The Experts below are selected from a list of 13257 Experts worldwide ranked by ideXlab platform
Wolfgang Schnick - One of the best experts on this subject based on the ideXlab platform.
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unmasking melon by a complementary approach employing electron diffraction solid state nmr spectroscopy and theoretical calculations structural characterization of a carbon nitride polymer
Chemistry: A European Journal, 2007Co-Authors: Bettina V Lotsch, Markus Doblinger, Jan Sehnert, Lena Seyfarth, Jurgen Senker, Oliver Oeckler, Wolfgang SchnickAbstract:Poly(aminoimino)heptazine, otherwise known as Liebig's melon, whose composition and structure has been subject to multitudinous speculations, was synthesized from melamine at 630 °C under the pressure of ammonia. Electron diffraction, solid-state NMR spectroscopy, and theoretical calculations revealed that the Nanocrystalline Material exhibits domains well-ordered in two dimensions, thereby allowing the structure solution in projection by electron diffraction. Melon ([C6N7(NH2)(NH)]n, plane group p2 gg, a=16.7, b=12.4 A, γ=90°, Z=4), is composed of layers made up from infinite 1D chains of NH-bridged melem (C6N7(NH2)3) monomers. The strands adopt a zigzag-type geometry and are tightly linked by hydrogen bonds to give a 2D planar array. The inter-layer distance was determined to be 3.2 A from X-ray powder diffraction. The presence of heptazine building blocks, as well as NH and NH2 groups was confirmed by 13C and 15N solid-state NMR spectroscopy using 15N-labeled melon. The degree of condensation of the heptazine core was further substantiated by a 15N direct excitation measurement. Magnetization exchange observed between all 15N nuclei using a fp-RFDR experiment, together with the CP-MAS data and elemental analysis, suggests that the sample is mainly homogeneous in terms of its basic composition and molecular building blocks. Semiempirical, force field, and DFT/plane wave calculations under periodic boundary conditions corroborate the structure model obtained by electron diffraction. The overall planarity of the layers is confirmed and a good agreement is obtained between the experimental and calculated NMR chemical shift parameters. The polymeric character and thermal stability of melon might render this polymer a pre-stage of g-C3N4 and portend its use as a promising inert Material for a variety of applications in Materials and surface science.
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unmasking melon by a complementary approach employing electron diffraction solid state nmr spectroscopy and theoretical calculations structural characterization of a carbon nitride polymer
Chemistry: A European Journal, 2007Co-Authors: Bettina V Lotsch, Markus Doblinger, Jan Sehnert, Lena Seyfarth, Jurgen Senker, Oliver Oeckler, Wolfgang SchnickAbstract:Poly(aminoimino)heptazine, otherwise known as Liebig's melon, whose composition and structure has been subject to multitudinous speculations, was synthesized from melamine at 630 °C under the pressure of ammonia. Electron diffraction, solid-state NMR spectroscopy, and theoretical calculations revealed that the Nanocrystalline Material exhibits domains well-ordered in two dimensions, thereby allowing the structure solution in projection by electron diffraction. Melon ([C6N7(NH2)(NH)]n, plane group p2 gg, a=16.7, b=12.4 A, γ=90°, Z=4), is composed of layers made up from infinite 1D chains of NH-bridged melem (C6N7(NH2)3) monomers. The strands adopt a zigzag-type geometry and are tightly linked by hydrogen bonds to give a 2D planar array. The inter-layer distance was determined to be 3.2 A from X-ray powder diffraction. The presence of heptazine building blocks, as well as NH and NH2 groups was confirmed by 13C and 15N solid-state NMR spectroscopy using 15N-labeled melon. The degree of condensation of the heptazine core was further substantiated by a 15N direct excitation measurement. Magnetization exchange observed between all 15N nuclei using a fp-RFDR experiment, together with the CP-MAS data and elemental analysis, suggests that the sample is mainly homogeneous in terms of its basic composition and molecular building blocks. Semiempirical, force field, and DFT/plane wave calculations under periodic boundary conditions corroborate the structure model obtained by electron diffraction. The overall planarity of the layers is confirmed and a good agreement is obtained between the experimental and calculated NMR chemical shift parameters. The polymeric character and thermal stability of melon might render this polymer a pre-stage of g-C3N4 and portend its use as a promising inert Material for a variety of applications in Materials and surface science.
