Spectroscopic characterization of extracts from humic and fulvic fractions: IR and1H NMR spectra

Summary Infrared and proton resonance spectra have been used to characterize fraction extracted sequentially from humic and fulvic acids by diethylether, acetone, dioxane, tetrahydrofuran, pyridine and dimethylformamide. The results showed that the same solvents extracted structurally similar components from both humic and fulvic acids. On the other hand, the spectra showed solvent-dependent differences, some being characteristic for a preponderance of aliphatic structures, others for aromatic structures.     

Synthesis and characterization of disubstituted arylcyanoximes and their several metal complexes

A series of new disubstituted halogenated arylcyanoximes was synthesized using nitrosation reaction of the respective phenylacetonitriles by CH₃–ONO at room temperature in isopropanol. Six synthesized colorless arylcyanoximes containing two F and/or Cl atoms at 2-, 4-, 5- and 6-positions were characterized by means of NMR, IR, UV–Vis spectroscopy and pK_a studies. Crystal structures were determined for four cyanoximes and revealed the presence of only the syn-isomers for fluorinated compounds in a solid state, while the chlorinated arylcyanoxime exists as anti-isomer in the crystal. However, five out of the six protonated arylcyanoximes HL exist as a mixture of syn- and anti-isomers in solutions. Deprotonation of HL with NaOC₂H₅ in ether solutions leads to yellow NaL which were used as precursors for the synthesis of a series of monovalent Ag, Tl and bivalent Pd, Pt complexes. Seven palladium and platinum arylcyanoximates of [M(HL)₂Cl₂] composition were synthesized and characterized. Obtained colored compounds are non-electrolytes in solution. However, in EtOH and DMSO solutions Pt(II) cyanoximates undergo two consecutive solvolysis reactions. First order rate constants were measured at 294 K for complexes in both solvents. Binding modes of the cyanoxime ligands and the possible solid state structures of the obtained coordination compounds are suggested on a basis of their IR spectra and MM-2 calculations. Because of their structural resemblance to the cisplatin family of anticancer drugs, synthesized Pd/Pt arylcyanoximates were tested in vitro against human colon carcinoma WiDr cell line using cis-[Pt(NH₃)₂Cl₂] as positive control. Results showed that two Pd(II) and Pt(II) cyanoximates containing oximino(2,4-dichlorophenyl)acetonitrile exhibit cytotoxicity at 0.25 mM concentrations.     

Properties of poultry litter humic acid fractions and their metal-complexes

Summary Molecularly homogenous fractions of humic acid extracted from poultry litter were characterized by elemental and functional group analysis, molecular weight determination, U.V. and infrared spectroscopy. The divalent and trivalent metal complexes prepared from different fractions of humic acid were characterized by infrared spectroscopy. The molecular weight of molecularly homogenous fractions of poultry litter humic acid ranged from 2545 to 40219. High amounts of functional groups in low molecular weight of humic acid fraction has been indicated by infrared spectra and by chemical analysis. The presence of chromophores C=C and C=O and auxochromes C−OH, C−NH were indicated by infrared and U.V. spectra of these humic acid fractions. Stable complex formation of Fe³⁺, Cu²⁺, and Zn²⁺ with −OH, −NH₂ and −COOH ligands of humic acid fractions involved electrovalent and coordinate-covalent bonds. Intensity of absorption bands of molecularly homogenous fractions of humic acid in I.R. spectra is differing depending upon the functional groups content of humic acid fractions. Journal paper No. 5. Department of Soil Science, R.A.U., T.C.A., Pusa-Dholi Campus, Dholi-843121, Muzaffarpur, Bihar, India.     

Effects of humic and fulvic acids on growth of tobacco

Summary Organic matter was extracted with a mixture of 0.1M Na₄P₂O₇ and 0.1M NaOH from soil and a commercial organic matter product, Aqua Humus, and separated into humic and fulvic acids according to their solubility in acid and alkaline solutions. They were purified by passage through a cation exchange resin, freeze-dried, and used for characterization and seedling growth studies. The CEC increased with pH for both humic and fulvic acids. Data from tobacco seedling studies show that humic and fulvic acids from both sources increased root number and length at low concentrations while at high concentrations, humic acids inhibited length and number of roots but fulvic acids had no effect. The results support the proposition that fractions of organic matter referred to as humic and fulvic acids affect root development by means other than as a source of nutrients.     

