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Surface-enhanced Raman scattering (SERS) spectra of a metal-complexing ligand, immobilized to a silver electrode surface, exhibits significant structural changes upon application of modest potentials. A detailed spectroscopic investigation shows that the potential applied to the electrode surface governs the tautomerization equilibrium of the immobilized ligand, p-((8-hydroxyquinoline)azo)benzenethiol (SHQ). Potential-dependent SERS spectra reveal that SHQ exists predominantly in a keto--hydrazone tautomeric form at applied potentials that are negative of -300 mV (vs Ag/AgCl), while the enol--azo tautomer is strongly favored at potentials positive of this value. The observed switching of the tautomer population occurs within a narrow range of applied potentials, ~200 mV (Ag/AgCl). Electrical control over the tautomerization equilibrium of immobilized SHQ governs the reactivity of the ligand toward metal ion complexation, where the enol--azo tautomer exhibits much greater affinity for metal ion binding compared to its keto--hydrazone counterpart. Accordingly, the potential applied to the electrode can be used to influence metal ion binding of immobilized SHQ through control over the tautomerization equilibrium, to produce an electrically switchable surface for metal ion complexation. Large differences in the electric dipole moment of the two tautomers, estimated from density functional theory calculations, suggested a model where the potential dependence arises from the interaction of the ligand dipole with electric fields that exist at a polarized electrode surface. This model accurately predicts the relative tautomer populations versus applied potential, at interfacial electric fields that are consistent with previous measurements of the vibratonal Stark effect at polarized interfaces. Potential applications of this technology to several areas of analytical chemistry are considered.

A comparative study of a metal migration model and an unstable tris(8-hydroxyquinoline) aluminum cationic model is presented to understand their roles in the luminescence degradation of organic light emitting devices. The analysis reveals that the operational stability of the devices is highly affected by the alterations in the device layer structures.

The effect of using pulsed current (pc) versus direct current (dc) driving mode on the electroluminescence (EL) efficiency and operational stability of tris(8-hydroxy-quinoline)aluminum (AlQ3)-based organic light-emitting devices are investigated. The result shows that the dependence of device stability on the driving mode correlates with the relative EL efficiency under the pc and dc driving modes.

The aim of a study is to evaluate the predictive ability of the electron density and electrostatic properties in the structure-activity relationship of styrylquinoline-type HIV-1 antiviral drugs. High-resolution X-ray diffraction experiments and ab initio theoretical calculations are used to derive the electron density and electrostatic properties of the progenitors of a potent HIV-1 IN inhibitor.

The preparation of substituted quinoline derivatives through a Friedlander condensation reaction utilizing the ionic liquid [bmim][B[F.sub.4]] as the reaction medium and iron chloride hexahydrate (Fe[Cl.sub.3] x 6[H.sub.2]O) as a catalyst is described. The advantages in using this method include its environmental friendliness, simple operating process in both mild and neutral reaction conditions, and good yields. Key words: ionic liquid, Friedlander reaction, quinoline derivatives, green chemistry. On decrit l'utilisation du [bmim][B[F.sub.4]], un liquide ionique, comme milieu reactionnel et de l'hexahydrate du chlorure de fer (Fe[Cl.sub.3]x6[H.sub.2]O) comme catalyseur pour la preparation de derives de quinoleines substituees par la reaction de condensation de Friedlander. Cette methode presente l'avantage d'etre benigne pour l'environnement, d'impliquer un processus d'operation simple, de se faire dans des conditions douces et neutres et de donner de bons rendements. Mots cles : liquide ionique, reaction de Friedlander, derives de la quinoleine, chimie verte. [Traduit par la Redaction]

A comparative study of the chemistry that takes place at the metal (Mg,Al)-on-Alq3 and Alq3-on-metal interfaces is presented. The chemical structure of interfaces between tris(8- hydroxy quinoline) aluminum (Alq3) and low work function metals such as magnesium (Mg), aluminum (Al), lithium (Li) potassium (K), and calcium (Ca) has been recently investigated, both theoretically and experimentally.

