Dobijanje i osobine CU(II)kompleksa Sa N,N’,N',N’’’-tetrakis(2-piridilmetil)-1,4,8,11-tetra a za ciklotetradekanom(tpmc)i pseudo halogenidima (NCO- ili NCSe-) - II deo

Two new Cu(II) complexes with N,N’,N",N’’’-tetrakis(2-pyridylmethyl) -1,4,8,11-tetraazacyclotetradecane (tpmc) and pseudohalides (NCO- or NCSe-) were isolated. Elemental analyses (C, H, N, Cu) corresponded to the formulas [Cu2(NCO)tpmc](ClO4)3. 2CH3CN and [Cu2(NCSe)2 tpmc] (ClO4)2. 2H2O. C2H5OH. The coordination mode of tpmc and these ambidentate pseudohalides, geometries spectral characteristics (VIS, IR) and other properties were compared with those of the previously described [Cu2(NCS)2tpmc] (ClO4)2. Antimicrobial activity towards selected bacteria and yeast was tested and found for the NCSe but not the NCO complex.Dobijena su dva nova Cu(II) kompleksa sa N,N’,N’’,N’’’-tetrakis(2-piridilmetil)-1,4,8,11-tetraazacikotetradekanom (tpmc) i pseudohalogenidima (NCO– ili NCSe–). Elementalna analiza (C, H, N Cu) odgovarala je formulama: [Cu2(NCO)tpmc](ClO4)3. 2CH3CN i [Cu2(NCSe)2 tpmc](ClO4)2. 2H2O. C2H5OH. Način koordinacije tpmc-a i ovih ambidentatnih pseudohalogenida, geometrijski raspored, spektralne karakteristike (VIS, IR) i dr. su upoređene sa ranije opisanim [Cu2(NCS)2tpmc](ClO4)2. Antimikrobna aktivnost prema nekim bakterijama i gljivicama je testirana i nađena samo u slučaju NCSe kompleksa

Mineral profile of the winter wheat grain: effects of soil tillage systems and nitrogen fertilization

The aim of this study was to analyze the impact of various systems of soil tillage and nitrogen doses on the mineral composition of the grain of the common winter wheat cultivar (Triticum aestivum ssp. vulgare), cv. Azra selected for the conventional intensive production. The field experiment was conducted on luvic chernozem in completely randomized blocks. Wheat was grown under three soil tillage systems: conventional tillage, mulch tillage and no -tillage, and the experiment included two doses of N fertilization (60 and 120 kg ha(-1)). Concentrations of eighteen elements (As, Al, Ba, Ca, Co, Cr, Cu, Fe, Hg, K, Mg, Mn, Ni, S, Sr, P, V and Zn) in wheat grain samples were determined by means of inductively coupled plasma with optical emission spectrometry (ICP OES). The results indicated that concentrations of the studied elements in the wheat grain were significantly affected by the tillage systems and fertilization rates (p lt 0.001), as well as by the interaction of these two factors. A smaller dose of nitrogen fertilizer (60 kg ha(-1)) had a significantly better impact on the concentration of macro- and microelements in the wheat grain than the dose of 120 kg N ha(-1). The reduced tillage systems and lower nitrogen rates in nutrition had a better effect on the increase of the content of the studied elements in the wheat grain than the conventional cultivation which applied higher nitrogen rates

RIQUALIFICAZIONE ENERGETICA DEGLI EDIFICI DEL WWF

Il lavoro svolto consiste nella valutazione energetica degli edifici dell’oasi della Laguna di Orbetello (Centro di Educazione Ambientale “A. Peccei”) e della sede centrale del WWF Italia a Roma. Per gli edifici dell’oasi, lo studio consiste in primo luogo nell’analisi del fabbisogno energetico degli edifici secondo la normativa vigente; in secondo luogo nella valutazione delle prestazioni delle coperture ventilate presenti, in termini di risparmio di calore entrante nell’edificio in estate; infine vengono proposti alcuni interventi di riqualificazione energetica suddivisi in cinque grandi aree di pertinenza: la messa in efficienza dell’involucro, la messa in efficienza degli impianti termico ed elettrico, lo sfruttamento delle risorse naturali costituite dalla radiazione solare (progetto di un impianto solare termico per la produzione di acqua calda sanitaria e ristrutturazione degli impianti fotovoltaici presenti), dall’acqua (riduzione del fabbisogno idrico, riciclo delle acque grigie, impianto di fitodepurazione) e dal combustibile producibile in loco (sostituzione delle caldaie obsolete presenti con caldaie a cippato). Per ogni intervento è stato proposto un modello di progettazione e dimensionamento degli impianti in gioco, ed è stato quindi dato un prospetto del risaparmio ottenibile in termini di diminuzione del fabbisogno di energia primaria, idrica e di combustibile. Tale procedimento è stato adottato anche per la valutazione energetica della sede centrale WWF di Roma, avvalendosi di opportune modifiche legate al diverso contesto

