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Four new Ni 16 molecular wheels with the general formula [L 4 Ni 16 (RCOO) 16 (H 2 O) x (MeOH) 12-x ] (where H 4 L=1,4-bis((E)-((2'-hydroxybenzyl)imino)methyl)-2,3-naphthalenediol, and R=H or Me) have been isolated and structurally characterised. Complexes C1-C3 (R=Me) were formed using nickel (II) acetate and presented as polymorphs with the same formulation of charged components. The same wheel-like architecture was observed in C4 (R=H), which was prepared using nickel (II) formate, demonstrating the potential for further versatility of the system. In contrast to similar four-fold symmetric Ni(II) wheel clusters, measurements of the static magnetic properties of C1 indicated the presence of dominant antiferromagnetic interactions and an S=0 ground state., (© 2024 The Author(s). Chemistry - An Asian Journal published by Wiley-VCH GmbH.)

The syntheses, coordination chemistry, and Mössbauer spectroscopy of hepta-iron(III) complexes using derivatised salicylaldoxime ligands from two categories; namely, 'single-headed' (H 2 L ) and 'double-headed' (H 4 L ) salicylaldoximes are described. All compounds presented here share a [Fe 3 -µ 3 -O] core in which the iron(III) ions are µ 3 -hydroxo-bridged in the complex C1 and µ 3 -oxo-bridged in C2 and C3 . Each compound consists of 2 × [Fe 3 -µ 3 -O] triads that are linked via a central [Fe(µ 2 -OH) 6 ] 3- ion. In addition to the charge balance and microanalytical evidence, Mössbauer measurements support the fact that the triads in C1 are µ 3 -OH bridged and are µ 3 -O bridged in C2 and C3 .

In the quest for optimal H 2 evolution (HE) through ethanol photoreforming, a dual cocatalyst-modified heterocatalyst strategy is utilized. Tin(II) sulfide (SnS) was hybridized with α-Fe 2 O 3 to form the heterocatalyst FeOSnS with a p-n heterojunction structure as confirmed by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), UV-vis diffusive reflectance spectroscopy (UV-vis DRS), and Brunauer-Emmett-Teller (BET) techniques. PdO x and PdO x /MnO x cocatalysts were loaded onto the FeOSnS heterocatalyst through the impregnation method, as verified by high-resolution transform electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and elemental mapping. Photocatalytic ethanol photoreforming resulted in the production of H 2 as the main product with a selectivity of 99% and some trace amounts of CH 4 . The FeOSnS2-PdO x 2%/MnO x 1% photocatalyst achieved the highest HE rate of 1654 μmol/g, attributed to the synergistic redox contribution of the PdO x and MnO x species., Competing Interests: The authors declare no competing financial interest., (© 2022 The Authors. Published by American Chemical Society.)

We report the synthesis and characterization of three dinuclear 3 d 3 d ' complexes, CuCu ( [ C u 2 I I L ( N O 3 ) 2 ] ), MnMn ( [ M n 2 I I L ( M e O H ) 2 ( N O 3 ) 2 ] ), and CuMn ([Cu II Mn II L (NO 3 ) 2 ]), that utilize the ligand, H 2 L (6,6'-dimethoxy-2,2'-[(1,3-propylene)dioxybis(nitrilomethylidyne)]diphenol). The relative stabilities of these complexes were investigated using experimental and computational techniques, revealing a non-Irving-Williams transmetalation, whereby a Mn II ion can displace a Cu II ion from its binding pocket in CuCu to yield the more stable CuMn complex. Magnetic characterization of the reported complexes revealed an unexpected ferromagnetic coupling between the two Cu II ions of CuCu with J = +63.0 cm -1 .

Conditions have been identified in which phenolic aldoximes and ketoximes of the types used in commercial solvent extraction processes can be doubly deprotonated and generate polynuclear Cu complexes with lower extractant:Cu molar ratios than those found in commercial operations. Electrospray mass spectrometry has provided an insight into the solution speciation in extraction experiments and has identified conditions to allow isolation and characterization of polynuclear Cu-complexes. Elevation of pH is effective in enhancing the formation of trinuclear complexes containing planar {Cu 3 -μ 3 -O} 4+ or {Cu 3 -μ 3 -OH} 5+ units. DFT calculations suggest that such trinuclear complexes are more stable than other polynuclear species. Solid structures of complexes formed by a salicylaldoxime with a piperidino substituent ortho to the phenolic OH group ( L 9 H 2 ) contain two trinuclear units in a supramolecular assembly, {[Cu 3 OH( L 9 H) 3 (ClO 4 )](ClO 4 )} 2 , formed by H-bonding between the central {Cu 3 -μ 3 -OH} 5+ units and oxygen atoms in the ligands of an adjacent complex. Whilst the lower ligand:Cu molar ratios provide more efficient Cu-loading in solvent extraction processes, the requirement to raise the pH of the aqueous phase to achieve this will make it impractical in most commercial operations because extraction will be accompanied by the precipitation (as oxyhydroxides) of Fe(III) which is present in significant quantities in feed solutions generated by acid leaching of most Cu ores.

