Oxygenated derivatives of polycyclic aromatic hydrocarbons (PAHs), or oxyPAHs, recently captured the interest of the scientific community for their photochemical reactivity in a water-ice matrix mimicking the interstellar medium. Furthermore, oxyPAHs are interesting molecules for the study of the origin of life for their prebiotic potential. However, their stability and transformation pathways under astrophysically relevant conditions have remained largely unexplored. Herein we report the photochemical behavior of 1-naphthol (1-HN) and 1,6- and 1,8-dihydroxynaphthalene (DHN) either as pure powdered solids or adsorbed on forsterite or anatase surface. All the compounds showed an extensive decrease of main vibrational bands, accompanied in the case of DHNs by the formation of new molecular species. Irradiation of 1,8-DHN at 80 K resulted in the IR-detectable generation of CO 2 (2340 cm -1 ), a process reported by other authors following irradiation of PAHs in water-ice analogues at 14 K. These results, when compared to model autoxidation experiments, indicated a high susceptibility of hydroxylated naphthalene derivatives to UV radiation leading to free radical and carbonyl-containing extended quinone intermediates (preliminary DFT calculations) with partial degradation and decarboxylation. On the basis of these results, oxyPAH formation and photoprocessing on minerals is proposed as a plausible pathway of PAHs transformation under astrochemical conditions of prebiotic relevance.

Solid State Photochemistry of Hydroxylated Naphthalenes on Minerals: Probing Polycyclic Aromatic Hydrocarbon Transformation Pathways under Astrochemically-Relevant Conditions

POTENTI, SIMONE;Fornaro, Teresa;Crescenzi, Orlando;Brucato, John R.;Barone, Vincenzo;D'Ischia, Marco
2018-01-01

Abstract

Oxygenated derivatives of polycyclic aromatic hydrocarbons (PAHs), or oxyPAHs, recently captured the interest of the scientific community for their photochemical reactivity in a water-ice matrix mimicking the interstellar medium. Furthermore, oxyPAHs are interesting molecules for the study of the origin of life for their prebiotic potential. However, their stability and transformation pathways under astrophysically relevant conditions have remained largely unexplored. Herein we report the photochemical behavior of 1-naphthol (1-HN) and 1,6- and 1,8-dihydroxynaphthalene (DHN) either as pure powdered solids or adsorbed on forsterite or anatase surface. All the compounds showed an extensive decrease of main vibrational bands, accompanied in the case of DHNs by the formation of new molecular species. Irradiation of 1,8-DHN at 80 K resulted in the IR-detectable generation of CO 2 (2340 cm -1 ), a process reported by other authors following irradiation of PAHs in water-ice analogues at 14 K. These results, when compared to model autoxidation experiments, indicated a high susceptibility of hydroxylated naphthalene derivatives to UV radiation leading to free radical and carbonyl-containing extended quinone intermediates (preliminary DFT calculations) with partial degradation and decarboxylation. On the basis of these results, oxyPAH formation and photoprocessing on minerals is proposed as a plausible pathway of PAHs transformation under astrochemical conditions of prebiotic relevance.
astrochemistry; Mars relevant irradiation conditions; mineral coating; oxidative polymerization; oxygenated polycyclic aromatic hydrocarbons; Geochemistry and Petrology; Atmospheric Science; Space and Planetary Science
File in questo prodotto:
Non ci sono file associati a questo prodotto.

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11384/78107
 Attenzione

Attenzione! I dati visualizzati non sono stati sottoposti a validazione da parte dell'ateneo

Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 10
  • ???jsp.display-item.citation.isi??? 9
social impact