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Nanocrystalline lanthanide nitride Materials synthesised by thermal treatment of amido and ammine metallocenes: X-ray studies and DFT calculations.
Chemistry: A European Journal, 2006Co-Authors: Ulrich Baisch, Sandro Pagano, Martin Zeuner, Noémi Barros, Laurent Maron, Wolfgang SchnickAbstract:The decomposition process of ammine lanthanide metallocenes was studied by X-ray diffractometry, spectroscopy and theoretical investigations. A series of ammine-tris(η5-cyclopentadienyl)lanthanide(III) complexes 1-Ln (Lanthanide (Ln)=Sm, Gd, Dy, Ho, Er, Yb) was synthesised by the reaction of [Cp3Ln] complexes (Cp=cyclopentadienyl) with liquid ammonia at −78 °C and structurally characterised by X-ray diffraction methods, mass spectrometry and vibrational (IR, Raman) spectroscopy. Furthermore, amido-bis(η5-cyclopentadienyl)lanthanide(III) complexes 2-Ln (Ln=Dy, Ho, Er, Yb) were synthesised by heating the respective ammine adduct 1-Ln in an inert gas atmosphere at temperatures of between 240 and 290 °C. X-ray diffraction studies, mass spectrometry and vibrational (IR, Raman) spectroscopy were carried out for several 2-Ln species and proved the formation of dimeric μ2-bridged compounds. Species 1-Ln are highly reactive coordination compounds and showed different behaviour regarding the decomposition to 2-Ln. The reaction of 1-Ln and 2-Ln with inorganic bases yielded lanthanide nitride LnN powders with an estimated crystallite size of between 40 and 90 nm at unprecedented low temperatures of 240 to 300 °C. Temperature-dependent X-ray powder diffraction and transmission electron microscopy (TEM) investigations were performed and showed that the decomposition reaction yielded Nanocrystalline Material. Structural optimisations were carried out for 1-Ln and 2-Ln by employing density functional (DFT) calculations. A good agreement was found between the observed and calculated structural parameters. Also, Gibbs free energies were calculated for 1-Ln, 2-Ln and the pyrolysis reaction to the nitride Material, and were found to fit well with the expected ranges.
Bettina V Lotsch - One of the best experts on this subject based on the ideXlab platform.
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unmasking melon by a complementary approach employing electron diffraction solid state nmr spectroscopy and theoretical calculations structural characterization of a carbon nitride polymer
Chemistry: A European Journal, 2007Co-Authors: Bettina V Lotsch, Markus Doblinger, Jan Sehnert, Lena Seyfarth, Jurgen Senker, Oliver Oeckler, Wolfgang SchnickAbstract:Poly(aminoimino)heptazine, otherwise known as Liebig's melon, whose composition and structure has been subject to multitudinous speculations, was synthesized from melamine at 630 °C under the pressure of ammonia. Electron diffraction, solid-state NMR spectroscopy, and theoretical calculations revealed that the Nanocrystalline Material exhibits domains well-ordered in two dimensions, thereby allowing the structure solution in projection by electron diffraction. Melon ([C6N7(NH2)(NH)]n, plane group p2 gg, a=16.7, b=12.4 A, γ=90°, Z=4), is composed of layers made up from infinite 1D chains of NH-bridged melem (C6N7(NH2)3) monomers. The strands adopt a zigzag-type geometry and are tightly linked by hydrogen bonds to give a 2D planar array. The inter-layer distance was determined to be 3.2 A from X-ray powder diffraction. The presence of heptazine building blocks, as well as NH and NH2 groups was confirmed by 13C and 15N solid-state NMR spectroscopy using 15N-labeled melon. The degree of condensation of the heptazine core was further substantiated by a 15N direct excitation measurement. Magnetization exchange observed between all 15N nuclei using a fp-RFDR experiment, together with the CP-MAS data and elemental analysis, suggests that the sample is mainly homogeneous in terms of its basic composition and molecular building blocks. Semiempirical, force field, and DFT/plane wave calculations under periodic boundary conditions corroborate the structure model obtained by electron diffraction. The overall planarity of the layers is confirmed and a good agreement is obtained between the experimental and calculated NMR chemical shift parameters. The polymeric character and thermal stability of melon might render this polymer a pre-stage of g-C3N4 and portend its use as a promising inert Material for a variety of applications in Materials and surface science.
