One-Step Transformations from ACQ Luminogens to DSEgens via the Boc Protection Process

Dual-state emission
luminogens (DSEgens), as a new type
of luminescent
materials that can effectively emit light in solution and solid state,
have attracted tremendous attention due to their potential application
in chemical sensing, biological imaging, organic electronic devices,
etc. In this study, two new rofecoxib derivatives ROIN and ROIN-B have been synthesized, and their photophysical
properties are fully investigated by experimental studies and theoretical
calculations. The key intermediate ROIN, resulting from
one-step conjugation of rofecoxib with an indole unit, shows the classical
aggregation-caused quenching (ACQ) effect. Meanwhile, by introducing
a tert-butoxycarbonyl (Boc) group on the basis of ROIN without enlarging the π conjugation system, ROIN-B was successfully developed with an obvious DSE property.
In addition, both fluorescent behaviors and their transformation from
ACQ to DSE were elucidated clearly by going through the analysis of
their single X-ray data. Moreover, the target ROIN-B,
as a new DSEgens, also displays reversible mechanofluorochromism and
lipid droplet-specific imaging ability in HeLa cells. Taken together,
this work proposes a precise molecular design strategy to afford a
new DSEgens, which may provide guidance for the future exploration
of new DSEgens.