Inspired by the crystal structure of a Mn III dinuclear complex we obtained featuring both Jahn-Teller (JT) elongation and compression distortions, we have modelled a series of complex cations based on the disordered crystal formulation; [Mn 2 (L1) 2 (μ 2 -OH) 2 ) 4+ (1), [Mn 2 (L1)(L2)(μ 2 -OH) 2 ) 4+ (2), [Mn 2 (L2)(L1)(μ 2 -OH) 2 ) 4+ (3), and [Mn 2 (L2) 2 (μ 2 -OH) 2 ) 4+ (4) (where L1 = (1 E ,1' E )-5- tert -butyl-3-(((4-(((5- tert -butyl-2-hydroxy-3-(( E )-(hydroxyimino)methyl)benzyl)(methyl)amino)methyl)benzyl)(methyl)amino)methyl)-2-hydroxybenzaldehyde and L2 = 3,3'-(1,4-phenylenebis(methylene))bis(methylazanediyl)bis(methylene)bis(5- tert -butyl-2-hydroxybenzaldehyde)) with different geometries to investigate the effects of the distortions on the magnetic coupling parameter. All computationally modelled dimers had a ferromagnetic interaction between the Mn III centres, with greater magnetic coupling calculated for complexes with both JT elongation and compression present. The ferromagnetic contribution to the J coupling was ascribed to the orthogonality of the singly occupied magnetic orbitals along with the cross-interaction between the unfilled Mn1(d x 2 - y 2 ) and singly occupied Mn2(d x 2 - y 2 ) orbitals. Constrained calculations showed that reducing the extent of the compression at Mn2 results in a concomitant increase in the dihedral angle between the JT axes, thereby reducing the relative magnitude of the magnetic coupling between Mn III centres.

Four tetranuclear heterobimetallic triangle complexes [L 3 Co 3 Dy(NO 3 ) 2 (H 2 O)(MeOH) 5 ](NO 3 ) (C1), [L 3 Co 3 Gd(NO 3 ) 3 (MeOH) 4 ] (C2), [L 3 Co 3 La(NO 3 ) 2 (H 2 O) 6 ](NO 3 )(H 2 O) (C3), and [L 3 Co 3 TbCl(NO 3 ) 2 (H 2 O) 0.5 (MeOH) 3.5 ] (C4), where H 2 L = 1,4-bisformylnaphthalene-2,3-diol, have been synthesised and structurally characterised. Each complex crystallises with a complete molecule in the asymmetric unit ( Z ' = 1) and displays near perfect octahedrality in two out of three Co II centres. The third Co II ion assumes a different coordination geometry in each complex: six-coordinate octahedral in C1, six-coordinate with a distortion towards trigonal prismatic in C2, five-coordinate trigonal bipyramidal in C3, and five-coordinate square pyramidal in C4; which has been attributed to increasing lanthanide cation size, coupled with a non-macrocyclic coordination environment. Continuous Shape Measurement (CShM) calculations and octahedral distortion parameter calculations were performed, using the SHAPE and OctaDist software packages, respectively, in order to aid in the assessment of each metal centre's local coordination geometry. The preliminary magnetic investigation of C3 found χ m T = 9.4 cm 3 K mol -1 at 300 K and M = 7.1 μ B at 1.8 K, which are approximately two thirds the maximum theoretical values for three Co II ions and indicates the presence of a relatively large zero-field splitting parameter ( D / k B = 65 K) operative in each Co II ion rather than exchange coupling between the Co II centres., Competing Interests: There are no conflicts of interest to declare., (This journal is © The Royal Society of Chemistry.)

We report the synthesis and characterization of seven new tetranuclear 3d-4f complexes derived from the 3:3:1 reaction of 1,4-diformylnaphthalene-2,3-diol (H 2 L ) with copper(II) nitrate and a lanthanide salt, Ln = Tb [ L 3 Cu 3 TbCl 2 (NO 3 ) 2 (H 2 O) 2 ] ( C1 ), Ho [ L 3 Cu 3 HoCl 3 (H 2 O) 3 (MeOH)](H 2 O) ( C2 ), Er [ L 3 Cu 3 ErCl 3 (H 2 O) 3.5 (MeOH) 0.5 ](H 2 O) ( C3 ), Gd [ L 3 Cu 3 Gd(NO 3 ) 2 (H 2 O) 2 (MeOH)](NO 3 ) ( C4 ), Dy [ L 3 Cu 3 Dy(NO 3 ) 2 (H 2 O) 2 (MeOH)](NO 3 ) ( C5 ), Yb [ L 3 Cu 3 Yb(NO 3 ) 2 (H 2 O) 2 (MeOH)](NO 3 ) ( C6 ), and La [ L 3 Cu 3 La(NO 3 ) 2 (H 2 O) 2 (MeOH)](NO 3 ) ( C7 ). Structural elucidation showed that the self-assembly using the acyclic ligand system was successful for all seven complexes, which exhibit the same near-planar Cu 3 LnO 12 core. Five complexes ( C1 , C2 , and C4 - C6 ) were magnetically characterized at 300 K and 1.8 K. Complexes C1 , C4 , and C5 were observed to have ferromagnetic ground states and showed appreciable frequency dependence in their AC magnetic measurements, which yielded effective barriers between 7.82(4) and 13.2(3) K, confirming the presence of single-molecule magnet properties., Competing Interests: The authors declare no competing financial interest., (© 2022 The Authors. Published by American Chemical Society.)

The synthesis and structural characterisation of four new heterometallic tetranuclear complexes is reported. Three L 3 Ni 3 Ln type complexes, where Ln = La (C1), Eu (C2), and Gd (C3), have been fully characterised including DC and AC magnetic measurements. A fourth complex featuring a diamagnetic Ba II ion at its centre is also reported with structural characterisation. Structural elucidation showed that all four complexes successfully self-assembled from a stoichiometric mixture of the acyclic ligand, 1,4-diformylnaphthalene-2,3-diol, with nickel(II) nitrate and the appropriate heavy metal salt to produce the same near planar Ni 3 MO 12 core. Ferromagnetic interactions were found to dominate the ground state of C3, exhibiting a maximal spin ground state of 13/2. The exchange coupling is quantitatively discussed along with the nickel(II) zero-field splitting effect. AC magnetic susceptibility experiments were carried out, but no frequency dependent signals were observed and thus no observable slow relaxation of magnetisation.

