We argue that the crystal “bis-glycine maleate”, reported by D. Balasubramanian et al., J. Cryst. Growth 312 (2010) 1855–1859, actually is glycinium hydrogen maleate previously reported by K. ...Rajagopal et al., Acta Crystallogr. E57 (2001) o751–o753.
► We investigated the existence of phases in the system glycine+maleic acid+H2O. ► We came to conclusion that only glycinium hydrogen maleate is formed in this system. ► We showed that “bis-glycine maleate” actually is previously known glycinium hydrogen maleate.
Shallow water magnetohydrodynamic (MHD) theory describing incompressible flows of plasma is generalized to the case of compressible flows. A system of MHD equations is obtained that describes the ...flow of a thin layer of compressible rotating plasma in a gravitational field in the shallow water approximation. The system of quasilinear hyperbolic equations obtained admits a complete simple wave analysis and a solution to the initial discontinuity decay problem in the simplest version of nonrotating flows. In the new equations, sound waves are filtered out, and the dependence of density on pressure on large scales is taken into account that describes static compressibility phenomena. In the equations obtained, the mass conservation law is formulated for a variable that nontrivially depends on the shape of the lower boundary, the characteristic vertical scale of the flow, and the scale of heights at which the variation of density becomes significant. A simple wave theory is developed for the system of equations obtained. All self-similar discontinuous solutions and all continuous centered self-similar solutions of the system are obtained. The initial discontinuity decay problem is solved explicitly for compressible MHD equations in the shallow water approximation. It is shown that there exist five different configurations that provide a solution to the initial discontinuity decay problem. For each configuration, conditions are found that are necessary and sufficient for its implementation. Differences between incompressible and compressible cases are analyzed. In spite of the formal similarity between the solutions in the classical case of MHD flows of an incompressible and compressible fluids, the nonlinear dynamics described by the solutions are essentially different due to the difference in the expressions for the squared propagation velocity of weak perturbations. In addition, the solutions obtained describe new physical phenomena related to the dependence of the height of the free boundary on the density of the fluid. Self-similar continuous and discontinuous solutions are obtained for a system on a slope, and a solution is found to the initial discontinuity decay problem in this case.
It is shown that the title paper reported by M.M. Wezhli et al. (Optik 127 (2016) 4258–4260) is completely erroneous. The so-called “glycine oxalate dihydrate” crystal is not a new crystal but ...instead is the well-known anhydrous glycinium hydrogen oxalate crystal.
Mixed salts of amino acids with different anions are of considerable interest from chemical and structural points of view and also as a source of new materials the properties of which can be ...controlled by appropriate choice of anions. Four such crystals, L-His2+·Cl−·HSO4− (P212121, Z=4), L-Arg2+·NO3−·ClO4− (δ-form, P21, Z=4), L-Arg2+·F−·NO3− (P1, Z=2), 2L-Arg2+·(F−⋯HF)·3NO3− (P212121, Z=4), have been characterized structurally and by IR and Raman spectra. The hydrogen bond between the carboxyl group and the fluoride ion (2.371(3)Å) in the structure of L-Arg2+·F−·NO3− is among the shortest known O–H⋯F type hydrogen bonds. The O–H⋯F hydrogen bond in the structure of 2L-Arg2+·(F−⋯HF)·3NO3− is even shorter (2.341(2)Å) and thus belongs to the shortest contacts among both Ο–Η⋯F and F–H⋯O types hydrogen bonds.
► Four crystalline amino acid salts with different anions have been obtained. ► Molecular and crystal structures were determined by XRD and vibrational spectroscopy. ► Very short O⋯F type H-bonds were found, two shorter than any previously known.
The crystal of diglycine picrate (glycine glycinum picrate) has been obtained from an aqueous solution containing stoichiometric quantities of the components. The species crystallizes in the ...monoclinic system (space group
P2
1/
c). The crystal structure was determined with high accuracy, IR and Raman spectra are discussed and compared with previous results, and the molecular structure is presented. It was shown that crystals of diglycine picrate obtained from the solution containing equimolar quantities may contain picric acid as impurity, which is the reason for the previously reported observation of second harmonic generation in this centrosymmetric crystal. With this example we want to point out the risk of misinterpretation of SHG signals in general.