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unmasking melon by a complementary approach employing electron diffraction solid state nmr spectroscopy and theoretical calculations structural characterization of a carbon nitride polymer
Chemistry: A European Journal, 2007Co-Authors: Bettina V Lotsch, Markus Doblinger, Jan Sehnert, Lena Seyfarth, Jurgen Senker, Oliver Oeckler, Wolfgang SchnickAbstract:Poly(aminoimino)heptazine, otherwise known as Liebig's melon, whose composition and structure has been subject to multitudinous speculations, was synthesized from melamine at 630 °C under the pressure of ammonia. Electron diffraction, solid-state NMR spectroscopy, and theoretical calculations revealed that the Nanocrystalline Material exhibits domains well-ordered in two dimensions, thereby allowing the structure solution in projection by electron diffraction. Melon ([C6N7(NH2)(NH)]n, plane group p2 gg, a=16.7, b=12.4 A, γ=90°, Z=4), is composed of layers made up from infinite 1D chains of NH-bridged melem (C6N7(NH2)3) monomers. The strands adopt a zigzag-type geometry and are tightly linked by hydrogen bonds to give a 2D planar array. The inter-layer distance was determined to be 3.2 A from X-ray powder diffraction. The presence of heptazine building blocks, as well as NH and NH2 groups was confirmed by 13C and 15N solid-state NMR spectroscopy using 15N-labeled melon. The degree of condensation of the heptazine core was further substantiated by a 15N direct excitation measurement. Magnetization exchange observed between all 15N nuclei using a fp-RFDR experiment, together with the CP-MAS data and elemental analysis, suggests that the sample is mainly homogeneous in terms of its basic composition and molecular building blocks. Semiempirical, force field, and DFT/plane wave calculations under periodic boundary conditions corroborate the structure model obtained by electron diffraction. The overall planarity of the layers is confirmed and a good agreement is obtained between the experimental and calculated NMR chemical shift parameters. The polymeric character and thermal stability of melon might render this polymer a pre-stage of g-C3N4 and portend its use as a promising inert Material for a variety of applications in Materials and surface science.
Oliver Oeckler - One of the best experts on this subject based on the ideXlab platform.
