Study on the Assembling and Fluorescence Properties of Rare Earth Supramolecular Fluorescent Ordered Aggregates in Ionic Liquids

doi:10.6023/A25010009

Abstract

Rare earth fluorescent ordered aggregates constructed based on ionic liquids can endow rare earth materials with superior fluorescence performance and rich structural morphologys. At the same time, cyclodextrins have received considerable attention in the research field of supramolecular aggregates due to their dynamic and reversible regulatory properties. In this work, an ionic liquid-type rare earth europium β-diketone amphiphilic complex [C₁₂mim][Eu(TTA)₄] (C₁₂mim=1-dodecyl-3-methylimidazole, TTA=4-methyltrifluoroacetophenone, abbreviated as C₁₂-Eu) was synthesized. Through the cooperative assembly of the ionic liquid-type surfactant (1-dodecyl-3-methylimidazolium bromide) and the host-guest interaction of β-cyclodextrin (abbreviated as β-CD), rare earth supramolecular fluorescent ordered aggregates with different morphologies were constructed in a protic ionic liquid, ethylammonium nitrate. The fluorescence properties and aggregation structures of aggregates were characterized by fluorescence spectroscopy, UV-vis spectroscopy, infrared spectroscopy, time-resolved fluorescence spectroscopy, laser confocal microscopy, and fluorescence microscopy. After assembling into ordered aggregates, the fluorescence intensity of the obtained materials increased significantly (by 3~8 times) and the lifetimes were much longer compared with those of other assemblies in the same solvent. Meanwhile, the fluorescence microscopy results demonstrated the successful doping of C₁₂-Eu and the formation of three distinct types of red fluorescent supramolecular aggregates: flakes, mini microtubes, and rare hollow tetragonal prismatic microtubes with square cross-sections. Furthermore, α-amylase was introduced to investigate the changes in fluorescence and aggregation structure of the aggregates over time. It was demonstrated that the aggregates were formed through inclusion complexes of cyclodextrins, and the enzyme-responsive regulation of the aggregates was also achieved.

Key words: rare earth, cyclodextrin, supramolecular, ionic liquid, enzyme response

Cite this article

Fei Li, Sijing Yi, Jiao Wang, Xiaoxia Liu, Wenmei Gao, Jingjing Li, Haifeng Zhang. Study on the Assembling and Fluorescence Properties of Rare Earth Supramolecular Fluorescent Ordered Aggregates in Ionic Liquids[J]. Acta Chimica Sinica, 2025, 83(5): 453-462.

Export EndNote|Reference Manager|ProCite|BibTeX|RefWorks

share this article

Fig. & Tab. 11

Figure 1. Illustration for the construction of rare earth supramolecular fluorescent aggregates assembled by [C12mim]Br, C12-Eu and β-CD

Figure 2. (a) The image of the C12-Eu-[C12mim]Br-β-CD ternary system (C12-Eu 0.001 mol/L, [C12mim]Br-β-CD 0~0.18 mol/L) under 365 nm ultraviolet lamp irradiation; Laser confocal bright field and dark field images under excitation at 405 nm of ternary system. The concentration of C12-Eu was 0.001 mol/L, and the [C12mim]Br-β-CD was added at concentrations of (b, c) 0.09 mol/L; (d, e) 0.12 mol/L; (f, g) 0.18 mol/L

Figure 3. Optical microscope magnified image of C12-Eu-[C12mim]Br-β-CD ternary system. The concentration of C12-Eu was 0.001 mol/L, and the [C12mim]Br-β-CD was added at concentrations of (a) flake (0.09 mol/L); (b) mini microtube (0.12 mol/L); (c, d) square microtube (0.18 mol/L); (e) multi- layer stacked structure (0.09 mol/L); (f) assembling square microtubes (0.18 mol/L)

Figure 4. Phase diagram of C12-Eu-[C12mim]Br-β-CD ternary system (C12-Eu 0.001 mol/L, [C12mim]Br-β-CD 0~0.18 mol/L)

