Mineral--organic interfacial processes: potential roles in the origins of life

Life is believed to have originated on Earth 4.4–3.5 Ga ago, via processes in which organic compounds supplied by the environment self-organized, in some geochemical environmental niches, into systems capable of replication with hereditary mutation. This process is generally supposed to have occurred in an aqueous environment and, likely, in the presence of minerals. Mineral surfaces present rich opportunities for heterogeneous catalysis and concentration which may have significantly altered and directed the process of prebiotic organic complexification leading to life. We review here general concepts in prebiotic mineral-organic interfacial processes, as well as recent advances in the study of mineral surface-organic interactions of potential relevance to understanding the origin of life

Toward Accurate and Efficient Predictions of Entropy and Gibbs Free Energy of Adsorption of High Nitrogen Compounds on Carbonaceous Materials

The adsorption of high nitrogen compounds (HNCs) on the selected adsorption sites of carbonaceous materials from the gas phase has been investigated by ab initio quantum chemical methods at the density functional level applying both periodic and cluster approaches with M06-2X and BLYP functionals including dispersion forces (BLYP-D2). Among the possible structures of the adsorption complexes, the most stable systems possess nitrogen-containing heterocycles in a parallel orientation toward the modeled carbon surface. The adsorption enthalpies, calculated using the rigid rotor-harmonic oscillator approach (RRHO), were in good agreement with available experimental data. This approach was shown to provide sufficiently accurate adsorption enthalpies from the gas phase for the HNC–carbon systems. The vibrational, rotational, and translation contributions to the adsorption entropy were also analyzed by the approach extended beyond the RRHO scheme. The effects of anharmonic vibrations and internal rotations of the adsorbate on the adsorption sites of the modeled carbon surface were estimated. The Gibbs free energies calculated using the RRHO approach were adjusted to take into account the heterogeneity of the carbon surfaces and underestimation of the adsorption enthalpies at the BLYP-D2­(PBC) level. The corrected Gibbs free energy values of adsorption are negative for all of the investigated HNC–carbon systems, and they agree well with available experimental data. This suggests an effective adsorption of selected high nitrogen compounds on carbonaceous materials from the gas phase at 298.15 K. Partition coefficients for distribution of high nitrogen compounds on modeled carbon surfaces were also predicted in good agreement with the experimental results

Adsorption of Nitrogen-Containing Compounds on the (100) α‑Quartz Surface: Ab Initio Cluster Approach

A cluster approach extended to the ONIOM methodology has been applied using several density functionals and Møller–Plesset perturbation theory (MP2) to simulate the adsorption of selected nitrogen-containing compounds [NCCs, 2,4,6-trinitrotoluene (TNT), 2,4-dinitrotoluene (DNT), 2,4-dinitroanisole (DNAN), and 3-nitro-1,2,4-triazole-5-one (NTO)] on the hydroxyated (100) surface of α-quartz. The structural properties were calculated using the M06-2X functional and 6-31G­(d,p) basis set. The M06-2X-D3, PBE-D3, and MP2 methods were used to calculate the adsorption energies. Results have been compared with the data from other studies of adsorption of compounds of similar nature on silica. Effect of deformation of the silica surface and adsorbates on the binding energy values was also studied. The atoms in molecules (AIM) analysis was employed to characterize the adsorbate–adsorbent binding and to calculate the bond energies. The silica surface shows different sorption affinity toward the chemicals considered depending on their electronic structure. All target NCCs are physisorbed on the modeled silica surface. Adsorption occurs due to the formation of multiple hydrogen bonds between the functional groups of NCCs and surface silanol groups. Parallel orientation of NCCs interacting with the silica surface was found to be favorable when compared with perpendicularly oriented NCCs. NTO was found to be the most strongly adsorbed on the silica surface among all of the considered compounds. Dispersion correction was shown to play an important role in the DFT calculations of the adsorption energies of silica–NCC systems