1,3-Alternate Calix[4]arene Functionalized With Pyrazole and Triazole Ligands as a Highly Selective Fluorescent Sensor for Hg2+ and Ag+ Ions
We report here the synthesis of a 1,3-alternate calix[4]arene 8, with bis-pyrazolylmethylpyrenes on the one end and bis-triazolylmethylphenyls on the other end, as a homoditropic fluorescent sensor for both Hg2+ and Ag+ ions. Calix[4]arene 3, with lower-rim bis-pyrazolylmethylpyrenes in cone conform...
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Frontiers Media S.A.
2020-11-01
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| Series: | Frontiers in Chemistry |
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| Online Access: | https://www.frontiersin.org/articles/10.3389/fchem.2020.593261/full |
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| author | Yin-Ju Chen Meng-Yu Chen Kun-Ti Lee Li-Ching Shen Hao-Chih Hung Hao-Che Niu Wen-Sheng Chung |
| author_facet | Yin-Ju Chen Meng-Yu Chen Kun-Ti Lee Li-Ching Shen Hao-Chih Hung Hao-Che Niu Wen-Sheng Chung |
| author_sort | Yin-Ju Chen |
| collection | DOAJ |
| description | We report here the synthesis of a 1,3-alternate calix[4]arene 8, with bis-pyrazolylmethylpyrenes on the one end and bis-triazolylmethylphenyls on the other end, as a homoditropic fluorescent sensor for both Hg2+ and Ag+ ions. Calix[4]arene 3, with lower-rim bis-pyrazolylmethylpyrenes in cone conformation, was also synthesized as a control compound. UV-Vis and fluorescence spectra were used for metal ions screening, and we found that both ligands 8 and 3 showed strong excimer emission of pyrenes when they are as a free ligand in CHCl3/MeOH (v/v, 3:1) solution; however, they both showed a high selectivity toward Hg2+ and Ag+ ions with strong fluorescence quenching and yet with different binding ratios. The fluorescence of ligand 8 was strongly quenched by Hg2+ but was only partially quenched by Ag+ ions; however, the fluorescence of ligand 3 was strongly quenched by Hg2+, Ag+, and Cu2+ ions. Job plot experiments showed that ligand 8 formed a 1:2 complex with both Hg2+ and Ag+ ions; ligand 3 formed a 1:1 complex with Hg2+, but it formed a 2:3 complex with Ag+. The binding constant of ligand 3 with Hg2+ and Ag+ ions was determined by the Benesi-Hildebrand plot of UV-vis titration experiments to be 2.99 × 103 and 3.83 × 103 M−1, respectively, while the association constant of ligand 8 with Hg2+ and Ag+ was determined by Hill plot to be 1.46 × 1012 and 9.24 × 1011 M−2, respectively. Ligand 8 forms a strong complex with either two Hg2+ or two Ag+ ions using both the upper and lower rims of the 1,3-alternate calix[4]arene as the binding pockets; hence, it represents one of the highly selective fluorescent sensors for the homoditropic sensing of Hg2+ and Ag+ ions. |
| first_indexed | 2024-12-13T05:16:12Z |
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| id | doaj.art-ecf008d311c945d9a6a0c7794749e565 |
| institution | Directory Open Access Journal |
| issn | 2296-2646 |
| language | English |
| last_indexed | 2024-12-13T05:16:12Z |
| publishDate | 2020-11-01 |
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| series | Frontiers in Chemistry |
