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All sourcesNASA NTRSDOE OSTI
NASA NTRS1991

Theoretical studies of the extraterrestrial chemistry of biogenic elements and compounds

Organic compounds, molecules related to those in living systems, are found in many different extraterrestrial environments. The study of organic astrochemistry is important to exobiology both because it demonstrates the ubiquity of processes which led to life on Earth and because the dust clouds where molecules are found are analogs of the solar nebula from which the Earth formed. In the long chain of events leading from the Big Bang, and a universe composed of atomic hydrogen and helium, to the emergence of life on Earth, molecular interstellar clouds are an early link, the most primitive objects which display any significant organic chemistry. One such cloud was the direct precursor to the solar system and to all objects which it contains. Theoretical methods are ideally suited to studying interstellar cloud chemistry. They have been applied to determine spectroscopic constants of candidate interstellar molecules, mechanisms of ion-molecule reactions, and composition of dust grains. Accurate predictions of rotational constants and dipole moments of long-chain carbon molecules HC13N, HC15N, and C5O have been made to aid in determining the size limit of gas-phase interstellar molecules. Models of gas-phase interstellar chemistry use reaction rate constants measured at room temperature and extrapolated to interstellar temperatures. The temperature dependence of NH3(+)+H2 yields NH4(+)+H is anomalous, however, with a minimum rate at about 100K, casting doubt on the extrapolation procedures. The temperature dependence has now been explained.

Defrees, D. J.↗
NASA NTRS2004

The Cassini-Huygens Mission: Exo/Astro/Cosmobiological Perspectives

One of the main objectives of the Cassini-Huygens mission is to explore Titan in great detail and to study in particular the many exobiological aspects of Titan, this exotic world which presents so many analogies with our planet. The Cassini orbiter and the Huygens probe, in a complementary way, will systematically study the many chemical and physical aspects of the different parts of what can be called the "geofluid" of Titan. Many of the twelve instruments of the Cassini orbiter and most of the six instruments of the Huygens probe will provide much information of crucial importance for our knowledge of the complexity of Titan's organic chemistry. This is particularly the case with the GC-M4S and ACP experiments which will provide the first in situ chemical (including isotopic and molecular) analyses of the gas and aerosol phases of Titan's atmosphere. Indeed, because of the presence of a dense atmosphere, mainly made of N2 with noticeable fraction of CH4, and of an environment very rich in organics, and of many couplings involved in the various parts of its geofluid, in spite of low temperatures and the absence of liquid water, Titan is a reference for studying prebiotic chemistry on a planetary scale. Many programs have recently been developed to study in detail Titan's chemistry, in direct connection with the Cassini-Huygens mission. They include new observations, development of photochemical models, laboratory determination of IR and UV spectra of organics of interest for Titan's atmosphere, and experimental studies, such as laboratory simulation of Titan's gas and aerosol organic chemistry. The paper will review the exobiological aspects of Titan. It will also present some of the new data concerning Titan s organic chemistry that have been obtained through the several possible approaches and discuss the exobiological implication of the potential scientific return of the Cassini-Huygens mission.

Raulin, F.↗
DOE OSTI2020

Exploration of oxidative chemistry and secondary organic aerosol formation in the Amazon during the wet season: explicit modeling of the Manaus urban plume with GECKO-A

The GoAmazon 2014/5 field campaign took place in Manaus, Brazil, and allowed the investigation of the interaction between background-level biogenic air masses and anthropogenic plumes. We present in this work a box model built to simulate the impact of urban chemistry on biogenic secondary organic aerosol (SOA) formation and composition. An organic chemistry mechanism is generated with the Generator for Explicit Chemistry and Kinetics of Organics in the Atmosphere (GECKO-A) to simulate the explicit oxidation of biogenic and anthropogenic compounds. A parameterization is also included to account for the reactive uptake of isoprene oxidation products on aqueous particles. The biogenic emissions estimated from existing emission inventories had to be reduced to match measurements. The model is able to reproduce ozone and NO x for clean and polluted situations. The explicit model is able to reproduce background case SOA mass concentrations but does not capture the enhancement observed in the urban plume. The oxidation of biogenic compounds is the major contributor to SOA mass. A volatility basis set (VBS) parameterization applied to the same cases obtains better results than GECKO-A for predicting SOA mass in the box model. The explicit mechanism may be missing SOA-formation processes related to the oxidation of monoterpenes that could be implicitly accounted for in the VBS parameterization.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS2012

