Chemistry

A series of 2,3-diarylindoles were synthesized from 2-iodoaniline and unsymmetrical diarylacetylenes using the Larock heteroannulation. Diarylacetylenes bearing electron-withdrawing substituents lead to 2,3-diarylindoles with substituted phenyl moieties at the 2-position as major products, while those with electron-donating groups preferably yield indole products with substituted phenyl moieties at the 3-position. The regioisomeric product ratios exhibit a clear correlation with Hammett σ(p) values. DFT calculations reveal the origin of this effect, displaying smaller activation energy barriers for those pathways leading to the major regioisomer.

PLZT fine powders have been synthesized by a hydrothermal process using lead acetate, lanthanum acetate, zirconium n-propoxide and titanium isopropoxide as starting materials. The synthesis was performed at 200°C for 8, 12 and 24 h. 4 M KOH was used as a mineralizer to adjust the pH to an optimum value for the mixed precursor solution. After hydrothermal treatment the solid portion was separated out, washed and dried at 100°C for 12 h, where PLZT fine powders were obtained. PLZT powders were characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The PLZT powders were pressed and sintered to obtain high density ceramics, which then were investigated by XRD and SEM. The dielectric properties of the ceramics were investigated by measurements of dielectric constant and dielectric loss as a function of temperature at a fixed frequency.

The preparation of dialkyl-substituted poly(2,5-didecyl-1,4-phenylene vinylene) (PDDPV) by the Horner-Emmons polycondensation is described. Its performance in an organic light-emitting diode (OLED) device architecture is compared with devices prepared from the analogous dialkoxy-substituted poly(2,5-didecyloxy-1,4-phenylene vinylene) (PDOPV) and the corresponding alkyl-alkoxy-substituted alternating copolymer. Additionally, the structure, stability, electrochemical, and optical properties of the PPVs were characterized by gel permeation chromatography, thermogravimetric analysis, NMR spectroscopy, cyclic voltammetry, UV-Visible spectroscopy, and fluorescence spectroscopy. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 41162.

This paper describes a simple strategy for preparing light-emitting poly (9, 9-didecy1fluoreny1-2, 7-vinylene)(PFV) by Horner-Emmons polymerization using aromatic dialdehydes and diphosphonates as monomers in the presence of potassium tert-...

In this study, the conjugated polymer, poly(1-methoxy-4-octyloxy)-para-phenylene vinylene (MO-p-PPV) was synthesized and cha-racterized. MO-p-PPV was synthesized according to Gilch polymerization mechanism by using 4-methoxyphenol as starting material in the presence of potassium tert-butoxide (1M in THF). The product was further purified by multiple precipitations in different sol-vents such as methanol, tetrahydrofuran, isopropyl alcohol and hexane. The final product was dried to afford MO-p-PPV as a red solid. The resulting polymer was completely soluble in common organic solvents. The structure of monomer and optical properties of polymer were characterized by proton nuclear magnetic resonance (1H-NMR) spectroscopy, UV-vis spectroscopy, and fluorescence spectroscopy. The UV-vis spectrum showed absorption maxima for MO-p-PPV at 491 nm. Similarly, fluorescence spectrum showed λmax emission at 540 nm.

This paper describes a simple strategy for synthesizing poly(9,9-dialkylfluorene-2, 7-vinylenes) (PFV) having high molecular weight by Gilch polymerization method. The structure and optical properties of PFV were characterized by gel permeation chromatography (GPC), NMR spectroscopy, UV-Vis spectroscopy, and fluorescence spectroscopy. UV-Vis absorption spectra showed the broad absorption band with λmax = 414 nm. It exhibited a greenish fluorescence at λmax emission = 453 nm with shoulder at 488 nm. Similarly, photoluminescence spectra of powder samples of PFV showed λmax emission = 505 nm with shoulder at 535 nm.

ABSTRACT: The preparation of dialkyl-substituted poly(2,5-didecyl-1,4-phenylene vinylene) (PDDPV) by the Horner-Emmons polycondensation is described. Its performance in an organic light-emitting diode (OLED) device architecture is compared with devices prepared from the analogous dialkoxy-substituted poly(2,5-didecyloxy-1,4-phenylene vinylene) (PDOPV) and the corresponding alkyl-alkoxy-substituted alternating copolymer. Additionally, the structure, stability, electrochemical, and optical properties of the PPVs were characterized by gel permeation chromatography, thermogravimetric analysis, NMR spectroscopy, cyclic voltammetry, UVVisible spectroscopy, and fluorescence spectroscopy.

ABSTRACT: This paper describes a simple new strategy for preparing poly(9,9-dialkylfluorenyl-2,7-vinylenes) (PFVs) having high molecular weights and no detectable saturated defects along the conjugated backbone. The new route utilizes a modified Horner-Emmons method by coupling suitably designed comonomers to form the targeted conjugated polymers. The newly prepared PFVs were directly compared to PFVs prepared via a previously established Gilch polymerization route. The structure and optical properties of all PFVs were characterized by gel permeation chromatography (GPC), NMR spectroscopy, UV-vis, fluorescence, and photoluminescence spectroscopy. The findings indicate that the modified Horner-Emmons route gave PFVs with lower molecular weights but substantially higher yields and fewer defects than those prepared by using the Gilch route.

Chiral imprinted mesoporous platinum was
electrochemically synthesized in the presence of mandelic
acid and Brij 56 surfactant as chiral and mesoporous templates,
respectively. The chiral cavity obtained by using
mandelic acid as a template can be used to distinguish between
enantiomers of other chiral molecules in which the
stereocentre has a correlated configuration with respect
to the imprinted one. This recognition versatility was
tested for the discrimination of DOPA enantiomers. Mesoporous
platinum electrodes imprinted with (R)-mandelic
acid preferentially react with l-DOPA and vice versa for
the (S)-mandelic acid imprinted one, which is more reactive
for d-DOPA.