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Tsonko Kolev - One of the best experts on this subject based on the ideXlab platform.
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the crystal structure and optical properties of 1 methyl 4 2 4 hydroxyphenyl ethenyl pyridinium Dihydrogenphosphate new aspects on crystallographic disorder and its effect on polarized solid state ir spectra
Dyes and Pigments, 2008Co-Authors: Tsonko Kolev, Bojidarka B Koleva, Michael Spiteller, Heike Mayerfigge, William S SheldrickAbstract:Abstract The novel, 1-methyl-4-[2-(4-hydroxyphenyl)ethenyl]pyridinium Dihydrogenphosphate salt was synthesized and its structure and properties elucidated spectroscopically, thermally and structurally, using single crystal X-ray diffraction, linear-polarized solid-state IR spectroscopy (IR-LD), UV–vis spectroscopy, TGA, DSC, DTA and MS. The compound crystallizes in the monoclinic P21/c space group and exhibits a pseudo layer structure with molecules linked by strong OH⋯O–P intermolecular hydrogen bonds of length 2.593 A. The Dihydrogenphosphate anions themselves form infinite chains through strong OH⋯O–P intermolecular hydrogen bonds of lengths 2.636 and 2.658 A. The crystallographic disorder of these systems and its effect on IR-LD spectra in the solid state are discussed. Solutions of different polarity show a significant CT band shift of up to 70 nm, corresponding to a molecular first hyperpolarizability value.
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Synthesis, spectroscopic and structural elucidation of sympathomimetic amine, tyraminium Dihydrogenphosphate
Amino Acids, 2008Co-Authors: Tsonko Kolev, Bojidarka B Koleva, Michael Spiteller, William S Sheldrick, Heike Mayer-figgeAbstract:The synthesis, isolation, spectroscopic and structural elucidation of sympathomimetic amine, tyramine Dihydrogenphosphate are of interest due to its biological activity and the establishing correlation between spectroscopic properties and structure. The complex approach for investigation included single crystal X-ray diffraction, new technique in linear-polarized IR-spectroscopy in solid state and quantum chemical calculations with a view to predict the electronic structure and vibrational data of interacting species in entitled compound, the correlation structure–spectroscopic properties as well as the influence of intermolecular interaction on IR-characteristic bands are carried out.
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Solid-state IR-LD spectroscopy of codeine and N-norcodeine derivatives
Central European Journal of Chemistry, 2006Co-Authors: Rumyana Bakalska, Bojidarka Ivanova, Tsonko KolevAbstract:Linear-dichroic infrared spectra (IR-LD) of 3-ethoxy-4-(N-norcodeino-)cyclobutene-1,2-dione (1) and codeine Dihydrogenphosphate (Codeinum phosphoricum) ( 2 ), oriented as solid suspensions in nematic liquid crystals, have been measured. IR characteristic band assignments were made, and used in stereo-structural predictions. The results were compared with crystallographic structures of similar organic systems, and found to be in good agreement.
William S Sheldrick - One of the best experts on this subject based on the ideXlab platform.
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the crystal structure and optical properties of 1 methyl 4 2 4 hydroxyphenyl ethenyl pyridinium Dihydrogenphosphate new aspects on crystallographic disorder and its effect on polarized solid state ir spectra
Dyes and Pigments, 2008Co-Authors: Tsonko Kolev, Bojidarka B Koleva, Michael Spiteller, Heike Mayerfigge, William S SheldrickAbstract:Abstract The novel, 1-methyl-4-[2-(4-hydroxyphenyl)ethenyl]pyridinium Dihydrogenphosphate salt was synthesized and its structure and properties elucidated spectroscopically, thermally and structurally, using single crystal X-ray diffraction, linear-polarized solid-state IR spectroscopy (IR-LD), UV–vis spectroscopy, TGA, DSC, DTA and MS. The compound crystallizes in the monoclinic P21/c space group and exhibits a pseudo layer structure with molecules linked by strong OH⋯O–P intermolecular hydrogen bonds of length 2.593 A. The Dihydrogenphosphate anions themselves form infinite chains through strong OH⋯O–P intermolecular hydrogen bonds of lengths 2.636 and 2.658 A. The crystallographic disorder of these systems and its effect on IR-LD spectra in the solid state are discussed. Solutions of different polarity show a significant CT band shift of up to 70 nm, corresponding to a molecular first hyperpolarizability value.
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Synthesis, spectroscopic and structural elucidation of sympathomimetic amine, tyraminium Dihydrogenphosphate
Amino Acids, 2008Co-Authors: Tsonko Kolev, Bojidarka B Koleva, Michael Spiteller, William S Sheldrick, Heike Mayer-figgeAbstract:The synthesis, isolation, spectroscopic and structural elucidation of sympathomimetic amine, tyramine Dihydrogenphosphate are of interest due to its biological activity and the establishing correlation between spectroscopic properties and structure. The complex approach for investigation included single crystal X-ray diffraction, new technique in linear-polarized IR-spectroscopy in solid state and quantum chemical calculations with a view to predict the electronic structure and vibrational data of interacting species in entitled compound, the correlation structure–spectroscopic properties as well as the influence of intermolecular interaction on IR-characteristic bands are carried out.
A P M Kentgens - One of the best experts on this subject based on the ideXlab platform.
