Development of Dendrimers:  Macromolecules for Use in Organic Light-Emitting Diodes and Solar Cells (original) (raw)

Solvents and Solvent Effects: An Introduction

Organic Process Research & Development, 2007

Solution chemistry is carried out in solvents, that is in liquids under the conditions of application, which can exert a considerable influence on the properties of the dissolved solute species. A short historical overview on the influence of solvents on chemical processes (equilibria, reaction rates) and physical processes (absorption spectra, crystallization) is presented. The term "solvent polarity" is discussed, and a solvatochromic parameter for its empirical determination is mentioned. A classification of solvents according to their chemical bonds is given, with special attention to supercritical fluids, fluorous solvents, and room temperature ionic liquids as promising new reaction media.

Conjugate systems in the construction of heterocycles and quaternary stereocenters

Pure and Applied Chemistry, 2007

The synthetic application of 4,5-bis-alkylidene-1,3-oxazolidin-2-ones led to the efficient and regioselective synthesis of 2-(3H)-benzoxazolones and diarylamines with a short methodology. They were also valuable synthons in a total synthesis of naturally occurring carbazoles. New enantiopure 4-oxazoline-2-one and 4-methylene-2-oxazolidinone were prepared via a one-pot microwave (MW)-promoted condensation of α-ketols and an enantiopure isocyanate. These enamides were efficient nucleophiles when added to Michael acceptors to give a series of compounds with quaternary stereocenters in fairly good stereoisomeric ratios. The novel approach for the synthesis of benzofurans and indoles by intramolecular cyclization of enaminones has been applied in the preparation of furobenzofurans starting from benzo-bis-enaminones.

Electrochemical processes at a flowing organic solvent∣aqueous electrolyte phase boundary

Electrochemistry Communications, 2007

A microfluidic double channel device was employed to study reactions at a flowing liquidjliquid interface in contact with a gold electrode. The rectangular flow cell was calibrated for both single phase liquid flow and biphasic liquidjliquid flow for the case of the immiscible N-octyl-2-pyrrolidone (NOP)jaqueous electrolyte system. The influence of flow direction and speed and liquid viscosity on the position of the phase boundary was examined.

Recent Advances in the Chemistry of Anellated Azaphospholes

Current Organic Chemistry, 2007

Azaphospholes are 6 aromatic heterocycles incorporating at least one 2 , 3 -phosphorus atom and one 3 , 3nitrogen atom. This review covers the synthesis, structural characterization, reactions and theoretical calculations of azaphospholes anellated to a six-or five-membered heterocyclic ring, reported during the last 10-12 years. Three synthetic methods, namely [4+1] cyclocondensation, [3+2] cyclocondensation and 1,5-electrocyclization make a variety of these phosphorus heterocycles available. The aromatic character of these compounds has been confirmed by carrying out density functional theory (DFT) calculations. Mainly 1 H, 13 C and 31 P NMR studies have been employed for the structural characterization. Almost all the functionalities present in the azaphosphole ring have been investigated and electrophilic substitution reactions of the 1-unsubstituted compounds and Diels-Alder reactions as well as 1,2-addition reactions to the >C=P-moiety have been accomplished successfully. The stereo-and regioselectivities observed in the Diels-Alder reactions have been explained on the basis of DFT calculations. Cheletropic cycloadducts formed from [4+1] cycloaddition of o-quinones on the 2 , 3 -P atom have been obtained. A variety of coordination compounds formed bycoordination of the 2 , 3 -P atom have been prepared.

Oxidation of N-heterocyclics: A green approach

Journal of Heterocyclic Chemistry, 2007

Environmentally benign oxidation methods satisfy the postulates of green chemistry. Heterocyclic Noxides have applications in synthetic organic chemistry, chemotherapy and agrochemicals. Synthesis of Noxides using green oxidants will be attractive over the conventional methods. The presence of the N-oxide group in the azine ring makes it more subject to electrophilic and nucleophilic attack and substantially expands the synthetic approaches for the modification of nitrogen-containing heterocyclics. That is the reason for the increasing interest in the chemistry of heterocyclic N-oxides. Some reactions adopted for oxidation of N-heterocyclics have been discussed. Stereochemical and spectroscopic aspects have been mentioned. It will be advantageous if anchored catalysts are employed for industrial exploitation. Several physiochemical aspects of various methods have been discussed.

Microinhomogeneity for aqueous mixtures of water-miscible organic solvents

Journal of the Ceramic Society of Japan, 2007

Mixing states for aqueous solutions of water-miscible organic solvents, acetonitrile and 1,4-dioxane, have been investigated at the molecular level by means of small-angle neutron scattering SANS and NMR relaxation. It has been shown that the organic solvent and water molecules are inhomogeneously mixed each other at the molecular level, although their mixtures are homogeneous at the macroscopic scale. Thus, both organic solvent clusters and water clusters coexist in the mixtures. The present investigation has also revealed that the microinhomogeneity of acetonitrile-water and 1,4-dioxane-water mixtures is gradually enhanced by cooling or adding salts toward phase separation. Based on the results, the effect of microinhomogeneity for solvent mixtures on chemical reactions was considered.