The construction of hybrid permeable-base transistors, in vertical architecture, is reported by using tris(8-hydroxyquinoline) aluminum as emitter, a thin gold layer as base, and n-type silicon as collector. These transistors have presented a high common-base current gain, can be operated at low driving voltages and allowed high density current.

The article explains the various different properties exhibited by the undoped zinc oxide anode film layers that are formed in the tris (8-hydroxyquinoline) aluminum organic light emitting diodes by the atomic layer deposition methodology. The external quantum efficiency of the system is shown to be around 1.5%, which is much better than that exhibited by other conventional devices.

Highly enantioselective 1,3-dipolar cycloaddition of C,N-cyclic azomethine imines with enals was employed to yield pharmaceutically interesting tetrahydroisoquinoline and piperidine motifs. The reaction was carried out in presence of titanium-BINOLate as catalyst.

Several solvent-inventory experiments are conducted to explain the accumulated proton-donating ability of the different solvent molecules involved in proton transfer. The discussed deprotonation of the alcohol molecule is shown to be the main mechanism controlling the rate of the reaction.

Slow correlated growth mode in energetic cluster vapor deposited organic light emissive material tris(8-hydroquinoline) aluminum is described. Phase modulated atomic force microscopy has shown very slow grain growth with thickness, with very small phase differences within the film, and fractal dimension calculated from correlation function has shown growth process consistent with diffusion-limited aggregation.

Hybrid vertical architecture transistors are prepared, which has shown magnetic-field dependent electrical characteristics by using tris-(8-hydroxyquinoline) aluminum ([Alq.sub.3]), sulfonated polyaniline (SPAN), and n-type silicon. The rate of electrons that cross emitter and base layers and reach the collector is shown to be affected by the magnetic field, which has led to magnetic-field-dependent common-emitter current gain larger than 1.

The magnetic field dependent current and electroluminescence (EL) of aluminum tris-(8-hydroxyquinoline) ([Alq.sub.3])-based organic light emitting diodes (OLEDs) are measured at different temperatures. The high field decrease in the EL is weakened and vanishes at higher temperatures, which is due to the field affected triplet-triplet annihilation process.

The fabrication and analysis of organic light-emitting devices (OLEDs) with a cohosted emitter of various component ratios is described. The parameters exploring the energy transfer process, the spectra overlap integrals and Forster's radius is calculated for understanding the dependence of luminance efficiency of the resulted OLEDs on the measured composition ratio.

A new Rh(I)-catalyzed tandem conjugate addition-Mannich cyclization reaction of imine-substituted electron-deficient alkenes with arylboronic acids is developed for producing 2,3,4-trisubstituted 1,2,3,4-tetrahydroquinolines. This example has involved imine group as a secondary electrophile in Rh(I)-catalyzed tandem reactions.

The fabrication and characterization of stable negative differential resistance (NDR) devices based on tris(8-hydroxyquinoline) aluminum ([Alq.sub.3]) are described. The studies have shown that injection of holes in these devices have played a vital role in NDR and resistive switching processes.

The synthesis and redox properties of a series of free-base and metal(II) quinoxalino(2,3-b']porphyrins and their use in an investigation of the substituent effects on the degree of communication between the porphyrin and its [beta],[beta]'-fused quinoxalino component are reported.

An efficient method is developed for 4-fucntionalized quinoline derivatives, 4-(1,3-dithian-2-ylidene)methyl)quinolines. Ethynyl ketene-S,S-acetals have reacted in a one-pot procedure with various arylamines and aldehydes under mild conditions to produce the corresponding quinoline derivatives via a consecutive arylimine formation, regiospecific aza-Diels-Alder reaction and reductive amination.

The deprotonation and regioselective reaction of 2H-pyra-zola[3,4-c]quinolines with a variety of electrophiles is described. This method provides a direct route to a class of pharmacologically interesting compounds.