Iron oxide nanoparticles (IONPs) have gained increasing attention in various biomedical and industrial sectors due to their physicochemical and magnetic properties. In the biomedical field, IONPs are being developed for enzyme/protein immobilization, magnetofection, cell labeling, DNA detection, and tissue engineering. However, in some established areas, such as magnetic resonance imaging (MRI), magnetic drug targeting (MDT), magnetic fluid hyperthermia (MFH), immunomagnetic separation (IMS), and magnetic particle imaging (MPI), IONPs have crossed from the research bench, received clinical approval, and have been commercialized. Additionally, in industrial sectors IONP-based fluids (ferrofluids) have been marketed in electronic and mechanical devices for some time. This review explores the historical evolution of IONPs to their current state in biomedical and industrial applications.

We report the synthesis and crystal structure of the first quinolino[7,8- h ]quinoline beryllium(II) complex of the general formula [BeL2(MeCN)Br]Br·MeCN, containing the ligand 4,9-dihydroxyquinolino[7,8- h ]quinoline (L2). The Be(II) cation is a great size match for the dinitrogen binding pocket of the quinolino[7,8- h ]quinoline ligand as indicated by minimal out-of-plane displacement and ligand distortion parameters.

Cu I complexes containing the bulky dialkylbiarylphosphane 2-(di-tert-butylphosphanyl)-2',4',6'-triisopropylbiphenyl ( t BuXPhos, L) and an ancillary ligand (Cl - , Br - , I - , MeCN, ClO 4 - or SCN - ) have been structurally characterized, namely, chlorido[2-(di-tert-butylphosphanyl)-2',4',6'-triisopropylbiphenyl-κP]copper(I), [CuCl(C 29 H 45 P)], 1, bromido[2-(di-tert-butylphosphanyl)-2',4',6'-triisopropylbiphenyl-κP]copper(I), [CuBr(C 29 H 45 P)], 2, [2-(di-tert-butylphosphanyl)-2',4',6'-triisopropylbiphenyl-κP]iodidocopper(I), [CuI(C 29 H 45 P)], 3, (acetonitrile-κN)[2-(di-tert-butylphosphanyl)-2',4',6'-triisopropylbiphenyl-κP]copper(I) hexafluoridophosphate, [Cu(CH 3 CN)(C 29 H 45 P)]PF 6 , 4, [2-(di-tert-butylphosphanyl)-2',4',6'-triisopropylbiphenyl-κP](perchlorato-κO)copper(I), [Cu(ClO 4 )(C 29 H 45 P)], 5, and di-μ-thiocyanato-κ 2 S:N;κ 2 N:S-bis{[2-(di-tert-butylphosphanyl)-2',4',6'-triisopropylbiphenyl-κP]copper(I)}, [Cu 2 (NCS) 2 (C 29 H 45 P) 2 ], 6. Iodide complex 3 shows significant Cu I -arene interactions, in contrast to its chloride 1 and bromide 2 counterparts, which is attributed to the weaker interaction between the iodide ion and the Cu I centre. When replacing iodide with an acetonitrile (in 4) or perchlorate (in 5) ligand, the reduced interaction between the Cu I atom and the ancillary ligand results in stronger Cu I -arene interactions. No Cu I -arene interactions are observed in dimer 6, due to the tricoordinated Cu I centre having sufficient electron density from the coordinated ligands.

Substituted [2.2]metaparacyclophanes are amongst the least studied of the simple cyclophanes. This is undoubtedly the result of the lengthy syntheses of these compounds. We report the simple synthesis of a rare example of a non-symmetric [2.2]metaparacyclophane. Treatment of [2.2]paracyclophane under standard nitration conditions gives a mixture of 4-nitro[2.2]paracyclophane, 4-hydroxy-5-nitro[2.2]metaparacyclophane and a cyclohexadienone cyclophane., (Copyright © 2021, Patel et al.)

Syntheses and magnetic and structural characterization of hexa-iron complexes of derivatized salicylaldoximes are discussed. Complexation of Fe(BF 4 ) 2 ·6H 2 O with each ligand (H 2 L1 and H 4 L2 ) in a methanolic-pyridine solution resulted in hexa-iron compounds ( C1 and C2 , respectively), which each contain two near-parallel metal triangles of [Fe 3 -μ 3 -O], linked by six fluoride bridges and stabilized by a hydrogen-bonded proton between the μ 3 -O groups. Within each metal triangle of C2 , Fe(III) ions are connected via the amine "straps" of (H 4 L2 -2H). Variable-temperature magnetic susceptibility and Mössbauer data of C1 and C2 indicate the presence of dominant antiferromagnetic interactions between the high-spin ( S = 5/2) Fe(III) centers. For C1 , two quadrupole doublets are observed at room temperature and 5 K, consistent with structural data from which discrete but disordered [Fe 3 -μ 3 -O] and [Fe 3 -μ 3 -OH] species were inferred. For C2 , a single sharp quadrupole doublet with splitting intermediate between those determined for C1 was observed, consistent with the symmetric [Fe 3 -μ 3 -O···H···μ 3 -O-Fe 3 ] species inferred crystallographically from the very short μ 3 -O···μ 3 -O separation. The differences in the physical properties of the complexes, as seen in the Mössbauer, X-ray, and magnetic data, are attributed to the conformational flexibility imparted by the nature of the linkages between the closely related ligands., Competing Interests: The authors declare no competing financial interest., (© 2021 The Authors. Published by American Chemical Society.)

We report the synthesis and characterization of four new tetranuclear Ni(ii) complexes, C1-C4, all of which exhibit defective dicubane cores. C1-C4 are derived from the same salicylaldoxime derived ligand, H2L1. Complexes C1 and C4 have isostructural cores, differing in structure only by solvate molecules. Magnetic and computational analyses have revealed that complexes C1, C2, and C4 exhibit competing ferro- and antiferromagnetic interactions, however the different solvated species in C1 and C4 leads to notably different magnitudes in their magnetic coupling constants. Theoretical magneto-structural studies show that the pairwise magnetic exchange interaction is highly dependent on the Ni-X-Ni angle, as revealed by orbital overlap calculations.

