{"title":"6-Aminocoumarin-derived Schiff base gelators: aggregation and sensing of CN−, Fe3+, Cu2+ and CO2 under different conditions†","authors":"Eshani Paul, Rameez Raza, Subrata Ranjan Dhara, Nabajyoti Baildya and Kumaresh Ghosh","doi":"10.1039/D4RA05503A","DOIUrl":null,"url":null,"abstract":"<p >Herein, we report the synthesis, characterization, supramolecular gelation and multiple applications of 6-aminocoumarin-derived Schiff bases <strong>1</strong> and <strong>2</strong>. Both Schiff bases underwent gelation in DMF–H<small><sub>2</sub></small>O (2 : 1, v/v), DMSO–H<small><sub>2</sub></small>O (2 : 1, v/v) and dioxane–H<small><sub>2</sub></small>O (2 : 1, v/v) involving weak forces. Furthermore, the gels were stable and exhibited good viscoelastic properties. The storage modulus (<em>G</em>′) of each gel was considerably higher than its loss modulus (<em>G</em>′′). The higher value of the crossover point and lower value of tan <em>δ</em> for the gel of Schiff base <strong>2</strong> compared to the gel of Schiff base <strong>1</strong> demonstrated the better gelation behaviour of <strong>2</strong> than that of <strong>1</strong> in DMF–H<small><sub>2</sub></small>O (2 : 1, v/v). Further, iodo-analogue <strong>2</strong> exhibited cross-linked helical morphology, whereas non-iodo analogue <strong>1</strong> exhibited long chain fibrous morphology, as observed <em>via</em> FESEM. These differences in morphology and viscoelastic behaviors were attributed to the iodo group present in <strong>2</strong>, which influenced its aggregation involving halogen bonding. To demonstrate their application, the DMF–H<small><sub>2</sub></small>O (2 : 1, v/v) gels of both <strong>1</strong> and <strong>2</strong> recognized CN<small><sup>−</sup></small> over a series of other anions by exhibiting a gel-to-sol phase change. Besides anion sensing, gels <strong>1</strong> and <strong>2</strong> selectively detected Fe<small><sup>3+</sup></small> and Cu<small><sup>2+</sup></small> ions over other metal ions <em>via</em> a gel-to-gel colour change. Finally, CN<small><sup>−</sup></small>-treated solutions of <strong>1</strong> and <strong>2</strong> allowed the successful detection of CO<small><sub>2</sub></small> by the naked eye. Moreover, the detection was possible using a test-kit method.</p>","PeriodicalId":102,"journal":{"name":"RSC Advances","volume":null,"pages":null},"PeriodicalIF":3.9000,"publicationDate":"2024-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.rsc.org/en/content/articlepdf/2024/ra/d4ra05503a?page=search","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"RSC Advances","FirstCategoryId":"92","ListUrlMain":"https://pubs.rsc.org/en/content/articlelanding/2024/ra/d4ra05503a","RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"CHEMISTRY, MULTIDISCIPLINARY","Score":null,"Total":0}
引用次数: 0
Abstract
Herein, we report the synthesis, characterization, supramolecular gelation and multiple applications of 6-aminocoumarin-derived Schiff bases 1 and 2. Both Schiff bases underwent gelation in DMF–H2O (2 : 1, v/v), DMSO–H2O (2 : 1, v/v) and dioxane–H2O (2 : 1, v/v) involving weak forces. Furthermore, the gels were stable and exhibited good viscoelastic properties. The storage modulus (G′) of each gel was considerably higher than its loss modulus (G′′). The higher value of the crossover point and lower value of tan δ for the gel of Schiff base 2 compared to the gel of Schiff base 1 demonstrated the better gelation behaviour of 2 than that of 1 in DMF–H2O (2 : 1, v/v). Further, iodo-analogue 2 exhibited cross-linked helical morphology, whereas non-iodo analogue 1 exhibited long chain fibrous morphology, as observed via FESEM. These differences in morphology and viscoelastic behaviors were attributed to the iodo group present in 2, which influenced its aggregation involving halogen bonding. To demonstrate their application, the DMF–H2O (2 : 1, v/v) gels of both 1 and 2 recognized CN− over a series of other anions by exhibiting a gel-to-sol phase change. Besides anion sensing, gels 1 and 2 selectively detected Fe3+ and Cu2+ ions over other metal ions via a gel-to-gel colour change. Finally, CN−-treated solutions of 1 and 2 allowed the successful detection of CO2 by the naked eye. Moreover, the detection was possible using a test-kit method.
期刊介绍:
An international, peer-reviewed journal covering all of the chemical sciences, including multidisciplinary and emerging areas. RSC Advances is a gold open access journal allowing researchers free access to research articles, and offering an affordable open access publishing option for authors around the world.