α-Trifluoromethyl-β-aryl enamines in the synthesis of trifluoromethylated heterocycles by the Fischer and the Pictet-Spengler reactions

α-Trifluoromethyl-β-aryl enamines were successfully used as synthetic equivalents of benzyltrifluoromethyl ketones in both the Fischer indole synthesis and the Pictet-Spengler reaction. Accordingly, 2-trifluoromethyl indoles and a variety of trifluoromethylated 4,5,6,7-terahydro-1H-pyridines including carbolines were synthesized in moderate to good yields.     

Dynamic reference electrode for investigation of fluoride melts containing beryllium difluoride

Existing designs of reference electrodes for potentiometric measurements in fluoride melts do not meet basic requirements of the long exposure corrosion tests to be performed. A new diaphragm-free three-electrode meter with a nonstationary (dynamic) beryllium reference electrode for the redox potential measurements was developed. Optimum conditions of forming dynamic beryllium reference electrode were determined in the laboratory tests in isothermal cell. The device for redox potential measurement was designed and it was shown that it is highly sensitive to changes redox potential within ±5 mV. Reliability and efficiency of diaphragm-free device with dynamic reference electrode was confirmed in the thermal convection corrosion loop operating more than 1200 h with molten 15LiF-58NaF-27BeF₂ mixture (mol%) at a maximum temperature of about 700 °C.     

Stored light in a plasmonic nanocavity based on extremely-small-energy-velocity modes

We propose a novel scheme of the plasmonic cavity that is based on the insulator–metal–insulator (IMI) waveguide of finite length. Surface plasmon polaritons (SPPs) guided by the IMI structure can exhibit extremely small energy velocity if the metal film is thin enough. In that case, the losses are determined mainly by the intrinsic properties of the metal rather than the geometry of the cavity. Accordingly, we should care only about the purity of the metal and need not accurately control the length of the cavity that simplifies the fabrication process. All dimensions of the cavity can be less than the wavelength of light, therefore it is a really nanoscale device. In this paper, we characterize the cavity analytically and demonstrate the stored light using our finite difference time domain (FDTD) code.     

Förster resonance energy transfer in hybrid associates of colloidal Ag<Subscript>2</Subscript>S quantum dots with thionine molecules

Nonradiative resonance energy transfer in hydrophilic hybrid associates of thionine molecules (TH⁺) with colloidal Ag₂S quantum dots (QDs) with average diameter of 3.5 nm was studied. Photoluminescence spectra and its decay shown that for these systems the supplemental photosensitization of recombination luminescence of Ag₂S QDs (1200 nm) from the region of TH⁺ fluorescence (618 nm) is possible. It was found that the average lifetime of TH⁺ molecules luminescence is shortened during their association with Ag₂S QDs. Approximation of luminescence decay by stretched exponent with value of parameter β =?0.5 indicates on the inductive-resonance dipole-dipole (Förster) mechanism of nonradiative energy transfer (FRET). The efficiency of FRET was 0.29–0.41.     

Georgiĭ Borisovich Bokiĭ (On the occasion of his 100th birthday)

Memorial Data

Georgiĭ Borisovich Bokiĭ (On the occasion of his 100th birthday)     

Novel Green Procedure for the Synthesis of 2-Arylbenzothiazoles Under Microwave Irradiation in Peg 200 Or Peg 400

An improved green procedure for the synthesis of 2-aryl- and 2-hetarylbenzothiazoles by condensation of equivalent amounts of 2,2′-diaminodiphenyldisulfides or 2-aminothiophenols and various aromatic aldehydes in PEG 200/400 under microwave irradiation has been developed. This method allows the synthesis of 2-arylbenzothiazoles in high yields and with high purity regardless of the state of the starting compounds (liquid or solid) or the nature of the substituents in the aromatic ring.     

Efficient synthesis and structure peculiarity of macrocycles with bi-indolizinylquinoxalinone moieties

Monoindolizinylquinoxalinepodands, easily available from indolizinylquinoxalines and various dihalides, undergo smooth oxidative dimerization in the presence of molecular iodine to afford corresponding macrocycles in good yields in a short reaction time. The use of inexpensive and readily available molecular iodine makes this method quite simple, more convenient, and practical. In solution the title macrocycles exist in an equilibrium of several conformations arising from restricted rotation around the Ind–Qx bonds (ca. C₂ symmetrical and nonsymmetrical forms). The population of the forms and exchange rate between them depends strongly on the spacer type (length).     

Design and Synthesis of a New Family of Fluorinated Liquid Crystals

A convenient and simple three‐step pathway to the new family of CF₂CF₂S‐bridged alkanes and CF₂S‐, CF₂O‐bridged alkenes and alkynes was elaborated by using catalytic olefination reaction as a key step of the synthetic sequence. The obtained compounds revealed attractive liquid crystalline characteristics.     

Conformational analysis of polymethine dyes derived from the 2-azaazulene

A systematic investigation of the conformational structure was performed for the series of symmetrical and unsymmetrical mono-, tri-, pentamethine cyanines, and styryl dyes bearing 2-azaazulenium terminal group. The rotation energy barriers of terminal groups were determined via the dynamic variable temperature NMR experiments. The conformational transformation energy was calculated by quantum chemical methods (B3LYP and M05-2X) both for the cases of considering the solvent influence and not tacking it into account. Based on the comparison of theoretical and experimental data, relative electron-donating abilities and geometrical features of the heterocyclic terminal groups in 2-azaazulenium dyes were estimated. The arrangement of certain heterocyclic nuclei in order of basicity by considering the results of the dynamic NMR investigations was proposed. Influence of the conjugated chain length and the solvent nature on the conformational lability of the investigated dye molecules was discussed.