{"title":"Ion valence-gated photochromism of an aza-crowned diarylethene.","authors":"Ayaka Takeguchi, Azusa Kikuchi, Kazuhide Ueno, Shinji Ishihara, Aki Nitta, Tetsuya Nakagawa, Takashi Ubukata, Yasushi Yokoyama","doi":"10.1007/s43630-023-00508-z","DOIUrl":null,"url":null,"abstract":"<p><p>A non-photochromic diarylethene 2o with an N-phenylaza-15-crown-5 was synthesized. When the nitrogen atom in the aza-crown ring was protonated, it became photochromic due to the prevention of a twisted intramolecular charge transfer (TICT). Although addition of a monovalent metal cation (Li<sup>+</sup>, Na<sup>+</sup>, K<sup>+</sup>, Rb<sup>+</sup>, Cs<sup>+</sup>, Cu<sup>+</sup>, Ag<sup>+</sup>) in acetonitrile could not stop the TICT so that it was not photochromic, the addition of a multivalent metal cation (Mg<sup>2+</sup>, Ca<sup>2+</sup>, Sr<sup>2+</sup>, Ba<sup>2+</sup>, Fe<sup>2+</sup>, Ni<sup>2+</sup>, Al<sup>3+</sup>, Sb<sup>5+</sup>) changed 2o to be photochromic due to the strong attraction of the lone pair on the nitrogen atom. In the presence of excess Cu<sup>2+</sup>, 2o was oxidized to be EPR-detectable 2o<sup>·+</sup>, which was thermally unstable as well as inert towards visible-light irradiation. However, 2o<sup>·+</sup> was further oxidized to be fairly stable 2o<sup>2+</sup> by the irradiation of 365-nm light in the presence of Cu<sup>2+</sup>. ESI-MS measurements strongly suggested the generation of 2o<sup>·+</sup> by mixing 2o with Cu(ClO<sub>4</sub>)<sub>2</sub> in acetonitrile, and the transformation of 2o<sup>·+</sup> to 2o<sup>2+</sup> by successive 365-nm light irradiation. Fe<sup>3+</sup> similarly worked as the oxidant, but the two-step oxidation of 2o to 2o<sup>2+</sup> occurred more easily.</p>","PeriodicalId":98,"journal":{"name":"Photochemical & Photobiological Sciences","volume":" ","pages":"133-151"},"PeriodicalIF":3.2000,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Photochemical & Photobiological Sciences","FirstCategoryId":"92","ListUrlMain":"https://doi.org/10.1007/s43630-023-00508-z","RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"2023/12/22 0:00:00","PubModel":"Epub","JCR":"Q3","JCRName":"BIOCHEMISTRY & MOLECULAR BIOLOGY","Score":null,"Total":0}
引用次数: 0
Abstract
A non-photochromic diarylethene 2o with an N-phenylaza-15-crown-5 was synthesized. When the nitrogen atom in the aza-crown ring was protonated, it became photochromic due to the prevention of a twisted intramolecular charge transfer (TICT). Although addition of a monovalent metal cation (Li+, Na+, K+, Rb+, Cs+, Cu+, Ag+) in acetonitrile could not stop the TICT so that it was not photochromic, the addition of a multivalent metal cation (Mg2+, Ca2+, Sr2+, Ba2+, Fe2+, Ni2+, Al3+, Sb5+) changed 2o to be photochromic due to the strong attraction of the lone pair on the nitrogen atom. In the presence of excess Cu2+, 2o was oxidized to be EPR-detectable 2o·+, which was thermally unstable as well as inert towards visible-light irradiation. However, 2o·+ was further oxidized to be fairly stable 2o2+ by the irradiation of 365-nm light in the presence of Cu2+. ESI-MS measurements strongly suggested the generation of 2o·+ by mixing 2o with Cu(ClO4)2 in acetonitrile, and the transformation of 2o·+ to 2o2+ by successive 365-nm light irradiation. Fe3+ similarly worked as the oxidant, but the two-step oxidation of 2o to 2o2+ occurred more easily.