Enantiomer Ratios of Meteoritic Sugar Derivatives

Carbonaceous meteorites contain a diverse suite of soluble organic compounds. Studies of these compounds reveal the Solar System's earliest organic chemistry. Among the classes of organic compounds found in meteorites are keto acids (pyruvic acid, etc.), hydroxy tricarboxylic acids (1), amino acids, amides, purines and pyrimidines. The Murchison and Murray meteorites are the most studied for soluble and insoluble organic compounds and organic carbon phases. The majority of (indigenous) meteoritic compounds are racemic, (i.e., their D/L enantiomer ratios are 50:50). However, some of the more unusual (non-protein) amino acids contain slightly more of one enantiomer (usually the L) than the other. This presentation focuses on the enantiomer analyses of three to six-carbon (3C to 6C) meteoritic sugar acids. The molecular and enantiomer analysis of corresponding sugar alcohols will also be discussed. Detailed analytical procedures for sugar-acid enantiomers have been described. Results of several meteorite analyses show that glyceric acid is consistently racemic (or nearly so) as expected of non-biological mechanisms of synthesis. Also racemic are 4-C deoxy sugar acids: 2-methyl glyceric acid; 2,4-dihydroxybutyric acid; 2,3-dihydroxybutyric acid (two diastereomers); and 3,4-dihydroxybutyric acid. However, a 4C acid, threonic acid, has never been observed as racemic, i.e., it possesses a large D excess. In several samples of Murchison and one of GRA 95229 (possibly the most pristine carbonaceous meteorite yet analyzed) threonic acid has nearly the same D enrichment. In Murchison, preliminary isotopic measurements of individual threonic acid enantiomers point towards extraterrestrial sources of the D enrichment. Enantiomer analyses of the 5C mono-sugar acids, ribonic, arabinonic, xylonic, and lyxonic also show large D excesses. It is worth noting that all four of these acids (all of the possible straight-chained 5C sugar acids) are present in meteorites, including the rare lyxonic acid, and their relative abundances are in equilibrium proportions. In addition (in contrast to the above D-only excesses), some of the above acids are found in biology as the L enantiomer. Whether rare are common, all of the 6C sugar acids that are present in sufficient amounts to allow enantiomer analysis (Mannonic, gluconic, altronic, talonic, idonic, gulonic, and galactonic) also, apparently, possess significant D excesses.

Cooper, George↗
NASA NTRS2015

Water as a Solvent for Life

"Follow the water" is our basic strategy in searching for life in the universe. The universality of water as the solvent for living systems is usually justified by arguing that water supports the rich organic chemistry that seeds life, but alternative chemistries are possible in other organic solvents. Here, other, essential criteria for life that have not been sufficiently considered so far, will be discussed.

terrestrial life↗
NASA NTRS2018

Is Water Necessary for Life?

