scholarly journals Detection of deuterated molecules, but not of lithium hydride, in the z = 0.89 absorber toward PKS 1830−211

2020 ◽  
Vol 637 ◽  
pp. A7
Author(s):  
S. Muller ◽  
E. Roueff ◽  
J. H. Black ◽  
M. Gérin ◽  
M. Guélin ◽  
...  
Keyword(s):  
Milky Way ◽  
Organic Molecules ◽  
Lithium Hydride ◽  
Time Span ◽  
Line Of Sight ◽  
Light Elements ◽  
Dark Cloud ◽  
Upper Limit ◽  
Intermediate Redshift ◽  
Complex Organic

Deuterium and lithium are light elements of high cosmological and astrophysical importance. In this work we report the first detection of deuterated molecules and a search for lithium hydride, 7LiH, at redshift z = 0.89 in the spiral galaxy intercepting the line of sight to the quasar PKS 1830−211. We used ALMA to observe several submillimeter lines of ND, NH2D, and HDO, and their related isotopomers NH2, NH3, and H218O, in absorption against the southwest image of the quasar, allowing us to derive XD/XH abundance ratios. The absorption spectra mainly consist of two distinct narrow velocity components for which we find remarkable differences. One velocity component shows XD/XH abundances that is about 10 times larger than the primordial elemental D/H ratio, and no variability of the absorption profile during the time span of our observations. In contrast, the other component shows a stronger deuterium fractionation. Compared to the first component, this second component has XD/XH abundances that are 100 times larger than the primordial D/H ratio, a deepening of the absorption by a factor of two within a few months, and a rich chemical composition, with relative enhancements of N2H+, CH3OH, SO2 and complex organic molecules. We therefore speculate that this component is associated with the analog of a Galactic dark cloud, while the first component is likely more diffuse. Our search for the 7LiH (1–0) line was unsuccessful and we derive an upper limit 7LiH/H2 = 4 × 10−13 (3σ) in the z = 0.89 absorber toward PKS 1830−211. Besides, with ALMA archival data, we could not confirm the previous tentative detections of this line in the z = 0.68 absorber toward B 0218+357; we derive an upper limit 7LiH/H2 = 5 × 10−11 (3σ), although this is less constraining than our limit toward PKS 1830−211. We conclude that, as in the Milky Way, only a tiny fraction of lithium nuclei are possibly bound in LiH in these absorbers at intermediate redshift.

scholarly journals Sulphur-bearing and complex organic molecules in an infrared cold core

2019 ◽  
Vol 491 (1) ◽  
pp. 427-439 ◽  
Author(s):  
Pedro P B Beaklini ◽  
Edgar Mendoza ◽  
Carla M Canelo ◽  
Isabel Aleman ◽  
Manuel Merello ◽  
...  
Keyword(s):  
Organic Molecules ◽  
Bright Spot ◽  
Dark Cloud ◽  
Hot Gas ◽  
The Core ◽  
Complex Organic ◽  
Cold Core ◽  
The Continuum

ABSTRACT Since the start of ALMA (Atacama Large Millimeter Array) observatory operation, new and important chemistry of infrared cold core was revealed. Molecular transitions at millimetre range are being used to identify and to characterize these sources. We have investigated the 231 GHz ALMA archive observations of the infrared dark cloud region C9, focusing on the brighter source that we called as IRDC-C9 Main. We report the existence of two substructures on the continuum map of this source: a compact bright spot with high chemistry diversity that we labelled as core, and a weaker and extended one, that we labelled as tail. In the core, we have identified lines of the molecules OCS(19−18), 13CS(5−4), and CH3CH2CN, several lines of CH3CHO and the k-ladder emission of 13CH3CN. We report two different temperature regions, while the rotation diagram of CH3CHO indicates a temperature of 25 K, the rotation diagram of 13CH3CN indicates a warmer phase at temperature of ∼450 K. In the tail, only the OCS(19−18) and 13CS(5−4) lines were detected. We used the nautilus and the radex codes to estimate the column densities and the abundances. The existence of hot gas in the core of IRDC-C9 Main suggests the presence of a protostar, which is not present in the tail.

scholarly journals Synthesis of solid-state complex organic molecules through accretion of simple species at low temperatures

2019 ◽  
Vol 15 (S350) ◽  
pp. 46-50
Author(s):  
D. Qasim ◽  
G. Fedoseev ◽  
K.-J. Chuang ◽  
V. Taquet ◽  
T. Lamberts ◽  
...  
Keyword(s):  
Solid State ◽  
Gas Phase ◽  
Low Temperatures ◽  
Laboratory Experiments ◽  
Organic Molecules ◽  
Primary Alcohol ◽  
Major Product ◽  
Activation Barriers ◽  
Upper Limit ◽  
Complex Organic

