Thiamine pyrophosphate intercalation in layered double hydroxides (LDHs): An active bio-hybrid catalyst for pyruvate decarboxylation

The intercalation of thiamine pyrophosphate (TPP) into Zn–Al and Mg–Al layered double hydroxides has been investigated using two different methods: the co-precipitation procedure (at different pH values) and the ion-exchange reaction. The structure of the hybrid materials was studied by X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) spectroscopy verifying that the TPP molecules prefer creating a bilayer arrangement at pH = 7.5, 7.75 and 8, while in the case of pH = 7 a monolayer of TPP molecules coexists in the interlayer space of LDHs. In addition, the thermal decomposition of the bio-hybrid materials was examined by thermogravimetry and differential thermal analysis (TG–DTA). The total amount of the deintercalated TPP molecules from LDHs was calculated after de-intercalation reactions in the presence of carbonate ions by Ultraviolet (UV) spectroscopy. Furthermore, the hybrid materials (TPP/LDH) have been tested as biomimetic catalysts for decarboxylation of pyruvic acid showing a comparable activity to the homogenous system (TPP). Our combined data confirm that thiamine pyrophosphate can be safely loaded and stored into LDHʹs layers forming a new bio-active hybrid material.