Molecular structure and reversible photodegradation in anthraquinone dyes

TL;DR

This study investigates how molecular structure influences reversible photodegradation in anthraquinone dyes, using fluorescence to directly measure undamaged populations and confirming the domain model of self-healing.

Contribution

It introduces fluorescence as a direct probe for undamaged dye populations and links specific structural features to self-healing behavior in anthraquinone dyes.

Findings

Certain anthraquinone structures are associated with self-healing.

Photodegradation and self-healing depend on time and temperature.

Results support the domain model of self-healing.

Abstract

Reversible photodegradation is a process that has been observed in several dye molecules, but the underlying mechanisms are not still well understood. In this contribution, we characterize a series of anthraquinone dyes to determine how self-healing depends on molecular structure. Past studies have used probing techniques that rely on linear absorption, two-photon fluorescence, and amplified spontaneous emission. Each of these probes provide an indirect measure of the populations of the damaged and undamaged species, requiring calibrations or assumptions to be made that might affect the accuracy of the results. The present studies use fluorescence as a probe, which is shown to directly measure the undamaged population. It is found that certain anthraquinone classes share common structural features that are associated with self healing. Furthermore, the time and temperature dependence of photodegradation and self-healing is found to be consistent with the domain model of self healing.