Intrinsic Luminescence from Nonaromatic Biomolecules

Novel emitters that do not contain traditional chromophores but only electron-rich moieties (e. g. amine, C=O, -OH, ether, and imide), which are classified as nonconventional luminophores, have been more frequently reported. Although more and more examples have been demonstrated, their emission mechanism remains unclear. The clustering-triggered emission (CTE) mechanism has previously been proposed to rationalize the luminescence of unconventional chromophores. Moreover, great attention has been paid to the distinctive inherent luminescence from nonaromatic biomolecules such as cellulose, starch, sugars, and nonaromatic amino acids and proteins. In this Review, we summarize these unconventional biomolecular luminophores and apply the CTE mechanism to rationalize such a phenomenon. This Review may shed new light on the understanding of intrinsic emission of nonaromatic biomolecules and decipher the intrinsic fluorescence from cells and tissues.