New hydrophobic L‐amino acid salts: maleates of L‐leucine,L‐isoleucine and L‐norvaline

Crystals of maleates of three amino acids with hydrophobic side chains [L‐leucenium hydrogen maleate, C₆H₁₄NO₂⁺·C₄H₃O₄⁻, (I), L‐isoleucenium hydrogen maleate hemihydrate, C₆H₁₄NO₂⁺·C₄H₃O₄⁻·0.5H₂O, (II), and L‐norvalinium hydrogen maleate–L‐norvaline (1/1), C₅H₁₁NO₂⁺·C₄H₃O₄⁻·C₅H₁₂NO₂, (III)], were obtained. The new structures contain C₂²(12) chains, or variants thereof, that are a common feature in the crystal structures of amino acid maleates. The L‐leucenium salt is remarkable due to a large number of symmetrically non‐equivalent units (Z′ = 3). The L‐isoleucenium salt is a hydrate despite the fact that L‐isoleucine is a nonpolar hydrophobic amino acid (previously known amino acid maleates formed hydrates only with lysine and histidine, which are polar and hydrophilic). The L‐norvalinium salt provides the first example where the dimeric cation L‐Nva...L‐NvaH⁺ was observed. All three compounds have layered noncentrosymmetric structures. Preliminary tests have shown the presence of the second harmonic generation (SGH) effect for all three compounds.     

Variability of Monomolecular Adsorption of Lignosulfonate Systems

Russian Journal of General Chemistry - Specific features of lignosulfonate systems FCLC and FCLC-2M, as well as of the raw materials for the preparation of these modified forms, the lignosulfonates...     

Synthesis and study of interconversions of new indoline spiropyrans based on 4-hydroxy-3,5-diformylbenzoic acid

The synthesis of new indoline spiropyran by the cyclocondensation in methanol revealed that the free aldehyde group of the target spiropyran is easily converted into the dimethyl acetal moiety without the addition of an acid catalyst, giving 8′-dimethoxymethyl-1,3,3-trimethylspiro[indoline-2,2′-2H-chromene]-5,6′-dicarboxylic acid as a single reaction product. The structure of this compound was confirmed by NMR spectroscopy and mass spectrometry. The molecular structure was also established by single-crystal X-ray diffraction. The Hirshfeld surfaces were generated and analyzed and intermolecular interactions in the crystal were investigated using the CrystalExplorer software package. The reverse hydrolysis reaction of dimethyl acetal to the aldehyde group proceeds under mild conditions in dimethyl sulfoxide, as shown by NMR spectroscopy.

     

Measurement of the Cross Section for the Process $${e^{+}e^{-}}{\to}{K}^{{+}}{K}^{{-}}{\pi}^{{0}}$$ with the SND Detector at Collision Energies of $$\sqrt{{s}}{=}{1.3{-}2.0}$$ GeV in the Center-of-Mass Frame

Physics of Atomic Nuclei - In an experiment with the SND detector at the VEPP-2000 $$e^{+}e^{-}$$ collider, the cross sections for the processes $$e^{+}e^{-}\to K^{+}K^{-}\pi^{0}$$ and...     

Study of the Process $${e}^{{+}}{e}^{{-}}{\to}{\eta\pi}^{{0}}{\gamma}$$ in the Cossision-Energy Range of $$\sqrt{{s}}{=}{1.05{-}2.00}$$ GeV

Physics of Atomic Nuclei - The process $$e^{+}e^{-}\to\eta\pi^{0}\gamma$$ is studied in the range of center-of-mass (c.m.) collision energies between 1.05 and 2.00 GeV on the basis of data...     

Synthesis of 5,10,15,20-tetra[6' -nitro-1,3,3-trimethylspiro- (indolino-2,2' -2H-chromen-5-yl)]porphyrin and its metal complexes

A new 5,10,15,20-tetrasubstituted porphyrin containing four 6’-nitro-1,3,3-trimethylspiro(indolino-2,2’-2H-chromene) substituents and its complexes with Zn²⁺ and Cu²⁺ ions were prepared and characterized by physicochemical methods of analysis.     

New indoline spiropyrans with highly stable merocyanine forms

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Chemistry of pyridoxine in drug design

Russian Chemical Bulletin - Pyridoxine and its derivatives, pyridoxamine and pyridoxal, are the three main forms of vitamin B6, which play exceptionally important biological roles in living...