Design and synthesis of phosphonium ionic liquids exhibiting strong fluorescence in various solvents and liquid or glassy state
Liquid fluorescent ILs (LFILs) are rare materials that exhibit strong photoluminescent properties in the pure liquid state without the need for a solvent. While ILs are known for their optical properties in solution, fluorescence in the pure liquid state is typically weak or absent due to quenching...
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Elsevier
2025-06-01
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| Series: | Journal of Ionic Liquids |
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| Online Access: | http://www.sciencedirect.com/science/article/pii/S2772422025000254 |
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| author | David King Yan P. Arnaiz Hari D. Mandal Haesook Han Pradip K. Bhowmik |
| author_facet | David King Yan P. Arnaiz Hari D. Mandal Haesook Han Pradip K. Bhowmik |
| author_sort | David King |
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| description | Liquid fluorescent ILs (LFILs) are rare materials that exhibit strong photoluminescent properties in the pure liquid state without the need for a solvent. While ILs are known for their optical properties in solution, fluorescence in the pure liquid state is typically weak or absent due to quenching phenomena. LFILs are extremely scarce in the literature, and only a few have been reported with absolute quantum yield (AQY) values to assess their fluorescence efficiency in the pure liquid state. A series of phosphonium ILs (PILs), containing fluorescent 5-(dimethylamino)-1-naphthalenesulfonate (DNS-) and 9,10-anthraquinone-2-sulfonate (AQS-), were synthesized as potential soft photoluminescent materials in solution and neat liquid state in very good to excellent yields. Additionally, mono and diphosphonium chloride ILs were prepared via an improved workup process to afford ILs with high purity (>99 %) compared to traditional methods. All fluorescent PILs possessed high thermal stabilities (Td = 332–383 °C) as determined by thermogravimetric analysis (TGA). The differential scanning calorimetry (DSC) thermograms for the PILs-DNS and PILs-AQS revealed that all of them were ILs, with most being RTILs and the triphenylphosphonium containing PILs existing as glassy ILs (Tg = 21.13 and 30.13 °C) at room temperature. Their photoluminescent properties in the solution state were studied in various organic solvents, with the PILs-DNS possessing AQY values upwards of 0.95 in solution and [P666,10]DNS exhibited an impressively high AQY of 0.35 in the liquid state. The PILs-AQS did not possess strong photoluminescent properties in solution and no fluorescence in the liquid or glassy state. The PILs-DNS and PILs-AQS demonstrated excellent photostability, exhibiting no significant photobleaching. Study of these novel PILs containing anionic fluorophores is necessary to contribute towards the scarcity of LFILs and offer prospects in a wide range of fields, including chemical/physical sensing, optoelectronics, and biological imaging. |
| format | Article |
| id | doaj-art-cef69e6d08c34d0994e8768d182a6cbb |
| institution | Kabale University |
| issn | 2772-4220 |
| language | English |
| publishDate | 2025-06-01 |
| publisher | Elsevier |
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| series | Journal of Ionic Liquids |
| spelling | doaj-art-cef69e6d08c34d0994e8768d182a6cbb2025-08-20T03:47:36ZengElsevierJournal of Ionic Liquids2772-42202025-06-015110015610.1016/j.jil.2025.100156Design and synthesis of phosphonium ionic liquids exhibiting strong fluorescence in various solvents and liquid or glassy stateDavid King0Yan P. Arnaiz1Hari D. Mandal2Haesook Han3Pradip K. Bhowmik4Department of Chemistry and Biochemistry, University of Nevada Las Vegas, 4505 S. Maryland Parkway, Box 454003, Las Vegas, NV 89154, USA; Corresponding author.Department of Chemistry and Biochemistry, University of Nevada Las Vegas, 4505 S. Maryland Parkway, Box 454003, Las Vegas, NV 89154, USADepartment of Biology and Chemistry, Texas A&M International University, 5201 University Boulevard, Laredo, TX 78041, USADepartment of Chemistry and Biochemistry, University of Nevada Las Vegas, 4505 S. Maryland Parkway, Box 454003, Las Vegas, NV 89154, USADepartment of Chemistry and Biochemistry, University of Nevada Las Vegas, 4505 S. Maryland Parkway, Box 454003, Las Vegas, NV 89154, USALiquid fluorescent ILs (LFILs) are rare materials that exhibit strong photoluminescent properties in the pure liquid state without the need for a solvent. While ILs are known for their optical properties in solution, fluorescence in the pure liquid state is typically weak or absent due to quenching phenomena. LFILs are extremely scarce in the literature, and only a few have been reported with absolute quantum yield (AQY) values to assess their fluorescence efficiency in the pure liquid state. A series of phosphonium ILs (PILs), containing fluorescent 5-(dimethylamino)-1-naphthalenesulfonate (DNS-) and 9,10-anthraquinone-2-sulfonate (AQS-), were synthesized as potential soft photoluminescent materials in solution and neat liquid state in very good to excellent yields. Additionally, mono and diphosphonium chloride ILs were prepared via an improved workup process to afford ILs with high purity (>99 %) compared to traditional methods. All fluorescent PILs possessed high thermal stabilities (Td = 332–383 °C) as determined by thermogravimetric analysis (TGA). The differential scanning calorimetry (DSC) thermograms for the PILs-DNS and PILs-AQS revealed that all of them were ILs, with most being RTILs and the triphenylphosphonium containing PILs existing as glassy ILs (Tg = 21.13 and 30.13 °C) at room temperature. Their photoluminescent properties in the solution state were studied in various organic solvents, with the PILs-DNS possessing AQY values upwards of 0.95 in solution and [P666,10]DNS exhibited an impressively high AQY of 0.35 in the liquid state. The PILs-AQS did not possess strong photoluminescent properties in solution and no fluorescence in the liquid or glassy state. The PILs-DNS and PILs-AQS demonstrated excellent photostability, exhibiting no significant photobleaching. Study of these novel PILs containing anionic fluorophores is necessary to contribute towards the scarcity of LFILs and offer prospects in a wide range of fields, including chemical/physical sensing, optoelectronics, and biological imaging.http://www.sciencedirect.com/science/article/pii/S2772422025000254SynthesisStructural designPhosphonium ionic liquidsDicationic ionic liquidsGlassFluorescence |
| spellingShingle | David King Yan P. Arnaiz Hari D. Mandal Haesook Han Pradip K. Bhowmik Design and synthesis of phosphonium ionic liquids exhibiting strong fluorescence in various solvents and liquid or glassy state Journal of Ionic Liquids Synthesis Structural design Phosphonium ionic liquids Dicationic ionic liquids Glass Fluorescence |
| title | Design and synthesis of phosphonium ionic liquids exhibiting strong fluorescence in various solvents and liquid or glassy state |
| title_full | Design and synthesis of phosphonium ionic liquids exhibiting strong fluorescence in various solvents and liquid or glassy state |
| title_fullStr | Design and synthesis of phosphonium ionic liquids exhibiting strong fluorescence in various solvents and liquid or glassy state |
| title_full_unstemmed | Design and synthesis of phosphonium ionic liquids exhibiting strong fluorescence in various solvents and liquid or glassy state |
| title_short | Design and synthesis of phosphonium ionic liquids exhibiting strong fluorescence in various solvents and liquid or glassy state |
| title_sort | design and synthesis of phosphonium ionic liquids exhibiting strong fluorescence in various solvents and liquid or glassy state |
| topic | Synthesis Structural design Phosphonium ionic liquids Dicationic ionic liquids Glass Fluorescence |
| url | http://www.sciencedirect.com/science/article/pii/S2772422025000254 |
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