The universality of water as the solvent for life is usually justified by its role in supporting the rich organic chemistry. It has been pointed out, however, that even richer synthetic chemistry is possible in other organic solvents. Does it mean that water is not necessary for life? Here, other, essential criteria for solvent for life that have not been sufficiently considered are discussed. In biological systems, complex molecules are not only constantly synthesized but also degraded. Solvent-mediated degradation is essential for regulating cell content, preventing overcrowding and allowing for recycling organic material. Achieving a balance between synthetic and degradative processes is facile in water, but not in many other organic liquids. Thus, the so-called “water paradox” according to which water is both necessary to life and toxic to biopolymer synthesis might not be paradoxical at all. The machinery of life is based on non-covalent interactions that do not involve making or breaking chemical bonds. Their strength needs to be properly tuned. If they are too weak, there might be undesired response to natural fluctuations of physical or chemical parameters. If they are too strong, the kinetics and energetics of cellular processes could adversely influenced. The solvent must allow for balancing these interactions, which provides strong, universal constraints on the medium for life. Water influences non-covalent interactions mainly by two mechanisms. First, it reduces strong, electrostatic interactions between molecules, chemical groups or atoms carrying electric charge or dipole. Second, it induces the hydrophobic effect, the tendency to remove non-polar (hydrophobic) molecules and groups from direct contact with aqueous solution and, instead, interact with each other. In living systems, the hydrophobic effect is largely responsible for self-organization of molecules to more complex structures, such as aggregation of lipid molecules to form biological membranes and protein folding. Water exists as stable liquid in a large temperature range, and the hydrophobic effects are a consequence of the temperature insensitivity of essential properties of its liquid state. In summary, water accomplishes an amazing feat – it reduces strong interactions between dissolved species and simultaneously increases the strength of weak interactions, bringing all of them to the right range. Once we consider not only synthetic capabilities but also other required traits of the solvent for life, no viable alternative to water is currently known.

Life↗
DOE OSTI2023

Climate, Variability, and Climate Sensitivity of “Middle Atmosphere” Chemistry Configurations of the Community Earth System Model Version 2, Whole Atmosphere Community Climate Model Version 6 (CESM2(WACCM6))

Abstract Simulating whole atmosphere dynamics, chemistry, and physics is computationally expensive. It can require high vertical resolution throughout the middle and upper atmosphere, as well as a comprehensive chemistry and aerosol scheme coupled to radiation physics. An unintentional outcome of the development of one of the most sophisticated and hence computationally expensive model configurations is that it often excludes a broad community of users with limited computational resources. Here, we analyze two configurations of the Community Earth System Model Version 2, Whole Atmosphere Community Climate Model Version 6 (CESM2(WACCM6)) with simplified “middle atmosphere” chemistry at nominal 1 and 2° horizontal resolutions. Using observations, a reanalysis, and direct model comparisons, we find that these configurations generally reproduce the climate, variability, and climate sensitivity of the 1° nominal horizontal resolution configuration with comprehensive chemistry. While the background stratospheric aerosol optical depth is elevated in the middle atmosphere configurations as compared to the comprehensive chemistry configuration, it is comparable among all configurations during volcanic eruptions. For any purposes other than those needing an accurate representation of tropospheric organic chemistry and secondary organic aerosols, these simplified chemistry configurations deliver reliable simulations of the whole atmosphere that require 35% and 86% fewer computational resources at nominal 1 and 2° horizontal resolution, respectively.

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS1994

Prebiotic chemistry in space; Proceedings of Symposia B1.4 and F3.3 of the COSPAR Scientific Assembly, 30th, Hamburg, Germany, July 11-21, 1994

A two-part symposium was held concerning topics in Solar System chemistry. The first part covered the organic chemistry ofsmall bodies of the interplanetray medium. It produced papers on the evolution, spectral properties and composition of organic matter in comets, interplanetary dust and asteroids. The second part covered cryochemistry and exobiology in planetary atmospheres (gas giant planets and their satellites) and in various astronomical ices.

Source record↗
DOE OSTI2020

Direct Oxidation of Primary Alcohols to Carboxylic Acids

Oxidation of primary alcohols to carboxylic acids is a fundamental transformation in organic chemistry, yet despite its simplicity, extensive use, and relationship to pH, it remains a subject of active research for synthetic organic chemists. Since 2013, a great number of new methods have emerged that utilize transition-metal compounds as catalysts for acceptorless dehydrogenation of alcohols to carboxylates. The interest in this reaction is explained by its atom economy, which is in accord with the principles of sustainability and green chemistry. Furthermore, the methods for the direct synthesis of carboxylic acids from alcohols is ripe for a modern survey, which we provide in this review.

