Association of copper(II) isonicotinamide moieties via different anionic bridging ligands: Two paths of ferromagnetic interaction in the azide coordination compound

Three isonicotinamide (isn) copper(II) complexes with different bridging ligands, azide, thiocyanate and sulfate, have been prepared. The molecular structure of [Cu₂(μ-1,1-N₃)₂(μ-1,3-N₃)₂(isn)₂]_n (1) is composed of binuclear species, Cu₂(μ-1,1-N₃)₂(isn)₂, inter-connected by additional four azide bridges in the end-to-end mode (1,3). This gives a CuN₄N square-pyramidal coordination sphere around each copper(II) ion. A trans mononuclear octahedral coordination sphere CuN₄S₂ is present in [Cu(μ-N,S-NCS)₂(isn)₂]_n (2), with thiocyanato ligands serving as bridges between the adjacent Cu(isn)₂ moieties. The third anionic ligand, i.e. sulfate, in {[Cu(μ-O,O’-SO₄)(H₂O)(isn)₂]·2H₂O}_n (3) completes the CuO₂N₂O square-pyramidal coordination sphere, and thus enables bridging between the mononuclear Cu(H₂O)(isn)₂ moieties. The ligands that bridge the principal building blocks, i.e. binuclear in 1 and mononuclear in 2 and 3, connect the axial ligands with the equatorial positions of the copper(II) coordination spheres in all three cases. A ferromagnetic interaction FM is found for 1, while 2 and 3 are paramagnetic. Therefore, the key structural difference between 1 on one hand, and 2 and 3 on the other, is found in the anionic ligand, serving in 1 also as the intra-binuclear bridge, showing the main path (J₁) for the FM interaction. Additionally, the inter-binuclear pathway in 1 gives another contribution (J₂) to the whole FM interaction seen herein (J₁ = 18.5 cm^–1, J₂ = 4.9 cm^–1).     

Supramolecular Architecture via Self-Complementary Amide Hydrogen Bonding in [Ag(pia)<Subscript>2</Subscript>](NO<Subscript>3</Subscript>)·H<Subscript>2</Subscript>O: Synthesis,Thermal and Structural Studies

Abstract  

The synthesis, thermal and spectral characterization and crystal structure of silver(I) complex with picolinamide, [Ag(C₆H₆N₂O)₂](NO₃)·H₂O, are reported. The silver(I) atom is chelated by two picolinamide (pia) ligands in approximately square planar geometry. The distortion within the coordination environment is mainly imposed by formation of the chelate rings, but it is also observed in two longer (Ag–O) and two shorter (Ag–N) bond lengths. The compound crystallizes in the triclinic space group P[`1]P\bar{1} with a = 7.1265(2) ?, b = 8.9157(4) ?, c = 12.9527(4) ?, α = 83.934(3)°, β = 86.094(2)°, γ = 67.023(3)° and Z = 2. Cationic complexes are linked through amide–amide hydrogen bonds of ‘head-to-head’ R ₂²(8) motif leading to infinite chains, while nitrate anions and H₂O molecules act only as a cross-link between such four symmetry related cationic chains via hydrogen bonds forming 2D supramolecular double sheets. Therefore, the ‘head-to-head’ amide interactions in [Ag(C₆H₆N₂O)₂](NO₃)·H₂O are robust enough to accommodate the usually disruptive NO₃ ⁻ anion and H₂O molecule and could be regarded as a tool for controlling the assembly of this silver complex.     

Uncommon isonicotinamide supramolecular synthons in copper(II) complexes directed by nitrate and perchlorate anions

The title compounds, trans‐diaquabis(nitrato‐κO)bis(pyridine‐4‐carboxamide‐κN¹)copper(II), [Cu(NO₃)₂(C₆H₆N₂O)₂(H₂O)₂], (I), and trans‐diaquatetrakis(pyridine‐4‐carboxamide‐κN¹)copper(II) bis(perchlorate), [Cu(C₆H₆N₂O)₄(H₂O)₂](ClO₄)₂, (II), are composed of mononuclear coordination entities involving Cu^II ions and isonicotinamide. In (I), the centrosymmetric tetragonally distorted octahedral copper(II) environment contains trans‐related isonicotinamide and water molecules in the equatorial plane and two nitrate ions occupying the axial sites. In (II), the equatorial plane of the C₂‐symmetric distorted octahedron is built up of four isonicotinamide ligands, while water molecules occupy the axial positions. The complex molecules of (I) and (II) are linked into three‐dimensional supramolecular frameworks by O—H...O and N—H...O hydrogen bonds. The nitrate and perchlorate ions are building blocks that disturb the robust R₂²(8) amide supramolecular motif commonly found in crystal structures of copper–isonicotinamide complexes.     

Propynylferrocene and (phenyl­ethyn­yl)­ferrocene

The title compounds, propynylferrocene, [Fe(C₅H₅)(C₈H₇)], (I), and (phenyl­ethyn­yl)ferrocene, [Fe(C₅H₅)(C₁₃H₉)], (II), are stabilized by weak C—H⋯π inter­actions. The C[triple‐bond]C bond distances in these mol­ecules are in the range 1.182 (3)–1.192 (3) Å. In (II), the ferrocenyl and phenyl groups are perpendicular, making an angle of 89.06 (13)°, which is a rare occurrence.     

