A new series of 2-aminoethyl-benzene-based
biomaterials, namely,
dopamine (DOP), tyramine (TYR), phenylethylamine (PEA), and epinephrine
(EPN), dissolved in dimethylsulfoxide (DMSO) have been investigated
for CO
2
capture upon activatiing their hydhydrochloride salts
with a NaOH pellet. Spectroscopic measurements, including ex situ
ATR-FTIR, 1D and 2D NMR experiments have been applied to verify
the formation of the sodium carbamate adducts (RR′N-CO
2
–
Na
+
). The emergence of new
peaks in the IR spectra ranging between 1702 and 1735 cm
–1
together with the chemical shift within 157–158 ppm in the
13
C NMR, as well as with cross-peaks obtained by
1
H-
15
N HSQC measurements at ca. 84 and 6.6 ppm verified
the formation of RR′N-CO
2
–
Na
+
products upon the chemical fixation of CO
2
. The
CO
2
sorption capacity of the examined biomaterials was
evaluated volumetrically, with a maximum value of 8.18 mmol CO
2
·g
–1
sorbent (36.0 (w/w)%, including
both chemisorption and physisorption), for 5 (w/v)% solutions measured
at 5 bar CO
2
and 25 °C, for TYR and PEA. DFT calculations
indicated that the intramolecular hydrogen bonding within the structural
motif of EPN-N-CO
2
–
Na
+
adduct
provides an exceptional stability compared to monoethanolamine and
other structurally related model compounds.