Quinoline-based fluorescent small molecules for live cell imaging.

Small molecule probes are essential tools for biomedical applications, with utility as cellular stains, labels for biomolecules, environmental indicators, and biosensors. However, a fluorophore's characteristics are difficult to predict solely through calculations or rational design, making the development of a core scaffold that is amenable to late stage functionalization particularly desirable. In this chapter, we describe the synthesis and application of a tunable quinoline scaffold that can be readily functionalized and optimized for a variety of imaging applications. We present a facile synthesis that results in three functional domains that influence the compound's photophysical properties, structural diversity, and polarization. We demonstrate a method with which to study the scaffold's tunable photophysical properties as a result of its structure and environment, and finally exhibit its utility in pH sensitive, live-cell imaging.