Determination of Gluconate Binding Properties on Magnetite Surface and Investigation of Carboxymethylation and Hydrazination Mechanisms of the Gluconated Magnetite Surface: A Computational Study

Abstract

In the present study, the probable binding structure of a gluconate molecule withmagnetite, (Fe3O4) nanoparticles, as well as, carboxymethylation and hydrazination mechanisms of thegluconate bound to the iron oxide surface have been computationally investigated by the DFT-B3LYPmethod. The B3LYP/LanL2DZ calculations together with experimental IR data available revealed thatthe probable binding structure of gluconate is bidentate bridged binding to the magnetite surface. Thecarboxymethylation and hydrazination mechanisms of gluconate were calculated at B3LYP/6-31+G(d,p) level of theory. The results indicate that the reaction between gluconate and chloroacetatein aqueous medium has one step mechanism passing through a low activation barrier (12.3 kcal/mol)with a reaction enthalpy of –42.8 kcal/mol. In addition, hydrazone bond formation reaction of thegluconate bound to the iron oxide surface has a highly-exothermic two-step-mechanism with barriersof 7.1 and 2.4 kcal/mol, respectively, in water. The activation barrier of the overall reaction is acceptedas the barrier of the first step since the barrier of this step is greater than that of the second one.Consequently, it can be predicted that both carboxymethylation and hydrazination reactions should bespontaneous under moderate conditions.