Figure 5. Excitation (a, inset: fluorescence intensity variation curve of LMCT peak relative to f-f transition, λEM=613 nm) and emission (b, inset: fluorescence intensity variation curve of 5D0→7F2 transition, λEX=395 nm) spectra of C12-Eu-[C12mim]Br-β-CD ternary system (C12-Eu 0.001 mol/L, [C12mim]Br-β-CD 0~0.24 mol/L)

Figure 6. Fluorescence decay curves of C12-Eu-[C12mim]Br-β-CD ternary system (C12-Eu 0.001 mol/L, [C12mim]Br-β-CD 0~0.18 mol/L) under excitation at 395 nm and observed at 613 nm

Figure 7. Comparison of fluorescence emission intensity values under excitation at 395 nm and observed at 613 nm for different systems of C12-Eu (0.001 mol/L), C12-Eu-[C12mim]Br (C12-Eu 0.001 mol/L, [C12mim]Br 0~0.18 mol/L), C12-Eu-β-CD (C12-Eu 0.001 mol/L, β-CD 0~0.18 mol/L), C12-Eu-[C12mim]Br-β-CD (C12-Eu 0.001 mol/L, [C12mim]Br-β-CD 0~0.18 mol/L)

Concentration/ (mol•L^-1)	τ/ms
Concentration/ (mol•L^-1)	C₁₂-Eu-β-CD	C₁₂-Eu-[C₁₂mim]Br	C₁₂-Eu-[C₁₂mim]Br-β-CD
0 0.03	0.202 0.225	0.202 0.274	0.202 0.202(84%), 0.537(16%)
0.06	0.214	0.299	0.193(49%), 0.771(51%)
0.09	0.212	0.333	0.197(17%), 0.824(83%)
0.12	0.265	0.380	0.198(16%), 0.822(84%)
0.15 0.18	0.277 0.298	0.395 0.397	0.184(5%), 0.831(96%) 0.177(2%), 0.825(98%)

Table 1. Fluorescence lifetime values (τ) for rare earth complexes (0.001 mol/L) under the addition of different concentrations of [C12mim]Br/β-CD (binary system, [C12mim]Br/β-CD 0~0.18 mol/L) or [C12mim]Br-β-CD (ternary system, [C12mim]Br-β-CD 0~0.18 mol/L)

Figure 8. UV-vis spectra of the C12-Eu-[C12mim]Br-β-CD ternary system (a, C12-Eu 0.001 mol/L, [C12mim]Br-β-CD 0~0.18 mol/L); FT-IR spectra of EAN, β-CD, C12-Eu-[C12mim]Br-β-CD ternary system (C12-Eu 0.001 mol/L, [C12mim]Br-β-CD 0.18 mol/L) and [C12mim]Br (b)

Figure 9. The fluorescence intensity quenching curves over time (T=37 ℃) after adding α-amylase (400 U/mL) of aggregates with structure of flake (C12-Eu 0.001 mol/L, [C12mim]Br-β-CD 0.09 mol/L), mini microtube (C12-Eu 0.001 mol/L, [C12mim]Br-β-CD 0.12 mol/L), and square microtube (C12-Eu 0.001 mol/L, [C12mim]Br-β-CD 0.18 mol/L)

Figure 10. Schematic diagram of secondary assembly of rare earth supramolecular aggregates

