Synthesis and characterization of [Cp*Fe-dicyclopenta(a,f)naphthalene-FeCp*] and [Cp*Fe-dicyclopenta(a,f)naphthalene-FeCp*] BF4

[Cp*Fe-dicyclopenta(a,f)naphthalene-FeCp*]ⁿ⁺ (Cp*=pentamethylciclopentadiene, n=0, 1), respectively named complexes V and VI, were synthesized and characterized. The X-ray structure has been solved and ¹H-, ¹³C-NMR and elemental analysis were performed for the n=0 complex. Cyclic voltammetry showed a potential difference of 360 mV within the two redox peaks. An absorption band at 850 nm was assigned to an intervalence band. The Mössbauer investigations show a uniform Fe²⁺ environment for the neutral compound and two sites, assigned to Fe²⁺ and Fe³⁺ for the monoxidized compound. The information gathered by all the previously mentioned techniques indicates that the studied binuclear compound belongs to the mixed valence class II using Robin and Day classification.     

Tin(IV) derivatives of 2,6-pyridinedicarboxylate: A Sn Mössbauer spectroscopic investigation

A series of organotin(IV) derivatives of 2,6-pyridinedicarboxylate has been investigated by Mössbauer spectroscopy in order to elucidate aspects concerning bonding and structural features in the solid state. A geometrical pattern of five-fold coordination at the metal centre has been revealed for SnCl₃Bu and SnClBu₃ derivatives. Trans stereochemistry for the butyl and vinyl groups of SnCl₂Bu₂ and SnCl₂(Vin)₂ derivatives has also been identified by this method. The isomer shift for the divinyl derivative is concurrent to a 7-coordinate metal centre contrasting to that for the dibutyl one. Although there is a discrepancy in isomer shift between these compounds, both have seven-fold coordination at the Sn(IV) nucleus. The resulting data has given evidence that 2,6-pyridinedicarboxylate is acting as a tridentate ligand through pyridil and carbolxylate moiety to all derivatives except for SnClBu₃. For the latter, the coordination mode occurs via carboxylate groups. The overall data support distorted geometrical pattern to all complexes in solid state.     

Cu(I) camphor coordination polymers: Synthesis and study of the catalytic activity for cyclization of 4‐pentyn‐1‐oic acid

The number of CuCl units per camphor ligand in [{CuCl}₂L]_n was extended to three or four in [{CuCl}₃L]_n ( 2 ) or [{CuCl}₄L]_n ( 1 ). The Hartree‐Fock ab initio calculations support the polymeric structure of 1 and 2 that catalyze the cyclization of 4‐pentyn‐1‐oic acid ( A ) forming 5‐methylenedihydrofuran‐2(3H)‐one ( B ) and/or 2‐methyl‐5‐oxotetrahydrofuran‐2‐ylpent‐4‐ynoate ( C ). The catalytic activity of 1 , 2 and other polynuclear Cu(I) complexes ( 3–5 ) was evaluated under solvent free conditions and/or solution. In the absence of solvent, catalyst 2 displays the highest activity and selectivity (75.8/23.1, C to B ratio, at 5.4% loading) while 4 reaches the highest level of A → B conversion (97.5 %) in solution. Selected reactions were followed by NMR and the kinetic constants calculated. A mechanism is proposed based on the equations used for the calculations. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 3316–3323     

Thermodynamics of uptake of cadmium by Chlorella marina

From voltammetric titration curves of living Chlorella marina cells with cadmium ion, at constant pH, the surface binding capacity of the alga was determined and interpreted in terms of average conditional equilibrium constants and of differential equilibrium function. Since the alga can live in estuaries, the influence of ionic strength and competition of alkaline and alkaline earth cations has been considered. Cadmium complexation with dead algae killed by heat or using formaldehyde has also been studied for comparison.     

Carbon-13 and proton NMR assignments of a new agathisflavone derivative

The (1)H and (13)C NMR spectra of 5-acetyl-7,4'-dimethoxyflavone-(6-8')-5'-acetyl-7',4'-dimethoxyflavone, a new agathisflavone derivative, were completely assigned on the basis of 1D and 2D NMR techniques.     

Efficient "total" extraction of perfluorooctanoate from polytetrafluoroethylene fluoropolymer

To determine the optimum conditions for the complete extraction of perfluorooctanoate (PFO) from polytetrafluoroethylene fluoropolymers, sample preparation and pressurized solvent extraction (PSE) conditions were investigated. Solvent extraction temperature, solvent residence time, relaxation time between extractions, and the effects of heating before PSE showed that methanol at 150 degrees C extraction temperature and a 12 min solvent residence time were the most efficient conditions. Preheating the polymer before extraction at 150 degrees C for 24 h significantly enhanced the quantity of PFO removed. Heating above 150 degrees C resulted in loss of PFO. PFO was determined by liquid chromatography with tandem mass spectrometry.     

Elementary operators and the Aluthge transform

We characterize essential normality for certain elementary operators acting on the Hilbert-Schmidt class. We find the Aluthge transform of an elementary operator of length one. We show that the Aluthge transform of an elementary 2-isometry need not be a 2-isometry. We also characterize hermitian elementary operators of length 2.     

Linearization of multipolynomials and applications

We prove that every multipolynomial between Banach spaces is the composition of a canonical multipolynomial with a linear operator, and that this correspondence establishes an isometric isomorphism between the spaces of multipolynomials and linear operators. Applications to composition ideals of multipolynomials and to multipolynomials that are of finite rank, approximable, compact, and weakly compact are provided.     

Managing new and differentiated remanufactured products

We study a firm that makes new products in the first period and uses returned cores to make remanufactured products (along with new products) in future periods. The remanufactured product is differentiated from the new product, so the firm needs to choose differentiated prices. We analyze the monopoly environment in two-period, multi-period (three, four and five) and infinite planning horizons, and characterize the optimal remanufacturing and pricing strategy for the firm. In the process, we identify remanufacturing savings thresholds that determine the production and pricing strategy for the firm. Among other results, we find—counter to intuition—that in a finite-horizon, multi-period setting, the optimal policy is not necessarily monotone in remanufacturing savings.