A comparative study between three experimentally known beryllium chelators (EDTA, NTP, and 10-HBQS) and two tetradentate tripodal di-pyridine-based receptors (HL and HL-NH 2 ), specifically designed to bind Be 2+ cations, has been undertaken in the aqueous phase at the B3LYP/6-311++G(d,p) computational level. The relative binding energies of these five ligand systems to a variety of first row and pre-transition metal cations have been calculated, specifically to investigate their binding strength to Be 2+ and the binding enhancement that a second sphere hydrogen bonding interaction could afford to the pyridyl based systems. The complexes of EDTA were calculated to have the highest average binding energy; followed by those of NTP, HL-NH 2 , HL, and finally 10-HBQS. The calculated binding energy of the HL-NH 2 Be complex, which includes second sphere interactions, was found to be almost 9% greater than the HL Be complex, with an average binding energy increase of 13.5% observed across all metals upon inclusion of second sphere hydrogen bonding., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Quinolino[7,8- h ]quinoline is a superbasic compound, with a p K aH in acetonitrile greater than that of 1,8-bis(dimethylaminonaphthalene) (DMAN), although its synthesis and the synthesis of its derivatives can be problematic. The use of halogen derivatives 4,9-dichloroquinolino[7,8- h ]quinoline ( 16 ) and 4,9-dibromoquinolino[7,8- h ]quinoline ( 17 ) as precursors has granted the formation of a range of substituted quinolinoquinolines. The basicity and other properties of quinolinoquinolines can be modified by the inclusion of suitable functionalities. The experimentally obtained p K aH values of quinolino[7,8- h ]quinoline derivatives show that N 4 , N 4 , N 9 , N 9 -tetraethylquinolino[7,8- h ]quinoline-4,9-diamine ( 26 ) is more superbasic than quinolino[7,8- h ]quinoline. Computationally derived p K aH values of quinolinoquinolines functionalized with dimethylamino (NMe 2 ), 1,1,3,3-tetramethylguanidino (N═C(NMe 2 ) 2 ) or N , N , N ', N ', N ″, N ″-hexamethylphosphorimidic triamido (N═P(NMe 2 ) 3 ) groups are significantly greater than those of quinolino[7,8- h ]quinoline. Overall, electron-donating functionalities are observed to increase the basicity of the quinolinoquinoline moiety, while the substitution of electron-withdrawing groups lowers the basicity.

In the quest for optimal heat dissipaters for magnetic fluid hyperthermia applications, monodisperse M x Fe 3- x O 4 (M = Fe, Mg, Zn) spinel nanoferrites were successfully synthesized through a modified organic-phase hydrothermal route. The chemical composition effect on the size, crystallinity, saturation magnetization, magnetic anisotropy, and heating potential of prepared nanoferrites were assessed using transmission electron microscopy (TEM), dynamic light scattering, X-ray diffraction (XRD), thermogravimetric analysis (TGA), energy-dispersive X-ray spectroscopy (EDS), atomic absorption spectroscopy (AAS), X-ray photoelectron spectroscopy (XPS), and vibrating sample magnetometer (VSM) techniques. TEM revealed that a particle diameter between 6 and 14 nm could be controlled by varying the surfactant ratio and doping ions. EDS, AAS, XRD, and XPS confirmed the inclusion of Zn and Mg ions in the Fe 3 O 4 structure. Magnetization studies via VSM revealed both the superparamagnetic nature of the nanoferrites and the dependence on substitution of the doped ions to the final magnetization. The broader zero-field cooling curve of Zn-doped Fe 3 O 4 was related to their large size distribution. Finally, a maximum rising temperature ( T max ) of 66 °C was achieved for an aqueous ferrofluid of nondoped Fe 3 O 4 nanoparticles after magnetic field activation for 12 min., Competing Interests: The authors declare no competing financial interest., (Copyright © 2020 American Chemical Society.)

Structures of aqueous [Be(H 2 O) 4 ] 2+ , its outer-sphere and inner-sphere complexes with F - , Cl - , and SO 4 2- , and dinuclear complexes with a [Be 2 (κ-OH)(κ-SO 4 )] + core have been studied through Car-Parrinello molecular dynamics (CPMD) simulations with the BLYP functional. According to constrained CPMD/BLYP simulations and pointwise thermodynamic integration, the free energy of deprotonation of [Be(H 2 O) 4 ] 2+ and its binding free energy with F - are 9.6 and -6.2 kcal/mol, respectively, in good accord with available experimental data. The computed activation barriers for replacing a water ligand in [Be(H 2 O) 4 ] 2+ with F - and SO 4 2- , 10.9 and 13.6 kcal/mol, respectively, are also in good qualitative agreement with available experimental data. These ligand-substitution reactions are indicated to follow associative interchange mechanisms with backside (S N 2-like) attack of the anion relative to the aquo ligand it is displacing. Outperforming static density functional theory computations of the salient kinetic and thermodynamic quantities involving simple polarizable continuum solvent models, CPMD simulations are validated as a promising tool for studying the structures and speciation of beryllium complexes in aqueous solution.

