Cucurbit[7]Uril-Based Supramolecular Polymers With Dual Photochromism and Fluorescence: From Host‒Guest Design to Smart Applications

Abstract

The development and fabrication of cucurbit[7]uril (Q[7])-based host‒guest supramolecular polymers remain challenging due to the limited cavity size of Q[7]. Herein, we designed and synthesized three thiophene-pyridinium guests and investigated their binding interactions with Q[7]. NMR, ESI-MS spectroscopy, and DFT calculations revealed that Q[7] can encapsulate one or two thiophene groups of the guests to form supramolecular complexes, including discrete inclusion complexes and supramolecular polymers. Importantly, all supramolecular complexes demonstrated reversible photochromism in the solid state, which is attributed to viologen radical generation, as confirmed by UV-vis-NIR, ESR, and DFT studies. Due to the aggregation caused quenching (ACQ) effect induced by the intermolecular π⋯π stacking interaction of thiophene groups within the Q[7] cavity, the Q[7]-based supramolecular polymers remained fluorescence-silent, whereas the discrete inclusion complexes showed enhanced fluorescence compared to their thiophene-pyridinium guests. The dual photochromic and fluorescence properties of the Q[7]-based supramolecular complexes render them suitable for applications in erasable inkless printing, multi-level anti-counterfeiting, and advanced information encryption. This study provides a strategy for constructing dual-functional supramolecular polymers using Q[7]-based host‒guest interactions.

Keywords

cucurbituril / fluorescence / host−guest chemistry / photochromism / supramolecular polymers

References

[1] J.-M. Lehn, “Toward Complex Matter: Supramolecular Chemistry and Self-Organization,” Proceedings of the National Academy of Sciences of the United States of America 99 (2002): 4763-4768.

[2] T. Aida, E. W. Meijer, and S. I. Stupp, “Functional Supramolecular Polymers,” Science 335 (2012): 813-817.

[3] M. J. Webber and R. Langer, “Drug Delivery by Supramolecular Design,” Chemical Society Reviews 46 (2017): 6600-6620.

[4] D. Xia, P. Wang, X. Ji, N. M. Khashab, J. L. Sessler, and F. Huang, “Functional Supramolecular Polymeric Networks: The Marriage of Covalent Polymers and Macrocycle-Based Host-Guest Interactions,” Chemical Reviews 120 (2020): 6070-6123.

[5] L. Escobar and P. Ballester, “Molecular Recognition in Water Using Macrocyclic Synthetic Receptors,” Chemical Reviews 121 (2021): 2445-2514.

[6] J. R. Wu, G. Wu, D. Li, and Y. W. Yang, “Macrocycle-Based Crystalline Supramolecular Assemblies Built With Intermolecular Charge-Transfer Interactions,” Angewandte Chemie International Edition 62 (2023): e202218142.

[7] D.-H. Qu, Q.-C. Wang, Q.-W. Zhang, X. Ma, and H. Tian, “Photoresponsive Host-Guest Functional Systems,” Chemical Reviews 115 (2015): 7543-7588.

[8] G. Yu, K. Jie, and F. Huang, “Supramolecular Amphiphiles Based on Host-Guest Molecular Recognition Motifs,” Chemical Reviews 115 (2015): 7240-7303.

[9] I. V. Kolesnichenko and E. V. Anslyn, “Practical Applications of Supramolecular Chemistry,” Chemical Society Reviews 46 (2017): 2385-2390.

[10] Z. Liu, S. K. M. Nalluri, and J. F. Stoddart, “Surveying Macrocyclic Chemistry: From Flexible Crown Ethers to Rigid Cyclophanes,” Chemical Society Reviews 46 (2017): 2459-2478.

[11] J. Murray, K. Kim, T. Ogoshi, W. Yao, and B. C. Gibb, “The Aqueous Supramolecular Chemistry of Cucurbit[n]Urils, Pillar[n]Arenes and Deep-Cavity Cavitands,” Chemical Society Reviews 46 (2017): 2479-2496.

