Excited-State Dynamics of Fluorogenic Molecules

Abstract

Fluorogenic molecules have attracted a significant share of both academic and industrial interests because of its wide range of real-time applications ranging from organic electronics to biochemical fields. The successful application of the fluorogenic molecules necessitates an in-depth understanding and manoeuvring of the photoinduced processes. In this chapter, we try to give a brief overview of the crucial excited-state processes and its role in the fluorescence property of a molecule. With the knowledge of the photophysical processes, we proceed with few examples where the origin of fluorogenic behaviour is discussed. Applications of fluorogenic molecules in various fields such as in ion sensing and in aggregated phase are stressed in this chapter. Specific interest is laid on Schiff base molecules where it is discussed how a significant improvement in quantum yield and lifetime can be achieved through various chemical modifications and by playing with the physical conditions. Those variations are explained in terms of non-radiative pathways especially the complex interplay of aggregation-induced enhancement of emission (AIEE) and aggregation-caused quenching (ACQ). Finally, with the help of few biological applications, the future of fluorogenic molecules is illustrated.