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unmasking melon by a complementary approach employing electron diffraction solid state nmr spectroscopy and theoretical calculations structural characterization of a carbon nitride polymer
Chemistry: A European Journal, 2007Co-Authors: Bettina V Lotsch, Markus Doblinger, Jan Sehnert, Lena Seyfarth, Jurgen Senker, Oliver Oeckler, Wolfgang SchnickAbstract:Poly(aminoimino)heptazine, otherwise known as Liebig's melon, whose composition and structure has been subject to multitudinous speculations, was synthesized from melamine at 630 °C under the pressure of ammonia. Electron diffraction, solid-state NMR spectroscopy, and theoretical calculations revealed that the Nanocrystalline Material exhibits domains well-ordered in two dimensions, thereby allowing the structure solution in projection by electron diffraction. Melon ([C6N7(NH2)(NH)]n, plane group p2 gg, a=16.7, b=12.4 A, γ=90°, Z=4), is composed of layers made up from infinite 1D chains of NH-bridged melem (C6N7(NH2)3) monomers. The strands adopt a zigzag-type geometry and are tightly linked by hydrogen bonds to give a 2D planar array. The inter-layer distance was determined to be 3.2 A from X-ray powder diffraction. The presence of heptazine building blocks, as well as NH and NH2 groups was confirmed by 13C and 15N solid-state NMR spectroscopy using 15N-labeled melon. The degree of condensation of the heptazine core was further substantiated by a 15N direct excitation measurement. Magnetization exchange observed between all 15N nuclei using a fp-RFDR experiment, together with the CP-MAS data and elemental analysis, suggests that the sample is mainly homogeneous in terms of its basic composition and molecular building blocks. Semiempirical, force field, and DFT/plane wave calculations under periodic boundary conditions corroborate the structure model obtained by electron diffraction. The overall planarity of the layers is confirmed and a good agreement is obtained between the experimental and calculated NMR chemical shift parameters. The polymeric character and thermal stability of melon might render this polymer a pre-stage of g-C3N4 and portend its use as a promising inert Material for a variety of applications in Materials and surface science.
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unmasking melon by a complementary approach employing electron diffraction solid state nmr spectroscopy and theoretical calculations structural characterization of a carbon nitride polymer
Chemistry: A European Journal, 2007Co-Authors: Bettina V Lotsch, Markus Doblinger, Jan Sehnert, Lena Seyfarth, Jurgen Senker, Oliver Oeckler, Wolfgang SchnickAbstract:Poly(aminoimino)heptazine, otherwise known as Liebig's melon, whose composition and structure has been subject to multitudinous speculations, was synthesized from melamine at 630 °C under the pressure of ammonia. Electron diffraction, solid-state NMR spectroscopy, and theoretical calculations revealed that the Nanocrystalline Material exhibits domains well-ordered in two dimensions, thereby allowing the structure solution in projection by electron diffraction. Melon ([C6N7(NH2)(NH)]n, plane group p2 gg, a=16.7, b=12.4 A, γ=90°, Z=4), is composed of layers made up from infinite 1D chains of NH-bridged melem (C6N7(NH2)3) monomers. The strands adopt a zigzag-type geometry and are tightly linked by hydrogen bonds to give a 2D planar array. The inter-layer distance was determined to be 3.2 A from X-ray powder diffraction. The presence of heptazine building blocks, as well as NH and NH2 groups was confirmed by 13C and 15N solid-state NMR spectroscopy using 15N-labeled melon. The degree of condensation of the heptazine core was further substantiated by a 15N direct excitation measurement. Magnetization exchange observed between all 15N nuclei using a fp-RFDR experiment, together with the CP-MAS data and elemental analysis, suggests that the sample is mainly homogeneous in terms of its basic composition and molecular building blocks. Semiempirical, force field, and DFT/plane wave calculations under periodic boundary conditions corroborate the structure model obtained by electron diffraction. The overall planarity of the layers is confirmed and a good agreement is obtained between the experimental and calculated NMR chemical shift parameters. The polymeric character and thermal stability of melon might render this polymer a pre-stage of g-C3N4 and portend its use as a promising inert Material for a variety of applications in Materials and surface science.
Jurgen Senker - One of the best experts on this subject based on the ideXlab platform.