[12] E. Krieg, M. M. C. Bastings, P. Besenius, and B. Rybtchinski, “Supramolecular Polymers in Aqueous Media,” Chemical Reviews 116 (2016): 2414-2477.

[13] R. Pinalli, A. Pedrini, and E. Dalcanale, “Biochemical Sensing With Macrocyclic Receptors,” Chemical Society Reviews 47 (2018): 7006-7026.

[14] J. W. Lee, S. Samal, N. Selvapalam, H. J. Kim, and K. Kim, “Cucurbituril Homologues and Derivatives: New Opportunities in Supramolecular Chemistry,” Accounts of Chemical Research 36 (2003): 621-630.

[15] J. Lagona, P. Mukhopadhyay, S. Chakrabarti, and L. Isaacs, “The Cucurbit[n]Uril Family,” Angewandte Chemie International Edition 44 (2005): 4844-4870.

[16] X.-L. Ni, X. Xiao, H. Cong, et al., “Cucurbit[n]Uril-Based Coordination Chemistry: From Simple Coordination Complexes to Novel Poly-Dimensional Coordination Polymers,” Chemical Society Reviews 42 (2013): 9480.

[17] A. E. Kaifer, “Toward Reversible Control of Cucurbit[n]Uril Complexes,” Accounts of Chemical Research 47 (2014): 2160-2167.

[18] K. I. Assaf and W. M. Nau, “Cucurbiturils: From Synthesis to High-Affinity Binding and Catalysis,” Chemical Society Reviews 44 (2015): 394-418.

[19] S. J. Barrow, S. Kasera, M. J. Rowland, J. Barrio, and O. A. Scherman, “Cucurbituril-Based Molecular Recognition,” Chemical Reviews 115 (2015): 12320-12406.

[20] L. Zhu, M. Zhu, and Y. Zhu, “Controlled Movement of Cucurbiturils in Host-Guest Systems,” ChemPlusChem 82 (2017): 30-41.

[21] R. L. Lin, J. X. Liu, K. Chen, and C. Redshaw, “Supramolecular Chemistry of Substituted Cucurbit[n]Urils,” Inorganic Chemistry Frontiers 7 (2020): 3217-3246.

[22] Y. Huang, R.-H. Gao, X.-L. Ni, et al., “Cucurbit[n]Uril-Based Supramolecular Frameworks Assembled Through Outer-Surface Interactions,” Angewandte Chemie International Edition 60 (2021): 15166-15191.

[23] H. Nie, Z. Wei, X.-L. Ni, and Y. Liu, “Assembly and Applications of Macrocyclic-Confinement-Derived Supramolecular Organic Luminescent Emissions From Cucurbiturils,” Chemical Reviews 122 (2022): 9032-9077.

[24] J. X. Liu, K. Chen, and C. Redshaw, “Stimuli-Responsive Mechanically Interlocked Molecules Constructed From Cucurbit[n]Uril Homologues and Derivatives,” Chemical Society Reviews 52 (2023): 1428-1455.

[25] E. Pazos, P. Novo, C. Peinador, A. E. Kaifer, and M. D. García, “Cucurbit[8]Uril (CB[8])-Based Supramolecular Switches,” Angewandte Chemie International Edition 58 (2019): 403-416.

[26] Y. H. Ko, E. Kim, I. Hwang, and K. Kim, “Supramolecular Assemblies Built With Host-Stabilized Charge-Transfer Interactions,” Chemical Communications 43 (2007): 1305-1315.

[27] S. M. Liu, P. Y. Zavalij, and L. Isaacs, “Cucurbit[10]Uril,” Journal of the American Chemical Society 127 (2005): 16798-16799.

