Solvent effects on the steady state photophysics of estrone and 17β-estradiol

Absorption and emission yields for estrone and 17β-estradiol were measured in a variety of room temperature solvents. Molar extinction coefficients were found to not vary as a function of solvent, while fluorescence yields were found to be significantly affected by the polarity and hydrogen-bond accepting ability of the solvent, with the yield for 17β-estradiol being highest in nonpolar, hydrogen-bond donating solvents, and lowest in the nonpolar, hydrogen-bond accepting solvent ethyl acetate. Estrone's emission yield was found to be a factor of ten smaller than 17β-estradiol's. Strong solvent and excitation wavelength dependences were found for the relative amounts of emission between estrone's two emission bands, with increased relative emission occurring in nonpolar aprotic solvents, and under higher excitation energies. These results are interpreted with the aid of vertical excitation energies from time-dependent density functional calculations using both explicit and implicit solvation models.     

Tailoring Disorder and Dimensionality: Strategies for Improved Solid Oxide Fuel Cell Electrolytes

Towards cooler solid oxide fuel cells: Disorder and dimensionality (see picture) play an important role in determining ion mobility of bulk and artificially nanolayered materials and should be considered in the design of new electrolytes with enhanced conductivity.

     

Characterization of PVC-Tetraruthenated Metalloporphyrins Modified Electrodes: Application as Electrocatalyst in the Nitrite Reduction

Summary: This paper describes the electrochemical reduction of nitrite ion in 0.1 M NaClO₄, on glassy carbon or ITO electrodes modified with mixtures PVC- tetraruthenated metalloporphyrins. This electrode is able to keep the extraordinary electrocatalytic properties of the macrocycle allowing multielectronic transfers and a great stability as a consequence of the inclusion of the macrocycles into a polymeric support such as PVC. On the other hand, the electrochemical reduction of nitrite ion on these modified electrodes studied by cyclic voltammetry shows an enhancement in the current values and lower overpotential compared with the activity of the bare glassy carbon electrode. Controlled potential electrolysis experiments verify the production of ammonia, hydrazine and hydroxylamine, showing the electrocatalytic character and the stability of this modified electrode.     

Bis(di‐2‐pyridylamine‐κ2N2,N2′)(nitrato‐κ2O,O′)nickel(II) nitrate

<!?tpct=26.8pt>In the ionic title compound, [Ni(NO₃)(C₁₀H₉N₃)₂]NO₃, the central Ni^II atom exhibits cis‐NiN₄O₂ octahedral coordination with three chelating ligands, viz. one nitrate anion and two di‐2‐pyridylamine (dpya) molecules. A second nitrate group acts as a counter‐ion. The complex cations and the nitrate anions are also linked by N—H...O hydrogen bonds. The compound was prepared in two different reproducible ways: direct synthesis from Ni(NO₃)₂ and dpya yielded systematically twinned crystals (the twinning law is discussed), while single crystals were obtained unexpectedly from the Ni(NO₃)₂/dpya/maleic acid/NaOH system.     

Reaction chemistry of tricarbonyl-η-pentadienylmanganese: Straightforward synthesis of stable manganese carbonyl terminal thiolates and a dinuclear bis(ethylenediaminyl) complex

Tricarbonyl-η⁵-pentadienylmanganese reacts with mercaptans RSH, R = Ph, C₆F₅, m-NH₂C₆H₄, p-NH₂C₆H₄, and HSCH₂CH₂ in the presence of ECH₂CH₂E, E = -PPh₂ or -NH₂ to give novel stable terminal thiolate mononuclear complexes fac-Mn(CO)₃(SR)(Ph₂PCH₂CH₂PPh₂-κ²-P,P′) for R = Ph, C₆F₅, m-NH₂C₆H₄, p-NH₂C₆H₄, and HSCH₂CH₂ and fac-Mn(CO)₃(SR)(H₂NCH₂CH₂NH₂-κ²-N,N′) for R = Ph and C₆F₅. Upon reaction of tricarbonyl-η⁵-pentadienylmanganese with ethylenediamine a dinuclear complex [fac-Mn(CO)₃(μ-H₂NCH₂CH₂NH-κ²-N,N′)]₂ was formed wherein the diaminyl ligand functions in the capacity of chelating and bridging ligand.     

