Photo- and Proton-Dual-Responsive Fluorescence Switch Based on a Bisthienylethene-Bridged Naphthalimide Dimer and Its Application in Security Data Storage

Efficient regulation of fluorescence in molecular systems has raised considerable interest in recent years because of its significant potential application in fluorescent probes,[1] sensors,[2] memory devices,[3] logic gates,[4] etc. A large number of fluorescent molecular switches with response to light,[5] temperature,[6] electrochemical potential,[7] pH,[2a,8] and metal ions[2b,9] have thus been investigated. However, most of these systems show on/off switching of fluorescence in only single-mode stimulus–response. For further practical applications, and also to enhance the multifunctionality of these systems, it is better to combine highly integrated modes into a single molecular unit that can exhibit multiresponsive modulation of luminescence.[10] As far as optoelectronic devices are concerned, a molecule that can undergo different types of transformations depending on the type of external stimulus is expected to play a significant role in multiple-mode and complex information processing.[11] For example, recent progress in information technologies has triggered an increased need for data protection and data security.[12] In the case of security needs, some very important or private information needs to be safely protected, that is, the recorded information can be firstly concealed and then secondly displayed in another mode when needed. However, with the use of traditional single-mode stimulus– response molecules as storage media, it is hard to achieve such a function. The development of multiresponsive fluo-