Molecular switching of nickel(ΙΙ) complexes using a hemilabile N,N′-bis(β-carbamoylethyl)1,2-diaminocyclohexane ligand

The reaction of NiCl₂·6H₂O with one equivalent hemilabile diaminodiamide ligand N,N′-bis(β-carbamoylethyl)1,2-diaminocyclohexane (1) gave a pale blue compound [Ni(C₁₂H₂₄N₄O₂)(H₂O)₂]₂·3H₂O·4Cl (2). With more than one equivalent ligands, 2 was transformed to a yellow species [Ni(C₁₂H₂₂N₄O₂)]·3H₂O (3) by the Ni–O to Ni–N bond rearrangement at two amide sites of the complex. The color change could be described as a pH dependent isomerization of the ligand. The results presented could be useful in the design of new Ni(II)-based switching materials.     

Synthesis,crystal structure and desulfurization properties of zig-zag 1D coordination polymer of copper(II) containing 4-methoxybenzoic acid ligand

ABSTRACT

Combustion of fuels containing organosulfur compounds has resulted in the emission of sulfur oxides (SO_x) into the atmosphere, therefore, causing serious environmental and health hazards. Herein, slightly distorted octahedral zig-zag 1D coordination polymer of copper(II) [Cu(4-mba)₂(H₂O)₃] was synthesized by reacting copper sulfate pentahydrate with a carboxylate-containing ligand (H-4mba?=?4-methoxybenzoic acid) and employed for sulfur compound uptake. The ligand coordinates to the copper(II) atom via two pairs of deprotonated ligating atoms (carboxylate oxygens) and two water molecules. Structural characterization also reveals that interplay of O–H···O, N–H···O, C-H···O and C–H···π interactions between lattice and coordinated water and ligands significantly contribute to the crystal packing leading to the formation and strengthening of three-dimensional supramolecular assembly. The complex, [Cu(4-mba)₂(H₂O)₃], show potential for desulfurization of fuel with an observed adsorption capacity of 9.6?mg/g at 32°C for 6?h. DFT calculations further revealed a transfer of electron sulfur-containing compounds and the complex, [Cu(4-mba)₂(H₂O)₃], thus leading to a stronger pi–pi interaction.     

Novel Copper(II) Complexes of <Emphasis Type="Italic">N</Emphasis>-Phenylanthranilic Acid Containing Ethanol and Hydroxo Ligands

The complexes, tetra-μ-[2-(phenylamino)benzoato](O,O′)-bis[(ethanol)copper(II)] (1) and di-μ-[2-(phenylamino)benzoato](O,O′)-bis[(hydroxo)copper(II)] (2), were synthesized by the reaction of N-phenylanthranilic acid and CuCl₂·2H₂O in an ethanol water mixture. In complex 1, each Cu(II) atom, which is in a slightly distorted square pyramidal environment, is coordinated equatorially by four N-phenylanthranilate O-atoms and axially by the ethanol O-atoms. In complex 2, [Cu₂(C₆H₅NHC₆H₄COO)₂(OH)₂], each Cu(II) atom, which is in tetrahedral environment, is coordinated by two N-phenylanthranilate O-atoms and hydroxo ligands. The crystal structure (monoclinic, P21/c space group) of complex 1 comprises a dinuclear [Cu₂(C₆H₅NHC₆H₄COO)₄(CH₃CH₂OH)₂] species and the dimer is located on a crystallographic inversion centre. The Cu(II) ions, 2.591(2) Å apart, are bridged by the carboxylate groups of four N-phenylanthranilate ligands. The complex molecules show three-dimensional supramolecular networks by O–H···O, C–H···O and C–H···π interactions.     

Synthesis,Surface and Antimicrobial Activities of Novel Cationic Gemini Surfactants

A series of novel cationic gemini surfactants [C_nH_2n+1–O–CH₂–CH(OH)–CH₂–N⁺(CH₃)₂–(CH₂)₂]₂·2Br^? [ 3a (n = 12), 3b (n = 14) and 3c (n = 16)] having a 2‐hydroxy‐1,3‐oxypropylene group [?CH₂–CH(OH)–CH₂–O–] in the hydrophobic chain have been synthesized and characterized. Their water solubility, surface activity, foaming properties, and antibacterial activity have been examined. The critical micelle concentration (CMC) values of the novel cationic gemini surfactants are one to two orders of magnitude smaller than those of the corresponding monomeric surfactants. Furthermore, the novel cationic gemini surfactants have better water solubility and surface activity than the comparable [C_nH_2n+1–N⁺(CH₃)₂–(CH₂)₂]₂·2Br^? (n‐4‐n) geminis. The novel cationic gemini surfactants 3a and 3b also exhibit good foaming properties and show good antibacterial and antifungal activities.     

