Mutual influence on aggregation and magnetic properties of graphene oxide and copper phthalocyanine through non-covalent, charge transfer interaction

Investigations on the non-covalent, charge transfer interaction between graphene oxide (GO) sheets and un-substituted copper phthalocyanine (CuPc) revealed their mutual influence on their structural, optical and magnetic properties. While charge transfer interaction is found to change the aggregation of CuPc from J to H state, and this change increasing with GO concentration, the aggregation/stacking of GO is also found to be getting modified (increasing in this study) on interaction with CuPc. The charge transfer interaction is suggested to be mostly occurring through carboxyl groups at the edges of GO sheets, which could be causing this stacking/aggregation change of GO. While GO, CuPc and the nanocomposites exhibited paramagnetic behaviour, the saturation magnetization of the nanocomposites is observed to be lower than that expected. This is correlated to the reduction in the total spin (J) of GO and its subsequent altered magnetic response, which is attributed to the charge transfer interaction with CuPc. This study shows the possibility of tuning the magnetic properties of GO through such non-covalent, charge transfer routes. The improved optical limiting behaviour of the nanocomposites is further attributed to the charge transfer interaction and the increase in stacking of GO.