In this study, we show that phosphate decreases the spore heat resistance by accelerating the rate of loss of cations from spores. Heat resistance of spores of Geobacillus stearothermophilus A1, D1, P3 and ATCC 12980 were determined in distilled water containing varying concentrations (0.1, 1 and 2% w/v) of di‑sodium phosphate. The average decimal reduction times (D value) for strains A1, D1, P3 and ATCC 12980 in distilled water were 5.8, 6.8, 5.7 and 9 min at 110 °C respectively. On the addition of 0.1, 1 and 2% w/v of di‑sodium phosphate, the average D 110 values of all the strains in distilled water were lowered by 50, 61 and 70% respectively. Addition of 0.05% w/v of Na-EDTA to distilled water resulted in lowering of the average D 110 value of all the strains by 55%. Heat resistance of spores of A1, D1, P3 and ATCC 12980 was found to be associated with the Dipicolinic Acid (DPA) content whose concentrations were 0.25, 0.30, 0.27 and 1.6 pg per spore respectively. Analysis by atomic absorption spectroscopy revealed that the phosphate present in the heating medium causes excess release of calcium from spores with 2% w/v phosphate being highly effective, thus confirming the chelating effect of phosphate. This study provides insight into the heat resistance and the increased heat sensitivity of spores of G. stearothermophilus A1, D1 and P3 in the presence of phosphate, which can be used in the design of Cleaning in Place (CIP) systems involving phosphate based cleaning agents to combat biofilms and spores in the dairy industry., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Two series of tetradentate tripodal di-pyridine-based receptors designed to bind Be 2+ cations have been studied in the aqueous phase at the B3LYP/6-311++G(d,p) computational level. The first series comprise simple tetrahedral receptors; the second series incorporates additional scaffolding groups capable of second sphere hydrogen-bonding in order to more finely tune the binding strength towards the Be 2+ cation. Out of the five ligand candidates, one containing a tri-pyridyl N-donor along with a phenolato O-donor (L1) exhibited a significant improvement in binding energy stabilisation (47.8 kJ mol -1 ) towards the Be 2+ cation in the presence of second-sphere H-bonding interactions.

Anion hydrolysis reactions between salicylaldoximato ligands (L'-L''') and copper and iron BF 4 - metal salts, have resulted in the formation of new salicylaldoximato borate containing transition metal complexes: [Fe 2 (L' + 2H) 2 ](BF 4 ) 2 (MeOH) 4 (C1), [Fe 3 (L'' + 4H)(OH) 2 (Py) 2 ](BF 4 ) 2 (H 2 O) 2 (Py) 2 (C2), and [Cu 2 (L''' + H) 2 Cl 2 ] (C3). Each of the complexes have been structurally characterised, revealing the indirect role boron plays in the formation of these complexes. For complexes C1 and C2, Mössbauer spectroscopy confirmed the existence of Fe(iii) oxidation states. SQUID magnetometry measurements were performed on complexes C2 and C3, revealing the presence of two competing exchange pathways between the three Fe(iii) centres in C2, with antiferromagnetic exchange dominating. For C3 weak antiferromagnetic exchange dominated between the two Cu(ii) centres.

Electrospray ionization mass spectrometry (ESI MS) is a powerful technique for the study of coordination complexes because of its ability to analyze solution systems involving very low concentrations of metal complexes. In this work, the coordination chemistry of Be ions with a selection of well-known 1,3-diketone and related 1,2-diketone ligands has been investigated using ESI MS. With acetylacetone (Hacac), a range of acac-containing ions is observed, including [Be(acac) 2 H] + , [Be(acac)(MeOH) n ] + ( n = 1, 2), and polynuclear species such as the dinuclear [Be 2 (acac) 3 ] + and trinuclear [Be 3 O(acac) 3 ] + . Density functional theory calculations indicate that the latter species has a central Be 3 (μ 3 -O) core, with each Be chelated (as opposed to being bridged) by an acac ligand. The effect of changing the substituents on 1,3-diketone was explored by an investigation of mixtures of Be 2+ with other 1,3-diketones such as dibenzoylmethane (Hdbm), where the [Be(dbm) 2 H] + ion showed a lesser tendency to undergo fragmentation and aggregation processes. Comparisons with the corresponding aluminum acetylacetone system were also made. In contrast, mixtures of Be 2+ and the 1,2-diketones diacetyl and phenanthrenequinone showed poor metal-ligand interactions. Be 2+ interacted with the 1,2-diketone benzil [PhC(O)C(O)Ph], forming the [Be(benzil) n ] 2+ ( n = 2-4) ions. The synthesis (from BeCl 2 ) and X-ray structures of the dibenzoylmethanato (dbm) complex Be(dbm) 2 and the benzil complex [BeCl 2 (benzil)] are also reported.

The synthesis of three planar chiral pseudo-gem disubstituted [2.2]paracyclophane-derived P,N-pre-ligands is reported along with preliminary results of their activity in the amination of aryl bromides and chlorides. The pseudo-gem aminophosphines were capable of mediating the coupling reaction at a loading of 1 mol%.

Tritrichomonas foetus is a flagellated protozoan parasite that colonizes the feline colon causing colitis and chronic foul smelling diarrhoea. Despite the efficacy of Ronidazole in the treatment of T. foetus, Ronidazole has been reported to cause neurotoxicity in some cats due to rapid absorption in the small intestine. A novel amphoteric derivative of chitosan was synthesised and characterized. A combination of time, pH, and an enzyme controlled system was used in a study of a new compression coated tablet for delivery of Ronidazole to the colon. Axial, radial swelling and erosion of selected tablets were carried out in various media. The effect of weight ratio, enzyme and pH on in vitro drug release profile was investigated. The results show that less than 2% of the drug was released in the physiological environment of the stomach and small intestine., (Copyright © 2016 Elsevier B.V. All rights reserved.)

