title: Photocatalysis and the origin of life: synthesis of nucleoside bases from formamide on TiO2(001) single surfaces.
abstract: We report the conversion of a large fraction of formamide (NH(2)CHO) to high-molecular-weight compounds attributed to nucleoside bases on the surface of a TiO(2) (001) single crystal in ultra-high vacuum conditions. If true, we present previously unreported evidence for making biologically relevant molecules from a C1 compound on any single crystal surface in high vacuum and in dry conditions. An UV light of 3.2 eV was necessary to make the reaction. This UV light excites the semiconductor surface but not directly the adsorbed formamide molecules or the reaction products. There thus is no need to use high energy in the form of photons or electrical discharge to make the carbon-carbon and carbon-nitrogen bonds necessary for life. Consequently, the reaction products may accumulate with time and may not be subject to decomposition by the excitation source. The formation of these molecules, by surface reaction of formamide, is proof that some minerals in the form of oxide semiconductors are active materials for making high-molecular-weight organic molecules that may have acted as precursors for biological compounds required for life in the universe.
authors.affiliation: Department of Chemistry, University of Auckland, Private Bag 92019, Auckland, New Zealand.
authors.forename: S D
authors.initials: SD
authors.lastname: Senanayake
authors.forename: H
authors.initials: H
authors.lastname: Idriss
mesh_terms: D002244:Carbon / Q000737:chemistry; D002384:Catalysis; D018360:Crystallography, X-Ray; D004583:Electrons; D005559:Formamides / Q000737:chemistry*; D008027:Light; D013058:Mass Spectrometry; D008956:Models, Chemical; D008958:Models, Molecular; D008970:Molecular Weight; D009584:Nitrogen / Q000737:chemistry; D000069497:Origin of Life; D012666:Semiconductors; D013052:Spectrometry, X-Ray Emission; D013499:Surface Properties; D013696:Temperature; D013997:Time Factors; D014025:Titanium / Q000737:chemistry*; D014466:Ultraviolet Rays
chemical_list: D005559:Formamides; C009495:titanium dioxide; C031066:formamide; D002244:Carbon; D014025:Titanium; D009584:Nitrogen