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structure of tetrakis melaminium bis Dihydrogenphosphate monohydrogenphosphate trihydrate from x ray powder diffraction and solid state nmr spectroscopy
Journal of Physical Chemistry C, 2008Co-Authors: V Brodski, Rene Peschar, H Schenk, Andreas Brinkmann, A P M KentgensAbstract:The crystal structure of the melamine phosphate salt tetrakis(melaminium) bis(Dihydrogenphosphate) monohydrogenphosphate trihydrate with as much as ten independent moieties in the unit cell was determined by a direct-space global optimization technique from X-ray powder diffraction data using additional geometry constraints obtained by 31P double-quantum solid-state NMR spectroscopy. The structure analysis of the compound and its comparison with other melamine phosphates reveals the packing and bonding characteristics that are important for melamine-phosphate salts with a melamine-to-phosphor ratio larger than one, which are promising environmental-friendly flame retardants.
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structure of melaminium dihydrogenpyrophosphate and its formation from melaminium Dihydrogenphosphate studied with powder diffraction data solid state nmr and theoretical calculations
Journal of Physical Chemistry B, 2004Co-Authors: V Brodski, Rene Peschar, H Schenk, Andreas Brinkmann, A P M Kentgens, B Coussens, A BraamAbstract:Melaminium dihydrogenpyrophosphate (bis(2,4,6-triamino-1,3,5-triazinium dihydrogenpyrophosphate, MPy), obtained as a crystalline powder by thermal treatment of melaminium Dihydrogenphosphate (MP), is the first intermediate in the synthesis of polymerized melamine phosphates that are used as environmental-friendly flame retardants. The crystal structure of MPy was determined by X-ray powder diffraction and the proposed hydrogen-bonding model was corroborated by solid-state NMR and periodic DFT calculations. A mechanism is proposed for the endothermic dehydration process that takes place in the reaction from MP to MPy, in accordance with energy calculations based on the optimized crystal structures of MPy and MP. A packing analysis of MPy and other melamine-containing compounds revealed some typical melamine packing motifs.
V Brodski - One of the best experts on this subject based on the ideXlab platform.
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structure of tetrakis melaminium bis Dihydrogenphosphate monohydrogenphosphate trihydrate from x ray powder diffraction and solid state nmr spectroscopy
Journal of Physical Chemistry C, 2008Co-Authors: V Brodski, Rene Peschar, H Schenk, Andreas Brinkmann, A P M KentgensAbstract:The crystal structure of the melamine phosphate salt tetrakis(melaminium) bis(Dihydrogenphosphate) monohydrogenphosphate trihydrate with as much as ten independent moieties in the unit cell was determined by a direct-space global optimization technique from X-ray powder diffraction data using additional geometry constraints obtained by 31P double-quantum solid-state NMR spectroscopy. The structure analysis of the compound and its comparison with other melamine phosphates reveals the packing and bonding characteristics that are important for melamine-phosphate salts with a melamine-to-phosphor ratio larger than one, which are promising environmental-friendly flame retardants.
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structure of melaminium dihydrogenpyrophosphate and its formation from melaminium Dihydrogenphosphate studied with powder diffraction data solid state nmr and theoretical calculations
Journal of Physical Chemistry B, 2004Co-Authors: V Brodski, Rene Peschar, H Schenk, Andreas Brinkmann, A P M Kentgens, B Coussens, A BraamAbstract:Melaminium dihydrogenpyrophosphate (bis(2,4,6-triamino-1,3,5-triazinium dihydrogenpyrophosphate, MPy), obtained as a crystalline powder by thermal treatment of melaminium Dihydrogenphosphate (MP), is the first intermediate in the synthesis of polymerized melamine phosphates that are used as environmental-friendly flame retardants. The crystal structure of MPy was determined by X-ray powder diffraction and the proposed hydrogen-bonding model was corroborated by solid-state NMR and periodic DFT calculations. A mechanism is proposed for the endothermic dehydration process that takes place in the reaction from MP to MPy, in accordance with energy calculations based on the optimized crystal structures of MPy and MP. A packing analysis of MPy and other melamine-containing compounds revealed some typical melamine packing motifs.
V Ramakrishnan - One of the best experts on this subject based on the ideXlab platform.
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raman and ir spectral studies ofl phenylalaninel phenylalaninium Dihydrogenphosphate anddl phenylalaninium Dihydrogenphosphate
Journal of Raman Spectroscopy, 2006Co-Authors: B Ravikumar, R K Rajaram, V RamakrishnanAbstract:The infrared (IR) and Raman spectra were recorded at room temperature for L-phenylalanine, L-phenylalaninium Dihydrogenphosphate, and DL-phenylalaninium Dihydrogenphosphate, and the observed bands were assigned. In the first compound, a phenylalaninium cation and a zwitterionic L-phenylalanine and in the latter compound two protonated DL-phenylalaninium cations have been identified. Presence of NH···O and OH···O hydrogen bonds are revealed from the spectra. The symmetry of the Dihydrogenphosphate anion is found to be retaining C2v symmetry in both crystals. Copyright © 2006 John Wiley & Sons, Ltd.
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raman and infrared spectral studies of dl threoninium Dihydrogenphosphate
Journal of Raman Spectroscopy, 2004Co-Authors: B Ravikumar, R K Rajaram, S Ramaswamy, Mohamed Ali M Jinnah, V RamakrishnanAbstract:Infrared and Raman spectra of DL-threoninium Dihydrogenphosphate crystal were recorded at room temperature and vibrational assignments of the observed wavenumbers were made. The extensive intermolecular hydrogen bonding in the crystal was identified by the shifting of bands due to the stretching and bending modes of the various functional groups. The Td symmetry of the phosphate anion is reduced to the lower symmetry C2v owing to the intermolecular hydrogen bonding and coordination. The splitting of degenerate modes and the appearance of infrared-inactive modes indicate the effect of the crystalline field on molecular vibrations. Copyright © 2004 John Wiley & Sons, Ltd.