The syntheses and single crystal X-ray analyses of five strapped salicylaldoxime/salicylaldimine based dicopper(ii) receptors utilising a new piperazine linker are described. The complexes form 2 + 2 metallocycles and the molecular structures of all four complexes possess a small internal cavity with the utilisation of a short piperazine linker. The molecular structures of complexes [Cu2(L(4) - H)(L(4) - 2H) ⊂ DMF]BF4·DMF, and [Cu2(L(4) - H)2Br]Br·1.25DMSO·H2O·MeOH, show that intramolecular H-bonding interactions due to the presence of -OH (oxime moiety) groups lead to a Pacman-like cleft arrangement of the two metal coordinating subunits in the metallo-macrocycle. The geometrical constraints brought about by this constrained cleft make the receptor coordinate strongly to a bromide anion involving both metal centres as evidenced by whereas in the larger tetrafluroborate anion is excluded. Absence of the oxime moiety around the metal coordination site of the ligand as demonstrated in the complexes [Cu2(L(5))2BF4](BF4)3, and [Cu2(L(5))2Br]Br3·2MeOH, resulted in less constrained dicopper(ii) helicate forms. For these complexes no anion size discrimination was observed. The addition of pyridine solvent to a slightly modified piperazine-linked ligand produces an expanded 3 + 3 tube-like tricopper complex [Cu3(L(4a) - H)3Py3](BF4)2·(MeOH)3·PF6·(H2O)3, , with two coordinated pyridine molecules occupying the newly formed cavity.

The synthesis and spectroscopic analysis of both "metal-only" and anion encapsulated salicylaldoxime-based complexes utilizing a new 1,3-xylyl strap are described. X-ray crystallographic analysis reveals that the aromatic spacer restricts the confirmation flexibility of the resulting complexes leading to dicopper(II) double helicate and dicopper(II) 2 + 2 "box" structural forms. The choice of the structural motif is influenced by the anion present, with the copper(II) nitrate-containing complex [NO3⊂(Cu2L(3)2)](NO3)3, 4, adopting a double helicate form, whereas the analogous copper(II) bromide complexes [2Br⊂(Cu2L(3)2)](Br)2, 5, and [2Br⊂(Cu2L(3)2)](BF4)2, 6, both adopt 2 + 2 "box" structural configurations. Spectroscopic analysis has shown an enhancement in the binding strength of ClO4(-) over the anions SO4(2-) and NO3(-). The enhanced rigidity caused by the use of the 1,3-xylyl spacer in this series of complexes has favored the formation of the "double loaded" dibromide complex.

In the title complex, [Cu(BF4)2(C5H5N)2], the Cu(II) ion is in an octa-hedral coordination environment and is surrounded by four pyridine and two tetra-fluoridoborate mol-ecules. The four pyridine mol-ecules are coordinated to the copper ion through their N atoms in the equatorial plane and display a right-handed screw arrangement around the Cu(II) ion. The remaining two trans positions in the octa-hedron are occupied by the BF4 (-) anions, each coordinating weakly through an F atom. The crystal packing shows a two-dimensional sheet structure parallel to the ab plane that is formed by C-H⋯F hydrogen-bonding inter-actions.

The structures of a series of tetracoordinate beryllium(II) complexes with ligands derived from tertiary-substituted amines have been computationally modeled and their (9)Be magnetic shielding values determined using the gauge-including atomic orbital (GIAO) method at the 6-311++g(2d,p) level. A good correlation was observed between calculated (9)Be NMR chemical shifts when compared to experimental values in polar protic solvents, less so for the values recorded in polar aprotic solvents. A number of alternative complex structures were modeled, resulting in an improvement in experimental versus computational (9)Be NMR chemical shifts, suggesting that in some cases full encapsulation on the beryllium atom was not occurring. Several of the synthesized complexes gave rise to unexpected fluorescence, and inspection of the calculated molecular orbital diagrams associated with the electronic transitions suggested that the rigidity imparted by the locking of certain conformations upon Be(II) coordination allowed delocalization across adjacent aligned aromatic rings bridged by Be(II).

A new efficient, low cost chitosan based biosorbent was successfully prepared and employed for the biosorption of copper ions from an aqueous solution using a fixed bed column. Pyromellitic dianhydride crosslinked chitosan as the new adsorbent was characterized by SEM, FTIR spectroscopy, X-ray diffraction, thermogravimetric analysis and solid state (13)C NMR analysis. Scanning electron microscopy coupled with an X-ray energy dispersed analysis for the copper-equilibrated biomass confirmed the presence of Cu(II) ions on the surface of the hydrogel. Thermogravimetric analysis showed a significant improvement in the thermal stability of the new hydrogel compared to pure chitosan. Kinetic models were applied to predict the breakthrough curves. This study shows that the prepared hydrogel based on modified chitosan could be utilized as an efficient bioadsorbent for the removal of copper ions from wastewater., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Unsatisfactory mechanical properties, poor heat resistance, dissolution in acidic media and high swelling ratios limit using chitosan as an adsorbent in industry. In this study, we used dianhydride derivatives famous for their exceptional mechanical and thermal characteristics and low water absorption. In this study, pyromellitic dianhydride (PMDA), benzophenone-3,3',4,4'-tetracarboxylic dianhydride (BTDA), 4,4'-oxydiphthalic dianhydride (ODPA) and 4,4'-(hexafluoroisopropylidene)diphthalic dianhydride (FDA) were utilised as crosslinking agents. Use of common crosslinking agents usually decreases the metal uptake capacity of chitosan. These novel crosslinking agents increased the metal uptake from 1.8 (ODPA/Cu 2+ ) to 7.8 (PMDA/Zn 2+ ) times. Langmuir and Freundlich adsorption models were applied to analyse the isotherms and isotherm constants. Kinetic, X-ray diffraction, pH, FTIR studies were also carried out., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

The synthesis and spectroscopic analysis of both "metal-only" and anion encapsulated dicopper(II) double helicates utilising a new 1,4-aryl spacer is described. X-Ray crystallographic analysis of the complexes reveal that the aromatic spacer increases rigidity in the complex, yet the complexes are still able to undergo a dramatic "coiling up" to bind anions. Spectroscopic analysis has shown a clear enhancement in the binding strength of SO(4)(2-) over the non-coordinating anions ClO(4)(-), NO(3)(-) and Br(-) which has been attributed to a combination of enhanced rigidity in the complex and an increased electrostatic interaction between the complex and the dianion.