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unmasking melon by a complementary approach employing electron diffraction solid state nmr spectroscopy and theoretical calculations structural characterization of a carbon nitride polymer
Chemistry: A European Journal, 2007Co-Authors: Bettina V Lotsch, Markus Doblinger, Jan Sehnert, Lena Seyfarth, Jurgen Senker, Oliver Oeckler, Wolfgang SchnickAbstract:Poly(aminoimino)heptazine, otherwise known as Liebig's melon, whose composition and structure has been subject to multitudinous speculations, was synthesized from melamine at 630 °C under the pressure of ammonia. Electron diffraction, solid-state NMR spectroscopy, and theoretical calculations revealed that the Nanocrystalline Material exhibits domains well-ordered in two dimensions, thereby allowing the structure solution in projection by electron diffraction. Melon ([C6N7(NH2)(NH)]n, plane group p2 gg, a=16.7, b=12.4 A, γ=90°, Z=4), is composed of layers made up from infinite 1D chains of NH-bridged melem (C6N7(NH2)3) monomers. The strands adopt a zigzag-type geometry and are tightly linked by hydrogen bonds to give a 2D planar array. The inter-layer distance was determined to be 3.2 A from X-ray powder diffraction. The presence of heptazine building blocks, as well as NH and NH2 groups was confirmed by 13C and 15N solid-state NMR spectroscopy using 15N-labeled melon. The degree of condensation of the heptazine core was further substantiated by a 15N direct excitation measurement. Magnetization exchange observed between all 15N nuclei using a fp-RFDR experiment, together with the CP-MAS data and elemental analysis, suggests that the sample is mainly homogeneous in terms of its basic composition and molecular building blocks. Semiempirical, force field, and DFT/plane wave calculations under periodic boundary conditions corroborate the structure model obtained by electron diffraction. The overall planarity of the layers is confirmed and a good agreement is obtained between the experimental and calculated NMR chemical shift parameters. The polymeric character and thermal stability of melon might render this polymer a pre-stage of g-C3N4 and portend its use as a promising inert Material for a variety of applications in Materials and surface science.
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unmasking melon by a complementary approach employing electron diffraction solid state nmr spectroscopy and theoretical calculations structural characterization of a carbon nitride polymer
Chemistry: A European Journal, 2007Co-Authors: Bettina V Lotsch, Markus Doblinger, Jan Sehnert, Lena Seyfarth, Jurgen Senker, Oliver Oeckler, Wolfgang SchnickAbstract:Poly(aminoimino)heptazine, otherwise known as Liebig's melon, whose composition and structure has been subject to multitudinous speculations, was synthesized from melamine at 630 °C under the pressure of ammonia. Electron diffraction, solid-state NMR spectroscopy, and theoretical calculations revealed that the Nanocrystalline Material exhibits domains well-ordered in two dimensions, thereby allowing the structure solution in projection by electron diffraction. Melon ([C6N7(NH2)(NH)]n, plane group p2 gg, a=16.7, b=12.4 A, γ=90°, Z=4), is composed of layers made up from infinite 1D chains of NH-bridged melem (C6N7(NH2)3) monomers. The strands adopt a zigzag-type geometry and are tightly linked by hydrogen bonds to give a 2D planar array. The inter-layer distance was determined to be 3.2 A from X-ray powder diffraction. The presence of heptazine building blocks, as well as NH and NH2 groups was confirmed by 13C and 15N solid-state NMR spectroscopy using 15N-labeled melon. The degree of condensation of the heptazine core was further substantiated by a 15N direct excitation measurement. Magnetization exchange observed between all 15N nuclei using a fp-RFDR experiment, together with the CP-MAS data and elemental analysis, suggests that the sample is mainly homogeneous in terms of its basic composition and molecular building blocks. Semiempirical, force field, and DFT/plane wave calculations under periodic boundary conditions corroborate the structure model obtained by electron diffraction. The overall planarity of the layers is confirmed and a good agreement is obtained between the experimental and calculated NMR chemical shift parameters. The polymeric character and thermal stability of melon might render this polymer a pre-stage of g-C3N4 and portend its use as a promising inert Material for a variety of applications in Materials and surface science.
Lena Seyfarth - One of the best experts on this subject based on the ideXlab platform.
