Further crystallographic evidence of NH· · ·π (system) and CO· · ·π (system) interactions: The structures of bis(diarylhydrazonecarbonyl)methylene derivatives [{ArPhCNNH—C(O)}2CH2] (Ar = Ph, 2‐C5H4N, 2‐C4H3S)

In this study are reported the syntheses of three bis(diarylhydrazonecarbonyl)methylene derivatives [{ArPhCNNH C(O)}₂CH₂] [Ar = 2 C₅H₄N (5), C₆H₅ (6), and 2‐C₄H₃S (7)], obtained by condensation of corresponding hydrazones with carbon suboxide, C₃O₂. The solid‐state self‐assembly of these carbonyl derivatives, giving rise to polymeric and dimeric networks, is described. In the formation of these structural features, in addition to N—H· · ·OC intermolecular hydrogen bonds, stabilizing intramolecular NH· · · π (systems) and intermolecular CO· · ·π (systems) interactions also seem to play an important role. Solution ¹H‐nmr data of compounds 5–7 indicate that the polymeric and dimeric structures are not maintained in solution and show the occurrence of keto‐enolic equilibria. © 1999 John Wiley & Sons, Inc. Biopoly 49: 541–549, 1999     

Photoluminescence properties of LiTi2 − xEux(PO4)3 phosphor

A solid‐state reaction route‐based LiTi_{2 ? x}Eu_x(PO₄)₃ was phosphor synthesized for the first time to evaluate its luminescence performance by excitation, emission and lifetime (τ) measurements. The LiTi_{2 ? x}Eu_x(PO₄)₃ phosphor was excited at λ_exci. = 397 nm to give an intense orange–red (597 nm) emission attributed to the ⁵D₀ → ⁷F₁ magnetic dipole (ΔJ = ±1) transition and red (616 nm) emission (⁵D₀ → ⁷F₂), which is an electric dipole (ΔJ = ±2) transition of the Eu³⁺ ion. Beside this, excitation and emission spectra of host LiTi₂(PO₄)₃ powder were also reported. The effect of Eu³⁺ concentration on luminescence characteristics was explained from emission and lifetime profiles. Concentration quenching in the LiTi_{2 ? x}Eu_x(PO₄)₃ phosphor was studied from the Dexter's model. Dipole–quadrupole interaction is found to be responsible for energy transfer among Eu³⁺ ions in the host lattice. The LiTi_{2 ? x}Eu_x(PO₄)₃ phosphor displayed a reddish‐orange colour realized from a CIE chromaticity diagram. We therefore suggest that this new phosphor could be used as an optical material of technological importance in the field of display devices. Copyright © 2016 John Wiley & Sons, Ltd.     

The effects of (±)-, (+)-, and (−)-atenolol,sotalol, and amosulalol on the rat left atria and portal vein

The effects of (±)-, (+)-, and (?)-atenolol, sotalol, and amosulalol alone on the rat left atria and portal vein and on the respective β₁- and β₂-adrenoceptor-mediated responses to isoprenaline have been determined. (±)-Atenolol at 10^?6 M had no effect whereas high concentrations of (+)- and (?)-sotalol, 10^?5–10^?4 M, and (±)-, (+)-, and (?)-amosulalol depressed the response of the rat left atria to cardiac stimulation which indicates membrane stabilizing activity. None of the drugs tested had any effect alone on the rat portal vein. The order of potency as antagonists was (±)-amosulalol > (±)-atenolol > (±)-sotalol at β₁-adrenoceptors and (±)-amosulalol > (±)-sotalol > (±)-atenolol at β₂-adrenoceptors. (±)-Atenolol and (±)-amosulalol are β₁-selective whereas (±)-sotalol is β₂-selective. For each of the racemic β-blockers, the β₁- and β₂-adrenoceptor blocking activity was predominantly due to the (?)-enantiomer. © 1993 Wiley-Liss, Inc.     

