Prebiotic photocatalytic reactivity of formamide in presence of TiO2

Laboratory experiments have shown that different chemical-physical mechanisms are respon-sible for the richness of molecules observed in space. Surface catalysis at low temperature by dust is considered necessary to justify the presence of, e.g., H2, H2O or CO2, as demonstrated experimentally. However, to describe the presence of more complex molecules, or radicals and even organic refractory material, irradiation processes due to ions and UV photons are required. Syntheses of organic molecules, occurring in space, have been performed in laboratory following dif-ferent strategies. Prebiotic reactions have been studied in the laboratory in conditions simulating the environments found on the early Earth and in space. Formamide is confirmed to be a promising route to understand the first chemical steps that brought simple C-bearing molecules towards largely complex mixtures of bio-macro-molecules. A large suite of pyrimidines (including cytosine and uracil) and purines have in fact been synthesized at 160 C using only formamide in the presence of cosmic-dust analogue silicates. In this work the reactivity of the formamide in presence of titanium dioxide is studied. TiO2 is an important photo-catalytic material, thus we have developed an experimental protocol to investigate the role of UV irradiation on bio-molecules formation. We have irradiated with UV light at the DXR-2 beamline of the DAFNE-L laboratory at the National Laboratories of Frascati (INFN, Italy) mixtures of formamide with two mineral forms of titanium dioxide: anatase and rutile. Results on photochemical synthesis will be presented and compared with those on thermal synthesis of biomolecules.