Photochemical stability and protective effect against oxidation and UV degradation of HCN polymers: an XPS study on pyrite surfaces

The effect of mineral surfaces on increasing molecular complexity has been considered an
important topic in studies on the origin of life [1]. In addition, HCN is considered a key molecule
in the research about the chemical evolution. Also, HCN polymers are considered keys in the
formation of the first protometabolic systems and they may be among the most readily formed
organic macromolecules in the solar system [2].
Recently, it was showed that the HCN-based polymeric films over pyrite surfaces act as
protective films. Preventing to the oxidation the high reactive pyrite surface under ambient
conditions of moisture, light an air of a standard chemistry lab. The unexpected behaviour of
the pyrite/HCN polymeric film encourages us to explore in deep these systems under early Earth
conditions due the new insight open in prebiotic chemistry [3].
Since the UV radiation can be an important factor in the increasing of the molecular complexity,
in this work the role of the protective films over pyrite surfaces were study by XPS after
irradiation of the samples during long exposure times. As a result, the formation of a film with
protective properties against corrosion by oxygen and UV radiation is identified, forming a stable
polymeric film under ambient conditions. These results raise the great potential of HCN
polymers for the development of a new class of cheap and easy-to-produce multifunctional
polymeric materials that also show promising and attractive insights into prebiotic chemistry.

 

1. G. Wächtershäuser, Chemistry & Biodiversity 4, 584 (2007).
2. C. N. Matthews, Origins Life Evol Biosphere 21, 421 (1991).
3. C. Pérez-Fernández, M. Ruiz-Bermejo, S. Gálvez-Martínez, and E. Mateo-Martí, RSC Advances 11, 20109 (2021).