Two arginine side-chain protecting groups, N(G)-4-methoxy-2,3,6-trimethylbenzensulfonyl group (Mtr) and N(G)-2,2,5,7,8-pentamethylchroman-6-sulfonyl (Pmc), have been investigated at both the Arg(1) and/or Arg(9) position of the bioactive peptide, Bradykinin using Fluorenylmethyloxycarbonyl (Fmoc) Solid Phase Peptide Synthesis. A more efficient synthesis of the peptide has been found when a combination of Arg(Mtr) is present at position 1 and Arg(Pmc) is present at position 9 giving a cleaved pure yield of 52%.

The preferential uptake of sulfate over the industrially important anions, chloride and nitrate and structurally similar dihydrogen phosphate has been achieved in aqueous media with a dicopper salicylaldoxime complex.

The synthesis and spectroscopic studies of a dicopper(II) double helicate capable of binding anions is described. X-Ray crystallographic analysis of three anion variations of the complex have shown that the helicate is capable of accommodating anions with an approximate volume of 0.09 nm(3) and smaller. ESI-MS revealed that the supramolecular complexes retain the 2 : 2 ligand : metal cluster in solution. Spectrometric analysis has shown the complex is capable of binding anions in a 1 : 1 ratio of helicate to anion, in the order SO(4)(2-) > HPO(4)(2-) > ClO(4)(-) approximately BF(4)(-) approximately NO(3)(-). We demonstrate that coordination to the metal centre, H-bonding and electrostatic interactions all play a role in encapsulating the anions.

Uptake of a tetrafluoroborate anion into the centre of a dicopper bis-salicylaldoxime complex causes a major contraction of the cavity and an increase in helicity.

Amide-functionalised salen ligands capable of extracting metal salts have been synthesised and characterised. Single-crystal X-ray structure determinations of complexes of NiSO4, [Ni(L)(SO4)], confirm that the ionophores are in a zwitterionic form with Ni(II) bound in the deprotonated salen moiety and the SO4(2-) ion associated with protonated pendant N'-amidopiperazine groups. Treatment of [Ni(L)(SO4)] with base removes the protons from the pendant amido-amine group resulting in loss of the SO4(2-) ion and formation of metal-only complexes of type [Ni(L-2H)], which have been characterized by single-crystal X-ray diffraction. Three of the ligands with solubilities suitable for solvent extraction studies show loading and stripping pH-profiles that are suitable for the recovery of CuSO4 or CuCl2 from industrial leach solutions. The copper-only complexes, [Cu(L-2H)], are selective for Cl- over SO4(2-) in both solvent extraction and bulk liquid membrane transport experiments and were found to bind Cl- in two steps via the formation of a 1:1:1 [Cu(L-H)Cl] assembly, followed by a 1:1:2 [Cu(L)Cl2] assembly as the pH of the aqueous phase is lowered. The anion transport selectivity was evaluated for a number of other mono-charged anions and interestingly the ligands were found to display a preference for the Br- ion. To probe the influence of the Hofmeister bias on the selectivity of anion complexation, single-phase potentiometric titration experiments were employed to investigate the binding of SO4(2-) and Cl- by one of the copper only complexes, [Cu(L-2H)] in 95 %/5 % MeOH/water. Under these conditions selectivity was reversed (SO4(2-)>Cl-) confirming that the Hofmeister bias, which reflects the relative hydration energies of the anions, dominates the selectivity of anion extraction from aqueous media into CHCl3.

The strength and selectivity of anion-binding by metal salt extractants have been assessed by defining the pH-dependence of anion uptake into a water-immiscible solution of the "metal-only" complexes; high Cl-/SO4(2-) selectivity of transport has been developed.

Zinc metal reduction of the cobalt(III) complex [Co(1,4-bcc)](+) (1,4-bcc = 1,4-bis-carboxymethylcyclam) produces the corresponding cobalt(II) complex which crystallises as the coordination polymer {[Co(1,4-bcc)]ZnCl(2)}(n). A method has been developed for removal of the cobalt(III) ion from [Co(1,4-bcc)](+) and isolation of the free ligand as its hydrochloride salt, H(2)(1,4-bcc).4HCl. This has been used for the preparation of new metal complexes, and the syntheses and characterisation of the copper(ii), nickel(ii), zinc(ii) and chromium(iii) complexes containing the 1,4-bcc ligand are described. X-Ray crystal structures of {[Co(1,4-bcc)]ZnCl(2)}(n).2.5H(2)O, {[Cu(1,4-bcc)]CuCl(2)}(n).0.25MeOH.H(2)O and [Cu(1,4-bcc)H]ClO(4) show the complexes to have the trans(O) geometry of the 1,4-bcc ligand, while the structure of [Cr(1,4-bcc)H(0.5)](ClO(4))(1.5).EtOH exhibits the cis(O) configuration.

The ligand 4,5-dicarboxyimidazole (H(2)DCI) and its methyl derivative 1-methyl-4,5-dicarboxyimidazole (H(2)MDCI) have been shown to bind to Be(II) forming a zwitterionic species that has been structurally characterized. A new dicarboxyimidazole-based polymer has been prepared and its Be-binding properties have been studied using NMR ((1)H and (9)Be) and fluorescence spectroscopy; it represents a rare example of beryllium binding to a polymer. Models of the mononuclear and polymeric Be(II)-binding sites have been studied using density functional theory (DFT), and the (9)Be NMR chemical shifts of these model materials have been calculated for the purpose of direct comparison to experimentally observed values. Differences in the binding modes of the mononuclear and polymeric species are discussed.

