Luminescent sensors and switches in the early 21st century

Abstract

Chemically induced switching of luminescence remains one of the more dramatic visual phenomena to be found in a laboratory. The past sliver of this century provides enough evidence that this phenomenon continues to entertain scientists in laboratories around the world in good numbers. It is also natural that such a humanly comprehensible signal would be put to good use in quantitating chemical species of various kinds, that is, luminescence sensors serve real-life needs in the wider world. Organic chemistry remains at the centre of this overall enterprise, since design, synthesis and characterization of mostly carbon-based molecules precedes the demonstration of luminescence switching. Our observation is that organic chemists as a community, especially those at the higher end of molecular synthesis, have largely remained aloof from luminescent sensors and switches. Our aim in this review is to appeal to this skillsbase and to suggest that luminescent sensors and switches can be a fitting creative output for hard-core organic chemists. After all, even molecules as small as aspirin had important enough social ramifications to inspire organic chemists. To keep this review within reasonable bounds, we will only track the trends of the past 5 years. Even then, we will only illustrate trends with those discoveries that caught our eye. Older literature will be cited only in an effort to note the foundations of these fresher discoveries. Readers wishing more background have a string of older reports to consult.