Two polymorphs of afobazole from powder diffraction data

Afobazole {systematic name: 2‐[2‐(morpholin‐4‐yl)ethylsulfanyl]‐1H‐benzimidazole} is a new anxiolytic drug and Actins, Auzins & Petkune [(2012). Eur. Patent EP10163962] described four polymorphic modifications. In the present study, the crystal structures of two monoclinic polymorphs, 5‐ethoxy‐2‐[2‐(morpholin‐4‐ium‐4‐yl)ethylsulfanyl]‐1H‐benzimidazol‐3‐ium dichloride, C₁₅H₂₃N₃O₂S²⁺·2Cl⁻, (II) and (IV), have been established from laboratory powder diffraction data. The crystal packing and conformation of the dications in (II) and (IV) are different. In (II), there are channels in the [001] direction, which offer atmospheric water molecules an easy way of penetrating into the crystal structure, thus explaining the higher hygroscopicity of (II) compared with (IV).     

Plasmon-assisted click chemistry at low temperature: an inverse temperature effect on the reaction rate

Plasmon assistance promotes a range of chemical transformations by decreasing their activation energies. In a common case, thermal and plasmon assistance work synergistically: higher temperature results in higher plasmon-enhanced catalysis efficiency. Herein, we report an unexpected tenfold increase in the reaction efficiency of surface plasmon-assisted Huisgen dipolar azide–alkyne cycloaddition (AAC) when the reaction mixture is cooled from room temperature to −35 °C. We attribute the observed increase in the reaction efficiency to complete plasmon-induced annihilation of the reaction barrier, prolongation of plasmon lifetime, and decreased relaxation of plasmon-excited-states under cooling. Furthermore, control quenching experiments supported by theoretical calculations indicate that plasmon-mediated substrate excitation to an electronic triplet state may play the key role in plasmon-assisted chemical transformation. Last but not least, we demonstrated the possible applicability of plasmon assistance to biological systems by AAC coupling of biotin to gold nanoparticles performed at −35 °C.

The decrease of reaction temperature can potentially lead to an increase of plasmon-assisted catalytic efficiency.     

Alkylation of the 2-hydroxypyridine anion in ionic liquid media

The alkylation reaction of the ambident 2-hydroxypyridine anion was examined in ionic liquid media. Ionic liquids increase the alkylation reaction rate in comparison with molecular liquids, as well as the level of impact on the reaction rates of the counter ion and/or additives, and the distribution of isomers of the reaction products in trans-formations of the ambident 2-hydroxypyridine anion. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 699–710, May, 2008.     

The Crystal and Molecular Structure of a Polymorph and a Pseudo-Polymorph of Droperidol

Abstract Crystals of two crystal modifications of droperidol: a hemihydrate (1) and the z polymorph (2), have been isolated and their structure determined using X-ray diffraction methods. Droperidol hemihydrate crystallized in the triclinic space group P − 1, with unit cell parameters a = 6.2842(15), b = 10.1473(8), c = 16.1850(2) ?; α = 102.554(9); β = 91.917(14); γ = 99.316(12)°; V = 991.6(3) ?³, and Z = 2. The droperidol z polymorph crystallized in the monoclinic space group P2₁/c, with unit cell parameters a = 20.0406(8), b = 7.4955(4), c = 12.9733(5) ?; β = 98.089(2)°; V = 1929.39(15) ?³, and Z = 4. In 1 and 2 two molecules of droperidol are joined by two N–H···O hydrogen bonds. The structure of 1 shows a possible additional hydrogen bond linking the two droperidol molecules via the water molecule. Graphical Abstract The crystal and molecular structure of a polymorph and a pseudo-polymorph of droperidol A. Actins, R. Arajs, S. Belakovs, L. Orola, and M. V. Veidis Crystals of two crystal modifications of droperidol: a hemihydrate and the z polymorph have been isolated and their structure determined using single crystal X-ray diffraction methods. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Structural Changes in Lymphocytes Membrane of Chernobyl Clean-up Workers from Latvia