Determination of Herbicide Difenzoquat Methyl Sulfate in Citruses and Baby Juices by Kinetic‐Spectrophotometric Method and HPLC Method

The purpose of this paper is to present a new kinetic‐spectrophotometric method which involve inexpensive equipment and which can be applied by all analyst who have to determine difenzoquate methyl sulfate (DFQ) residues in citruses and baby juices. The method is based on the inhibited effect of DFQ on the oxidation of sulfanile acid (SA) by hydrogen peroxide in phosphate buffer in presence Cu(II) ion. The reaction was monitored spectrophotometrically by measuring the increase in absorbance of the reaction product at 370 nm. The proposed inhibited method permits determination of DFQ over the range 0.36 to 1.80 μg/mL and 1.80 to 7.20 μg/mL, with quantification limit of 0.184 μg/mL. The relative standard deviations are 0.73‐2.90% for the concentration interval of DFQ 1.80‐0.36 μg/mL. The method was successfully applied to determination of DFQ residues in citruses and baby juices. The HPLC method is used to verify the results. The results obtained for the same samples by the two methods are quite comparable.     

Synthesis of pyrazoles via CuI-mediated electrophilic cyclizations of α,β-alkynic hydrazones

Synthesis of pyrazoles via electrophilic cyclization of α,β-alkynic hydrazones by copper(I) iodide is described. When treated with copper(I) iodide in the presence of triethylamine in refluxing acetonitrile, α,β-alkynic hydrazones, prepared readily from hydrazines and propargyl aldehydes and ketones, undergo electrophilic cyclization to afford pyrazole derivatives in good to excellent yields. The reaction appears to be general for a variety of α,β-alkynic hydrazones and tolerates the presence of aliphatic, aromatic, and ferrocenyl moieties with electron-withdrawing and electron-donating substituents.     

The Chemical Composition of Oils and Cakes of Ochna serrulata (Ochnaceae) and Other Underutilized Traditional Oil Trees from Western Zambia

Currently, the negative effects of unified and intensive agriculture are of growing concern. To mitigate them, the possibilities of using local but nowadays underused crop for food production should be more thoroughly investigated and promoted. The soybean is the major crop cultivated for vegetable oil production in Zambia, while the oil production from local oil-bearing plants is neglected. The chemical composition of oils and cakes of a three traditional oil plant used by descendants of the Lozi people for cooking were investigated. Parinari curatellifolia and Schinziophyton rautanenii oils were chiefly composed of α-eleostearic (28.58–55.96%), linoleic (9.78–40.18%), and oleic acid (15.26–24.07%), whereas Ochna serrulata contained mainly palmitic (35.62–37.31%), oleic (37.31–46.80%), and linoleic acid (10.61–18.66%); the oil yield was high (39–71%). S. rautanenii and O. serrulata oils were rich in γ-tocopherol (3236.18 μg/g, 361.11 μg/g, respectively). The O. serrulata oil also had a very distinctive aroma predominantly composed of p-cymene (52.26%), m-xylene (9.63%), γ-terpinene (9.07%), o-xylene (7.97), and limonene (7.23%). The cakes remaining after oil extraction are a good source of essential minerals, being rich in N, P, S, K, Ca, and Mg. These plants have the potential to be introduced for use in the food, technical, or pharmaceutical industries.     

Linking air-sea energy exchanges and European anchovy potential spawning ground

The physical and chemical processes of the sea greatly affect the reproductive biology of fishes, mainly influencing both the numbers of spawned eggs and the survivorship of early stages up to the recruitment period. In the central Mediterranean, the European anchovy constitutes one of the most important fishery resource. Because of its short living nature and of its recruitment variability, associated to high environmental variability, this small pelagic species undergo high interannual fluctuation in the biomass levels. Despite several efforts were addressed to characterize fishes spawning habitat from the oceanographic point of view, very few studies analyze the air-sea exchanges effects. To characterize the spawning habitat of these resources a specific technique (quotient rule analysis) was applied on air-sea heat fluxes, wind stress, sea surface temperature and turbulence data, collected in three oceanographic surveys during the summer period of 2004, 2005 and 2006. The results showed the existence of preferred values in the examined physical variables, associated to anchovy spawning areas. Namely, for heat fluxes the values were around −40 W/m², for wind stress 0.04–0.11 N/m2, for SST 23°C, and 300 − 500 m³s⁻³ for wind mixing. Despite the obtained results are preliminary, this is the first relevant analysis on the air-sea exchanges and their relationship with the fish biology of pelagic species.     

Phytochemical Profile and Antioxidant Activities of Coleus amboinicus Lour. Cultivated in Indonesia and Poland

Coleus amboinicus Lour., Lamiaceae, is a perennial herb that is native to Indonesia and also cultivated in Africa, Asia and Australia. The major phytochemicals responsible for its bioactivity are rosmarinic acid (RA) and its analogues, flavonoids and abietane diterpenoids. The possibility of cultivation in a colder climate would extend the use of this herb and provide new opportunities to herb growers and livestock farmers. Our study to compare feed value and phytochemical composition of C. amboinicus plants cultivated in its original region, Indonesia, and in Poland. The crude protein content was significantly higher in plants cultivated in Indonesia compared to those cultivated in Poland—21% and 13% of dry matter, respectively. The higher ADF contents were detected in C. amboinicus cultivated in Indonesia, 38–41%, in comparison to 34% in plants cultivated in Poland. The phytochemical composition was also significantly influenced by the cultivation location. Polish samples were higher in polyphenols (RA and its analogues), and also had 1.5–2-fold higher antioxidant potential, as measured by DPPH scavenging, phosphomolybdenum reduction and Fenton reaction driven lipid peroxidation. The Indonesian samples contained more diterpenoid compounds, such as dihydroxyroyleanone, and the sum of terpenoids was ca. 10 times higher than in samples from Poland (15.59–23.64 vs. 1.87 µg/g of extracts). In conclusion, C. amboinicus is suitable for cultivation in non-optimal climatic conditions but some nutritional properties and bioactivity are significantly affected.