Radical-doped asymmetrical naphthalenediimides derivatives: Multiple stimuli chromism and their mechanical grinding toning with organic molecules

Abstract Realizing multiple stimuli responsiveness in organic molecular systems is very important and highly desirable to broaden their potential applications in smart materials. Such stimuli responsive materials are usually required in nontrivial multistep synthesis. In the present research, a series of asymmetrical naphthalene diimide derivatives (NDIs), which display interesting multiple external stimuli responsiveness including ultrafast photochromism and chemical stimulation chromism, with the generations of organic radical anions and charge transfer, were obtained by simple synthetic process. Importantly, the multicolored functionality was ingeniously achieved by mixing commercially available materials (guest molecules) and the readily-made asymmetrical NDIs through mechanical grinding under solvent-free conditions. Noteworthy the charge transfer processes, strongly depending on the distinctive structures of NDIs molecules as well as the weak intermolecular interactions, can be induced by external stimuli (i. e. light, chemical, or grinding). Subsequently, significant stimuli responsiveness as well as multicolored properties were realized and the underlying weak interactions-assisted charge transfer mechanism was thoroughly unearthed.