Establishing a molecular relationship between chondritic and cometary organic solids

Abstract

Multidimensional solid-state NMR spectroscopy is used to refine the identification and abundance determination of functional groups in insoluble organic matter (IOM) isolated from a carbonaceous chondrite (Murchison, CM2). It is shown that IOM is composed primarily of highly substituted single ring aromatics, substituted furan/pyran moieties, highly branched oxygenated aliphatics, and carbonyl groups. A pathway for producing an IOM-like molecular structure through formaldehyde polymerization is proposed and tested experimentally. Solid-state 13 C NMR analysis of aqueously altered formaldehyde polymer reveals considerable similarity with chondritic IOM. Carbon X-ray absorption near edge structure spectroscopy of formaldehyde polymer reveals the presence of similar functional groups across certain Comet 81P/Wild 2 organic solids, interplanetary dust particles, and primitive IOM. Variation in functional group concentration amongst these extraterrestrial materials is understood to be a result of various degrees of processing in the parent bodies, in space, during atmospheric entry, etc. These results support the hypothesis that chondritic IOM and cometary refractory organic solids are related chemically and likely were derived from formaldehyde polymer. The fine-scale morphology of formaldehyde polymer produced in the experiment reveals abundant nanospherules that are similar in size and shape to organic nanoglobules that are ubiquitous in primitive chondrites.

Two homologous series of alkylpyridines in the Murchison meteorite

“…Relatively simple aldehydes such as formaldehyde and acetaldehyde can be found in molecular clouds, and may have been present in protoplanetary disks and primordial solar nebulae (e.g., Charnley, 2004;Tielens, 2005;Snyder, 2006;Dutrey et al, 1997). Formation of a formaldehyde polymer by aldol condensation has been emphasized for a possible origin of insoluble organic matter (IOM) in meteorites (Cody et al, 2011;Kebukawa et al, 2013). This study further indicates a contribution of aldol condensation products to soluble organic matter (SOM).…”

X-ray absorption near edge structure spectroscopic study of Hayabusa category 3 carbonaceous particles

“…Their spectral patterns of aromatic/ olefinic carbon, aromatic ketone, and carboxyl carbon are typical of those observed from terrestrial coal (Cody et al 1998;Bassim et al 2012) and kerogen (Bernard et al 2012) and even extraterrestrial organic solids from chondritic meteorites and IDPs (e.g., Flynn et al 2003;Cody et al 2011). This does not necessarily imply that our category 3 particles are coal or chondritic organics, but the findings do suggest the presence of some form of heterogeneous macromolecule formed through chemical processing in a natural environment.…”

“…; Ade et al 1992;Urquhart et al 1999), but it has been applied to a broad range of research areas. In cosmochemistry, STXM has been applied for organic chemical analyses of interplanetary dust particles (IDPs) (Flynn et al 2003(Flynn et al , 2013Busemann et al 2009), particles from Comet Wild 2 (Sanford et al 2006;Cody et al 2008a;De Gregorio et al 2010), acid-insoluble organic solids from chondritic meteorites (Cody et al 2008b, Cody et al 2011, and an Antarctic ultracarbonaceous micrometeorite (Yabuta et al 2013). Thus, an abundant database of XANES spectra for both terrestrial and extraterrestrial organic compounds is available for the chemical characterization of unknown carbonaceous samples.…”

Cosmochemistry: Understanding the Solar System through analysis of extraterrestrial materials

“…Some meteorites and comets contain abundant organic matter of nonbiologic origin. How that matter forms and evolves is complex, and the work by Cody et al (30) reviews what we know about the processes that occur on small bodies that produce complex organic molecules. Finally, in acknowledgment of the fact that advances in cosmochemistry are highly technology-dependent, two papers are dedicated to the analytical methods themselves.…”