Construction of two lanthanide complexes based on N- and O-donors: synthesis, luminescence, and biological activities

<p>Two new isostructural dinuclear complexes, Ln₂(4-cpa)₆(phen)₂ (Ln = Eu (<b>1</b>); Tb (<b>2</b>), 4-cpa^– = 4-chlorophenylacetate, phen = 1,10-phenanthroline), have been hydrothermally synthesized and characterized by IR spectroscopy, elemental analysis, thermogravimetric analysis, powder X-ray diffraction, and single-crystal X-ray diffraction. The lanthanides are bridged by two bidentate and two tridentate carboxylato groups to give centrosymmetric dimers with Ln···Ln separations of 3.967(2) and 3.937(3) Å for <b>1</b> and <b>2</b>, respectively. Each metal is nine-coordinate and exhibits a distorted tricapped trigonal prismatic geometry. Both <b>1</b> and <b>2</b> emit characteristic, intense luminescence at room temperature with lifetimes up to 0.890 ms (at 611 nm) and 0.995 ms (at 543 nm). Poor luminescence efficiency is observed for <b>2</b>. 4-Chlorophenylacetate, <b>1</b> and <b>2</b> have been screened for their phytogrowth-inhibitory activities against <i>Brassica napus</i> L. and <i>Echinochloa crusgalli</i> L., and the results are compared with the activity of quizalofop-P-ethyl.</p

Graphene Field-Effect Transistor as a High-Throughput Platform to Probe Charge Separation at Donor–Acceptor Interfaces

In organic and low-dimensional materials, electrons and holes are bound together to form excitons. Effective exciton dissociation at interfaces is essential for applications such as photovoltaics and photosensing. Here, we present an interface-sensitive, time-resolved method that utilizes graphene field effect transistor as an electric-field sensor to measure the charge separation dynamics and yield at donor–acceptor interfaces. Compared to other interface-sensitive spectroscopy techniques, our method has a much reduced measurement time and can be easily adapted to different material interfaces. Hence, it can be used as a high throughput screening tool to evaluate the charge separation efficiency in a large number of systems. By using zinc phthalocyanine/fullerene interface, we demonstrate how this method can be used to quantify the charge separation dynamics and yield at a typical organic donor–acceptor interface

Solubility and Characterization of CO₂ in 40 mass % <i>N</i>‑Ethylmonoethanolamine Solutions: Explorations for an Efficient Nonaqueous Solution

The CO₂ solubility in <i>N</i>-ethylmonoethanolamine (EMEA) solutions was investigated using the vapor–liquid equilibrium (VLE) and the absorption–desorption apparatus. A tertiary amine, <i>N</i>,<i>N</i>-diethylethanolamine (DEEA), was used as a novel solvent, and other nonaqueous solvents, diethylene glycol, triethylene glycol, benzyl alcohol, <i>n</i>-butyl alcohol and polyethylene glycol-200, were used for comparison. The EMEA + DEEA solution displayed a much higher CO₂ solubility than other nonaqueous solutions though lower than the EMEA + H₂O solution in the VLE experiment. However, the EMEA + DEEA solution exhibited a higher cyclic absorption capacity than EMEA + H₂O solution in the cyclic absorption–desorption experiment. The reaction mechanism of EMEA + DEEA + CO₂ was investigated by ¹³C NMR spectroscopy, which indicated that the nonaqueous solvent of DEEA participated in the chemical absorption of CO₂, and thus improved the CO₂ solubility. The tertiary amine DEEA used as a nonaqueous solvent shows more excellent performance than alcohols and glycols

Progress curves for the activation of diphenolase of mushroom tyrosinase by α-arbutin

<p>. The reaction media (3.0 mL) contained 0.5 mM L-Dopa in 50 mM phosphate buffer (pH 6.8), the indicated concentration of α-arbutin, and mushroom tyrosinase (6.67 µg/mL). The concentrations of α-arbutin for curves 1∼3 were 0, 5, 10 mmol·L⁻¹.</p

Kinetic parametes of diphenolase by α-arbutin.

<p>Kinetic parametes of diphenolase by α-arbutin.</p

Lineweaver-Burk plots for activation of α-arbutin on mushroom tyrosinase for the catalysis of L-Dopa at 30°C, pH 6.8.

<p>The reaction media (3.0 mL) contained 50 mM phosphate buffer (pH 6.8), different concentrations of L-Dopa assubstrate,different concentrations of α-arbutin and mushroom tyrosinase (6.67 µg/mL). Concentrations of α-arbutin for curves 1∼3 were 0, 5, 10 mmol·L⁻¹, respectively.</p

Progress curves for the inhibition of monophenolase of mushroom tyrosinase by α-arbutin at 30°C.

<p>The reaction media (3.0 mL) contained 0.5 mM L-tyrosine in 50 mM phosphate buffer (pH 6.8), the indicated concentration of α-arbutin, and mushroom tyrosinase (20 µg/mL). The concentrations of α-arbutin for curves 1∼4 were 0, 1.67, 3.34, 4.18 mmol·L⁻¹. The reaction was started by the addition of the enzyme.</p

Activation rate of diphenolase of mushroom tyrosinase by α-arbutin.

<p>Assay conditions: 3.0 ml 50 mM phosphate buffer pH 6.8, containing 0.5 mM L-Dopa, different concentrations of α-arbutin and mushroom tyrosinase (6.67 µg/mL).</p

Effects of α-arbutin on the enzyme activity and the lag time of monophenolase activity of mushroom tyrosinase.

<p>Assay conditions: 3.0 ml 50 mM phosphate buffer pH 6.8, containing 0.5 mM L-tyrosine. The reaction was started by the addition of the enzyme (20 µg/mL).</p

The chemical structure of ascorbic acid.

<p>The chemical structure of ascorbic acid.</p