AbstractComplex organic molecules (COMs) have been detected in the gas-phase in cold and lightless molecular cores. Recent solid-state laboratory experiments have provided strong evidence that COMs can be formed on icy grains through ‘non-energetic’ processes. In this contribution, we show that propanal and 1-propanol can be formed in this way at the low temperature of 10 K. Propanal has already been detected in space. 1-propanol is an astrobiologically relevant molecule, as it is a primary alcohol, and has not been astronomically detected. Propanal is the major product formed in the C2H2 + CO + H experiment, and 1-propanol is detected in the subsequent propanal + H experiment. ALMA observations towards IRAS 16293-2422B are discussed and provide a 1-propanol:propanal upper limit of < 0.35–0.55, which are complemented by computationally-derived activation barriers in addition to the performed laboratory experiments.

scholarly journals Complex organic molecules in diffuse clouds along the line of sight to Sagittarius B2 (Corrigendum)

2018 ◽  
Vol 610 ◽  
pp. C2 ◽  
Author(s):  
V. Thiel ◽  
A. Belloche ◽  
K. M. Menten ◽  
R. T. Garrod ◽  
H. S. P. Müller
Keyword(s):  
Organic Molecules ◽  
Line Of Sight ◽  
Diffuse Clouds ◽  
Complex Organic

scholarly journals Complex organic molecules in diffuse clouds along the line of sight to Sagittarius B2

2017 ◽  
Vol 605 ◽  
pp. L6 ◽  
Author(s):  
V. Thiel ◽  
A. Belloche ◽  
K. M. Menten ◽  
R. T. Garrod ◽  
H. S. P. Müller
Keyword(s):  
Organic Molecules ◽  
Line Of Sight ◽  
Diffuse Clouds ◽  
Complex Organic

The formation of glycine and other complex organic molecules in exploding ice mantles

2014 ◽  
Vol 168 ◽  
pp. 369-388 ◽  
Author(s):  
J. M. C. Rawlings ◽  
D. A. Williams ◽  
S. Viti ◽  
C. Cecchi-Pestellini ◽  
W. W. Duley
Keyword(s):  
Gas Phase ◽  
Molecular Clouds ◽  
Organic Molecules ◽  
Alternative Mechanism ◽  
Hydrogen Atoms ◽  
Interstellar Gas ◽  
Dark Cloud ◽  
Short Period ◽  
Molecular Abundances ◽  
Complex Organic

Complex Organic Molecules (COMs), such as propylene (CH3CHCH2) and the isomers of C2H4O2 are detected in cold molecular clouds (such as TMC-1) with high fractional abundances (Marcelino et al., Astrophys. J., 2007, 665, L127). The formation mechanism for these species is the subject of intense speculation, as is the possibility of the formation of simple amino acids such as glycine (NH2CH2COOH). At typical dark cloud densities, normal interstellar gas-phase chemistries are inefficient, whilst surface chemistry is at best ill defined and does not easily reproduce the abundance ratios observed in the gas phase. Whatever mechanism(s) is/are operating, it/they must be both efficient at converting a significant fraction of the available carbon budget into COMs, and capable of efficiently returning the COMs to the gas phase. In our previous studies we proposed a complementary, alternative mechanism, in which medium- and large-sized molecules are formed by three-body gas kinetic reactions in the warm high density gas phase. This environment exists, for a very short period of time, after the total sublimation of grain ice mantles in transient co-desorption events. In order to drive the process, rapid and efficient mantle sublimation is required and we have proposed that ice mantle ‘explosions’ can be driven by the catastrophic recombination of trapped hydrogen atoms, and other radicals, in the ice. Repeated cycles of freeze-out and explosion can thus lead to a cumulative molecular enrichment of the interstellar medium. Using existing studies we based our chemical network on simple radical addition, subject to enthalpy and valency restrictions. In this work we have extended the chemistry to include the formation pathways of glycine and other large molecular species that are detected in molecular clouds. We find that the mechanism is capable of explaining the observed molecular abundances and complexity in these sources. We find that the proposed mechanism is easily capable of explaining the large abundances of all three isomers of C2H4O2 that are observationally inferred for star-forming regions. However, the model currently does not provide an obvious explanation for the predominance of methyl formate, suggesting that some refinement to our (very simplistic) chemistry is necessary. The model also predicts the production of glycine at a (lower) abundance level, that is consistent with its marginal detection in astrophysical sources.

Variation of the amount of hydrogen along the galactic ridge

1967 ◽  
Vol 31 ◽  
pp. 171-172
Author(s):  
Th. Schmidt-Kaler
Keyword(s):  
Surface Brightness ◽  
Milky Way ◽  
Neutral Hydrogen ◽  
Line Of Sight ◽  
Optical Surface ◽  
Hydrogen Density ◽  
Continuous Radiation ◽  
Galactic Longitude

The integralNHof neutral-hydrogen density along the line of sight is determined from the Kootwijk and Sydney surveys. The run ofNHwith galactic longitude agrees well with that of thermal continuous radiation and that of the optical surface brightness of the Milky Way.

