Sulphur linked six 1,8–naphthalimide–phenyl/naphthalene conjugates (NATs 1–6), were designed, synthesized and fully characterized by 1H NMR, 13C NMR and mass spectroscopy. The effects of aromatic substituent and molecular rigidity in NATs 1–6 on the absorption, fluorescence and aggregation induced emission (AIE)/aggregation induced emission enhancement (AIEE) were explored. NATs 1–5 and 6 were shown AIE and AIEE behavior in THF: water mixtures respectively. Molecular flexibility provided by the thioether linkage override steric hindrance in the 2,6–dimethylbenzenethiol–naphthalimide conjugate. The formation of nano–aggregates in THF: water (1:9 v/v) solution of NATs 1–6 were further confirmed by dynamic light scattering and transmission electron microscope.