Naphthalene-based fluorophores: Structure, properties and applications

Naphthalene-based fluorophores have been widely used in different applications such as fluorescent sensors, biological/medical labels, in the development of lightharvesting systems and materials for light-emitting diodes. Typically, the naphthalene scaffold has low molecular weight and its properties depend strongly on the number, type and position of the substituent groups in the ring. Although the unsubstituted naphthalene is poorly fluorescent, when donor and acceptor groups are attached to positions 2 and 6 of the ring, the fluorescence increases significantly through an Intramolecular Charge Transfer (ICT) mechanism. Substantial changes in the fluorescence spectrum, quantum yield and lifetime are often observed with solvent changes or as a result of binding to a substrate. All aspects related with the design, synthesis and photophysical properties of the naphthalene-based fluorophores will be highlighted in this chapter. Also, naphthalene-based fluorescent chemosensors incorporating a specific binding site for sensing cations and anions will also be focused in this chapter.