Synthesis, Crystal Structure, Spectroscopic and Thermal Properties of a Novel Complex of Hydantoin-5-acetic acid with Co(II)

The complex, tetraaqua bis(hydantoin-5-acetato) cobalt(II) was synthesized by the reaction of hydantoin-5-acetic acid and CoCl₂·6H₂O presence of NaHCO₃. The structure of the complex was determined by X-Ray single crystal data the thermal analyses, FT–IR and magnetic susceptibility data are also presented. The monoclinic crystal of the title compound, [Co(C₅H₅N₂O₄)₂(H₂O)₄], lie across centers of inversion in space group P21/c. The complex features a distorted octahedral [CoO₆] coordination with hydantoin-5-acetato and water ligands. The hydantoin-5-acetato anion is bonded to the cobalt(II) ion via its deprotonated carboxylic acid O atom. The complex molecules show three dimensional supramolecular networks by O–H···O and N–H···O interactions.     

Proposal and verification of a kinetic mechanism model for NOx removal with hydrazine hydrate

A relatively precise kinetic mechanism of NO_x reduction using N₂H₄·H₂O in a selective non‐catalytic reduction process was proposed and verified by experiment in this study. The dominant radicals and reactions were confirmed, and the proper ranges of key parameters were determined through sensitivity analysis. Both experimental and simulation results show that the effective temperatures exhibit a bimodal distribution with the optimum temperatures being approximately 893 and 1248 K and the lower temperature window falling in the range of 848–973 K. The optimum residence time of the reaction was 0.2–0.35 s under the research conditions, and a longer residence time would lead to the regeneration of NO_x. The normalized stoichiometric ratio (NSR) of 3.0 corresponded to the lowest temperature window, and a higher NSR value would make the temperature window shift to a higher temperature range. This kinetic mechanism model for the N₂H₄·H₂O‐based De‐NO_x process will serve its precise application. © 2014 American Institute of Chemical Engineers AIChE J, 61: 904–912, 2015     

Conductance and spectroscopy of protonic beta and beta″-aluminas

Five protonic beta and beta″-aluminas; viz hydrated sodium beta-alumina (1,24Na₂O·11Al₂O₃), hydronium beta-alumina (1.24H₂O·11Al₂O₃·2.6H₂O), partially dehydrated hydronium beta-alumina (1.24H₂O·11Al₂O₃·1.3H₂O), hydrogen beta-alumina (1.24H₂O·11Al₂O₃) and hydronium beta″-alumina (0.84H₂O·0.8MgO·5Al₂O₃·2.8H₂O) were examined by broad band nuclear magnetic resonance from ?196°C to 200°C. The spectra of hydronium beta-alumina and hydronium beta″-alumina are consistent with a mixed composition of H₂O, H₃O⁺ and H⁺ species in the conducting plane. Hydrogen beta-alumina and partially dehydrated hydronium beta-alumina appear to contain only relatively isolated (2.6–2.7Å) protons; no evidence of molecular water or hydronium ions is found. Water molecules intercalated into the conduction plane of sodium beta-alumina do not appear to be in rapid motion, even at 167°C, but are relatively stationary. The onset of motional narrowing in hydronium beta″-alumina occurs at ?40°C but not until +30°C in hydronium beta-alumina. This is consistent with the higher conductivity reported for hydronium beta″-alumina, 10^?3–10^?5 (ohm-cm)^?1 at 25°C, in comparison to 10^?10–10^?11 (ohm-cm)^?1 for hydronium beta-alumina at 25°C.     

Light‐scattering study of poly(hydroxy ester ether) in N,N‐dimethylacetamide solution

Static and dynamic light‐scattering techniques were used to study biodegradable thermoplastic poly(hydroxy ester ether) in N,N‐dimethylacetamide (DMAc). A weight‐average molecular weight M_W = 6.4 × 10⁴ g/mol, radius of gyration R_G = 9.4 nm, second‐virial coefficient A₂ = 1.05 × 10^?3 mol mL/g², translational diffusion coefficient D = 1.34 × 10^?7 cm²/s, and hydrodynamic radius R_H = 8.3 nm are reported. In addition, the effect of H₂O on the polymer chain's conformation and architecture in a DMAc/H₂O solution is evaluated. Results suggest that H₂O makes the mixed solvent poorer as well as promotes polymer chain branching via intramolecular transesterification. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1737–1745, 2001     

Adsorption of chlorophyll-a from acetone solution on natural and activated bentonite