The synthesis and characterization of nucleotide complexes involving an asymmetric metal

The synthesis of cobalt and chromium complexes of H₄ATP and H₄GTP in which the metal is asymmetric are reported. These compounds were characterized by visible spectroscopy, fast atom bombardment mass spectroscopy (FAB MS), and ³¹P NMR. The mass spectral data allow identification of the complexes to be made from ions in the molecular weight region. The effect of an asymmetric metal greatly alters the appearance of the ³¹P NMR spectra in comparison to complexes which do not have this feature. Complexes of uridine diphosphoglucose, UDPG, are also reported. The effect of an asymmetric metal ion on the chromatographic and spectral properties of the complexes are discussed.     

Water quality and soil properties of ponds as influenced by Makhana (Euryale ferox) cultivation

Summary Analysis of regularly collected samples of soil and water from Makhana (Euryale ferox) growing ponds indicated that pH of soil and water were established near neutrality and C/N of soil near ten. Bicarbonate dominated soil extract while chloride dominated standing water. During grand growth period (March to June), Ca²⁺+Mg²⁺, NH ₄ ⁺ K⁺ increased while Na⁺ increased during decay of the plant (July to September) both in soil and plants. The soil had high contents of micro-nutrients, K and P. S.A.R. of soil was 3 to 4 times that of water. Free energy of exchange indicated stability and spontaneity.     

The impact of corncob biochar and poultry litter on pepper (Capsicum annuum L.) growth and chemical properties of a silty-clay soil

Red pepper (Capsicum annuum L.) is one of the most commonly cultivated vegetable in the Mediterranean region. This study evaluated the effects of biochar derived from corncob and poultry litter on growth of red pepper (Capsicum annuum L.) and some chemical properties of a silty clay soil. The experiment consisted of two factors, i.e., biochar doses (0, 0.5, 1.0 and 2%) and poultry litter doses (0, 0.5, 1.0 and 2%). The number of days to 50% flowering, plant height, stem diameter, total number of leaves per plant, the number of main branches per plant, fresh root weight, root length, dry shoot weight, macro (P and K) and micro (Fe, Zn, Cu and Mn) nutrient concentrations of leaves were determined to compare the efficiency biochar and poultry litter. Moreover, post-harvest soil analysis was conducted to measure pH, organic matter, and macro and micronutrient contents. Biochar had varying impact on plant growth parameters, whereas poultry litter alone or in combination with biochar increased macro and micronutrient concentrations of soil and improved most of the growth parameters of red pepper. In contrast, sole biochar application had no significant impact on most of the growth parameters. Wider C/N ratio (107.7) of corncob derived biochar restricted the nitrogen supply for plant growth. The combination of 0.5% biochar and 2% poultry litter resulted in the highest plant height (36.7 cm) and stem diameter (0.69 cm). The results revealed that application of single biochar derived from corncob is insufficient to supply adequate nutrients for optimal plant growth. The application of biochar alone enhances carbon sequestration in soils, however most biochars like cornconb biochar do not contain sufficient available plant nutrients. Therefore, biochars should be applied along with mineral fertilizers or organic materials such as poultry manure which is rich in available plant nutrients.     

Potentiometric and calorimetric study on stability of nicotinamide complexes of silver(I) and copper(II) in aqueous ethanol and dimethylsulfoxide

The complex formation between silver(I) and nicotinamide as well as between copper(II) and nicotinamide in water-ethanol and water-dimethylsulfoxide media was studied by means of potentiometric technique. The heat of complex formation was measured using the method of precision calorimetry. The experimental data have been considered from the point of view of thermodynamic characteristics of the reagents and their solvation.     

