# Meta‐Connected Oligo‐Azobenzenes Outperform Their Para Counterparts

## TL;DR

This study shows that meta-connected oligo-azobenzenes are better at maintaining individual photoswitchable units compared to para-connected ones.

## Contribution

The study reveals that meta-connection preserves individual photoswitchability in oligo-azobenzenes, unlike para-connection.

## Key findings

- Meta-connected azobenzene subunits remain individually photoswitchable.
- Para-connected subunits lose individuality due to excitonic delocalization.
- Meta-oligo-azobenzenes are better candidates for functional polymer studies.

## Abstract

Systems with multiple photoswitchable units in one molecule have attracted considerable attention in the past years as they are useful for a broad variety of possible applications. Especially, linked azobenzenes sharing one benzene ring are of high interest since their direct linkage introduces an additional photoswitchable unit at only small increase in molecular weight. In this spirit, linear oligo‐azobenzenes had been synthesized, though their photochemical properties have only been investigated for short chain lengths. In this study, we use (time‐dependent) density functional methodology for the evaluation of the excitations of meta‐ and para‐connected oligo‐azobenzenes to predict their switching ability. It becomes apparent, that the meta connection pattern enables each azobenzene subunit to act as an individual switchable unit, whereas they are strongly coupled and loose their individuality in para connection. Therefore, meta‐oligo‐azobenzenes are ideal candidates for future studies of azobenzene‐based functional polymers, while para‐oligo‐azobenzenes are not.

Meta switches better. Our computational investigation of quasi‐linear oligo‐azobenzenes with para‐ and meta‐connectivity reveals meta to result in oligomers with individually photoswitchable azobenzene subunits. In contrast, the excitonic delocalization in para lets the azobenzene subunits lose their individuality resulting in vanishing photoswitchability with oligomer length.