Imine as a Linchpin Approach for Distal C(sp2)–H Functionalization

2020 ◽  
Author(s):  
Sukdev Bag ◽  
Sadhan Jana ◽  
Sukumar Pradhan ◽  
Suman Bhowmick ◽  
Nupur Goswami ◽  
...  
Keyword(s):  
Organic Molecules ◽  
Bond Activation ◽  
Bond Formation ◽  
Ancillary Ligand ◽  
Significant Challenge ◽  
Site Selectivity ◽  
Directing Group ◽  
Covalently Linked ◽  
Complex Organic ◽  
Post Functionalization

<p>Despite the widespread applications of C–H functionalization, controlling site selectivity remains a significant challenge. Covalently attached directing group (DG) served as an ancillary ligand to ensure proximal <i>ortho</i>-, distal <i>meta</i>- and <i>para</i>-C-H functionalization over the last two decades. These covalently linked DGs necessitate two extra steps for a single C–H functionalization: introduction of DG prior to C–H activation and removal of DG post-functionalization. We introduce here a transient directing group for distal C(<i>sp<sup>2</sup></i>)-H functionalization <i>via</i> reversible imine formation. By overruling facile proximal C-H bond activation by imine-<i>N</i> atom, a suitably designed pyrimidine-based transient directing group (TDG) successfully delivered selective distal C-C bond formation. Application of this transient directing group strategy for streamlining the synthesis of complex organic molecules without any necessary pre-functionalization at the distal position has been explored.</p>

scholarly journals A Sustainable Improvement of ω-Bromoalkylphosphonates Synthesis to Access Novel KuQuinones

Organics ◽  
2021 ◽  
Vol 2 (2) ◽  
pp. 107-117
Author(s):  
Mattia Forchetta ◽  
Valeria Conte ◽  
Giulia Fiorani ◽  
Pierluca Galloni ◽  
Federica Sabuzi
Keyword(s):  
Metal Oxides ◽  
Phosphonic Acid ◽  
Organic Molecules ◽  
Building Blocks ◽  
Reaction Conditions ◽  
Phosphonic Acids ◽  
Sustainable Improvement ◽  
Phosphonate Esters ◽  
First Time ◽  
Complex Organic

Owing to the attractiveness of organic phosphonic acids and esters in the pharmacological field and in the functionalization of conductive metal-oxides, the research of effective synthetic protocols is pivotal. Among the others, ω-bromoalkylphosphonates are gaining particular attention because they are useful building blocks for the tailored functionalization of complex organic molecules. Hence, in this work, the optimization of Michaelis–Arbuzov reaction conditions for ω-bromoalkylphosphonates has been performed, to improve process sustainability while maintaining good yields. Synthesized ω-bromoalkylphosphonates have been successfully adopted for the synthesis of new KuQuinone phosphonate esters and, by hydrolysis, phosphonic acid KuQuinone derivatives have been obtained for the first time. Considering the high affinity with metal-oxides, KuQuinones bearing phosphonic acid terminal groups are promising candidates for biomedical and photo(electro)chemical applications.

scholarly journals Not Just Transporters: Alternative Functions of ABC Transporters in Bacillus subtilis and Listeria monocytogenes

2021 ◽  
Vol 9 (1) ◽  
pp. 163
Author(s):  
Jeanine Rismondo ◽  
Lisa Maria Schulz
Keyword(s):  
Bacillus Subtilis ◽  
Listeria Monocytogenes ◽  
Abc Transporters ◽  
Organic Molecules ◽  
Atp Hydrolysis ◽  
The Past ◽  
Wide Range ◽  
Regulatory Functions ◽  
Complex Organic ◽  
Detoxification Mechanisms

ATP-binding cassette (ABC) transporters are usually involved in the translocation of their cognate substrates, which is driven by ATP hydrolysis. Typically, these transporters are required for the import or export of a wide range of substrates such as sugars, ions and complex organic molecules. ABC exporters can also be involved in the export of toxic compounds such as antibiotics. However, recent studies revealed alternative detoxification mechanisms of ABC transporters. For instance, the ABC transporter BceAB of Bacillus subtilis seems to confer resistance to bacitracin via target protection. In addition, several transporters with functions other than substrate export or import have been identified in the past. Here, we provide an overview of recent findings on ABC transporters of the Gram-positive organisms B. subtilis and Listeria monocytogenes with transport or regulatory functions affecting antibiotic resistance, cell wall biosynthesis, cell division and sporulation.

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