Sturmian maximizing measures for the piecewise-linear cosine family

Let T be the angle-doubling map on the circle $\mathbb{T}$ , and consider the 1-parameter family of piecewise-linear cosine functions $f_\theta :\mathbb{T} \to \mathbb{R}$ , defined by $f_\theta (x) = 1 - 4d_\mathbb{T} (x,\theta )$ . We identify the maximizing T-invariant measures for this family: for each ?? the f _?? -maximizing measure is unique and Sturmian (i.e. with support contained in some closed semi-circle). For rational p/q, we give an explicit formula for the set of functions in the family whose maximizing measure is the Sturmian measure of rotation number p/q. This allows us to analyse the variation with ?? of the maximum ergodic average for f _?? .     

Synthesis, Crystal Structure and Conformational Studies of Schiff-Base Compound 2-{[4-(Phenyldiazenyl)Phenyl]Iminomethyl}-5-Bromophenol

Abstract  

Schiff-base compound 2-{[4-(Phenyldiazenyl)phenyl]iminomethyl}-5-bromo phenol (1), containing an azo group was synthesized from the reaction of p-aminoazobenzene with 5-bromosalicylaldehyde and characterized by elemental analyses, FT-IR spectroscopy and X-ray single-crystal diffraction analysis. Molecular orbital calculation has been carried out using density functional method (B3LYP) at 6-31G basis set. Compound 1 crystallizes in the orthorhombic system, space group Pca2₁, with a = 12.1781(2) ?, b = 4.4894(10) ?, c = 27.7841(5) ?, V = 1519.02(5) ?³, and Z = 4. Compound 1 displays a trans configuration with respect to the C=N and N=N double bonds.     

Matrix representations of split Bezoutians

Inverses of symmetric (or skewsymmetric) Toeplitz matrices as well as of centrosymmetric (or centro-skewsymmetric) Toeplitz-plus-Hankel matrices can be represented as sums of two split Bezoutians which are highly structured matrices since all of their rows and columns are symmetric or skewsymmetric vectors. Thus it is desirable to find matrix representations for split Bezoutians B. This is the main aim of the present paper.Recursion formulas for the entries of B are presented, bases of very simple split Bezoutians or of sparse matrices are constructed, and B is represented as a corresponding linear combination. Moreover, matrix representations of Gohberg/Semencul type are established.     

Integrating the regulatory and utility firm perspectives,when measuring the efficiency of electricity distribution

Several DEA applications for benchmarking in utility regulation use classical models, which reveal inconsistencies due to Pareto inefficient targets. The natural course of action would be to incorporate weight restrictions, reflecting value judgments and requiring interaction between analyst and decision maker. We show that weight restricted DEA models still present some inconsistencies, since it is not possible to ensure that the target both dominates the observed DMU and lies on the empirical production frontier.     

Dirubidium fluoro­trioxophosphate,Rb2PO3F,at 290 and 130 K,and dicaesium fluoro­trioxophosphate,Cs2PO3F,at 240 and 100 K

The structure of Rb₂PO₃F was determined at 290 and 130 K, while that of Cs₂PO₃F was determined at 240 and 100 K. Both compounds belong to the β‐K₂SO₄ family. The structure analysis did not reveal signs of a phase transition in either compound. Crystal chemical considerations do not favour the presence of a phase transition in either Rb₂PO₃F or Cs₂PO₃F. However, glass‐like phase transitions were observed by differential scanning calorimetry in slightly humid samples at 175 and 177 K for Rb₂PO₃F and Cs₂PO₃F, respectively, but were not observed in well dried samples. The bond distances are normal and Cs₂PO₃F is twinned.