acceptorless dehydrogenation↗
NASA NTRS1980

Chemical research projects office: An overview and bibliography, 1975-1980

The activities of the Chemical Research Projects Office at Ames Research Center, Moffett Field, California are reported. The office conducts basic and applied research in the fields of polymer chemistry, computational chemistry, polymer physics, and physical and organic chemistry. It works to identify the chemical research and technology required for solutions to problems of national urgency, synchronous with the aeronautic and space effort. It conducts interdisciplinary research on chemical problems, mainly in areas of macromolecular science and fire research. The office also acts as liaison with the engineering community and assures that relevant technology is made available to other NASA centers, agencies, and industry. Recent accomplishments are listed in this report. Activities of the three research groups, Polymer Research, Aircraft Operating and Safety, and Engineering Testing, are summarized. A complete bibliography which lists all Chemical Research Projects Office publications, contracts, grants, patents, and presentations from 1975 to 1980 is included.

Kourtides, D. A.↗
DOE OSTI2020

Advances in supramolecular host-mediated reactivity

Since the trailblazing discoveries of Lehn, Cram and Pedersen, supramolecular chemistry has established itself as a cornerstone of organic chemistry. Supramolecular hosts offer defined microenvironments that mimic the active sites of enzymes, utilizing specific host–guest interactions to enable remarkable rate enhancements and product selectivity. The development of a diverse array of self-assembled hosts, coupled with the increased demand for shorter and greener synthetic routes, have spurred significant progress in the field of supramolecular catalysis. This Review Article covers recent advances in the field, ranging from novel organic reactivity aided by supramolecular hosts to catalytic cooperation between hosts and organometallic compounds or metal nanoparticles. Furthermore, strides have also been made in the synthetic application of these hosts in site-selective substrate modifications and challenging photochemical reactions. These efforts have enabled the incorporation of non-covalent macromolecular catalysis in natural product syntheses, evidencing their unique advantages as a synthetic tool, and their powerful potential for practical applications.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Dehydration of gas-phase benzyl amine alcohols studied at atmospheric pressure

Gas-phase ion chemistry is a useful approach for the investigation of physical organic chemistry and the study of reactivity, structure, and thermochemical properties of ionic and neutral organic substrates. Herein, one-step dehydration of gas-phase benzyl amine alcohols to give benzazetidines was discovered without the use of catalysts. Mechanistic investigations of the gas-phase dehydration reactions were explored to study the possible influence of charged microdroplet acceleration during electrospray ionization (ESI) and collisions occurring during ion transfer through the atmospheric pressure interface (API) of the mass spectrometer. The product ion distribution was observed to be less sensitive to droplet effects (spray distance and voltage), and temperature of transfer capillary in the API. However, the product ion distribution exhibit high sensitivity to different S-lens radio frequency (RF) voltage of the API, providing evidence that the dehydration reaction is driven by collisions during ion transfer in the API. With this insight, we developed atmospheric pressure thermal dissociation platform that allowed thermal-induced collisions outside of the mass spectrometer when the benzyl amine alcohols are carried through a heated coiled tube. Up to 98% dissociation efficiency was achieved with the coiled tube heated to a temperature of 200 °C, yielding only the desired benzazetidine product. Finally, by performing the atmospheric pressure thermal dissociation experiment outside of the mass spectrometer, we believe it will be straightforward to collect the dehydration product.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Strapped calix[4]pyrroles: from syntheses to applications

Supramolecular chemistry is a central topic in modern chemistry. It touches on many traditional disciplines, such as organic chemistry, inorganic chemistry, physical chemistry, materials chemistry, environmental chemistry, and biological chemistry. Supramolecular hosts, inter alia macrocyclic hosts, play critical roles in supramolecular chemistry. Calix[4]pyrroles, non-aromatic tetrapyrrolic macrocycles defined by sp 3 hybridized meso bridges, have proved to be versatile receptors for neutral species, anions, and cations, as well as ion pairs. Compared to the parent system, octamethylcalix[4]pyrrole and its derivatives bearing simple appended functionalities, strapped calix[4]pyrroles typically display enhanced binding affinities and selectivities. In this review, we summarize advances in the design and synthesis of strapped calix[4]pyrroles, as well as their broad utility in molecular recognition, supramolecular extraction, separation technology, ion transport, and as agents capable of inhibiting cancer cell proliferation. Future challenges within this sub-field are also discussed.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2026