| spelling | doaj.art-ecf008d311c945d9a6a0c7794749e5652022-12-21T23:58:25ZengFrontiers Media S.A.Frontiers in Chemistry2296-26462020-11-01810.3389/fchem.2020.5932615932611,3-Alternate Calix[4]arene Functionalized With Pyrazole and Triazole Ligands as a Highly Selective Fluorescent Sensor for Hg2+ and Ag+ IonsYin-Ju ChenMeng-Yu ChenKun-Ti LeeLi-Ching ShenHao-Chih HungHao-Che NiuWen-Sheng ChungWe report here the synthesis of a 1,3-alternate calix[4]arene 8, with bis-pyrazolylmethylpyrenes on the one end and bis-triazolylmethylphenyls on the other end, as a homoditropic fluorescent sensor for both Hg2+ and Ag+ ions. Calix[4]arene 3, with lower-rim bis-pyrazolylmethylpyrenes in cone conformation, was also synthesized as a control compound. UV-Vis and fluorescence spectra were used for metal ions screening, and we found that both ligands 8 and 3 showed strong excimer emission of pyrenes when they are as a free ligand in CHCl3/MeOH (v/v, 3:1) solution; however, they both showed a high selectivity toward Hg2+ and Ag+ ions with strong fluorescence quenching and yet with different binding ratios. The fluorescence of ligand 8 was strongly quenched by Hg2+ but was only partially quenched by Ag+ ions; however, the fluorescence of ligand 3 was strongly quenched by Hg2+, Ag+, and Cu2+ ions. Job plot experiments showed that ligand 8 formed a 1:2 complex with both Hg2+ and Ag+ ions; ligand 3 formed a 1:1 complex with Hg2+, but it formed a 2:3 complex with Ag+. The binding constant of ligand 3 with Hg2+ and Ag+ ions was determined by the Benesi-Hildebrand plot of UV-vis titration experiments to be 2.99 × 103 and 3.83 × 103 M−1, respectively, while the association constant of ligand 8 with Hg2+ and Ag+ was determined by Hill plot to be 1.46 × 1012 and 9.24 × 1011 M−2, respectively. Ligand 8 forms a strong complex with either two Hg2+ or two Ag+ ions using both the upper and lower rims of the 1,3-alternate calix[4]arene as the binding pockets; hence, it represents one of the highly selective fluorescent sensors for the homoditropic sensing of Hg2+ and Ag+ ions.https://www.frontiersin.org/articles/10.3389/fchem.2020.593261/fullfluorescent sensormercury (II) sensorsilver (I) sensorhomoditropic13-alternate calix[4]arene |
| spellingShingle | Yin-Ju Chen Meng-Yu Chen Kun-Ti Lee Li-Ching Shen Hao-Chih Hung Hao-Che Niu Wen-Sheng Chung 1,3-Alternate Calix[4]arene Functionalized With Pyrazole and Triazole Ligands as a Highly Selective Fluorescent Sensor for Hg2+ and Ag+ Ions Frontiers in Chemistry fluorescent sensor mercury (II) sensor silver (I) sensor homoditropic 1 3-alternate calix[4]arene |
| title | 1,3-Alternate Calix[4]arene Functionalized With Pyrazole and Triazole Ligands as a Highly Selective Fluorescent Sensor for Hg2+ and Ag+ Ions |
| title_full | 1,3-Alternate Calix[4]arene Functionalized With Pyrazole and Triazole Ligands as a Highly Selective Fluorescent Sensor for Hg2+ and Ag+ Ions |
| title_fullStr | 1,3-Alternate Calix[4]arene Functionalized With Pyrazole and Triazole Ligands as a Highly Selective Fluorescent Sensor for Hg2+ and Ag+ Ions |
| title_full_unstemmed | 1,3-Alternate Calix[4]arene Functionalized With Pyrazole and Triazole Ligands as a Highly Selective Fluorescent Sensor for Hg2+ and Ag+ Ions |
| title_short | 1,3-Alternate Calix[4]arene Functionalized With Pyrazole and Triazole Ligands as a Highly Selective Fluorescent Sensor for Hg2+ and Ag+ Ions |
| title_sort | 1 3 alternate calix 4 arene functionalized with pyrazole and triazole ligands as a highly selective fluorescent sensor for hg2 and ag ions |
| topic | fluorescent sensor mercury (II) sensor silver (I) sensor homoditropic 1 3-alternate calix[4]arene |
| url | https://www.frontiersin.org/articles/10.3389/fchem.2020.593261/full |
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