Abstract:Pressure-induced oligomerization was found from high-pressure experiments at 25 °C on alanine powder soaked in its saturated aqueous solution. The oligomerization to alanylalanine occurred at 5 GPa. The maximum yields of alanylalanine and trialanine were, respectively, 1.1 × 10(-3) and 1.3 × 10(-4) at 11 GPa.
“…The similar oligomer formation mechanism was found for alanine at pressures 9–11 GPa and 300 K, where alanylalanine and trialanine were formed via alanine dehydration and C-N bond formation 29 . Although we found PAH oligomerization at 3.5 GPa and 500–773 K, the average intermolecular distances of experimental products should be longer than that at a reaction threshold, because the diffraction patterns (and crystal structures) of these hydrocarbons do not undergo significant changes at selected parameters 20 .…”
Section: Resultssupporting
confidence: 71%
“…It was emphasized in the previous studies that the formation of oligomers simultaneously at high pressures and high temperatures was promoted by energetically activating hydrocarbons under influence of catalysts – copper or platinum 18 , 61 . However in present study and in previous studies 23 , 29 oligomerization of organic compounds was observed at high pressures without any active catalyst. Figure 6 PAHs oligomerization and carbonization mechanism at high pressure and temperature.…”
Temperature-induced oligomerization of polycyclic aromatic hydrocarbons (PAHs) was found at 500–773 K and ambient and high (3.5 GPa) pressures. The most intensive oligomerization at 1 bar and 3.5 GPa occurs at 740–823 K. PAH carbonization at high pressure is the final stage of oligomerization and occurs as a result of sequential oligomerization and polymerization of the starting material, caused by overlapping of π-orbitals, a decrease of intermolecular distances, and finally the dehydrogenation and polycondensation of benzene rings. Being important for building blocks of life, PAHs and their oligomers can be formed in the interior of the terrestrial planets with radii less than 2270 km.
“…The similar oligomer formation mechanism was found for alanine at pressures 9–11 GPa and 300 K, where alanylalanine and trialanine were formed via alanine dehydration and C-N bond formation 29 . Although we found PAH oligomerization at 3.5 GPa and 500–773 K, the average intermolecular distances of experimental products should be longer than that at a reaction threshold, because the diffraction patterns (and crystal structures) of these hydrocarbons do not undergo significant changes at selected parameters 20 .…”
Section: Resultssupporting
confidence: 71%
“…It was emphasized in the previous studies that the formation of oligomers simultaneously at high pressures and high temperatures was promoted by energetically activating hydrocarbons under influence of catalysts – copper or platinum 18 , 61 . However in present study and in previous studies 23 , 29 oligomerization of organic compounds was observed at high pressures without any active catalyst. Figure 6 PAHs oligomerization and carbonization mechanism at high pressure and temperature.…”
Temperature-induced oligomerization of polycyclic aromatic hydrocarbons (PAHs) was found at 500–773 K and ambient and high (3.5 GPa) pressures. The most intensive oligomerization at 1 bar and 3.5 GPa occurs at 740–823 K. PAH carbonization at high pressure is the final stage of oligomerization and occurs as a result of sequential oligomerization and polymerization of the starting material, caused by overlapping of π-orbitals, a decrease of intermolecular distances, and finally the dehydrogenation and polycondensation of benzene rings. Being important for building blocks of life, PAHs and their oligomers can be formed in the interior of the terrestrial planets with radii less than 2270 km.
“…[1][2][3][4][5][6][7][8] High pressures can substantially alter intermolecular interactions of organic molecules resulting in pressure-induced structural changes and chemical reactions including poly-and oligomerization. 2,3,5,7,9,10 For instance, extreme conditions realized during cometary or meteor impacts are thought to facilitate the chemistry needed to produce polypeptides and other biologically relevant molecules from simple precursors. 7,11,12 Understanding the room temperature structural behavior and equa-tion of state (EOS) for glycine under static compression is a critical step for clarifying the role of elevated thermodynamic conditions on the possible formation of polypeptides.…”
“…[21][22][23][24] Recently, the pressure-induced oligomerization of L-alanine at room temperature was reported. 25,26 The oligomerization might occur partially when distances between the neighboring L-alanine molecules decrease with increasing pressure and finally approaches the reaction threshold. 25 However, the detailed mechanism of the oligomerization has not been revealed.…”
Section: Introductionmentioning
confidence: 99%
“…25,26 The oligomerization might occur partially when distances between the neighboring L-alanine molecules decrease with increasing pressure and finally approaches the reaction threshold. 25 However, the detailed mechanism of the oligomerization has not been revealed. Investigation of the effects of pressure on the intermolecular interactions in amino acid crystals may provide essential a) Author to whom correspondence should be addressed: shinozaki.aya@ sci.hokudai.ac.jp.…”
Pressure-response on the crystal structure of deuterated α-glycine was investigated at room temperature, using powder and single-crystal X-ray diffraction, and powder neutron diffraction measurements under high pressure. No phase change was observed up to 8.7 GPa, although anisotropy of the lattice compressibility was found. No significant changes in the compressibility and the intramolecular distance between non-deuterated α-glycine and deuterated α-glycine were observed. Neutron diffraction measurements indicated the distance of the intermolecular D⋯O bond along with the c-axis increased with compression up to 6.4 GPa. The distance of another D⋯O bond along with the a-axis decreased with increasing pressure and became the shortest intermolecular hydrogen bond above 3 GPa. In contrast, the lengths of the bifurcated N-D⋯O and C-D⋯O hydrogen bonds, which are formed between the layers of the α-glycine molecules along the b-axis, decreased significantly with increasing pressure. The decrease of the intermolecular distances resulted in the largest compressibility of the b-axis, compared to the other two axes. The Hirshfeld analysis suggested that the reduction of the void region size, rather than shrinkage of the strong N-D⋯O hydrogen bonds, occurred with compression.
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