References 44

[1]	Zhong, Y. W.; Qian, X. N.; Ma, C.; Liu, K.; Zhang, H. J. Acta Chim. Sinica. 2023, 81, 1624. (in Chinese)
	(钟越文, 钱希宁, 马超, 刘凯, 张洪杰, 化学学报, 2023, 81, 1624.) doi: 10.6023/A23070323
[2]	Li, P.; Li, H. R. Coord. Chem. Rev. 2021, 441, 213988.
[3]	Armelao, L.; Quici, S.; Barigelletti, F.; Accorsi, G.; Bottaro, G.; Cavazzini, M.; Tondello, E. Coord. Chem. Rev. 2010, 254, 487.
[4]	Zeng, Z. C.; Huang, B. L.; Wang, X.; Lu, L.; Lu, Q. Y.; Sun, M. J.; Wu, T.; Ma, T. F.; Xu, J.; Xu, Y. S.; Wang, S. A.; Du, Y. P.; Yang, C. H. Adv. Mater. 2020, 32, 2004506.
[5]	Bünzli, J. C. G. Coord. Chem. Rev. 2015, 293, 19.
[6]	Wang, C.; Li, H.; Dong, J. T.; Chen, Y. X.; Luan, X. K.; Li, X. N.; Du, X. Z. Chem. - Eur. J. 2022, 28, e202202050.
[7]	Wang, J. Y.; de Kool, R. M.; Velders, A. H. Langmuir. 2015, 31, 12251.
[8]	Harris, M.; Carron, S.; Vander Elst, L.; Laurent, S.; Parac‐Vogt, T. N. Eur. J. Inorg. Chem. 2015, 2015, 4572.
[9]	Liu, R. M.; Feng, Y. H.; Li, Z.; Lu, S.; Guan, T. Y.; Li, X. J.; Liu, Y.; Chen, Z.; Chen, X. Y. Acta Chim. Sinica. 2022, 80, 423. (in Chinese)
	(刘若湄, 冯艳辉, 李卓, 卢珊, 关天用, 李幸俊, 刘䶮, 陈卓, 陈学元, 化学学报, 2022, 80, 423.) doi: 10.6023/A22010001
[10]	Xu, L. M.; Feng, L. Z.; Han, Y. C.; Jing, Y. Y.; Xian, Z. Y.; Liu, Z.; Huang, J. B.; Yan, Y. Soft Matter. 2014, 10, 4686.
[11]	Liu, J.; Morikawa, M.; Kimizuka, N. J. Am. Chem. Soc. 2011, 133, 17370.
[12]	Fang, G. H.; Yang, X. W.; Chen, S. M.; Wang, Q. X.; Zhang, A. W.; Tang, B. Coord. Chem. Rev. 2022, 454, 214352.
[13]	Lu, Y. Q.; Zou, H.; Yuan, H.; Gu, S. Y.; Yuan, W. Z.; Li, M. Q. Eur. Polym. J. 2017, 91, 396.
[14]	Dan, Z. L.; Cao, H. Q.; He, X. Y.; Zeng, L. J.; Zou, L. L.; Shen, Q.; Zhang, Z. W. Int. J. Pharm. 2015, 483, 63.
[15]	Zhou, C. C.; Cheng, X. H.; Zhao, Q.; Yan, Y.; Wang, J. D.; Huang, J. B. Langmuir. 2013, 29, 13175.
[16]	Wei, Z. Y.; Wu, Z. K.; Ru, S.; Ni, L. B.; Wei, Y. G. Chem. J. Chinese Universities. 2022, 43, 190. (in Chinese)
	(魏哲宇, 吴志康, 茹诗, 倪鲁彬, 魏永革, 高等学校化学学报, 2022, 43, 190.)
[17]	Yuan, Y.; Nie, T. Q.; Fang, Y. F.; You, X. R.; Huang, H.; Wu, J. J. Mater. Chem. B. 2022, 10, 2077.
[18]	Zhang, Y. M.; Liu, Y. H.; Liu, Y. Adv. Mater. 2020, 32, 1806158.
[19]	Xiao, X.; Huang, J. B. Langmuir. 2024, 40, 15407.
[20]	Liu, K.; Ma, C.; Wu, T. Y.; Qi, W. L.; Yan, Y.; Huang, J. B. Curr. Opin. Colloid Interface Sci. 2020, 45, 44.
[21]	Wang, Y. F.; He, L. L.; Ding, L. L.; Zhao, X. Y.; Ma, H.; Luo, Y. H.; Ma, S. S.; Xiong, Y. M. Chem. Mater. 2023, 35, 5723.
