemental analysis and single crystal X-ray crystallography.

Ethylene oligomerization studies by nickel(ii) complexes chelated by (amino)pyridine ligands: experimental and density functional theory studies.

Reductions of imine compounds 2-methoxy-N-(1-(pyridin-2-yl)ethylidene)ethanamine (L1), 2-methoxy-N-((pyridin-2-yl)methylene)ethanamine (L2), N,N-diethyl-N-((pyridin-2-yl)methylene)ethane-1,2-diamine (L3) and 2-((pyridin-2-yl)methyleneamino)ethanol (L4) using NABH4 produced their corresponding amine analogues N-(2-methoxyethyl)-1-(pyridin-2-yl)ethanamine (L1a), 2-methoxy-N-((pyridin-2-yl)methyl)-ethanamine (L2a), N,N-diethyl-N-((pyridin-2-yl)methyl)ethane-1,2-diamine (L3a) and 2-((pyridin-2-yl)methylamino)ethanol (L4a) in good yields. Reactions of the (amino)pyridine ligands L1a–L4a with [NiBr2(DME)] afforded nickel(II) complexes, [NiBr2(L1a)2] (1), [NiBr2(L2a)2] (2), [NiBr2(L3a)2] (3) and [NiBr2(L4a)2] (4), respectively in quantitative yields. Molecular structures of complexes 2 and 4 confirmed the formation of the bis(chelated)nickel(II) complexes.

Packing forces in dichloridobis(3,5-diphenyl-1H-pyrazole-κN(2))cobalt(II) dichloromethane hemisolvate.

The title compound, [CoCl2(C15H12N2)2]·0.5CH2Cl2, was crystallized from a binary mixture of dichloromethane and hexane and a dimeric supramolecular structure was isolated. The Co(II) centre exhibits a distorted tetrahedral geometry, with two independent pyrazole-based ligands occupying two coordination sites and two chloride ligands occupying the third and fourth coordination sites.

(Pyridyl)benzoazole ruthenium(II) and ruthenium(III) complexes: role of heteroatom and ancillary phosphine ligand in the transfer hydrogenation of ketones.

The synthesis and structural characterization of ruthenium complexes supported by 2-(2-pyridyl)benzoazole ligands and their evaluation as catalysts in the transfer hydrogenation of ketones are reported. Reactions of 2-(2-pyridyl)benzoimidazole (L1), 2-(2-pyridyl)benzothiazole (L2) and 2-(2-pyridyl)benzoxazole (L3) with RuCl3·3H2O produced the corresponding complexes [RuCl3(L1)] (1), [RuCl3(L2)] (2) and [RuCl3(L3)] (3), respectively. Similarly, treatment of L1-L3 with RuCl2(PPh3)2 afforded the corresponding Ru(II) complexes [RuCl2(PPh3)2(L1)] (4), [RuCl2(PPh3)2(L2)] (5) and [RuCl2(PPh3)2(L3)] (6), respectively.

Structural and kinetic studies of the polymerization reactions of ε-caprolactone catalyzed by (pyrazol-1-ylmethyl)pyridine Cu(II) and Zn(II) complexes.

The structural and kinetic studies of polymerization reactions of ε-caprolactone (ε-CL) using (pyrazolylmethyl)pyridine Cu(II) and Zn(II) complexes as initiators is described. Reactions of 2-(3,5-dimethylpyrazol-1-ylmethyl)pyridine (L1) and 2-(3,5-diphenylpyrazol-1-ylmethyl)pyridine (L2) with Zn(Ac)2·2H2O or Cu(Ac)2·2H2O produced the corresponding complexes [Zn(Ac)2(L1)] (1), [Cu(Ac)2(L1)] (2), [Zn(Ac)2(L2)] (3) and [Cu2(Ac)4(L2)2] (4) respectively. Solid state structures of 1 and 4 confirmed that complexes 1 and 4 are monomeric and dimeric respectively and that L1 is bidentate in 1 while L2 is monodentate in 4.

2-[(3,5-Diphenyl-1H-pyrazol-1-yl)meth-yl]pyridine.

The title compound, C(21)H(17)N(3), crystallizes with the phenyl ring in the 3-position coplanar with the pyrazole ring within 4.04 (5)°, whereas the phenyl ring in the 5-position forms a dihedral angle of 50.22 (3)° with the pyrazole ring.

Spatial distribution and temporal trend in concentration of carbofuran, diazinon and chlorpyrifos ethyl residues in sediment and water in Lake Naivasha, Kenya.

Chlorpyrifos ethyl was found to be widely distributed in water and sediment in Lake Naivasha. Higher levels were reported in sediment (11.2-30.

[Bis(pyridin-2-ylmeth-yl) ether]trichlorido-rhodium(III) dichloro-methane monosolvate: unusual hydrolysis of the methyl-ene bridge in (pyrazolylmeth-yl)pyridine.

In the title compound, [RhCl(3)(C(12)H(12)N(2)O)]·CH(2)Cl(2), the Rh(III) atom shows a slightly distorted octa-hedral geometry being coordinated by two N atoms and one O atom from the 2,2'-(oxydimethanedi-yl)dipyridine ligand and three Cl atoms. Two Cl atoms adopt a trans arrangement to the two pyridyl N atoms, while the third Cl atom and the O atoms occupy the axial site. The Rh-Cl bonds that are trans to the pyridyl N atoms are slightly longer than the Rh-Cl bond distance trans to the O atom.

Positional disorder manifested as compositional in a pseudo-C2-symmetrical Pd complex.

The title compound {2-[3,5-bis(trifluoromethyl)-1H-pyrazol-1-ylmethyl]-6-(3,5-dimethyl-1H-pyrazol-1-ylmethyl)pyridine}methylpalladium(II) tetrakis[3,5-bis(trifluoromethyl)phenyl]borate, [Pd(C(18)H(18)F(6)N(5))][B(C(8)H(3)F(6))(4)], crystallizes as discrete cations and anions. The cation possesses a pseudo-twofold axis about which positional disorder of the tridentate ligand is exhibited. The four substituents on the two pyrazole rings exhibit CH(3)/CF(3) disorder, while all other atoms are ordered.

Trans-bis[3,5-bis(trifluoromethyl)-1H-pyrazole-kappaN2]dichloropalladium(II) monohydrate.

The palladium(II) center in the title compound, trans-[PdCl2(C5H2F6N2)2].H2O, possesses a distorted square-planar geometry. The NH groups are positioned on the same side of the PdN2Cl2 coordination plane.