Conditions for the Synthesis of 4,5-Diaryl-3-hydroxy-2,2'-bipyridine-6-carbonitriles by the Reaction of 1,2,4-Triazine-5-carbonitriles with 2-Aminooxazoles

Russian Journal of Organic Chemistry - Various conditions for the inverse electron-demand aza-Diels–Alder reaction in the series of 5-aryl-3-(2-pyridyl)-1,2,4-triazine-5-carbonitriles and...     

Orientational transition in the cholesteric layer induced by electrically controlled ionic modification of the surface anchoring

A reorientation of cholesteric liquid crystal with a large helix pitch induced by the electrically controlled ionic modification of the surface anchoring has been studied. In initial state, the cholesteric helix is untwisted completely owing to the normal surface anchoring specified by the cations adsorbed at the substrates. As a result, the homeotropic director configuration is observed within the cell. Under the action of DC electric field, one of the substrates becomes free from the layer of surface active cations, therefore, setting the planar surface anchoring. The latter, in turn, leads to the formation of the hybrid chiral structure. The threshold value and dynamic parameters have been estimated for this process as well as the range of control voltages, which do not allow the electrohydrodynamic instabilities. The twisted hybrid director configuration observed in the experiment has been analysed by means of the simulation of polarisation change of light propagating through the cholesteric layer with asymmetric (planar and homeotropic) surface anchoring on the cell substrates.     

Triplet energy studies of thiophene and para-phenylene based oligomers

A series of conjugated materials based on oligomers of the para-phenylene type and oligothiophenes was prepared, and their phosphorescence spectra were recorded at 77 K using a pulsed flash-lamp as a light source and gated detection. The triplet energies of the oligomers were estimated and correlated with their chemical structure. It was found that simple changes in the building block sequence in the thiophene-containing oligomers allowed for tuning the triplet energy from 1.86 to 2.35 eV (530-670 nm). Hypsochromic shifts and little variation of the triplet energy were obtained with increasing length of the pi-system for thiophene end-capped oligomers, contrary to the usual behavior of unsubstituted oligomers. The experimental results were supported with theoretical computations from density functional theory (B3LYP/6-31G*) calculations, which indicated that changes in the geometry and delocalization of the triplet excited state account for the trends in the triplet energy evolution.     

Mechanochemical Approach towards Multi-Functionalized 1,2,3-Triazoles and Anti-Seizure Drug Rufinamide Analogs Using Copper Beads

Highly regiospecific, copper-salt-free and neat conditions have been demonstrated for the 1,3-dipolar azide-alkyne cycloaddition (AAC) reactions under mechanochemical conditions. A group of structurally challenging alkynes and heterocyclic derivatives was efficiently implemented to achieve highly functionalized 1,4-disubstituted-1,2,3-triazoles in good to excellent yield by using the Cu beads without generation of unwanted byproducts. Furthermore, the high-speed ball milling (HSBM) strategy has also been extended to the synthesis of the commercially available pharmaceutical agent, Rufinamide, an antiepileptic drug (AED) and its analogues. The same strategy was also applied for the synthesis of the Cl-derivative of Rufinamide. Analysis of the single crystal XRD data of the triazole was also performed for the final structural confirmation. The Cu beads are easily recoverable from the reaction mixture and used for the further reactions without any special treatment.     

Synthesis and Photoluminescent Properties of 4,5-Diaryl-3-hydroxy- and 3-Methoxypyridine-6-carbonitriles

Russian Journal of Organic Chemistry - 3-Hydroxy-4-(4-methoxyphenyl)-5-phenyl-2,2'-bipyridine-6-carbonitrile was synthesized by the aza-Diels–Alder reaction between...     

Synthesis of 5-Methyl-1,2,4-triazolo[1,5-a]pyrimidin-7(4H)-one in Supercritical Carbon Dioxide

Russian Journal of General Chemistry - 5-Methyl-1,2,4-triazolo[1,5-a]pyrimidin-7(4H)-one, an intermediate product in the synthesis of the antiviral drug Triazid®, was obtained for the first...     

Single-Crystal X-Ray Diffraction Studies in a Series of 5-Pentafluorophenyl-2,2'-bipyridines and Their Fused Analogs

Structure of three 6-aryl-5-pentafluorophenyl-2,2'-bipyridines has been studied by means of single-crystal X-ray diffraction analysis. The effect of some functional fragments on the structural organization of compounds, in particular, donor and acceptor substituents in the aryl moiety, as well as annulated benzene and cyclopentane rings on the molecular structure and crystal packing of pentafluorophenyl-modified 2,2'-bipyridine ligand systems has been analyzed.     

Magnetic-field control of the transmission of a photonic crystal with a liquid-crystal defect

The method of modulation of transmittance of a multilayer photonic crystal with a nematic liquid-crystal defect upon the orientational transition from the homeotropic to the planar state is investigated. The orientation of the director of the nematic is controlled by a magnetic field in the B-effect mode. The method of recurrent relations is used for numerical simulation of transmission spectra of the photonic crystal structure under investigation.     

Synthesis of 1-amino-2,5-di(2-thienyl)benzenes as potential monomers for the preparation of hybrid polythiophene anionic sensors

A convenient method for the synthesis of 1-amino-2,5-di(2-thienyl)benzenes was proposed. The method involves in situ generation of aryne intermediates from 1-halo-2,5-di-(2-thienyl)benzenes in the presence of strong bases followed by reactions of the arynes with polyfunctional primary and secondary amines. The products obtained in 75?C85% yields are promising monomers for the preparation of polythiophene anionic sensors. Polymerization of dibrominated 1-piperidino-2,5-di(2-thienyl)benzene gave the corresponding poly[(bithiophenediyl)(phenylene)].     

Brønsted acidic ionic liquid–catalyzed tandem trimerization of indoles: An efficient approach towards the synthesis of indole 3,3′-trimers under solvent-free conditions

We have observed the role of 1-butane sulfonic acid-3-methylimidazolium tosylate, [BSMIM]OTs, as an organocatalyst for the tandem type trimerization of indoles to synthesize indole 3,3′-trimers under neat conditions. Using this developed protocol synthesis of indole trimers with various substituted indoles, which are biologically important, has been reported. From the control experiments and literature, a possible mechanism has been proposed via the generation of indolinium cation in the presence of the ionic liquid catalyst. The catalyst has been recycled for several times. The significant advantages of our methodology are clean reaction with very short time, no chromatography for purification, commercially available substrates, neat reaction conditions, and in the absence of metal. Using the protocol, the MDM2-p53 inhibitor has been synthesized in gram scale with high yield.