The adsorption of chlorophyll-a on bentonite desiccated at 110°C, untreated and acid-treated with H₂SO₄ solutions over a concentration range between 0·25 and 2·50 mol dm^?3, from acetone solution at 25°C has been studied. The adsorption isotherms may be classified as using Giles' classification, as type S (untreated sample and 0·25 mol dm^?3 H₂SO₄-treated sample), type H (0·50 mol dm^?3 H₂SO₄-treated sample) and type L (1·00 and 2·50 mol dm^?3 H₂SO₄-treated samples). This fact suggests that the bentonite surfaces (low, high and medium affinity, respectively) behave in differently relation to the adsorption of the chlorophyll-a molecules. The experimental data points have been fitted to the Freundlich equation in order to calculate the adsorption capacities (K_f) of the samples; K_f values range from 0·43 mg kg^?1 for the untreated bentonite up to 108·89 mg kg^?1 for the 0·50 M H₂SO₄-treated bentonite. The removal efficiencies (R) have also been calculated and range from 5·71% for the untreated bentonite up to 85·18% for the 0·50 M H₂SO₄-treated bentonite.     

Synthesis of Lead(II) Minoxidil Coordination Polymer: A New Precursor for Lead(II) Oxide and Lead(II) Hydroxyl Bromide

A new lead(II) coordination polymer, [PbBr₂(C₉H₁₅N₅O)]_n (1), where C₉H₁₅N₅O is (2,4-diamino-6-piperidine-1-yl) pyrimidine N-oxide (minoxidil) is synthesized and characterized. Polymer 1 is synthesized in methanol by sonochemical and hydrothermal methods from lead(II) acetate, KBr and the minoxidil ligand. The crystal structure of [PbBr₂(C₉H₁₅N₅O)]_n indicates a syndiotactic coordination polymer. The Pb(II) atom lies on a mirror plane; the mirror plane is perpendicular to the pyrimidine ring bisecting the piperidine ring. N–H···O intramolecular and C–H···Br, N–H···N strong intermolecular interactions were observed. Micro-rods of PbO and nano-plates of PbOHBr were prepared by thermal decomposition of the nano-structured [PbBr₂(C₉H₁₅N₅O)]_n as a precursor. Characterization of the products was carried out using X-ray crystallography, elemental analysis, FTIR spectroscopy, scanning electron microscopy, energy dispersive X-ray analysis and thermal analysis. The sonochemical method resulted in a significant reduction of reaction time, reaction temperature and particle sizes of the products.     

Utilization of response surface methodology to optimize the culture media for the production of rhamnolipids by Pseudomonas aeruginosa AT10

Pseudomonas aeruginosa AT10 produced a mixture of surface‐active rhamnolipids when cultivated on mineral medium with waste free fatty acids as carbon source. The development of the production process to an industrial scale included the design of the culture medium. A 2⁴ full factorial, central composite rotational design and response surface modelling method (RSM) was used to enhance rhamnolipid production by Pseudomonas aeruginosa AT10. The components that are critical for the process medium were the carbon source, the nitrogen source (NaNO₃), the phosphate content (K₂ HPO₄/KH₂PO₄ 2:1) and the iron content (FeSO₄·7H₂O). Two responses were measured, biomass and rhamnolipid production. The maximum biomass obtained was 12.06 g dm^?3 DCW, when the medium contained 50 g dm^?3 carbon source, 9 g dm^?3 NaNO₃, 7 g dm^?3 phosphate and 13.7 mg dm^?3 FeSO₄·7H₂O. The maximum concentration of rhamnolipid, 18.7 g dm^?3, was attained in medium that contained 50 g dm^?3 carbon source, 4.6 g dm^?3 NaNO₃, 1 g dm^?3 phosphate and 7.4 mg dm^?3 FeSO₄·7H₂O. © 2002 Society of Chemical Industry     

Isomer Directed Synthesis of Two 3D Cadmium(II) Compounds: Structure Variation and Energetic Performance