The catalytic enantioselective petasis-type reaction of quinolines is found to be very important in the synthesis of the biologically active compounds, tetrahydroquinolines. An analysis shows that such an organocatalyst activates the organoboronic acids, which helps in the describe transformation due to the generation of a chiral complex, in addition to the activation of an electrophile and nucleophile.

A study shows that the new series of indole-based receptors namely 2,3-diindol-3'yl quinoxalines (DIQ, 6 and 7) provide a new series of anion receptors that are particularly effective for the dihydrogen phosphate anion. It is seen that receptor bis(indolyl) allows for the visual detection of this anion via the production of a simple, anion-triggered color change.

Photoemission spectroscopy is used to investigate the evolution of the interface electronic structure of a sandwich structure involving aluminum oxide and tris(8-hydroxyquinoline) aluminum (Alq), that is, (Alq/Al[O.sub.x]/Alq). The results have shown that the deposition of the top Alq layers have led to an asymmetry in the electronic energy level alignment with respect to the Al[O.sub.x] interlayer.

Stark absorption spectroscopy is applied to 6-hydroxyquninoline (6-HQ) doped in polymer films of poly (methyl methacrylate) and poly (vinyl alcohol) at a temperature rang of 50-300 Kelvin. The results reveal that the molecular motion of 6-HQ in a polymer is very sensitive to the microenvironment of the surrounding matrix.

Equilibrium geometry configuration of the 'CH'/N substituted Alq3 and Gaq3 derivatives are calculated by density functional theory. It is shown that the change of 'CH'/N substituted position on 8-hydroxyquinoline ligand is a powerful approach for the tuning of emitting color.

The photoluminescence properties of an amorphous tris(8-hydroxyquinoline) aluminum (Alq3) thin film heavily doped with fac tris(2-phenylpyridine) iridium [Ir(ppy)3] at 8 K is characterized. The triplet energy of Alq3 is estimated to be 2.03 eV from the highest energy peak of the phosphorescence spectrum.

The synthesis of zwitterionic benzoquinonemonoimine is presented. It is shown that it is constituted of two chemically connected 6 Pi electron subunits and its reactivity with electrophiles like H(super +), CH(sub 3)(super +), and metal salts is studied.

A systematic thickness dependence study on the delay time in transient electroluminescence, using Alq3 based bilayer organic light-emitting diodes, is discussed. The results showed that the electron mobility extracted from the time delay is independent of the thickness of the Alq3 layer.

The low-lying triplet states of 10-hydroxybenzo [h] quinolines and its halogenated derivatives 7,9-diiodo-10-hydroxybenzo [h]- quinoline (DIHBQ) in an excited-state intramolecular proton-transfer (ESIPT) process are investigated. Results show that in addition to the protic-solvent perturbation photoinduced breakage of the intramolecular hydrogen bond in 3-hydroxyflavones played a role in the prohibition of ESIPT reaction in 77 K methylcyclohexane glassy matrixes.

Formation of energetically favored, stable oligomer of [(Znq2)](sub 4) tetramer configuration in both the single crystal and the vacuum-deposited thin films of zinc(II) bis-(8-hydroxyquinoline) (Znq2) is reported. Analysis of electronic structure of [(Znq2)](sub 4) calculated by ab initio Hartree-Fock (HF) method reveals a localization and energy shift of high-lying occupied and low-lying unoccupied states of symmetry related ligands located on opposite sides of the supramolecular structure resulting in a dipole moment for [(Znq2)](sub 4) tetramer close to zero.

The electroluminescent properties of three different structures (A:ITO/SiO2/Alq3/SiO2/Al, B:ITO/Alq3/SiO2/Al and C:ITO/SiO2/Alq3/Al based on the tris-(8-hydroxyquinoline) aluminum thin films are investigated. Results showed a blue electroluminescence at 457 nm was obtained from device (A) and (B) and the green emission at 518 nm was obtained from device (C).