Pantaleone Stefano, Corno Marta, Rimola Albert, Balucani Nadia, Ugliengo Piero
Dipartimento di Chimica and Nanostructured Interfaces and Surfaces (NIS) Centre, Università degli Studi di Torino, via P. Giuria 7,, I-10125 Torino, Italy.
Dipartimento di Chimica, Biologia e Biotecnologie, Università degli Studi di Perugia, Via Elce di Sotto 8, I-06123 Perugia, Italy.
ACS Earth Space Chem. 2023 Sep 21;7(10):2050-2061. doi: 10.1021/acsearthspacechem.3c00167. eCollection 2023 Oct 19.
Phosphorus (P) is a fundamental element for whatever form of life, in the same way as the other biogenic macroelements (SONCH). The prebiotic origin of P is still a matter of debate, as the phosphates present on earth are trapped in almost insoluble solid matrixes (apatites) and, therefore, hardly available for inclusion in living systems in the prebiotic era. The most accepted theories regard a possible exogenous origin during the Archean Era, through the meteoritic bombardment, when tons of reactive P in the form of phosphide ((Fe,Ni)P, schreibersite mineral) reached the primordial earth, reacting with water and providing oxygenated phosphorus compounds (including phosphates). In the last 20 years, laboratory experiments demonstrated that the corrosion process of schreibersite by water indeed leads to reactive phosphates that, in turn, react with other biological building blocks (nucleosides and simple sugars) to form more complex molecules (nucleotides and complex sugars). In the present paper, we study the water corrosion of different crystalline surfaces of schreibersite by means of periodic DFT (density functional theory) simulations. Our results show that water adsorbs molecularly on the most stable (110) surface but dissociates on the less stable (001) one, giving rise to further reactivity. Indeed, subsequent water adsorptions, up to the water monolayer coverage, show that, on the (001) surface, iron and nickel atoms are the first species undergoing the corrosion process and, in a second stage, the phosphorus atoms also get involved. When adsorbing up to three and four water molecules per unit cell, the most stable structures found are the phosphite and phosphate forms of phosphorus, respectively. Simulation of the vibrational spectra of the considered reaction products revealed that the experimental band at 2423 cm attributed to the P-H stretching frequency is indeed predicted for a phosphite moiety attached to the schreibersite (001) surface upon chemisorption of up to three water molecules.
磷（P）是任何生命形式的基本元素，与其他生物源宏量元素（SONCH）一样。磷的益生元起源仍是一个有争议的问题，因为地球上存在的磷酸盐被困在几乎不溶的固体基质（磷灰石）中，因此在益生元时代几乎无法用于纳入生命系统。最被接受的理论认为，在太古代时期，通过陨石撞击可能存在外源起源，当时数吨以磷化物（(Fe,Ni)P，磷铁镍矿矿物）形式存在的活性磷到达原始地球，与水反应并提供氧化态的磷化合物（包括磷酸盐）。在过去20年中，实验室实验表明，磷铁镍矿被水腐蚀的过程确实会产生活性磷酸盐，这些磷酸盐进而与其他生物构建块（核苷和单糖）反应形成更复杂的分子（核苷酸和复合糖）。在本文中，我们通过周期性密度泛函理论（DFT）模拟研究了磷铁镍矿不同晶体表面的水腐蚀。我们的结果表明，水以分子形式吸附在最稳定的（110）表面，但在较不稳定的（001）表面发生解离，从而产生进一步的反应活性。实际上，后续的水吸附，直至水单层覆盖，表明在（001）表面，铁和镍原子是首先经历腐蚀过程的物种，在第二阶段，磷原子也会参与其中。当每个晶胞吸附多达三个和四个水分子时，发现的最稳定结构分别是磷的亚磷酸盐和磷酸盐形式。对所考虑反应产物的振动光谱模拟表明，对于在化学吸附多达三个水分子后附着在磷铁镍矿（001）表面的亚磷酸盐部分，确实预测到了归因于P-H伸缩频率的2423 cm处的实验谱带。
