Theoretical study of interaction of Fe13O8@Zn48O48 cluster with dopamine: Magnetic and optical properties

Abstract

In this study, we modelled the interaction of Fe13O8 and Fe13O8@Zn48O48 (core@shell) cluster with a biologically active dopamine molecule using density functional theory. First, the electronic, magnetic and optical properties of core@shell, Fe13O8@Zn48O48 cluster investigated and compared with isolated Fe13O8 and Zn48O48 clusters. Fe13O8@Zn48O48 cluster is found to be energetically stable. For Fe13O8 and Fe13O8@Zn48O48 clusters have the net magnetic moment 42 μB. The decrease in HOMO-LUMO gap of core@shell cluster as compared to that of isolated clusters reflects the higher reactivity. The results of the site dependent interaction of Fe13O8 and Fe13O8@Zn48O48 clusters with dopamine molecule are presented. The interaction strength is determined in terms of the cluster-dopamine complex binding energy and found to be enhanced for core@shell cluster than the Fe13O8. Furthermore, the calculated results predict that in presence of dopamine, the magnetic moment of Fe13O8 and Fe13O8@Zn48O48 cluster remains unaffected. The analysis of optical spectra of core@shell indicates the obvious red shift compared to Zn48O48 clusters. The optical spectra of Fe13O8@Zn48O48-dopamine shows the higher oscillator strength as compared to that of Fe13O8-dopamine complex. Fe13O8-dopamine complex gives rise to more quenched oscillator strengths as compared to that of bare iron oxide cluster. These results indicate interesting magneto-optical behaviour, which can be useful for biomedical applications.