Photoactivity and optical applications of organic materials containing selenium and tellurium

Abstract

Sulfur-containing compounds, particularly derivatives of thiophene, are well studied for organic optoelectronic applications. Incorporating selenium or tellurium in place of sulfur imparts different physical properties due to the fundamental differences of these atoms relative to their lighter analogues. This has a profound influence on the properties of molecules and materials that incorporate chalcogens that may ultimately lead to new opportunities and applications. This mini-review will focus on the quantitative and qualitative photophysical characteristics of organic materials containing selenium and tellurium as well as their emerging applications as molecular photoactive species, including light-emitting sensors, triplet sensitizers, and beyond.

Fig. 1. (a) Representative photophysical pathways of an organochalcogen chromophore/fluorophore include absorption, fluorescence, intersystem crossing (ISC), reverse ISC, phosphorescence, and non-radiative decay. (b) Representative photophysical pathways of an organochalcogen fluorescent probe that is off when non-radiative decay occurs through triplet quenching, and on when Förster Resonance Energy Transfer (FRET) occurs to a fluorescent acceptor.

Fig. 2. Discussed photoactive compounds containing selenium and tellurium.

Fig. 3. Peroxynitrite oxidation of selenium inhibits photoinduced electron transfer (PET) to a cyanine dye, resulting in fluorescence. The sensor is regenerated by exposure to glutathione. Reprinted with permission from ref. 33. Copyright 2011 ACS.

Fig. 4. Photosensitization of singlet oxygen through the triplet state of tellurorhodamine. Reprinted with permission from ref. 64. Copyright 2019 RSC.

Gabrielle C. Hoover

Dwight S. Seferos