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unmasking melon by a complementary approach employing electron diffraction solid state nmr spectroscopy and theoretical calculations structural characterization of a carbon nitride polymer
Chemistry: A European Journal, 2007Co-Authors: Bettina V Lotsch, Markus Doblinger, Jan Sehnert, Lena Seyfarth, Jurgen Senker, Oliver Oeckler, Wolfgang SchnickAbstract:Poly(aminoimino)heptazine, otherwise known as Liebig's melon, whose composition and structure has been subject to multitudinous speculations, was synthesized from melamine at 630 °C under the pressure of ammonia. Electron diffraction, solid-state NMR spectroscopy, and theoretical calculations revealed that the Nanocrystalline Material exhibits domains well-ordered in two dimensions, thereby allowing the structure solution in projection by electron diffraction. Melon ([C6N7(NH2)(NH)]n, plane group p2 gg, a=16.7, b=12.4 A, γ=90°, Z=4), is composed of layers made up from infinite 1D chains of NH-bridged melem (C6N7(NH2)3) monomers. The strands adopt a zigzag-type geometry and are tightly linked by hydrogen bonds to give a 2D planar array. The inter-layer distance was determined to be 3.2 A from X-ray powder diffraction. The presence of heptazine building blocks, as well as NH and NH2 groups was confirmed by 13C and 15N solid-state NMR spectroscopy using 15N-labeled melon. The degree of condensation of the heptazine core was further substantiated by a 15N direct excitation measurement. Magnetization exchange observed between all 15N nuclei using a fp-RFDR experiment, together with the CP-MAS data and elemental analysis, suggests that the sample is mainly homogeneous in terms of its basic composition and molecular building blocks. Semiempirical, force field, and DFT/plane wave calculations under periodic boundary conditions corroborate the structure model obtained by electron diffraction. The overall planarity of the layers is confirmed and a good agreement is obtained between the experimental and calculated NMR chemical shift parameters. The polymeric character and thermal stability of melon might render this polymer a pre-stage of g-C3N4 and portend its use as a promising inert Material for a variety of applications in Materials and surface science.
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unmasking melon by a complementary approach employing electron diffraction solid state nmr spectroscopy and theoretical calculations structural characterization of a carbon nitride polymer
Chemistry: A European Journal, 2007Co-Authors: Bettina V Lotsch, Markus Doblinger, Jan Sehnert, Lena Seyfarth, Jurgen Senker, Oliver Oeckler, Wolfgang SchnickAbstract:Poly(aminoimino)heptazine, otherwise known as Liebig's melon, whose composition and structure has been subject to multitudinous speculations, was synthesized from melamine at 630 °C under the pressure of ammonia. Electron diffraction, solid-state NMR spectroscopy, and theoretical calculations revealed that the Nanocrystalline Material exhibits domains well-ordered in two dimensions, thereby allowing the structure solution in projection by electron diffraction. Melon ([C6N7(NH2)(NH)]n, plane group p2 gg, a=16.7, b=12.4 A, γ=90°, Z=4), is composed of layers made up from infinite 1D chains of NH-bridged melem (C6N7(NH2)3) monomers. The strands adopt a zigzag-type geometry and are tightly linked by hydrogen bonds to give a 2D planar array. The inter-layer distance was determined to be 3.2 A from X-ray powder diffraction. The presence of heptazine building blocks, as well as NH and NH2 groups was confirmed by 13C and 15N solid-state NMR spectroscopy using 15N-labeled melon. The degree of condensation of the heptazine core was further substantiated by a 15N direct excitation measurement. Magnetization exchange observed between all 15N nuclei using a fp-RFDR experiment, together with the CP-MAS data and elemental analysis, suggests that the sample is mainly homogeneous in terms of its basic composition and molecular building blocks. Semiempirical, force field, and DFT/plane wave calculations under periodic boundary conditions corroborate the structure model obtained by electron diffraction. The overall planarity of the layers is confirmed and a good agreement is obtained between the experimental and calculated NMR chemical shift parameters. The polymeric character and thermal stability of melon might render this polymer a pre-stage of g-C3N4 and portend its use as a promising inert Material for a variety of applications in Materials and surface science.