Two inorganic mixtures of copper and sodium compounds have been synthesized and characterized with different measurement techniques. The thermal property of these mixtures has been studied to low temperature up to 223 from 573 K with DSC. The specific heat capacity of this mixture has been measured in atmospheric O₂ at a rate of 10 K min^?1 from 573 to 223 K and vice versa in two thermal cycles. The net specific heat capacity of these mixtures is found endothermic in first and second thermal cycles. The net specific heat capacity of 0.5Cu₂(PO₄)(OH); 3.5CuH(PO₄)₂·H₂O; 2NaHSO₄·H₂O (CuPHS) during first thermal cycle is ?71203.05 J kg^?1 K^?1 and in second thermal cycle is ?73881.67 J kg^?1 K^?1 between temperature range of 303–223 K. The net specific heat capacity of mixture 0.5Cu₂(PO₄)(OH); 3.5CuH(PO₄)₂; 2Na₂SO₄(CuPS) in first thermal cycle is ?21158.37 J kg^?1 K^?1 and in second thermal cycle is?45739.92 J kg^?1 K^?1 between temperature range of 298–573 K. As both mixtures are endothermic in nature in all cycles, it can be used as heat storage material.The average crystallite size of mixture 0.5Cu₂(PO₄)(OH); 3.5CuH(PO₄)₂·H₂O; 2NaHSO₄·H₂O and 0.5Cu₂(PO₄)(OH); 3.5CuH(PO₄)₂; 2Na₂SO₄ is ~47 and ~17.3 nm, respectively.     

A green process for recovery of H2SO4 and Fe2O3 from FeSO4·7H2O by modeling phase equilibrium of the Fe(П)– –H+–Cl– system

Ferrous sulfate heptahydrate FeSO₄·7H₂O is a major waste produced in titanium dioxide industry by the sulfate process and has caused heavy environmental problem. A new green process for the treatment of FeSO₄·7H₂O was proposed to make use of iron source and recycle sulfate source as H₂SO₄. It was found that by adding concentrated HCl to the FeSO₄ solution, FeCl₂·4H₂O was crystallized out, which was subsequently calcined to produce Fe₂O₃ and HCl. Concentrated H₂SO₄ solution (about 65 wt %) was obtained by evaporating the FeCl₂·4H₂O‐saturated filtrate. To facilitate the process development and design, the solubilities of FeCl₂·4H₂O in HCl, H₂SO₄, and HCl + H₂SO₄ solutions were measured and the experimental data were regressed with both the mixed‐solvent electrolyte model and the electrolyte NRTL model. On the basis of the prediction of the optimum conditions for the crystallization of FeCl₂·4H₂O, material balance of the new process was calculated. FeCl₂·4H₂O and Fe₂O₃ were obtained from a laboratory‐scale test with about 70% recovery of ferrous source for a single cycle, indicating the feasibility of the process. © 2017 American Institute of Chemical Engineers AIChE J, 63: 4549–4563, 2017     

24-Membered octanuclear manganese metalladiazamacrocycle

The novel macrocyclic octanuclear manganese(III) 24-metallacrown-8 [Mn₈(C₉₆N₁₆O₂₄H₁₀₄)₆(DMF)₇(H₂O)·3DMF·4.5H₂O (1), has been self-assembly synthesized and characterized. The pentadentate ligand is N-isobutyryl-5-methylsalicylhydrazide (H₃ibumshz). The supramolecular complex assumes a nearly planar cyclic structure with succession of eight structural moieties of the type [Mn(III)–N–N₈ and measure ～22.74 Å in outer diameters. The chiralities of the manganese centers on the metalladiazamacrocycle occur in alternating ···ΔΛΔΛ··· configurations. The title 24-metallacrown-8 has no crystallographic centrosymmetry. The magnetic property of the title 24-metallacrown-8 exhibits a weak antiferromagnetic exchange interaction.     

Unexpected guest-controlled formation of two-layered structure in supramolecular adduct of [W3S4(H2O)9]4+ and cucurbituril

A new supramolecular adduct {[W₃S₄(H₂O)₈Cl][(PyH⊂C₃₆H₃₆N₂₄O₁₂)]}Cl₄·15.5H₂O (1·15.5H₂O) was obtained when pyridine was added to the reaction mixture of cucurbituril and [W₃S₄(H₂O)₉]⁴⁺ in 3 M HCl. X-ray crystal structure analysis of 1·15.5H₂O revealed layered motive of the structure with two different types of cucurbituril molecules. A PyH⁺ molecule is encapsulated in the cavity of each of the cucurbituril molecule. Under vacuum it loses 13.5 H₂O molecules and gives {[W₃S₄(H₂O)₈Cl][(PyH⊂C₃₆H₃₆N₂₄O₁₂)]}Cl₄·2H₂O (1·2H₂O).     

The solvatothermal synthesis and the crystal structure of polymeric N-methylpyridinium octamolybdate(VI), (Me–NC5H5)4n[Mo8O26]n

The reaction of (PyH)₂[MoOCl₅] with pyridine and methanol in the presence of CoCl₂·6H₂O and H₂C₂O₄·2H₂O at 130 °C under solvatothermal conditions afforded (Me–NC₅H₅)_4n[Mo₈O₂₆]_n 1. The structure consists of infinite molybdenum oxide chains bearing a negative charge and N-methylpyridinium cations. Eight {MoO₆} octahedra are arranged in an edge-sharing manner to form compact octamolybdate subunits which are connected through pairs of Mo–O–Mo bridges into extended one-dimensional arrays.     