[22]	Zhou, W. L.; Chen, Y.; Liu, Y. Acta Chim. Sinica. 2020, 78, 1164. (in Chinese)
	(周维磊, 陈湧, 刘育, 化学学报, 2020, 78, 1164.) doi: 10.6023/A20100486
[23]	Xu, W.; Liang, W.; Wu, W.; Fan, C.; Rao, M.; Su, D.; Zhong, Z.; Yang, C. Chem. Eur. J. 2018, 24, 16677.
[24]	Samanta, S. K.; Ghorai, S. K.; Ghosh, S. J. J. Photochem. Photobiol., A. 2013, 252, 145.
[25]	Zhang, W. J.; Chen, Y.; Zhang, S. P.; Tang, S. K.; Chen, X. Q.; Cui, G. Y. C. J. Inorg. Organomet. Polym. Mater. 2018, 28, 1294.
[26]	Ribeiro, A. O.; Serra, O. A. J. Inclusion Phenom. Macrocyclic Chem. 2010, 67, 281.
[27]	Lei, N. N.; Shen, D. Z.; Wang, X. F.; Wang, J.; Li, Q. T.; Chen, X. J. Colloid Interface Sci. 2018, 529, 122.
[28]	Dutta, R.; Kundu, S.; Sarkar, N. Biophys. Rev. 2018, 10, 861.
[29]	Adawiyah, N.; Moniruzzaman, M.; Hawatulaila, S.; Goto, M. Med. Chem. Commun. 2016, 7, 1881.
[30]	Prodius, D.; Mudring, A. V. Coord. Chem. Rev. 2018, 363, 1.
[31]	Yi, S. J.; Yao, M. H.; Wang, J.; Chen, X. Phys. Chem. Chem. Phys. 2016, 18, 27603.
[32]	Li, Q. R.; Yi, S. J.; Chen, X. ACS Omega. 2019, 4, 9843.
[33]	Yi, S. J.; Wang, J.; Chen, X. Chem. Chem. Phys. 2015, 17, 20322.
[34]	Li, Q. R.; Song, S. H.; Feng, Z. Y.; Qiu, J.; Sun, M.; Chen, X. Langmuir. 2020, 36, 2911.
[35]	Zhang, J. J.; Shen, X. H. J. Phys. Chem. B. 2013, 117, 1451.
[36]	Zhou, C. C.; Cheng, X. H.; Yan, Y.; Wang, J. D.; Huang, J. B. Langmuir. 2014, 30, 3381.
[37]	Xiao, X.; Xu, Z. R.; Wang, W. K.; Sun, S. Y.; Qiao, Y.; Jiang, L. X.; Yan, Y.; Huang, J. B. Langmuir. 2021, 37, 8348. doi: 10.1021/acs.langmuir.1c01226 pmid: 34210141
[38]	Wang, J.; Wang, T.; Hu, Y. M.; Zhang, X. N.; Ma, Y. Y.; Lv, H. M.; Xu, S. S.; Wang, Y. L.; Jiang, Z. K. J. Mater. Sci. 2021, 56, 10979.
[39]	Guo, Y. W.; Liu, J.; Tang, Q. L.; Li, C. C.; Zhang, Y. Y.; Wang, Y.; Wang, Y. X.; Bi, Y. P.; Snow, C. D.; Kipper, M. J.; Belfiore, L. A.; Tang, J. G. Int. J. Mol. Sci. 2022, 23, 6597.
[40]	Hao, Q.; Kang, Y. T.; Xu, J. F.; Zhang, X. Langmuir. 2021, 37, 6062. doi: 10.1021/acs.langmuir.1c00781 pmid: 33961441
[41]	Shen, J. L.; Song, L. F.; Xin, X.; Wu, D.; Wang, S. B.; Chen, R. Colloids Surf., A. 2016, 509, 512.
[42]	Kang, Y. T.; Cai, Z. G.; Tang, X. Y.; Liu, K.; Wang, G. T.; Zhang, X. ACS Appl. Mater. Interfaces. 2016, 8, 4927.
[43]	Siva, S.; Nayaki, S. K.; Rajendiran, N. Carbohydr. Polym. 2015, 122, 123.
[44]	Zhang, J. J.; Shen, X. H.; Wu, A. H.; Zhang, C. F.; Chen, Q. D.; Gao, H. C. Sci. China: Chem. 2010, 53, 2019.

稀土超分子荧光有序聚集体在离子液体中聚集及荧光性能的研究