In the present work crystal structures of (L-ArgH2)(BF4)2 (I) and (L-ArgH2)(ClO4)2 (II) isostructural salts have been determined. They crystallize in triclinic system with space group P1 and Z = 1. ...Structure features of the (I) and (II) were compared with respective data of previously known (L-ArgH)(BF4) and (L-ArgH)(ClO4) salts with singly charged L-argininium(+) cation. Infrared and Raman spectra of the (I) and (II) are compared with spectra of (L-ArgH)(BF4) and (L-ArgH)(ClO4) salts. The presence of cation and anions and hydrogen bonds between them are reflected in the IR and Raman spectra. The crystals (I) and (II) exhibit second harmonic generation activity.
The structure and hydrogen bonds of (L-ArgH2)(BF4)2 Display omitted
•Crystal structure of L-argininium(2+) bis(tetrafluoroborate) has been determined.•Crystal structure of L-argininium(2+) bis(perchlorate) has been determined.•Infrared and Raman spectra of the obtained crystals are registered and discussed.
► A new member of the family of salts of amino acids with dimeric cation is presented. ► The O⋯O distance in the dimeric cation is longest among salts with l-alanine l-alaninium cation. ► The ...presence of dimeric cation is reflected in the Infrared spectrum.
Preparation, crystal and molecular structure as well as vibrational spectra of the crystal l-alanine l-alaninium picrate monohydrate are described. The title crystal is monoclinic, space group P21. The asymmetric unit contains one dimeric (l-Ala⋯l-Ala+) cation, one picrate anion and a water molecule. The O⋯O distance in the dimeric cation is equal to 2.553(2)Å. The IR and Raman spectra are interpreted based on the structure.
•New L-prolinium phosphite crystal was grown.•Crystal structure was determined.•The crystal is characterized by vibrational spectral, thermal, NLO properties.
Single crystal of L-prolinium phosphite ...was grown by evaporation method from aqueous solution. It crystallizes in the orthorhombic system (space group P212121, Z=4). The asymmetric unit contains one L-prolinium cation and one phosphite (HPO2(OH))− anion. The phosphite anions form a chain by hydrogen bond OH…O with O…O distance 2.5601(15)Å parallel 010. The L-prolinium cations bridge two chains of anions by OH…O and NH…O hydrogen bonds with O…O and N…O distances 2.505(2)Å and 2.718(2)Å respectively. The infrared and Raman spectra are registered and discussed. Thermal behavior was studied. Phase-matched SHG was observed.
l-Tryptophan l-tryptophanium chloride Ghazaryan, V.V.; Fleck, M.; Petrosyan, A.M.
Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy,
02/2015, Letnik:
136
Journal Article
Recenzirano
Display omitted
•Single crystal of 2l-Trp·HCl was obtained for the first time.•Crystal and molecular structure of 2l-Trp·HCl has been determined.•The existence of dimeric (l-Trp⋯l-TrpH) cation is ...established.•IR and Raman spectra of 2l-Trp·HCl were studied and compared with spectra of previously known l-Trp·HCl.
l-Tryptophan l-tryptophanium chloride is a new salt with (A⋯A+) type dimeric cation. It crystallizes in the monoclinic system (space group P21, Z=2). The asymmetric unit contains one zwitterionic l-tryptophan molecule, one l-tryptophanium cation and one chloride anion. The dimeric cation is formed by a OH⋯O hydrogen bond with the O⋯O distance equal to 2.5556(18)Å. The infrared and Raman spectra of the crystal are studied and compared with the spectra of l-tryptophanium chloride.
Single crystals of LuAG:Ce co-doped with Ca2+ were grown by the vertical Bridgman method and studied for optical properties, γ-irradiation induced absorption, scintillation light yield and decay. It ...is shown that addition of Ca2+ may efficiently limit the radiation induced absorption associated with presence of trace amounts of Yb. In bulk crystals with balanced Ca2+/Ce concentration the absorption induced in the emission range around 520nm is less than 1m−1, after the dose 1kGy and 860Gy/h dose rate. The light yield of LuAG:Ce upon co-doping with Ca2+ is preserved, while the fraction of the delayed recombination leading to slow scintillation components is decreased. The effects of Ca2+ were not favorable in Pr-doped LuAG studied so far. The absorption induced in the emission range around 300–400nm range in the Ca-free LuAG:Pr, after the irradiation dose 1kGy, is about 35m−1, while it is above 100m−1 in the Ca co-doped LuAG:Pr.
•Single crystals of LuAG:Ce(Pr) co-doped with divalent Ca.•Charge compensation mechanisms and competition between traps.•The magnitude of slow decay components is decreased.•Compositions showing improved radiation hardness.
