Pillararenes: Younger Luminescent Supramolecular Systems

<div>Since the development of supramolecular chemistry, synthetic macrocycles</div><div>have also played an inevitable role in constructing the host-guest system. Among</div><div>pillar[n]arenes, in short pillarenes, a decade-old younger member in the supramolecular</div><div>family, after reported by Ogoshi et al. in 2008, has gained considerable attention. Due</div><div>to the straightforward preparation methods, tunable cavity size, and symmetrical</div><div>architecture makes it an ideal candidate in the supramolecular family. With this</div><div>perspective, this chapter discusses a brief introduction to the synthesis,</div><div>characterization, and structural features of different sizes of pillarenes. The presence of</div><div>a confined hydrophobic and π-electron-rich cavity provided by a paraxyl ether or</div><div>hydroquinone units offers a unique host-guest recognition capability towards positively</div><div>charged and neutral molecules. Notably, the presence of a cavity with an aromatic wall</div><div>provides a broad luminescent platform for various photophysical studies. This chapter</div><div>elaborates on the contribution of pillarenes in tuning the photophysical properties of the</div><div>small guest molecules and the formation of luminescent supramolecular materials.</div><div>Further, the functionalization on the outer of the pillarenes has influenced the</div><div>photophysical responses such as absorption and fluorescence, which paved a pathway</div><div>for the development of supramolecular organic light-emitting functional material and</div><div>novel sensor materials also discussed in this chapter. Finally, this chapter discusses all</div><div>the progress and applications of luminescence pillarenes and their derivatives.</div>