Piperazine appended naphthalimide-based organic scaffolds exhibiting efficient aggregation induced emission (AIE) and selective picric acid sensing

Abstract

AIEgens (5a−5c &6a−6c) derived from piperazine-appended naphthalimide have been synthesized via strategic modifications following multi-step process. Resulting compounds have been thoroughly characterized by spectroscopic techniques (IR, NMR (1H &13C), HRMS, UV/Vis and fluorescence spectroscopy). The compounds under study represent an asymmetric donor-acceptor (D-A) system with a D-A′-π-A construct. Expectedly, these display efficient aggregation-induced emission (AIE) which has been followed by UV/Vis, fluorescence, fluorescence lifetime and morphological (SEM) studies. Morphological studies on these systems revealed spherical nanostructures in aggregated state. These compounds display solid-state emission and solvatochromism. It has been observed that the donor unit plays a crucial role in directing photophysical properties including AIE. Moreover, synthesized compounds exhibited selective sensing toward picric acid. Further, DFT studies have been performed to support and co-relate the physical properties.