Search results for "solu"

1990

Intrinsic viscosities, [η], second virial coefficients, A2, and interaction potentials, g12, for the ternary systems alcohol (1)/3-heptanone (2)/poly(1-vinyl-2-pyrrolidone) (3), with the unbranched alcohols methanol, ethanol and 1-propanol, were determined at 25°C. Taking into account the dependence of the viscometric interaction parameter, B, with the molecular weight of the polymer, the unperturbed dimensions parameter, KΘ, of the polymer was unambiguously obtained. Relationships between ΔKΘ (defined as ΔKΘ = ΔK − KΘ) and excess Gibbs energies, GE, and between excess viscosity, Δ[η], and GE allow to obtain equations relating A2 to ΔKΘ or to Δ[η]. Therefore, A2 can be evaluated from experi…

ChemInform Abstract: Water-Soluble Palladium Nanoparticles: Click Synthesis and Applications as a Recyclable Catalyst in Suzuki Cross-Couplings in Aq…

2011

Polyethylene glycol-tagged macrocycle (I) is prepared by a three-fold copper-catalyzed [3 + 2] cycloaddition reaction.

DNA-binding studies of a series of novel water-soluble derivatives of 1,4-dihydropyridine

2018

Aim. to determine DNA interaction modes for a series of 1,4-dihydropyridines with different biological activities synthesized in the Latvian Institute of Or-ganic Synthesis. Methods. Affinity of the compounds to DNA was detected by UV/VIS spec-trometry and re-proofed by means of spectrofluorimetry, EBr extrusion assay, cyclic voltammetry and DNA melting. Radical scavenging was tested by electron paramagnetic resonance spectros-copy, peroxynitrite binding was monitored spectrophotometrically, protection of DNA against hydroxyl radical was determined by gel electrophoresis. Results. In a series of water-soluble monocyclic derivatives of 1,4-dihydropyridine with carboxylate groups in position-…

Absolute Configuration Determination of 2,3-Dihydro-1H,5H-pyrazolo[1,2-a]pyrazoles Using Chiroptical Methods at Different Wavelengths

2016

A correlation between the absolute configuration and chiroptical properties of nonracemic 1,6,7-trisubstituted 2,3-dihydro-1H,5H-pyrazolo[1,2-a]pyrazoles was studied. A series of 16 novel representatives were prepared by Cu-catalyzed [3 + 2] cycloadditions of racemic (Z)-2-benzylidene-5-oxopyrazolidin-2-ium-1-ides to tert-butyl (S)-(3-oxopent-4-yn-2-yl)carbamate, and their structures were determined by NMR, VCD, ECD, and X-ray diffraction. A clear correlation between the sign of specific rotation and configuration at position C(1) allows for easy determination of the absolute configuration of 1,6,7-trisubstituted 2,3-dihydro-1H,5H-pyrazolo[1,2-a]pyrazoles by ECD and NMR. While VCD, requirin…

Über die lösungswärme von polystyrol in verschiedenen lösungsmitteln

1951

An einem Polystyrol mit einem Molekulargewicht von ca. 20 000 werden die Losungs-warmen in verschiedenen Losungsmitteln in einem Kalorimeter bestimmt. Die meisten Losungsvorgange verlaufen exotherm, in einem Fall (Cyclohexan) wird jedoch bei der Auflosung Warme von der Umgebung aufgenommen. Es wird festgestellt, das die Trocknung der Praparate sehr wichtig fur die Reproduzierbarkeit der Messungen ist. Ferner wird orientierend die Abhangigkeit der Losungswarme vom Polymerisationsgrad sowie von der Konzentration der entstehenden Losung festgestellt. Es wird auserdem orientierend die Mischungswarme von Athylbenzol in verschiedenen Losungsmitteln bestimmt. Measurements of the heat of solution o…

ChemInform Abstract: Synthesis of Highly Substituted Hexahelicenes

2014

C2-Symmetric hexahelicenes 3a–3g, which bear four or six alkoxy chains, were prepared in eight-to-nine reaction steps in high overall yields. The final step consisted of a twofold oxidative photocyclization of the corresponding 2,7-bis(2-phenylethenyl)naphthalenes. Long (and branched) chains provide a good solubility and processability, which is a prerequisite for applications in organic synthesis and materials science.

Ionic Liquids in Biphasic Ethylene Polymerisation

2011

Over the past several years there has been a considerable increase in the interest of ionic liquids as versatile reaction media for a wide variety of synthetic processes. The popularity of ionic liquids has been related primarily to their unique physical and chemical properties, which can be tailored by the judicious selection of cations and anions. These properties make it possible to use ionic liquids as solvents for many organic, inorganic, and organometallic compounds, including catalysts and co-catalysts, for various types of reactions. In particular, the polar but weakly coordinating character of ionic liquids enables them to be applied as mediums in catalysis, to immobilize various k…

Solid Solutions in the Xanthone–Thioxanthone Binary System: How Well Are Similar Molecules Discriminated in the Solid State?

2020

The binary system of xanthone–thioxanthone has been explored, showing that two solid solutions (formed based on xanthone and thioxanthone parent structures, respectively) exist for this system. One...

Novel electrolytes for electrochemical double layer capacitors based on 1,1,1,3,3,3-hexafluoropropan-2-ol

2012

Abstract 1,1,1,3,3,3-Hexafluoropropan-2-ol (HFIP) was tested for its applicability as solvent in electrolytes for energy storage devices. A comprehensive characterization with respect to solubility, conductivity, as well as chemical and electrochemical stability was carried out with different conducting salts. Furthermore, different HFIP solutions containing standard supporting electrolytes and alkali metal fluorides, respectively, were applied in electrochemical double layer capacitor cells. Their behavior was studied with impedance spectroscopy and cyclic voltammetry at low scan rates and compared to the current benchmark electrolytes based on propylene carbonate (PC) and acetonitrile (AN…

Introduction of a luminescent sensor for tracking trace levels of hydrazine in insect pollinated cropland flowers

2021

In recent years the excessive use of hydazine containing chemical pesticides and insecticides in farming practices is well pronounced, which directly or indirectly impart a great threat towards the total environment. Considering the above fact we are motivated to introduce a new, efficient and simple chemodosimeter (NCD) based on a carbazole-naphthalimide framework to recognize and estimate the mutagenic hydrazine within several affected cropland flowers. Probe NCD can detect hydrazine in a nanomolar range (65 nM or 2 ppb) in the presence of other metal ions, anions and amines, which gives it not only great potential but also makes it selective and sensitive. The sensing mechanism is confir…