This project will see the development and application of new, bespoke fluorescent molecular systems based on rylene diimide. Fluorescence provides a tunable, exquisitely sensitive readout allowing for detailed investigation and application down to the level of single molecules. This approach will be used to to study chemical reactions, energy transfer phenomena, design new tools and methodologies for microscopy (including emerging superresolution techniques) and develop 'designed for purpose' systems for a range of applications. The knowledge gained and proofs-of-principle established will impact in fields as diverse as energy storage and transduction, imaging and diagnostics and chemical reactions and catalysis.