TY - JOUR
T1 - PKa determination of graphene-like materials
T2 - Validating chemical functionalization
AU - Orth, Elisa S.
AU - Ferreira, José G.L.
AU - Fonsaca, Jéssica E.S.
AU - Blaskievicz, Sirlon F.
AU - Domingues, Sergio H.
AU - Dasgupta, Archi
AU - Terrones, Mauricio
AU - Zarbin, Aldo J.G.
N1 - Publisher Copyright:
© 2016 Elsevier Inc.
PY - 2016/4/1
Y1 - 2016/4/1
N2 - We report a novel pKa determination for different graphene-like samples: graphene oxide (GO), reduced GO (rGO), graphene nanoribbons (GNR), oxidized GNR (GONR), thiol- and imidazole-functionalized GO (GOSH and GOIMZ, respectively) and thiol-functionalized GONR (GONRSH). Using the specialized computational program BEST7 for treating titration curves, pKas for different functional groups were discriminated (confirmed by infrared spectra) and their composition quantified. Overall, three equilibria were distinguished, two relative to carboxylic acids exhibiting different acidic degrees (pKa1~4.0 and pKa2~6.0) and one relative to alcohols (pKa4~10.0). Upon functionalization on carboxylate sites, thiol (pKaGOSH/GONRSH=6.7) and imidazole (pKaGOIMZ=6.6) moieties were discerned, followed by a decrease of their carboxylate percentage (compared to the precursors), thus allowing determining the degree of functionalization (48% and 36% of thiol content for GOSH and GONRSH respectively, and 29% of imidazole for GOIMZ). The proposed method is innovative and simpler when compared to the traditional tools usually employed to quantify chemical functionalization.
AB - We report a novel pKa determination for different graphene-like samples: graphene oxide (GO), reduced GO (rGO), graphene nanoribbons (GNR), oxidized GNR (GONR), thiol- and imidazole-functionalized GO (GOSH and GOIMZ, respectively) and thiol-functionalized GONR (GONRSH). Using the specialized computational program BEST7 for treating titration curves, pKas for different functional groups were discriminated (confirmed by infrared spectra) and their composition quantified. Overall, three equilibria were distinguished, two relative to carboxylic acids exhibiting different acidic degrees (pKa1~4.0 and pKa2~6.0) and one relative to alcohols (pKa4~10.0). Upon functionalization on carboxylate sites, thiol (pKaGOSH/GONRSH=6.7) and imidazole (pKaGOIMZ=6.6) moieties were discerned, followed by a decrease of their carboxylate percentage (compared to the precursors), thus allowing determining the degree of functionalization (48% and 36% of thiol content for GOSH and GONRSH respectively, and 29% of imidazole for GOIMZ). The proposed method is innovative and simpler when compared to the traditional tools usually employed to quantify chemical functionalization.
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U2 - 10.1016/j.jcis.2016.01.013
DO - 10.1016/j.jcis.2016.01.013
M3 - Article
C2 - 26803603
AN - SCOPUS:84955507338
SN - 0021-9797
VL - 467
SP - 239
EP - 244
JO - Journal of Colloid And Interface Science
JF - Journal of Colloid And Interface Science
ER -