Doping of [In2(phen)3Cl6]·CH3CN·2H2O Indium‐Based Metal–Organic Framework into Hole Transport Layer for Enhancing Perovskite Solar Cell Efficiencies

Perovskite solar cells (PSCs) have gained a promising position during the past few years. However, as far as it goes, there is rare combination of the merits of metal–organic framework with PSCs. In this work, a 3D metal–organic framework, namely, [In₂(phen)₃Cl₆]·CH₃CN·2H₂O (In2) is first introduced into hole transport material of PSCs through band alignment engineering. By this facile strategy, the pinholes in the hole transport layer are effectively reduced, and the migration of Au into the entire PSC structure can be alleviated simultaneously. Meanwhile, In2 also plays a role in enhancing the light absorption of perovskite, which is due to: (1) the large particles of In2 acting as light scattering centers; (2) the emission wavelength of In2 is almost the same as the excitation wavelength of perovskite. Consequently, short‐current density (J_sc), open circuit voltage (V_oc), and fill factor (FF) gain a significant increase from 19.53 to 21.03 mA cm^?2, 0.98 to 1.01 V, and 0.67 to 0.74, respectively. Thereby, the power conversion efficiency is remarkably enhanced from 12.8% to 15.8%. In the end, the stability of PSCs should also be improved.     

Poduction of free radicals from phenol and tocopherol by bleomycin-iron(II) complex.

Oxygen-bubbling of 1:1 bleomycin(BLM)-Fe(II) complex efficiently generates hydroxy radical which is inhibited by catalase. Hydroxy radical produced from BLM-Fe(II)-O₂ system oxidizes 2,6-di-tert-butyl-p-cresol and α-tocopherol to form the corresponding phenoxy and tocopheroxyl radicals, respectively. These free radicals were identified by the ESR hyperfine structures.     

Study on the resonance Rayleigh scattering and resonance non‐linear scattering spectra of ion‐association complexes of [PdI4]2−‐protein systems and their analytical applications

In an acid medium solution, proteins such as bovine serum albumin, human serum albumin, ovalbumin, hemoglobin, lysozyme, γ‐globulin, α‐chymotrypsin and papain could react with [PdI₄]^2? by virtue of electrostatic attraction and hydrophobic force to form ion‐association complexes. As a result, the resonance Rayleigh scattering (RRS) and resonance nonlinear scattering such as second‐order scattering (SOS) and frequency doubling scattering (FDS) intensities were enhanced greatly and new scattering spectra appeared. The maximum scattering peaks of RRS, SOS and FDS were at 367, 720 and 370 nm, respectively. The enhanced RRS, SOS and FDS intensities were directly proportional to the concentrations of proteins. The detection limits for the different proteins were 2.4–11.8 ng/mL for RRS method, 9.5–47.9 ng/mL for SOS method and 4.6–18.5 ng/mL for FDS method. In this work, the influences of the interaction of [PdI₄]^2? with proteins on spectral characteristics of RRS, SOS and FDS were investigated and the optimum conditions were tested. Meanwhile, the effects of coexisting substances were tested and the results showed that the method exhibited a good selectivity. Based on the above research, a highly sensitive, simple and rapid method for the determination of trace amounts of proteins by resonance light scattering technique has been developed. It can be applied to the determination of proteins in tablet, human serum and urine samples. Copyright © 2009 John Wiley & Sons, Ltd.     

Potential‐resolved electrochemiluminescence of Ru(bpy)32+/C2O42− system on gold electrode

The electrogenerated chemiluminescence of Ru(bpy)₃²⁺/C₂O₄^2? system on a pre‐polarized Au electrode was studied using a potential‐resolved electrochemiluminescence (PRECL) method. Two anodic ECL peaks were observed at 1.22 V (vs. SCE) (EP1), 1.41 V (vs. SCE) (EP2), respectively. The effects of the concentration of oxalate and Ru(bpy)₃²⁺, adsorbed sulphur, CO₂, O₂, pH of the solution and pretreatment of the Au electrode on the two PRECL peaks were examined. The surface state of the pre‐oxidized gold electrode was also studied using the X‐ray photoelectron spectroscopy (XPS) technique. Moreover, comparative studies on i–E and I–E curves were carried out and a possible mechanism involving both the catalytic and the direct electro‐oxidation pathways was proposed for the ECL of Ru(bpy)₃²⁺/C₂O₄^2? system. EP1 is attributed to the Ru(bpy)₃^2/3+ reaction catalysed by C₂O₄^2? to generate Ru(bpy)₃^2+*. EP2 is likely because C₂O₄^2? was oxidized at the electrode to form CO₂^?·, followed by reaction with Ru(bpy)₃³⁺ to generate Ru(bpy)₃^2+*. Copyright © 2002 John Wiley & Sons, Ltd.     

