Molecular Engineering of Naphthalimide-based Dyad Systems to Generate Multifaceted Materials

Abstract

The search for multifunctional organic materials with tuneable photophysical properties has gained significant momentum in recent years. In this work, we demonstrate that molecular engineering of naphthalimide-based systems provide an effective strategy for programming their optical and self-assembly characteristics. By introducing a bulky substituent at the middle of a naphthalimide dyad, aggregation-induced emission enhancement (AIEE) was successfully achieved, leading to significantly enhanced solid-state luminescence. The structural modification also promoted the formation of diverse self-assembled nano- and micro-scale architectures. Furthermore, these naphthalimide systems exhibited intriguing charge-transfer interactions with electron-rich aromatic solvents, including toluene, mesitylene, and anisole. The resulting charge-transfer complexes displayed pronounced red-shifted emission with Stokes shifts of up to 100 nm. Notably, the complexes showed an unusual temperature-dependent photophysical response characterized by an increase in emission intensity upon heating, accompanied by a slight hypsochromic shift of the emission maximum. The study provides valuable insights into the development of advanced luminescent systems and offers new opportunities for designing functional materials for applications in sensing, nanotechnology, and optoelectronic devices.