[28] J. Yang, X. Hu, M. Fan, and S. Liu, “Aqueous-Phase Tunable Multi-Color Luminescent Supramolecular Assemblies Based on Cucurbit[10]Uril-Enhanced Intermolecular Charge-Transfer Interactions,” Organic Chemistry Frontiers 10 (2023): 422-429.

[29] D. Sun, Y. Wu, X. Han, and S. Liu, “Achieving Enhanced Photochromic Properties of Diarylethene Through Host-Guest Interaction in Aqueous Solution,” Chemistry-A European Journal 27 (2021): 16153-16160.

[30] Y. Luo, S. Gan, W. Zhang, et al., “A New Cucurbit[10]Uril-Based AIE Fluorescent Supramolecular Polymer for Cellular Imaging,” Materials Chemistry Frontiers 6 (2022): 1021-1025.

[31] Y. Liu, H. Yang, Z. Wang, and X. Zhang, “Cucurbit[8]Uril-Based Supramolecular Polymers,” Chemistry-An Asian Journal 8 (2013): 1626-1632.

[32] J. Kim, I.-S. Jung, S.-Y. Kim, et al., “New Cucurbituril Homologues: Syntheses, Isolation, Characterization, and X-Ray Crystal Structures of Cucurbit[n]Uril (n = 5, 7, and 8),” Journal of the American Chemical Society 122 (2000): 540-541.

[33] W. Ong and A. E. Kaifer, “Unusual Electrochemical Properties of the Inclusion Complexes of Ferrocenium and Cobaltocenium With Cucurbit[7]Uril,” Organometallics 22 (2003): 4181-4183.

[34] W. S. Jeon, K. Moon, S. H. Park, et al., “Complexation of Ferrocene Derivatives by the Cucurbit[7]Uril Host: A Comparative Study of the Cucurbituril and Cyclodextrin Host Families,” Journal of the American Chemical Society 127 (2005): 12984-12989.

[35] R. Wang, L. Yuan, and D. H. Macartney, “Stabilization of the (E)-1-Ferrocenyl-2-(1-Methyl-4-Pyridinium)Ethylene Cation by Inclusion in Cucurbit[7]Uril,” Organometallics 25 (2006): 1820-1823.

[36] C. Chen, J.-K. Sun, Y.-J. Zhang, X.-D. Yang, and J. Zhang, “Flexible Viologen-Based Porous Framework Showing X-Ray Induced Photochromism With Single-Crystal-to-Single-Crystal Transformation,” Angewandte Chemie International Edition 56 (2017): 14458-14462.

[37] X.-J. Sun, J. Zhang, and Z.-Y. Fu, “Polyoxometalate Cluster Sensitized With Copper-Viologen Framework for Efficient Degradation of Organic Dye in Ultraviolet, Visible, and Near-Infrared Light,” ACS Applied Materials & Interfaces 10 (2018): 35671-35675.

[38] C.-M. Yu, P.-H. Wang, Q. Liu, L.-Z. Cai, and G.-C. Guo, “Modulating Fading Time of Photochromic Compounds by Molecular Design for Erasable Inkless Printing and Anti-Counterfeiting,” Crystal Growth & Design 21 (2021): 1323-1328.

[39] M. Chang, D. Liang, F. Zhou, et al., “Photochromic and Electrochromic Hydrogels Based on Ammonium- and Sulfonate-Functionalized Thienoviologen Derivatives,” ACS Applied Materials & Interfaces 14 (2022): 15448-15460.

[40] Y.-J. Zhang, C. Chen, B. Tan, L.-X. Cai, X.-D. Yang, and J. Zhang, “A Dual-Stimuli Responsive Small Molecule Organic Material With Tunable Multi-State Response Showing Turn-On Luminescence and Photocoloration,” Chemical Communications 52 (2016): 2835-2838.

[41] S.-L. Li, M. Li, Y. Zhang, H.-M. Xu, and X.-M. Zhang, “Tri(Pyridinyl)Pyridine Viologen-Based Kagome Dual Coordination Polymer With Selective Chromic Response to Soft X-Ray and Volatile Organic Amines,” Inorganic Chemistry 59 (2020): 9047-9054.

