Single molecule multiphotochromism with diarylethenes.

Area of Science:

• Supramolecular Chemistry
• Materials Science
• Organic Electronics

Background:

• Single photochromes act as molecular switches, with isomers enabling on/off states.
• Multiphotochromic molecules, integrating multiple photochromic units, promise complex data processing (e.g., byte storage).
• Diarylethene groups are key components in thermally stable organic photochromes.

Purpose of the Study:

• To review multiswitchable molecular systems incorporating diarylethene units.
• To identify limitations and challenges in current multiphotochromic systems.
• To highlight promising advancements and the role of theoretical simulations in designing efficient molecules.

Main Methods:

• Overview of synthesized multiphotochromic molecular systems, particularly those with diarylethene moieties.
• Analysis of limitations including side reactions, hindered photoreactivity, cumulative spectra, and lack of selective control.
• Discussion of theoretical simulation techniques like time-dependent density functional theory (TD-DFT) for structure-property analysis.

Main Results:

• Existing multiphotochromic systems often suffer from poor reversibility and interference between photochromic units.
• Many systems display cumulative absorption spectra instead of distinct new features upon switching.
• Selective photoisomerization control remains a significant challenge due to overlapping spectral responses.

Conclusions:

• Asymmetric diarylethene dimers/trimers and hybrid systems (e.g., diarylethene-fulgimide) show promise.
• Theoretical simulations are crucial for understanding structure-property relationships and guiding the design of improved molecular switches.
• Further development is needed to overcome limitations in reversibility, selectivity, and spectral distinguishability for practical applications.