Physical and chemical effects of litter on plant establishment in semi-natural grasslands

A field experiment was conducted in a semi-natural grassland to study the interspecific variation in the effect of litter on seedling emergence and establishment and separate physical from chemical effects. Seeds of seven forb species were sown in plots subjected to either litter amendment (0, 400 or 900 g m⁻²) or water extracts of litter (corresponding to 400 and 900 g litter m⁻²). In addition, an extract was treated with activated carbon to estimate the possible effects of secondary chemical compounds. The response to plant litter differed amongst species: negative, neutral and positive responses were observed. Anthriscus sylvestris was the only species with a strong positive response to litter. We found no consistent relation between seed size and response to plant litter. Physical effects of litter were generally stronger than chemical effects. However, water extract of litter inhibited emergence in three species. Activated carbon removed the negative effect of the litter extract, which suggests that the effect was caused by an inhibitory chemical compound rather than by increased competition in response to nutrients added via the extract. The balance between facilitative and inhibitory effects of litter depended on species identity and litter quantity. Facilitative effects dominated at low and intermediate quantities of litter, and inhibitory effects at high litter quantities. One species, Campanula rotundifolia, showed a switch from positive to negative responses with increasing quantities of litter. However, we found no general threshold for litter quantity valid across species.     

Supported organometallic complexes. Part 27: novel sol-gel processed rhodium(I) complexes: synthesis, characterization, and catalytic reactions in interphases

A novel T-silyl functionalized cationic (COD)(dppp)rhodium(I) complex was sol-gel processed with various amounts of the co-condensing agents MeSi(OMe)₂(CH₂)₆(OMe)₂SiMe and MeSi(OMe)₂(CH₂)₃(C₆H₄)(CH₂)₃(OMe)₂SiMe to give novel stationary phases for ‘Chemistry in Interphases’. The polysiloxane matrices and the integrity of the rhodium(I) complex centers were investigated by means of multinuclear solid-state NMR (¹³C, ²⁹Si, ³¹P) and EXAFS spectroscopies. Dynamic NMR measurements show an increasing mobility of the matrix and the reactive centers with a higher amount of the co-condensing component. The accessibility of the anchored rhodium(I) centers was scrutinized by the metal catalyzed hydrogenation of 1-hexene. All applied xerogels show remarkable activities and selectivities. An enhancement of the activities is achieved when polar solvents are used. SEM micrographs reveal the morphology of the hybrid materials and energy dispersive X-ray spectroscopy (EDX) suggests that the distribution of the elements is in satisfying agreement with the applied composition.     

Synthesis and characterization of 2-quinoxalinol Schiff-base metal complexes

The reaction of uranyl acetate with (2,2′-(1E,1′E)-(2-benzyl-3-hydroxyquinoxaline-6,7-diyl)bis(azan-1-yl-1-ylidene)bis(methan-1-yl-1-ylidene) diphenol) (H₂L1) at room temperature in methanol and chloroform yields the UO₂L1 complex. Crystals were grown through solvent diffusion of the ligand-metal complex in dimethyl formamide with diethyl ether to prepare: UO₂L1 · DMF (1). Complexes with 2,2′-(1E,1′E)-(2-benzyl-3-hydroxyquinoxaline-6,7-diyl)bis(azan-1-yl-1-ylidene)bis(methan-1-yl-1-ylidene)dibenzene-1,4-diol (H₂L2) and 2,2′-(1E,1′E)-(2-hydroxy-3-isopropylquinoxaline-6,7-diyl)bis(azan-1-yl-1-ylidene)bis(methan-1-yl-1-ylidene)diphenol (H₂L3) were also prepared, and crystals of the uranyl complexes (UO₂L2 · DMF (2) and (3)) grown from DMF/ether. A fourth complex UO₂L4 · H₂O (4) was prepared through layering a solution of the tetra-tert-butyl substituted 2-quinoxalinol salen ligand H₂L4 in acetone with an aqueous solution containing uranyl acetate. The complexes exhibit a symmetric core featuring a slightly distorted bicapped pentagonal geometry around the uranium center with two oxo-groups and two imine groups from the ligand chelating the ligand and the fifth site in the coordination plane of the ligand occupied by a solvent molecule. These compounds have been characterized using solution (NMR and UV-Vis) and solid-state (IR, X-ray crystallography) techniques. Complexes of H₂L4 with early transition metals; Mn²⁺, Co²⁺, Ni²⁺, and Cu²⁺ are also prepared and characterized for comparison of solution and spectroscopic characteristics.     

