Heterocyclic Anions of Astrobiological Interest

Cole, Callie A.; Demarais, Nicholas J.; Yang, Zhibo; Snow, Theodore P.; Bierbaum, Veronica M.

doi:10.1088/0004-637x/779/2/181

Cited by 20 publications

(35 citation statements)

References 44 publications

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“…30,31 The reactivity of biomolecule fragments is also essential to this end. In this study, we expand our previous work on the interstellar formation pathways, 32,33 reactivity, 34 and fragmentation 35 of complex interstellar organics through an analysis of uracil and its anionic derivatives. Former fragmentation studies on uracil involve primarily cations, ranging from protonated species 36,37 to metal cation complexes.…”

Section: Introductionmentioning

confidence: 84%

“…Experimental data are gathered using a modified Finnigan LCQ Deca XP Plus ion trap. This instrument has been described in our previous work, 35 and is outlined here in brief. Ions are generated from an electrospray ionization (ESI) source with a spray voltage of 4.5 kV, a flow of 5-10 mL min À1 , and heated capillary temperatures of 200-250 1C.…”

Section: Experimental Methodsmentioning

confidence: 99%

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Anionic derivatives of uracil: fragmentation and reactivity

Cole

Wang

Snow

et al. 2014

Phys. Chem. Chem. Phys.

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Uracil is an essential biomolecule for terrestrial life, yet its prebiotic formation mechanisms have proven elusive for decades. Meteorites have been shown to contain uracil and the interstellar abundance of aromatic species and nitrogen-containing molecules is well established, providing support for uracil's presence in the interstellar medium (ISM). The ion chemistry of uracil may provide clues to its prebiotic synthesis and role in the origin of life. The fragmentation of biomolecules provides valuable insights into their formation. Previous research focused primarily on the fragmentation and reactivity of cations derived from uracil. In this study, we explore deprotonated uracil-5-carboxylic acid and its anionic fragments to elucidate novel reagents of uracil formation and to characterize the reactivity of uracil's anionic derivatives. The structures of these fragments are identified through theoretical calculations, further fragmentation, experimental acidity bracketing, and reactivity with several detected and potential interstellar species (SO2, OCS, CS2, NO, N2O, CO, NH3, O2, and C2H4). Fragmentation is achieved through collision induced dissociation (CID) in a commercial ion trap mass spectrometer, and all reaction rate constants are measured using a modification of this instrument. Experimental data are supported by theoretical calculations at the B3LYP/6-311++G(d,p) level of theory. Lastly, the astrochemical implications of the observed fragmentation and reaction processes are discussed.

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Section: Introductionmentioning

confidence: 84%

Section: Experimental Methodsmentioning

confidence: 99%

Anionic derivatives of uracil: fragmentation and reactivity

Cole

Wang

Snow

et al. 2014

Phys. Chem. Chem. Phys.

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“…1 However, the interest in anions diminished because, due to a lack of spectroscopic data, they could not be detected. This has changed recently when the first anions were observed in the interstellar medium, [2][3][4] reactivating the interest in theory 5,6 and experiments [7][8][9][10][11][12][13] with anion-molecule reactions, including associative detachment reactions. Also photodetachment of electrons from anions including interstellar anions has been reported.…”

Section: Introductionmentioning

confidence: 99%

H/D exchange in reactions of OH⁻ with D₂ and of OD⁻ with H₂ at low temperatures

Mulin

Roučka

Jusko

et al. 2015

Phys. Chem. Chem. Phys.

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Using a cryogenic linear 22-pole rf ion trap, rate coefficients for H/D exchange reactions of OH(-) with D2 (1) and OD(-) with H2 (2) have been measured at temperatures between 11 K and 300 K with normal hydrogen. Below 60 K, we obtained k1 = 5.5 × 10(-10) cm(3) s(-1) for the exoergic . Upon increasing the temperature above 60 K, the data decrease with a power law, k1(T) ∼T(-2.7), reaching ≈1 × 10(-10) cm(3) s(-1) at 200 K. This observation is tentatively explained with a decrease of the lifetime of the intermediate complex as well as with the assumption that scrambling of the three hydrogen atoms is restricted by the topology of the potential energy surface. The rate coefficient for the endoergic increases with temperature from 12 K up to 300 K, following the Arrhenius equation, k2 = 7.5 × 10(-11) exp(-92 K/T) cm(3) s(-1) over two orders of magnitude. The fitted activation energy, EA-Exp = 7.9 meV, is in perfect accordance with the endothermicity of 24.0 meV, if one accounts for the thermal population of the rotational states of both reactants. The low mean activation energy in comparison with the enthalpy change in the reaction is mainly due to the rotational energy of 14.7 meV contributed by ortho-H2 (J = 1). Nonetheless, one should not ignore the reactivity of pure para-H2 because, according to our model, it already reaches 43% of that of ortho-H2 at 100 K.

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“…The chemical proprieties of heterocyclic organosulfur compounds are of considerable interest in modern research. In particular thiirane, thiazole and thiadiazoles have been found to have important biological107, pharmacological108–110 and technological111–113 applications; furthermore they are believed to play a significant role in astrochemical processes114,115 and prebiotic chemistry 116,117. With the exception of thiirane, the planarity of these molecules, highlighted by an inertial defect (Δ = I c − I b − I a ) close to zero, leads to a dependence among the inertia moments, so it is necessary to select one of their possible couples in the fitting procedure14.…”

Section: Semi-experimental Equilibrium Structuresmentioning

confidence: 99%

Structural features of the carbon–sulfur chemical bond: a semi-experimental perspective

et al. 2016

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In this work semi-experimental and theoretical equilibrium geometries of 10 sulfur-containing organic molecules, as well as 4 oxygenated ones, are determined by means of a computational protocol based on density functional theory. The results collected in the present paper further enhance our online database of accurate semi-experimental equilibrium molecular geometries, adding 13 new molecules containing up to 8 atoms, for 12 of which the first semi-experimental equilibrium structure is reported, to the best of our knowledge. We focus in particular on sulfurcontaining compounds, aiming both to provide new accurate data on some rather important chemical moieties, only marginally represented in the literature of the field, and to examine the structural features of carbon-sulfur bonds in the light of the previously presented linear regression approach. The structural changes issuing from substitution of oxygen by sulfur are discussed to get deeper insights on how modifications in electronic structure and nuclear potential can affect equilibrium geometries. With respect to our previous works, we perform non-linear constrained optimizations of equilibrium SE structures with a new general and user-friendly software under development in our group with updated definition of useful statistical indicators.

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Heterocyclic Anions of Astrobiological Interest

Cited by 20 publications

References 44 publications

Anionic derivatives of uracil: fragmentation and reactivity

Anionic derivatives of uracil: fragmentation and reactivity

H/D exchange in reactions of OH⁻ with D₂ and of OD⁻ with H₂ at low temperatures

Structural features of the carbon–sulfur chemical bond: a semi-experimental perspective

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Heterocyclic Anions of Astrobiological Interest

Cited by 20 publications

References 44 publications

Anionic derivatives of uracil: fragmentation and reactivity

Anionic derivatives of uracil: fragmentation and reactivity

H/D exchange in reactions of OH− with D2 and of OD− with H2 at low temperatures

Structural features of the carbon–sulfur chemical bond: a semi-experimental perspective

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H/D exchange in reactions of OH⁻ with D₂ and of OD⁻ with H₂ at low temperatures