Noetzel Jan, Schienbein Philipp, Forbert Harald, Marx Dominik
Lehrstuhl für Theoretische Chemie, Ruhr-Universität Bochum, D-44780, Bochum.
Present Address, Department of Physics, Imperial College London, Exhibition Rd, South Kensington, London, SW7 2AZ, United Kingdom.
Angew Chem Int Ed Engl. 2024 Jul 8;63(28):e202402120. doi: 10.1002/anie.202402120. Epub 2024 Jun 3.
Supercritical water provides distinctly different solvation properties compared to what is known from liquid water. Despite its prevalence deep in the Earth's crust and its role in chemosynthetic ecosystems in the vicinity of hydrothermal vents, molecular insights into its solvation mechanisms are still very scarce compared to what is known for liquid water. Recently, neutral metal particles have been detected in hydrothermal fluids and proposed to explain the transport of gold species to ore deposits on Earth. Using ab initio molecular dynamics, we elucidate the solvation properties of small gold species at supercritical conditions. The neutral metal clusters themselves contribute enormous THz intensity not because of their intramolecular vibrations, but due to their pronounced electronic polarization coupling to the dynamical supercritical solvent, leading to a continuum absorption up to about 1000 cm. On top, long-lived interactions between the gold clusters and solvation water leads at these supercritical conditions to a sharp THz resonance that happens to be close to the one due to H-bonding in liquid water at ambient conditions. The resulting distinct resonances can be used to analyse the solvation properties of neutral metal particles in supercritical aqueous solutions.
与液态水相比，超临界水具有截然不同的溶剂化性质。尽管它在地壳深处普遍存在，并且在热液喷口附近的化学合成生态系统中发挥作用，但与液态水相比，对其溶剂化机制的分子层面理解仍然非常匮乏。最近，在热液流体中检测到了中性金属颗粒，并提出它们可以解释地球上金物种向矿床的迁移。通过从头算分子动力学，我们阐明了超临界条件下小金物种的溶剂化性质。中性金属簇本身贡献了巨大的太赫兹强度，这并非由于其分子内振动，而是由于它们与动态超临界溶剂的显著电子极化耦合，导致高达约1000 cm的连续吸收。此外，在这些超临界条件下，金簇与溶剂化水之间的长寿命相互作用导致了一个尖锐的太赫兹共振，该共振恰好与环境条件下液态水中氢键导致的共振相近。由此产生的独特共振可用于分析超临界水溶液中中性金属颗粒的溶剂化性质。