Lead–vitamin complex [Pb(C19H15N7O6)]·4H2O and its application in bioimaging

A new lead–vitamin complex [Pb(C₁₉H₁₅N₇O₆)]·4H₂O with strong fluorescence was successfully used as biological fluorescent probe for cellular bioimaging.     

Two intra-molecular inter-ligand C(aromatic)–H⋯O(carboxyl) interactions reinforce the formation of a single Cu(II)–N4(pza) bond in the molecular recognition between pyrazine-2-carboxamide (pza) and the (iminodiacetato)copper(II) chelate. Synthesis,molecular and crystal structure and properties of [Cu(IDA)(pza)(H2O)]·H2O

Aqua(pyrazine-2-carboxamide)(iminodiacetato)copper(II) monohydrate, [Cu(IDA)(pza)(H₂O)]·H₂O, was synthesised and characterised by thermal, spectral, magnetic and X-ray diffraction methods. Its crystal structure was solved to a final R1=0.058. The Cu(II) atom exhibits a square base pyramidal coordination (type 4+1) with IDA ligand in mer-tridentate configuration [Cu–N(aliphatic) 1.986(7), Cu–O(carboxyl) 1.933(6) and 1.938(5) Å], the Cu–N4(pza) bond [1.984(7) Å] and Cu–O(apical aqua) bond [2.347(8) Å]. The N4-monodentate ligand role of pza is in contrast with that of the N,O-bidentate pza-Cu(II) chelation in [Cu(pza)₂(ClO₄)₂] or [Cu(acac)(pza)(ClO₄)]·H₂O. In the molecular recognition between Cu(IDA) chelate and pza the Cu–N4(pyridine-like) coordination mode is preferred because it enables the additional contribution of two weak intra-molecular inter-ligand C(aromatic)–H⋯O (IDA) interactions.     

Synthesis,structure and superoxide dismutase activity of a novel tetranuclear copper(II) complex Na2[Cu4Na2(TACNTA)4(H2O)6]·(H2O)26

A novel tetranuclear copper(II) complex Na₂[Cu₄Na₂(TACNTA)₄(H₂O)₆]·(H₂O)₂₆, where TACNTA is 1,4,7-triazacyclononane-1,4,7-triacetate, was synthesized and characterized by X-ray crystallography. The result shows that each copper(II) ion is six-coordinated to three nitrogen atoms and three oxygen atoms of ligand TACNTA and adopts distorted octahedral coordination geometry. The superoxide (·O₂^?) dismutation activity of the complex was also investigated by the riboflavin–methionine–nitro blue tetrazolium assay.     

Four New Metal–Organic Supramolecular Networks Based on Aromatic Acid and Flexible Bis(imidazole) Ligand: Synthesis,Structures and Luminescent Properties

Four new metal–organic supramolecular networks, namely, [Zn(H₂pdc)₂(H₂O)₂]·2H₂O·bbi (1), {[Cd(Hpdc)₂]·2H₂O₂·H₂bbi}_n (2), [Zn(BA)₂(bbi)]_n (3), and {[Cd(BA)₂(bbi)]·H₂O}_n (4) (H₃pdc = 3,5-pyrazoledicarboxylic acid, HBA = 3-hydroxybenzoic acid and bbi = 1,1′-(1,4-butanediyl)bis(imidazole)) have been synthesized under hydrothermal conditions and characterized by IR spectra, elemental analyses, and single-crystal X-ray diffraction analyses. Compound 1 possesses zero-dimensional (0D) structure, which is finally extended into a two-dimensional (2D) supramolecular network via O–H···O and C–H···O hydrogen bonds. Complex 2 displays a 2D network structure built from Cd²⁺ atoms interconnected by Hpdc^2? ligands. The adjacent networks are further assembled into three-dimensional (3D) supramolecular structure through O–H···O hydrogen bonds. Compounds 3 and 4 show similar one-dimensional (1D) chains, in which four-coordinated Zn(II) atoms and six-coordinated Cd(II) atoms are bridged by bbi ligands. Through O–H···O and C-H···O hydrogen bonding interactions, the 1D chains are further packed into 2D and 3D supramolecular frameworks for 3 and 4, respectively. Obviously, the structural differences among compelxes 1–4 are attributed to the different central metal atoms and organic ligands. In addition, compounds 1–4 exhibit blue fluorescent emission in the solid state at room temperature.