Energy-Level and Molecular Engineering of Organic D-pi-A Sensitizers in Dye-Sensitized Solar Cells

A series of organic D-pi-A sensitizers composed of different triarylamine donors in conjugation with the thienothiophene unit and cyanoacrylic acid as an acceptor has been synthesized at a moderate yield. Through tuning the number of methoxy substituents on the triphenylamine donor, we have gradually red-shifted the absorption of sensitizers to enhance device efficiencies.

Hydrothermal Synthesis, Structures, and Luminescent Properties of Seven d(10) Metal-Organic Frameworks Based on 9,9-Dipropylfluorene-2,7-Dicarboxylic Acid (H(2)DFDA)

A series of Zn(II) and Cd(II) metal-organic frameworks, namely, [Zn(DFDA)] (1), [Cd(DFDA)(C2H5OH)] (2), [Zn-2(DFDA)(2)(L-1)(2)](2) center dot 3H(2)O (3), [Cd-2(DFDA)(2)(L-1)(2)] (4), [Zn(DFDA)(L-2)] (5), [Cd(DFDA)(L-2)(DMF)] (6), and [Zn(DFDA)(L-3)] (7) (where DFDA = 9,9-dipropylfluorene-2,7-dicarboxylate anion, L-1 = 1,4-bis(imidazol-1-ylmethyl)benzene, L-2 = 1,1'-(1,4-butanediyl) bis(imidazole), L-3 = 2,2'-bipyridine) have been synthesized under hydrothermal conditions and structurally characterized. Compound 1 exhibits a three-dimensional (3D framework containing one-dimensional (1D) Zn(II)-O clusters, with (4(8).6(7)) topology. Compound 2 contains hydrophobic channels built from infinite 1D Cd(II)-O clusters, with (4(8).5(4).6(3)) topology.

Selective separation of yttrium by CA-100 in the presence of a complexing agent

The selective separation of Y from yttrium solution containing small heavy rare earth (HRE) impurities (Ho, Er, Tm, Yb, Lu) by liquid-liquid extraction using CA-100 in the presence of a water-soluble complexing agent of ethylenediaminetetraacetic acid (EDTA) was experimentally studied at 298K. Experiments were carried Out in two feeds, Feed-I: [RE](f) = 4.94 x 10(-3) M, Y = 98.5%, HRE (Ho, Er, Tm, Yb, Lu) = 1.5%; Feed-II: [RE](f) = 4.94 x 10(-3) M, Y = 99.9%, HRE (Ho, Er, Tm, Yb, Lu) = 0.1%, as a function of equilibrium pH (pH(eq)), the concentration ratio of [EDTA]:[HRE impurities]. It was shown that the extraction of HRE in the presence of EDTA was suppressed when compared to that of Y because of the masking effect, while the selective extraction of Y was enhanced and the separation factors increased to maximum at appropriate condition for Feed-I: Y/Ho = 1.53, Y/Er = 3.09, Y/Tm = 5.61, Y/Yb = 12.04, Y/Lu = 27.51 at pH 4.37 and [EDTA]:[HRE impurities] = 4: 1, for Feed-II: Y/Ho = 1.32, Y/Er = 1.91, Y/Tm = 2.00, Y/Yb = 3.05, Y/Lu = 3.33 at pH 4.42 and [EDTA]: [HRE impurities] = 8:1. The separation and purification of Y by this method was discussed.

Aggregation behavior of amphiphilic D-pi-A molecules bearing recognition group

Aggregation behavior of two amphiphilic D-pi -A molecules bearing barbituric acid as both recogniton group and electron-drawing substituent, 5-(4-dodecyl oxybenzylidene)-(1H, 3H)-2,4,6-pyrimidine trione (PB12) and 5-(4-N,N-didodecyl aminobenzylidene)-(1H,3H)-2,4,6-pyrimidine trione (AB(12)) was studied by UV-visible, fluorescence, and surface voltaic spectroscopies (SPS). The experimental results indicate that PB12 tends to form J-aggregate and AB(12) tends to form H-aggregate under increasing concentration. An intramolecular twisted charge transfer (TICT) emission around 500 nm is observed when J-aggregate is formed between PB12 molecules, and an excimer emission around 600 nm is observed when H-aggregate is formed between AB(12) molecules.

Electrochemical and spectroscopic study of vitamin D-2 by in situ thin layer CD spectroelectrochemistry

The electrooxidation of vitamin D-2 (VD2) was studied by cyclic voltammetry and in situ circular dichroic (CD) spectroelectrochemistry for the first time, The mechanism of electrooxidation and some useful kinetic and adsorption parameters were obtained. The results showed that the oxidation of VD2 in ethanol solution is an irreversible diffusion controlled process following a weak adsorption of the electroinactive product at a glassy carbon electrode, which blocks the electrochemical reaction. The electrooxidation occurs mainly at the triene moieties of the VD2 molecule. The CD spectroelectrochemical data were treated by the double logarithm method together with nonlinear regression, from which the formal potential E-0 = 1.08 V, alphan = 0.245, the standard electrochemical rate constant k(0) = 4.30( +/- 0.58) x 10(-4) cm s(-1) and the adsorption constant beta = 1.77(+/- 0.25) were obtained. (C) 2001 Elsevier Science B.V. All rights reserved.