Complexation of trace metals with humic acids from soil,sediment and sewage

ABSTRACT

Metal—humate interactions in aqueous and terrestrial ecosystems control the speciation of trace metals and hence, their bioavailability and toxicity. The present study investigated the complexation interactions of copper, cadmium and lead, in their divalent states, with humic acids extracted from three different sources: the treated sewage from a treatment plant, Yamuna river bed sediment, and Yamuna river flood plain soil, all at Okhla, Delhi, employing ion selective electrode potentiometry. The conditional stability constants of the complexes were computed from Scatchard plots. The influences of the two important metal speciation factors, viz., pH and ionic strength of the reaction medium on the conditional stability constants were ascertained by investigating the reactions under three different pH: 5.0, 6.0 and 7.0 and three different ionic strengths: 0.01, 0.03 and 0.1. Stabilities of metal—humic acid (HA) complexes follow the order: Cu-HA > Pb-HA > Cd-HA for humic acids from any single source and are found to increase with a rise in pH and fall in a ionic strength of the medium. The humic acids extracted from the soil and the sediment emerged as stronger complexing agents, as compared to that extracted from sewage.     

Copper(I) and silver(I) tertiary phosphines complexes: Synthesis, X-ray structures and spectroscopic characterization

Six new complexes, [Cu₄I₄(PPh₂Cy)₄]·2H₂O (1), [CuI(PPhCy₂)₂] (2), [CuCl(PPhCy₂)₂] (3), and [CuBr(PPh₃)₃]·CH₃CN (4), [Ag(PPhCy₂)₂(NO₃)] (5), [Ag(PCy₃)(NO₃)]₂ (6) [where Ph = phenyl, Cy = cyclohexyl], have been synthesized and structurally characterized by X-ray diffraction, IR absorption spectra and NMR spectroscopic studies (except complex 4). The X-ray diffraction analysis of complex (1), pseudo polymorph of complex [Cu₄I₄(PPh₂Cy)₄], reveals a stella quadrangula structure. The four corners of the cube are occupied by copper(I) atoms and four I atoms are present at the alternative corners of the cube, further more the copper(I) atoms are coordinated to a monodentate tertiary phosphine. Complexes (2) and (3) are isostructural with trigonal planar geometry around the copper(I) atom. The crystal structure of complex (4) is a pseudo polymorph of complex [CuBr(PPh₃)₃] and the geometrical environment around the copper(I) centre is distorted tetrahedral. In the Ag^I complexes (5) and (6), the central metal atoms have pseudo tetrahedral and trigonal planar geometry, respectively. Spectroscopic and microanalysis results are consistent with the single crystal X-ray diffraction studies.     

畜禽粪便施用对稻麦轮作土壤质量的影响

通过采集试验区长期施用鸡粪 (PL)、猪粪 (LM) 和化肥 (CF) 的稻麦轮作耕层和犁底层土壤,分析了不同施肥处理土壤有机碳和养分含量、土壤物理结构特征、土壤生物学性质的差异,探讨了长期施用畜禽粪便对土壤质量的影响。研究结果显示,长期施用畜禽粪便耕层和犁底层土壤有机碳含量显著高于施用化肥处理(P<0.05);与CF处理比较,PL和LM处理土壤氮、磷、钾全量和有效养分含量均明显增加,其中耕层土壤Olsen-P 含量为施用化肥处理的7-8倍,速效钾含量比施用化肥土壤高89.2%-102.9%。施用畜禽粪便明显改善了土壤物理结构,其耕层土壤大孔隙体积、中孔隙体积和总孔隙度分别为CF处理土壤的1.48-1.70倍,1.35-1.75倍和1.07-1.11倍;土壤团聚体水稳定性显著增强,而土壤抗张强度显著降低。施用畜禽粪便土壤微生物和生化性质也明显高于施用化肥土壤,其中LM处理耕层土壤MBC和MBN最大,分别是CF处理土壤的2.1倍和1.5倍;施用畜禽粪便土壤脲酶和转化酶活性也分别为施用化肥土壤的3.5-6.7倍和1.6-2.1倍。相关分析显示,土壤有机碳含量与各肥力指标间均表现出极显著相关(P<0.01)。研究结果说明,长期施用畜禽粪便土壤质量显著高于仅施化肥土壤。     

