Nanohybrids of phenolic antioxidant intercalated into MgAl-layered double hydroxide clay

A sterically hindered phenol-type antioxidant, 3-(3, 5-di-tert-butyl-4-hydroxy-phenyl)-propionic acid (BHPPA) has been successfully intercalated into Mg-Al layered double hydroxide (LDH) by utilizing the structural memory effect. The intercalated layered structure was characterized by powder X-ray diffraction, FT-IR spectroscopy and scanning electron microscopy (SEM). The increase in basal spacing from 0.77 to 2.80 nm suggests the tilted bilayer arrangement of BHPPA anion into LDH galleries which is further confirmed by structural modelling. The antioxidant activity of resulting hybrids was assessed against 2,2-diphenyl-2-picrylhydrazil radical (DPPH) and monitored by UV-Vis spectroscopy. In resulting layered hybrids, antioxidant retains its activity and exhibit significant free radical scavenging ability. The thermal stability of the antioxidant was markedly enhanced after intercalation into the LDH host. Overall results reveal the existence of possible supramolecular host–guest interactions and offer an inorganic/organic (I/O) LDH/antioxidant assembly as new multifunctional layered nanomaterial.

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► Intercalation of hindered phenolic antioxidant into LDHs galleries was demonstrated.
► Bilayer molecular arrangement of antioxidant was observed by structural modelling.
► After intercalation the thermal stability of antioxidant improved by 100°C.
► Immobilized antioxidant exhibit sustained free radical scavenging activity.