Heteroatom-connected ferrocenyl substituted naphthalimides

Abstract

A family of heteroatom (oxygen, sulphur and nitrogen) connected ferrocenyl naphthalimides 3a–3f were designed and synthesized by the nucleophilic aromatic substitution and Buchwald coupling reactions. The effects of the heteroatom and ferrocenyl group on the photonic and electrochemical properties of the ferrocenyl naphthalimides were explored. The electronic absorption spectra of the ferrocenyl naphthalimides 3a–3f show a red shifted absorption as compared to 4-bromonaphthalimide 2. The nitrogen atom connected FcNMIs (3e and 3f) show a considerable red shift, whereas oxygen and sulphur connected FcNMIs (3a–3d) show a moderate red shift. The computational calculations show good agreement with the experimental results. The ferrocenyl naphthalimide containing a nitrogen atom (3e and 3f) show high thermal stability compared to the oxygen and sulphur containing dyes 3a–3d. The single crystal X-ray structures of 3a and 3c are reported and these crystal structures form 2-D network.