Abstract
Collisional intermolecular interactions between excited states form short-lived dimers and complexes that lead to the emergence of excimer/exciplex emission of lower energy, a phenomenon which must be differentiated from the photoluminescence (PL) arising from the monomeric molecules. Although the utilization of noncovalent bonding interactions, leading to the generation of excimer/exciplex PL, has been investigated extensively, precise control of the aggregates and their persistence at very low concentrations remains a rare phenomenon. In the search for a fresh approach, we sought to obtain exciplex PL from permanent structures by incorporating anthracene moieties into pyridinium-containing mechanically interlocked molecules. Beyond the optical properties of the anthracene moieties, their π-extended nature enforces [π···π] stacking that can overcome the Coulombic repulsion between the pyridinium units, affording an efficient synthesis of an octacationic homo[2]catenane. Notably, upon increasing the ionic strength by adding tetrabutylammonium hexafluorophosphate, the catenane yield increases significantly as a result of the decrease in Coulombic repulsions between the pyridinium units. Although the ground-state photophysical properties of the free cyclophane and the catenane are similar and show a charge-transfer band at ∼455 nm, their PL characters are distinct, denoting different excited states. The cyclophane emits at ∼562 nm (quantum yield ϕF = 3.6%, emission lifetime τs = 3 ns in MeCN), which is characteristic of a disubstituted anthracene-pyridinium linker. By contrast, the catenane displays an exciplex PL at low concentration (10-8 M) with an emission band centered on 650 nm (ϕF = 0.5%, τs = 14 ns) in MeCN and at 675 nm in aqueous solution. Live-cell imaging performed in MIAPaCa-2 prostate cancer cells confirmed that the catenane exciplex emission can be detected at micromolar concentrations.
Original language | English (US) |
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Pages (from-to) | 7956-7967 |
Number of pages | 12 |
Journal | Journal of the American Chemical Society |
Volume | 142 |
Issue number | 17 |
DOIs | |
State | Published - Apr 29 2020 |
ASJC Scopus subject areas
- General Chemistry
- Biochemistry
- Catalysis
- Colloid and Surface Chemistry
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CCDC 1983954: Experimental Crystal Structure Determination
Garci, A. (Contributor), Beldjoudi, Y. (Contributor), Kodaimati, M. S. (Contributor), Hornick, J. E. (Contributor), Nguyen, M. T. (Contributor), Cetin, M. M. (Contributor), Stern, C. L. (Contributor), Roy, I. (Contributor), Weiss, E. A. (Contributor) & Stoddart, J. F. (Contributor), Cambridge Crystallographic Data Centre, 2020
DOI: 10.5517/ccdc.csd.cc24lgjr, http://www.ccdc.cam.ac.uk/services/structure_request?id=doi:10.5517/ccdc.csd.cc24lgjr&sid=DataCite
Dataset
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CCDC 1983956: Experimental Crystal Structure Determination
Garci, A. (Contributor), Beldjoudi, Y. (Contributor), Kodaimati, M. S. (Contributor), Hornick, J. E. (Contributor), Nguyen, M. T. (Contributor), Cetin, M. M. (Contributor), Stern, C. L. (Contributor), Roy, I. (Contributor), Weiss, E. A. (Contributor) & Stoddart, J. F. (Contributor), Cambridge Crystallographic Data Centre, 2020
DOI: 10.5517/ccdc.csd.cc24lglt, http://www.ccdc.cam.ac.uk/services/structure_request?id=doi:10.5517/ccdc.csd.cc24lglt&sid=DataCite
Dataset
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CCDC 1983955: Experimental Crystal Structure Determination
Garci, A. (Contributor), Beldjoudi, Y. (Contributor), Kodaimati, M. S. (Contributor), Hornick, J. E. (Contributor), Nguyen, M. T. (Contributor), Cetin, M. M. (Contributor), Stern, C. L. (Contributor), Roy, I. (Contributor), Weiss, E. A. (Contributor) & Stoddart, J. F. (Contributor), Cambridge Crystallographic Data Centre, 2020
DOI: 10.5517/ccdc.csd.cc24lgks, http://www.ccdc.cam.ac.uk/services/structure_request?id=doi:10.5517/ccdc.csd.cc24lgks&sid=DataCite
Dataset