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Proton‐Gated Ring‐Closure of a Negative Photochromic Azulene‐Based Diarylethene
Author(s) -
Hou Ian ChengYi,
Berger Fabian,
Narita Akimitsu,
Müllen Klaus,
Hecht Stefan
Publication year - 2020
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.202007989
Subject(s) - diarylethene , photoswitch , photochromism , protonation , azulene , photochemistry , chemistry , deprotonation , molecular switch , proton , molecule , ring (chemistry) , proton nmr , computational chemistry , stereochemistry , organic chemistry , ion , physics , quantum mechanics
Proton‐responsive photochromic molecules are attractive for their ability to react on non‐invasive rapid optical stimuli and the importance of protonation/deprotonation processes in various fields. Conventionally, their acidic/basic sites are on hetero‐atoms, which are orthogonal to the photo‐active π‐center. Here, we incorporate azulene, an acid‐sensitive pure hydrocarbon, into the skeleton of a diarylethene‐type photoswitch. The latter exhibits a novel proton‐gated negative photochromic ring‐closure and its optical response upon protonation in both open and closed forms is much more pronounced than those of diarylethene photoswitches with hetero‐atom based acidic/basic moieties. The unique behavior of the new photoswitch can be attributed to direct protonation on its π‐system, supported by 1 H NMR and theoretical calculations. Our results demonstrate the great potential of integrating non‐alternant hydrocarbons into photochromic systems for the development of multi‐responsive molecular switches.