The luminescence properties of Sr2–1.5x−1.5yP2O7:xDy3+,yCe3+ phosphor for near‐UV‐based white LEDs synthesized by a chemical co‐precipitation method

A series of Sr₂P₂O₇:Dy³⁺, Sr₂P₂O₇:Ce³⁺ and Sr₂P₂O₇:Dy³⁺,Ce³⁺ phosphors was synthesized via the one‐step calcination process for the precursors prepared by co‐precipitation methods. The phases, morphology, quantum efficiency and photoluminescence properties of the obtained phosphors were characterized systematically. These results show that the near‐spherical particles prepared through calcining the precursors by means of ammonium dibasic phosphate co‐precipitation (method 3) have the smallest particle size and strongest emission intensity among the three methods in the paper. With Dy³⁺ concentration increasing in Sr₂P₂O₇:Dy³⁺ phosphors, the luminescence intensity first increases, reaches maximum, and then decreases. A similar trend was followed by Sr₂P₂O₇:Ce³⁺ with Ce³⁺concentration increasing. A successful attempt was made to initiate the energy transfer mechanism from Ce³⁺ to Dy³⁺ in the host lattice and an overlap between the emission band of Ce³⁺ and the excitation band of Dy³⁺ indicated that the Ce³⁺ → Dy³⁺ energy transfer may indeed exist. It is clear that the photoluminescence intensity of Dy³⁺ as well as the quantum efficiency of the phosphor can be enhanced markedly by co‐doping Ce³⁺. Sr₂P₂O₇:Dy³⁺,Ce³⁺ has its (CIE) chromaticity coordinates in the bluish‐white‐light region, near the standard illuminant D₆₅. The CIE 1913 chromaticity coordinates of Sr₂P₂O₇:Dy³⁺ phosphors fall in the white‐light region, and are adjacent to the ideal white‐light coordinates. In addition, the colour temperature and colour tone of Sr₂P₂O₇:Dy³⁺ could be adjusted by changing the relative concentration of Dy³⁺. In short, Sr₂P₂O₇:Dy³⁺ can be a promising single‐phased white‐light emitting phosphor for near‐UV (NUV) w‐LEDs.     

The pyrolysis of (−)‐(S)‐nicotine: Racemization and decomposition

The pyrolytic behaviour of (?)‐(S)‐nicotine in methanol was investigated using on‐line pyrolysis GC/MS to establish whether racemization to the R(+) antipode occurs and to identify other products of pyrolysis. The conditions used included pyrolysing the sample for 15 seconds in an atmosphere of 9% oxygen in nitrogen (275ml/min total flow) across the temperature range of 200°C–1000°C. A chiral Cyclodex‐B analytical column (30m × 0.25mm i.d. × 0.25 μm film thickness) was used to separate the enantiomers of nicotine, although the two enantiomer peaks were not baseline resolved. The results of the experiment shows that there is no increase in (+)‐(R)‐nicotine levels across a wide temperature range. This suggests that the elevated levels of (+)‐R‐nicotine observed in tobacco smoke (compared to tobacco leaf material) are not due to the pyrolytic auto‐racemization of (?)‐(S)‐nicotine but are a result of more complex interactions between (?)‐(S)‐nicotine and other smoke components. The pyrolysis of isotopically labelled nicotine established that nicotine undergoes thermal decomposition to β‐nicotyrine which in turn may decompose to other products. Chirality 2010. © 2009 Wiley‐Liss, Inc.     

Exceptionally Enhanced Electrode Activity of (Pr,Ce)O2−δ‐Based Cathodes for Thin‐Film Solid Oxide Fuel Cells

It is shown that an electrochemically‐driven oxide overcoating substantially improves the performance of metal electrodes in high‐temperature electrochemical applications. As a case study, Pt thin films are overcoated with (Pr,Ce)O_2?δ (PCO) by means of a cathodic electrochemical deposition process that produces nanostructured oxide layers with a high specific surface area and uniform metal coverage and then the coated films are examined as an O₂‐electrode for thin‐film‐based solid oxide fuel cells. The combination of excellent conductivity, reactivity, and durability of PCO dramatically improves the oxygen reduction reaction rate while maintaining the nanoscale architecture of PCO layers and thus the performance of the PCO‐coated Pt thin‐film electrodes at high temperatures. As a result, with an oxide coating step lasting only 5 min, the electrode resistance is successfully reduced by more than 1000 times at 500 °C in air. These observations provide a new direction for the design of high‐performance electrodes for high‐temperature electrochemical cells.     