Visokospinski Co(II) kompleksi sa pendantnim oktaazamakrociklom i karboksilatima

Three new binuclear Co(II) mixed-ligand complexes with N,N′,N′′,N′′′-tetrakis( 2-pyridylmethyl)-1,4,8,11-tetraazacyclotetradecane (tpmc) and mono- or dicarboxylate ligands were prepared and some of their physical properties were determined. The general formulas: [Co2(HCOO)2tpmc](ClO4)2·4H2O, [Co2(CH3COO)2tpmc](ClO4)2 and [Co2(tpht)tpmc](ClO4)2·4H2O (tphtH2 = terephthalic acid) were proposed on the basis of elemental analyses (C,H,N) and molar conductivity. UV/Vis absorption and IR spectra, magnetic and CV measurements were used to study their geometries and properties. For the monocarboxylate complexes, an exo coordination of Co(II) with four nitrogens from tpmc and bis-bidentate bonded HCOO-/CH3COO- in the trans position is assumed. Tpmc adopts the chair conformation. For the dicarboxylate complex, it is supposed that a terephthalate dianion, as well as methylene chains from cyclam bridge two Co(II) atoms, while tpmc is in the boat conformation. The complexes were stable against chemical and electrochemical oxidation of Co(II) to Co(III). The data are compared with those for the previously published Cu(II) complexes containing the corresponding ligands and mutual similarities or differences were considered. Finally, some antibacterial activity of the complexes was found.Dobijena su tri nova dinuklearna Co(II) mešovito-ligandna kompleksa sa N,N′,N′′,N′′′- -tetrakis(2-piridilmetil)-1,4,8,11-tetraazaciklotetradekanom (tpmc) i mono- ili dikarboksilato ligandima i određena su neka njihova fizička svojstva. Opšte formule: [Co2(HCOO)2tpmc](ClO4)2·4H2O, [Co2(CH3COO)2tpmc](ClO4)2 i [Co2(tpht)tpmc](ClO4)2·4H2O (tphtH2 = tereftalna kiselina) predložene su na osnovu rezultata analize (C,H,N) i merenja molarne električne provodljivosti. UV/Vis i IR spektri, magnetna i CV merenja korišćena su za proučavanje geometrije i osobina ovih jedinjenja. Za monokarboksilatne komplekse predložena je exo koordinacija Co(II) sa četiri azotova atoma tpmc-a i bis-bidentatno vezanim HCOO¯/CH3COO¯) u trans položaju. Tpmc zauzima konformaciju stolice. Pretpostavljeno je da tereftalatni dianjon, kao i metilenske grupe ciklama premošćuju dva atoma Co(II), a tpmc je u konformaciji lađe. Kompleksi su stabilni prema hemijskoj i elektrohemijskoj oksidaciji Co(II) u Co(III). Podaci su upoređeni sa ranije objavljenim Cu(II) kompleksima koji sadrže odgovarajuće ligande i razmatrane su međusobne sličnosti i razlike. Najzad, utvrđena je izvesna antimikrobna aktivnost kompleksa

Thermal stability and degradation of Co(II), Cd(II), and Zn(II) complexes with N-benzyloxycarbonylglycinato ligand

Thermal behavior of Co(II), Cd(II), and Zn(II) complexes with N-benzyloxycarbonylglycinato ligand was investigated using the results of TG, DSC and DTG analysis obtained at different heating rates (2.5 to 30 A degrees C min(-1)), from room temperature to about 900 A degrees C. Mechanisms of complex degradation, as well as enthalpies of the degradation processes were determined. It is shown that thermal stability of investigated complexes correlates with their crystal structures, especially with the presence of crystallization and coordinated water molecules. The values of dehydration enthalpies are discussed and correlated with composition of the complexes. Kissinger's, Ozawa's, and Friedman's isoconversion methods were used for the determination of kinetic parameters: the pre-exponential factor A and the apparent activation energy E (a). For all three complexes and all steps of degradation, the values of kinetics parameters obtained by Kissinger's and Ozawa's methods are in good agreement. The results obtained by Friedman's method showed that some decomposition steps are simple and some others are complex ones