The structures of a series of beryllium containing complexes have been optimized at the B3LYP/6-31G(d) level and their (9)Be magnetic shielding values have been determined using B3LYP/6-311G+g(2d,p) and the gauge-including atomic orbital (GIAO) method. The calculated chemical shifts are in excellent agreement with experimental values. The performance of a variety of NMR methods (SGO, IGAIM, CSGT) were also examined but were found to be inferior to the GIAO method at the chosen level of theory employed. The theoretical method has been utilized to predict the beryllium chemical shifts of structurally characterized complexes for which no measured (9)Be NMR spectrum exists, and to investigate a literature complex with an unusual (9)Be NMR chemical shift. A new standard for beryllium NMR in nonaqueous solvents has been suggested.

A bis(pyridine-armed) acyclic Schiff base ligand L1 has been synthesised from 3,6-diformylpyridazine and two equivalents of 2-(2-aminoethyl)pyridine. Reduction of this ligand using NaBH(4) resulted in the formation of the amine analogue L2. Complexes of the form [M(2)L1(mu-X)]Y(2)ClO(4)[where: M = Cu(II), X = OH(-) and Y = ClO(4)(-) 1, Cl(-) 2, Br(-) 3 or I(-) 4; M = Co(II), X = OH(-) and Y = ClO(4)(-) 5; M = Ni(II), X = SCN(-) 6 or X = N(3)(-) 7 and Y = ClO(4)(-)], and [Cu(2)L2(mu-OH)](ClO(4))(3) 8 were prepared and characterised. The complexes 1 and 5-7 have been characterised by single-crystal X-ray diffraction. The acyclic L1 ligand provides three nitrogen donor atoms per metal centre, including a pyridazine bridge between the metal centres, and the anion X also bridges the two metal centres. As required, coordinating solvent molecules or additional anions make up the remainder of the coordination sphere. The two copper centres of 1 are very strongly antiferromagnetically coupled (2J=-1146 cm(-1))via the pyridazine and hydroxide ion bridges, whereas the competing antiferromagnetic pyridazine bridging pathway and ferromagnetic 1,1-bridging azide pathway resulted in the observation of weak antiferromagnetic exchange in the dinickel(II) complex 7 (2J=-14 cm(-1)). Electrochemical examination of L1, L2 and complexes 1 and 5-8 revealed multiple redox processes. These have been tentatively assigned to a mixture of metal centred and ligand centred redox processes on the basis of cyclic voltammetry and coulometry results and comparisons with literature examples.

A new series of meso-substituted diaryl free-base and metalloporphyrins have been prepared. Each arene has been substituted with both a methyl group in the ortho position and a formyl group in the meta position. Rotation of the arene units is prevented at room temperature due to the steric restrictions imposed by the flanking methyl groups at the porphyrin beta-pyrrolic positions on the methyl groups at the ortho position on the meso-substituted arene unit. This allowed the alpha alpha and alpha beta atropisomers of this porphyrin to be separated and characterised. X-Ray crystallographic determination of the structure of the free-base porphyrin revealed a very flat porphyrin core. Metallation resulted in the isolation and characterisation of the nickel, zinc and copper derivatives. The assignments of the alpha alpha and alpha beta isomers are confirmed by X-ray crystallographic determination of the structures of the Cu(II) analogues. The copper alpha alpha structure exhibits a very twisted porphyrin core, the copper alpha beta structure is also distorted, but to a lesser degree. The activation energy for rotation has been calculated for each of the 2H, Ni and Zn derivatives. The energy required to rotate the arene ring increases in the order Ni < Zn approximately 2H. No significant difference in the free energy of rotation was observed between experiments carried out with the alpha alpha and small alpha beta isomers.

10,25-Di-tert-alkyl-14,21-dimethyl-3,6,14,21-tetraazatricyclo[21.3.1.18,12]octacosa-1(27),2,6,8,10,12(28),23,25-octaene-27,28-diol macrocycles form Ni(II) and Cu(II) complexes in which the metal cation and the sulfate anion are bound in separated sites in a zwitterionic form of the ligand. The nonyl-substituted macrocycle shows a higher affinity for SO(4)(2-) and a lower binding strength for Cu(2+) than open chain analogues, the pH-dependences for which fall in ranges which allow loading of CuSO(4) at pH approximately 4 and easy stripping to recycle the ligand. X-Ray structure determinations of the Cu(II) and Ni(II) sulfate complexes of the tert-butyl substituted ligand suggest that the de-tuning of M(2+)-binding results from a distortion from planarity of the "salen" N(2)O(2)(2-) donor set imposed by the incorporation of the hexamethylene strap in the ligand and reveal that the sulfate is bound as a hydrate in a 2:2:2:2, ligand-M(2+)-SO(4)(2-)-H(2)O, assembly.

Structure analysis of the title compound, C(9)H(6)BrNO, has established that bromination of an 8-hydroxyquinoline derivative occurred in the 7-position. Intermolecular and weak intramolecular O-H.N hydrogen bonds are present, the former causing the molecules to pack as hydrogen-bonded dimers in the solid state.

The pH-dependence of simultaneous metal- and sulfate-loading of simple salen derivatives demonstrates the feasibility of their application as extractants for recovery of base metals from the leaching of sulfidic ores. The efficacy of the ligands depends on the templating of the sulfate binding site by the attendant metal ion.

A spin crossover transition (350 K, μ eff =3.15 μ B per Co atom; 4.5 K, μ eff =0.70 μ B per Co atom) and weak antiferromagnetic exchange (2 J=-11.7 cm -1 ) between the octahedral, doubly pyridazine bridged cobalt(II) ions are features of the structurally characterized complex [Co II 2 L(NCS) 2 (SCN) 2 ] (the ligand L is shown)., (© 1999 WILEY-VCH Verlag GmbH, Weinheim, Fed. Rep. of Germany.)