The channel behavior of gramicidin D in the self-assembled monolayer

It was found for the first time that gramicidin D (GD) molecules can be incorporated into the ODM monolayer which is self-assembled on the surface of the gold electrode and form monovalent cation channels.

Electrochemical study of gramicidin D forming ion-permeable channels in the bilayer lipid membranes

Gramicidin within the lipid bilayer matrix is a well-known channel-forming polypeptide, but the mechanism of the ions across the membrane induced by gramicidin is not well understood. We found that at very low concentration of gramicidin in a bilayer lipid membrane, the channel behavior was controlled by the voltage applied across the membrane. When the voltage is higher than 75 mV, the channel is closing, while lower than 75 mV, the channel is opening. But when the concentration of the gramicidin in the BLMs is high, the channel behavior is changed into voltage-independent. (C) 1998 Elsevier Science Ltd. All rights reserved.

DOPAMINE D-1 RECEPTOR MECHANISMS IN THE COGNITIVE PERFORMANCE OF YOUNG-ADULT AND AGED MONKEYS

Dopamine (DA) D-1 receptor compounds were examined in monkeys for effects on the working memory functions of the prefrontal cortex and on the fine motor abilities of the primary motor cortex. The D-1 antagonist, SCH23390, the partial D-1 agonist, SKF38393, and the full D-1 agonist, dihydrexidine, were characterized in young control monkeys, and in aged monkeys with naturally occurring catecholamine depletion. In addition, SKF38393 was tested in young monkeys experimentally depleted of catecholamines with chronic reserpine treatment. Injections of SCH23390 significantly impaired the memory performance of young control monkeys, but did not impair aged monkeys with presumed catecholamine depletion. Conversely, the partial agonist, SKF38393, improved the depleted monkeys (aged or reserpine-treated) but did not improve young control animals. The full agonist, dihydrexidine, did improve memory performance in young control monkeys, as well as in a subset of aged monkeys. Consistent with D, receptor mechanisms, agonist-induced improvements were blocked by SCH23390. Drug effects on memory performance occurred independently of effects on fine motor performance. These results underscore the importance of DA D-1 mechanisms in cognitive function, and provide functional evidence of DA system degeneration in aged monkeys. Finally, high doses of D-1 agonists impaired memory performance in aged monkeys, suggesting that excessive D-1 stimulation may be deleterious to cognitive function.

2-D and 3-D processing and interpretation of multi-fold ground penetrating radar data:a case history from an archaeological site

A 2.5-D and 3-D multi-fold GPR survey was carried out in the Archaeological Park of Aquileia (northern Italy). The primary objective of the study was the identification of targets of potential archaeological interest in an area designated by local archaeological authorities. The second geophysical objective was to test 2-D and 3-D multi-fold methods and to study localised targets of unknown shape and dimensions in hostile soil conditions. Several portions of the acquisition grid were processed in common offset (CO), common shot (CSG) and common mid point (CMP) geometry. An 8×8 m area was studied with orthogonal CMPs thus achieving a 3-D subsurface coverage with azimuthal range limited to two normal components. Coherent noise components were identified in the pre-stack domain and removed by means of FK filtering of CMP records. Stack velocities were obtained from conventional velocity analysis and azimuthal velocity analysis of 3-D pre-stack gathers. Two major discontinuities were identified in the area of study. The deeper one most probably coincides with the paleosol at the base of the layer associated with activities of man in the area in the last 2500 years. This interpretation is in agreement with the results obtained from nearby cores and excavations. The shallow discontinuity is observed in a part of the investigated area and it shows local interruptions with a linear distribution on the grid. Such interruptions may correspond to buried targets of archaeological interest. The prominent enhancement of the subsurface images obtained by means of multi-fold techniques, compared with the relatively poor quality of the conventional single-fold georadar sections, indicates that multi-fold methods are well suited for the application to high resolution studies in archaeology.

Specific Adsorption of Trace Amounts of Calcium and Strontium by Hydrous Oxides of Iron and Aluminum1

Freshly prepared Fe and Al hydrous oxide gels and the amorphous product of heating gibbsite selectively adsorbed traces of Ca and Sr from solutions containing a large excess (∼1M) of NaNO3. The fraction of the added Ca (Sr) adsorbed depended principally on the suspension pH, the amount of solid present, and to a lesser extent on the NaNO3 concentration. Significant Ca and Sr adsorption occurred on the Fe and Al gels, and heated gibbsite, at pH values below the points of zero charge (8.1, 9.4, and 8.3±0.1, respectively), indicating specific adsorption. The pH (± 0.10) at which 50% of the Ca was adsorbed (pH50) occurred at pH 7.15 for the Fe gel (0.093M Fe), 8.35 for the Al gel (0.093M Al), and 6.70 for the heated gibbsite (0.181M Al); for Sr, the pH50 values were 7.10, 9.00, and 6.45, respectively. For the Fe gel and heated gibbsite, an empirical model based on the law of mass action described the pH dependence of adsorption reasonably well and suggested that for each Ca or Sr fraction adsorbed, approximately one proton was released. Failure of the Al gel to fit this model may have resulted from its rapid aging.