Fulvic acid characterization in an alluvial sediment sequence: differences between clay and sand environments

Fulvic acids (FAs) from the whole Quaternary sequence (to a depth of 26 m) of the alluvial sediment of the Sava river (taken from a site in Novi Beograd, Belgrade, Yugoslavia) were investigated with the aim of examining the effect of the environment (clay or sand) on their characteristics. Characterization of the FAs was carried out by correlating the results obtained by various instrumental techniques (u.v.-vis. and i.r. spectroscopy, fluorimetry). Differences were noticed between the FAs, depending on whether they originated from sand or clay, which indicates that the hydrogeological environment represents an important factor in determining their characteristics, though the role of the precursor material may be significant. FAs found in clay layers are less aliphatic, have a greater non-aliphatic hydroxyl group content and exhibit more similar fluorescence ntensities compared to FAs originating from sand. The greater mutual similarities of the clay FAs in comparison to those from sands is a result of diagenesis occurring in a more "closed" system

Mixed cobalt(III) complexes with aromatic amino acids and diamine - Part V. Thermal investigation of (1,2-diaminoethane)bis(S-tyrosinato)cobalt(III) complex diastereomers

Thermal properties of (1,2-diaminoethane)bis(S-tyrosinato)cobalt(III) complex diastereomers are investigated by means of TG technique in 293-873 K temperature range. This is a first thermal study of [Co(S-aa)(2)en](+) (S-aa = anion of S-amino acid; en = 1,2-diaminoethane) complex diastereomers. It is shown that thermal decompositions of these complexes are multi-step degradation processes, which in some cases can be satisfactory separated into individual steps, depending on the molecular symmetry. It is proposed that the degradation processes occur with cleavage of the side chain of one S-tyrosinato ligand, followed by the cleavage of the second side chain by further heating. The proposed pathways of decomposition are in accordance with results of thermal degradation of noncoordinated S-tyrosine [F. Rodante, G. Marrosu, G. Catalani, Thermochim. Acta 194 (1992) 197-213]. In the case of diastereomers which crystallize with water molecules, the departure of both hygroscopic and crystal water occurs before. The corresponding kinetic and thermodynamic parameters of some processes were determined. (c) 2004 Elsevier B.V. All rights reserved

SEM/EDX and XRD characterization of silver nanocrystalline thin film prepared from organometallic solution precursor

The Ag nano-structured thin films prepared on flat glass substrates have been studied. The ball-like silver nanoparticles have been synthesized in large quantity by using a modified method of hydrolytic decomposition of silver complexes with amino types ligands formed in ethanol aqueous solution. SEM analysis revealed that Ag nanoparticles are all sphere shaped with bimodal size (40 and 70 nm) distribution. The results of XRD powder pattern examination show that Ag nanoparticles are pure phase, well crystallized. The unit cell dimensions measured on synthesized Ag nano films show small but frequent contraction in comparison to Ag metal standard

Original scientific paper High-spin binuclear Co(II) complexes with a pendant

octaazamaclocycle and carboxylate

NH...pi interactions stabilize the most-hindered rotamer of the (S)-tyrosinato side group in bis[(S)-tyrosinato](diamine)cobalt(III) complexes: An NMR spectroscopic and DFT study

Conformational analysis based on an analysis of the vicinal alpha- and beta-proton coupling constants of (S)-tyrosinato ligands in diastereomers of a bis[(S)-tyrosinato](1,3-diaminopropane)cobalt(III) complex is used to calculate the mol fractions of the three most stable rotamers (t, g, h) of the (S)-tyrosinato ligand's side groups in D2O solution. The results of this conformational analysis indicate a population increase in the sterically least favorable rotamer h in diastereomers of Cl-molecular symmetry (complexes 5 and 6). The TOCSY spectrum of complex 6 in aqueous solution shows an exceptionally small chemical shift of one NH2 proton from the coordinated diamine, which is explained by an interligand NH center dot center dot center dot pi interaction. These findings demonstrate the persistence of this weak, noncovalent interaction in water solution. DFT calculations for complex 6, whose diamine ring is in a chair conformation, indicate that the complex with an h conformation in both its (S)-tyrosinato ligand side-residues, which yields the most frequent NH center dot center dot center dot pi interactions, represents an energy minimum. The fact that coordinated 1,3-diaminopropane in the examined complex 6 is in a chair conformation in aqueous solution is proved by the NMR analysis. (c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005