The ballad of LLM agents: philosophical reasoning for chemistry

Large language models (LLMs) show remarkable potential for scientific reasoning but often produce unreliable or scientifically unactionable outputs when faced with multi-step logic, domain grounding, and interpretability challenges, especially in complex fields like chemistry and materials science. Here, we introduce a framework of philosophical reasoning agents, inspired by canonical thinkers such as Socrates, Descartes, Kant, and Hume, to guide LLM behavior via structured prompt engineering. These agents embody distinct reasoning paradigms (dialectical inquiry, deductive logic, rule-based judgment, and empirical validation) and are evaluated across multiple chemistry subdomains, physical, analytical, general, inorganic, and organic chemistry, using the ChemBench benchmark. Our agentic prompting approach yields substantial accuracy gains on open-ended numerical chemistry questions, with gains of +11.5 percentage points for GPT-4o with Hume, +4.5 percentage points for GPT-5 with Kant, and +21.8 percentage points for GPT-5.1 with Socrates at the strict 1% error threshold, relative to the corresponding base models. Beyond accuracy, we observe benchmark-level model–agent performance patterns, suggesting that different prompting styles interact differently with each base model. These findings demonstrate that embedding philosophy-of-science principles into multi-agent frameworks can improve and produce interpretable, adaptive, and domain-aligned scientific LLMs.

Harb, Hassan [Argonne National Laboratory (ANL), A↗
NASA NTRS1978

Exobiology and the origin of life

Research supported wholly or in part by NASA is summarized, Topics covered include the molecular analysis of ultraviolet-photoproduced organic solids synthesized under simulated Jovian conditions; the molecular analysis of organic solids produced by electrical discharge in reducing atmospheres; the organic chemistry of interstellar grains; the spectra of possible organic solids present as aerosols in planetary atmospheres; far infrared studies of organic polymers of possible astrophysical interest; organic dust synthesized in reducing environments by ultraviolet radiation or electric discharge; the diffusion of galactic civilizations; eavesdropping on galactic civilizations; Lander imaging as a detector of life on Mars; and continuing puzzles about Mars. Bibliographic data is included for four additional publications not supported by NASA grant, but related to the objectives of the program.

Sagan, C.↗
NASA NTRS2005

Keto-acids in Carbonaceous Meteorites

The Murchison and Murray meteorites are the best-characterized carbonaceous meteorites with respect to organic chemistry and are generally used as references for organic compounds in extraterrestrial material. Among the classes of organic compounds found in these meteorites are amino acids, carboxylic acids, hydroxy acids, purines, and pyrimidines. Such compounds, important in contemporary biochemistry, are thought to have been delivered to the early Earth in asteroids and comets and may have played a role in early life and/or the origin of life. Absent among (today's) critically important biological compounds reported in carbonaceous meteorites are keto acids, i.e., pyruvic acid, acetoacetic acid, and higher homologs. These compounds are key intermediates in such critical processes as glycolysis and the citric acid cycle. In this study several individual meteoritic keto acids were identified by gas chromatography-mass spectrometry (GC-MS) (see figure below). All compounds were identified as their trimethylsilyl (TMS), isopropyl ester (ISP), and tert-butyldimethylsilyl (tBDMS) derivatives. In general, the compounds follow the abiotic synthesis pattern of other known meteorite classes of organic compounds [1,2]: a general decrease in abundance with increasing carbon number within a class of compounds and many, if not all, possible isomers present at a given carbon number. The majority of the shown compounds was positively identified by comparison of their mass spectra to commercially available standards or synthesized standards.

Cooper, G.↗