Immunological and chemical characterization of hamster brain polyribosomes-cytomatrix complexes

We have studied the cytoskeletal nature of a brain subcellular fraction previously shown to contain polyribosomes. We have identified the major proteins of this fraction by electrophoretic comparison to a standard cytoskeletal fraction and by immunodetection. These methods have shown the presence of actin, glial fibrillary acidic protein, and neurofilament triplet proteins. We have also studied the effect of various ions and nonionic detergents on the stability of this structure. It was stable in presence of Triton X-100 up to 2% but disrupted by 200 mM K⁺ acetate.Abbreviations CMT cytomatrix - CSK cytoskeleton - DOC sodium deoxycholate - DTT dithiothreitol - EGTA ethylenglycolbis (-Ether)-N,N-N-N-Tetraacetic Acid - GFAP glial fibrillary acidic protein - PR polyribosome - PRCMC polyribosomes-cytomatrix complex     

Synthesis and structural characterization of mixed-ligand silver(I) complexes containing diphosphazanes and bidentate N-donor ligands

The reactions of a self-assembled silver(I) coordination polymer, [Ag₂{μ-PrⁱN(PPh₂)₂}(μ-NO₃)₂]_n (1) with various bidentate N-donor ligands such as DABCO, 2,2′-bipyridyl and 1,10-phenanthroline yield 1-D helices or π-π stacked polymers, depending on the chelate vector of the N-donor ligand. The molecular structures of the resultant complexes, [Ag₂{μ-PrⁱN(PPh₂)₂}(DABCO)(NO₃)₂]_n (2), [Ag₂{μ-PrⁱN(PPh₂)₂}(2,2′-bipy)₂(NO₃)₂] (3) and [Ag₂{μ-PrⁱN(PPh₂)₂}(1,10-phen)₂](NO₃)₂ (4) have been confirmed by single-crystal X-ray diffraction. Complex 2 exists as an infinite helical polymer because of the exo-bidentate nature of DABCO. Complex 3 assumes a 2D grid motif as a result of intermolecular π-π stacking among adjacent bipyridine moieties. The phenanthroline complex 4 exhibits strong inter- and intramolecular π-π stacking interactions.     

Synthesis, characterization and structure of metallocene dicyanamide complexes

The bis(cyclopentadienyl) complexes [Cp₂Ti(dca)]₂O and Cp₂V(dca)₂ (dca = dicyanamide) have been prepared by reaction of sodium dicyanamide with aqueous solution of titanocene dichloride and vanadocene dichloride, respectively. The X-ray structure analyses of both complexes confirmed monodentate coordination of dicyanamide ligand through the terminal nitrogen atom of cyano group.     

Self-assembly and cytotoxicity study of waterwheel-like dinuclear metal complexes: the first metal complexes appended with multiple free hydroxamic acid groups

Two waterwheel-like dinuclear complexes [M(2)(PHA)(4)(H(2)O)(2)] (M = Cu(II) (1), Zn(II) (2); HPHA = phthal-hydroxamic acid) appended with four free hydroxamic acid groups, namely, free hydroxamic acid metal complexes (FHAMCs) have been synthesized and characterized. The crystal structure of complex 1 was determined by single crystal X-ray diffraction, which adopts the paddlewheel motif with four bidentate carboxylate ligands joining two Cu(II) ions. The relative cytotoxicities of compounds 1 and 2 against SMMC-7721 and HO-8910 cell lines are similar and more predominant than HPHA (IC(50): Cu(II)>Zn(II)>HPHA). The synergic effect of the bound water molecules, multiple free hydroxamic acid groups and dimetal active sites with bridging carboxylate may have significant impacts on their pharmacological activity. As the prototype for a new class of hydroxamic acid derivatives, the self-assembly of FHAMCs presents a promising new strategy in designing multiple hydroxamic acids with remarkable bioactivities.