NMR investigation of the interaction of (+)- and (−)-flurbiprofen with β-cyclodextrin

The sodium salts of (+)-(S)- and (−)-(R)-2-(2-fluoro-4-biphenylyl)propionic acid (flurbiprofen, FBP) form 1:1 inclusion complexes with β-cyclodextrin (β-CD) having different association constants. Proton selective relaxation rate measurements revealed the existence of superior aggregated forms for both complexes (+)-FBP/β-CD and (−)-FBP/β-CD; information about their stereochemistry has been obtained by 2D ROESY analysis. © 1996 Wiley-Liss, Inc.     

Biotransformation of (±)-α-ionone and β-ionone by cultured cells of Caragana chamlagu

Suspension cultures of Caragana chamlagu (Leguminosae) convert (±)-α-ionone (1) into (±)-3-oxo-α-ionone (3) as the major product and β-ionone (2) into 5,6-epoxy-β-ionone (6) as the sole product. It is interesting to note that the cultured cells of C. chamlagu convert regioselectively the cycloolefinic part of 1 into the corresponding unsaturated carbonyl compound, allylic alcohol and epoxide as the oxidation products, whereas the suspension cultures of Nicotiana tabacum (Solanaceae) convert the unsaturated carbonyl of 1 into the corresponding saturated ketones and alcohols as reduction products.     

Comparison of the potencies of (+)- and (−)-2-ethylhexanoic acid in causing peroxisome proliferation and related biological effects in mouse liver

Male C57BL/6 mice were exposed to 1% (w/w) (+)- or (?)-2-ethylhexanoic acid or an equimolar mixture of these enantiomers in their diet for 4 or 10 days. A significant increase in liver weight and a 2- to 3-fold increase in the protein content of the mitochondrial fraction were seen in all cases. Peroxisomal palmitoyl-CoA oxidation was increased 2- to 3.5-fold after 4 days of treatment and 4- to 5-fold after 10 days, while the corresponding increases in peroxisomal lauroyl-CoA oxidase activity were 2- to 3-fold and 9- to 12-fold, respectively. Peroxisomal catalase activity was unchanged, whereas the microsomal and cytosolic activities were increased 2- to 3-fold and 6- to 16-fold, respectively. These treatments also induced microsomal ω-hydroxylation of lauric acid 7-fold and soluble epoxide hydrolase activity in the mitochondrial and cytosolic fractions, as well as microsomal epoxide hydrolase activity about 50–100%. The only significant differences observed between the effects of (+)-2-ethylhexanoic acid and its (?)-enantiomer were on peroxisomal palmitoyl-CoA oxidation and lauroyl-CoA oxidase activity after 4 days of treatment. In both these cases the (+)-enantiomer resulted in increases which were 50–75% greater than those seen with the (?)-form. © 1994 Wiley-Liss, Inc.     

Biooptical characteristics of PSII and PSI in 33 species (13 pigment groups) of marine phytoplankton,and the relevance for pulse‐amplitude‐modulated and fast‐repetition‐rate fluorometry1

We studied the variability of in vivo absorption coefficients and PSII‐scaled fluorescence excitation (fl‐ex) spectra of high light (HL) and low light (LL) acclimated cultures of 33 phytoplankton species that belonged to 13 different pigment groups (PGs) and 10 different phytoplankton classes. By scaling fl‐ex spectra to the corresponding absorption spectra by matching them in the 540–650 nm range, we obtained estimates for the fraction of total chl a that resided in PSII, the absorption of light by PSII, PSI, and photoprotective carotenoids. The in vivo red peak absorption maxima ranged from 673 to 679 nm, reflecting bonding of chl a to different pigment proteins. A simple approach is presented for quantifying intracellular self‐shading and evaluating the impact of photoacclimation on biooptical characteristics of the different PGs examined. In view of these results, parameters used in the calculation of oxygenic photosynthesis based on pulse‐amplitude‐modulated (PAM) and fast‐repetition‐rate (FRR) fluorometers are discussed, showing that the ratio between light available to PSII and total absorption, essential for the calculation of the oxygen release rate (using the PSII‐scaled fluorescence spectrum as a proxy) was dependent on species and photoacclimation state. Three subgroups of chromophytes exhibited 70%–80%, 60%–80%, and 50%–60% chl a in PSII‐LHCII; the two subgroups of chlorophytes, 70% or 80%; and cyanobacteria, only 12%. In contrast, the mean fraction for chromo‐ and chlorophytes of quanta absorbed by PSII was 73% in LL‐ and 55% in HL‐acclimated cells; thus, the corresponding ratios 0.55 and 0.73 might be used as correction factors adjusting for quanta absorbed by PSII for PAM and FRR measurements.