Modular synthesis of 4-aminocarbonyl substituted 1,8-naphthalimides and application in single molecule fluorescence detection

Enlightened approach to fluorescent sensors

28 February 2018

A family of fluorescent molecules that has illuminated several dark corners of biology, and can act as a molecular sensor, could soon see even wider use after a team of chemists improved its synthesis.

The family, known as 1,8-naphthalimides, is so versatile because of the many fluorescence-modifying chemical side chains that can be attached to it. For example, side chains that interact with fluoride or carbon dioxide have been developed and could help researchers study sources of the greenhouse gas. In the presence of their target, the sensor’s light output undergoes an easily detectable shift.

But until now the restrictive, multi-step synthetic method for attaching these side chains limited the modifications that could be made.

Palladium-catalysed cross coupling chemistry can attach all manner of side chains to 1,8-naphthalimides in a single step, a team led by Trent Ashton at Deakin University, Australia, has now shown. Using their new method, the team made a sensor that can fluoresce so strongly that individual molecules were visible through a microscope — a first for a 1,8-naphthalimide family member.

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References

1. Chemical Communications 53, 12298–12301 (2017). doi: 10.1039/c7cc07922b