ABM (3-aminobenzanthrrone derivative) developed at the Riga Technical University, Riga, Latvia) has been previously shown as a potential probe for determination of the immune state of patients with different pathologies .The fist study (using probe ABM) of peripheral blood mononuclear cells (PBMC) membranes of 97 Chernobyl clean-up workers from Latvia was conducted in 1997. Now we repeatedly examine the same (n = 54) individuals in dynamics. ABM spectral parameters in PBMC suspension, fluorescence anisotropy and blood plasma albumin characteristics were recorded. In 1997 screening showed 5 different patterns of fluorescence spectra, from which in 2007 we obtained only two. These patterns of spectra had never been previously seen in healthy individuals or patients with tuberculosis, multiple sclerosis, rheumatoid arthritis, etc., examined by us. Patterns of ABM fluorescence spectra are associated with membrane anisotropy and conformational changes of blood plasma albumin. We observed that in dynamics 1997–2007 the lipid compartment of the membrane became more fluid while the lipid-protein interface became more rigid. The use of probe ANS and albumin auto-fluorescence allowed show conformational alterations in Chernobyl clean-up workers blood plasma. It is necessary to note that all investigated parameters significantly differ in observed groups of patients. These findings reinforce our understanding that that the cell membrane is a significant biological target of radiation. The role of the membrane in the expression and course of cell damage after radiation exposure must be considered. So ten years dynamic of PBMC membrane characteristics by ABM (spectral shift and anisotropy indexes) in Chernobyl clean-up workers reveal progressive trend toward certain resemblance with those of chronic B-cell lymphoid leukemia.     

Dissipation in turbulent plasma due to reconnection in thin current sheets

We present in situ measurements in a space plasma showing that thin current sheets the size of an ion inertial length exist and are abundant in strong and intermittent plasma turbulence. Many of these current sheets exhibit the microphysical signatures of reconnection. The spatial scale where intermittency occurs corresponds to the observed structures. The reconnecting current sheets represent a type of dissipation mechanism, with observed dissipation rates comparable to or even dominating over collisionless damping rates of waves at ion inertial length scales (x100), and can have far reaching implications for small-scale dissipation in all turbulent plasmas.     

Alkylation of ambident indole anion in ionic liquids

Alkylation of indole salts in different ionic liquids is reported. Ionic liquids increase the alkylation reaction rate of ambident indole anion and reduce the effects of counter ions and/or additives, the alkylation reaction rates being independent of the presence of small amounts of protic solvents or water.      

Positive and negative electrospray ionization-collision-induced dissociation of sulfur- containing zwitterionic liquids

The mass spectrometric properties of several (1,2-dimethyl-1H-imidazol-3-ium-3-yl)-alkane-1-sulfonates (alkane=ethyl, propyl and butyl) are investigated in this study. These substances, named zwitterionic liquids (ZILs), were synthesized using classical transformations and analyzed in positive and negative electrospray ionization mode using collision-induced dissociation (0-50 eV). We have also performed regioselective deuterium labeling of the alkyl chain of 3-(1,2-dimethyl-1H-imidazol-3-ium-3-yl)-propane-1-sulfonates. Thus, the mass spectra of isotopically-labeled compounds were used for the confirmation of fragmentation pathways of ZILs. Briefly, the data obtained in this study show that the fragmentation of ZILs is dependent on the alkyl chain length between the imidazolium ring and the sulfonate group. In positive electrospray mode, the main fragments are the imidazolium ring containing even electron ions. On the other hand, in negative electrospray mode, sulfur-containing radical-anions are dominant.     

Electrical impedance spectroscopy of ionic liquid 1-ethyl-3-methylimidazolium methanesulfonate (ECOENG™ 110)

Ionic liquid “ECOENG? 110”, a promising electrolyte for electrochemical devices, was investigated by impedance spectroscopy. Metallic electrodes (Pt, Cu, Ag, and Mo) as well as carbon were used for the electrochemical characterization. The dependences of the real and imaginary impedance, polarization resistance and electrochemical capacity of the double layer on the electrode potential were investigated using electrical equivalent circuits of R₁(QR₂) and R₁[Q(R₂W)] types.