Monomers of Glycine and Serine Have a Limited Ability to Hydrate in the Atmosphere

The
role of atmospheric aerosols on climate change is one of the biggest
uncertainties in most global climate models. Organic aerosols have
been identified as potential cloud condensation nuclei (CCN), and
amino acids are organic molecules that could serve as CCN. Amino acids
make up a significant portion of the total organic material in the
atmosphere, and herein we present a systematic study of hydration
for two of the most common atmospheric amino acids, glycine and serine.
We compute DLPNO/CCSD­(T)//M08-HX/MG3S thermodynamic properties and
atmospheric concentrations of Gly­(H2O)n and Ser­(H2O)n, where n = 1–5. We predict that serine–water clusters
have higher concentrations at n = 1 and 5, while
glycine–water clusters have higher concentrations at n = 2–4. However, both glycine and serine are inferred
to exist primarily in their nonhydrated monomer forms in the absence
of other species such as sulfuric acid.