[42] X. Li, J. Yang, and Y.-W. Yang, “Recent Advances of Stimuli-Responsive Viologen-Based Nanocomposites,” Materials Chemistry Frontiers 7 (2023): 1463-1481.

[43] F. Biedermann, V. D. Uzunova, O. A. Scherman, W. M. Nau, and A. D. Simone, “Release of High-Energy Water as an Essential Driving Force for the High-Affinity Binding of Cucurbit[n]Urils,” Journal of the American Chemical Society 134 (2012): 15318-15323.

[44] J. Yu, H. Yu, J. Niu, Z. Lei, and Y. Liu, “Tunable Nano-Supramolecules Based on Cucurbiturils for Near-Infrared Phosphorescence Imaging,” Nano Letters 24 (2024): 16124-16131.

[45] G. Liu, Y.-M. Zhang, C. Wang, and Y. Liu, “Dual Visible Light-Triggered Photoswitch of a Diarylethene Supramolecular Assembly With Cucurbit[8]Uril,” Chemistry-A European Journal 23 (2017): 14425-14429.

[46] S.-H. Li, X. Xu, Y. Zhou, Q. Zhao, and Y. Liu, “Reversibly Tunable White-Light Emissions of Styrylpyridiniums With Cucurbiturils in Aqueous Solution,” Organic Letters 19 (2017): 6650-6653.

[47] B. Garai, A. Mallick, and R. Banerjee, “Photochromic Metal-Organic Frameworks for Inkless and Erasable Printing,” Chemical Science 7 (2016): 2195-2200.

[48] D.-D. Yang, H.-W. Zheng, Y.-H. Fang, et al., “Multistimuli-Responsive Materials Based on Zn(II)-Viologen Coordination Polymers and Their Applications in Inkless Print and Anticounterfeiting,” Inorganic Chemistry 61 (2022): 7513-7522.

[49] Q. Wang, M.-C. Liu, W.-Q. Sun, R.-L. Lin, R.-G. Lin, and J.-X. Liu, “Solid-State Supramolecular Inclusion Complexes of β-Cyclodextrin With Carboxyphenyl Viologens Showing Photochromic Properties,” Journal of Physical Chemistry C 126 (2022): 844-850.

[50] D.-X. Xia, X. Wang, W.-Q. Sun, R.-L. Lin, J.-X. Liu, and Y.-W. Yang, “Chameleon-Inspired Supramolecular Materials Based on Cucurbit[7]Uril and Viologens Exhibiting Full-Color Tunable Photochromic Behavior,” Chemical Engineering Journal 484 (2024): 149551.

[51] M. J. Frisch, G. W. Trucks, H. B. Schlegel, et al., Gaussian 16, Revision C.01 (Gaussian, Inc., 2019).

[52] A. D. Becke, “Density-Functional Thermochemistry. III. The Role of Exact Exchange,” Journal of Chemical Physics 98 (1993): 5648-5652.

[53] R. Krishnan, J. S. Binkley, R. Seeger, and J. A. Pople, “Self-Consistent Molecular Orbital Methods. XX. A Basis Set for Correlated Wave Functions,” Journal of Chemical Physics 72 (1980): 650-654.

[54] S. Grimme, S. Ehrlich, and L. Goerigk, “Effect of the Damping Function in Dispersion Corrected Density Functional Theory,” Journal of Computational Chemistry 32 (2011): 1456-1465.

[55] T. Lu and F. Chen, “Multiwfn: A Multifunctional Wavefunction Analyzer,” Journal of Computational Chemistry 33 (2012): 580-592.

[56] T. Lu, “A Comprehensive Electron Wavefunction Analysis Toolbox for Chemists, Multiwfn,” Journal of Chemical Physics 161 (2024): 082503.

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