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Yang Z, Huo Y, Liu Y, Du G, Zhang W, Zhou L, Zhan L, Ren X, Duan W, Gong S. Axially chiral 1,4-dihydropyridine derivatives: aggregation-induced emission in exciplexes and application as viscosity probes. RSC Adv 2019; 9:32219-32225. [PMID: 35530811 PMCID: PMC9072944 DOI: 10.1039/c9ra06553a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Accepted: 09/25/2019] [Indexed: 12/14/2022] Open
Abstract
By combining the fluorophores of axially chiral 1,1′-binaphthol (BINOL) and 1,4-dihydropyridine derivatives, axially chiral 1,4-dihydropyridine derivatives ((R)-/(S)-2) with aggregation-induced emission (AIE) in exciplexes were designed and synthesized. (R)-/(S)-2 emitted low fluorescence in THF solutions of their locally excited states; however, they emitted red-shifted fluorescence in the aggregate state upon exciplex formation. Moreover, (R)-/(S)-2 showed linear and multi-exponential relationships between their local excited and exciplex fluorescence intensities and the viscosity of the medium, which allowed us to determine the viscosities of different mixed solvents. In addition, as an axially chiral viscosity probe, (R)-/(S)-2 show excellent CD signals and have potential applications in the fields of chiral recognition and fluorescence imaging, which will broaden the new family of AIE fluorophores. To the best of our knowledge, there are few reports of axially chiral intramolecular exciplex-mediated AIE molecules. Axially chiral 1,4-dihydropyridine derivatives ((R)-/(S)-2) with aggregation-induced emission (AIE) in exciplex were designed and synthesized. They have excellent CD signals and can determine the different viscosity in mixed solvents.![]()
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Safko TM, Kertesz M, Weiss RG. Photophysics of N,N-dimethyl-3-(1-indolyl)propan-1-ammonium chloride and related derivatives. Photochem Photobiol Sci 2017; 16:1546-1555. [PMID: 28876020 DOI: 10.1039/c7pp00199a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The photophysical properties of two new indole derivatives have been examined by steady-state and dynamic spectroscopic methods. The ground-state structures and conformations of 3-(1-indolyl)-N,N-dimethylpropan-1-ammonium chloride (InCl) and 3-(1-indolyl)-N,N,N-trimethylpropan-1-ammonium chloride (MeInCl) have been examined through density functional theory calculations. These calculations reveal a preference for a 'closed' conformation which places the cationic ammonium group in proximity to the π-electron cloud in low polarity environments. This interaction is best described as an intramolecular hydrogen-π bond in the case of InCl and a cation-π interaction for MeInCl. The ground-state conformational equilibria are influenced by changes in the dielectric constant of the solvent, resulting in a variety of photophysical behaviors. The excitation/emission spectra, fluorescence quantum yields, and excited-state lifetimes, are reported for InCl, MeInCl, and a reference compound, 1-methylindole, in 1,4-dioxane (ε = 2), acetonitrile (ε = 37), and water (ε = 78) where solubility allows. Data from these solvents provide evidence for independent fluorescence quenching pathways for InCl and MeInCl. In addition, they lead to insights into the complexities of indole photophysics by demonstrating the sensitivity of the locally-excited states to changes in charge-density and solvent environment.
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Affiliation(s)
- Trevor M Safko
- Department of Chemistry, Georgetown University, 37th and O Streets, NW, Washington, DC 20057-1227, USA
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Chong H, Fron E, Liu Z, Boodts S, Thomas J, Harvey JN, Hofkens J, Dehaen W, Van der Auweraer M, Smet M. Acid-Sensitive BODIPY Dyes: Synthesis through Pd-Catalyzed Direct C(sp 3 )-H Arylation and Photophysics. Chemistry 2017; 23:4687-4699. [PMID: 28134471 DOI: 10.1002/chem.201700015] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2017] [Indexed: 01/01/2023]
Abstract
A novel palladium-catalyzed direct C(sp3 )-H arylation of the methyl group at the 8-position of BODIPY by bromoarenes was established. A deprotonative cross-coupling process was supposed to be involved in the reaction. This approach allowed us to attach electron-donating/withdrawing, halogen substituted aryls and a heteroaryl with a yield running from 55 to 99 %. Novel pH sensors, which in the absence of acid showed the occurrence of photoinduced electron transfer, were synthesized by attaching dimethylaniline to the methyl at the C8-position of BODIPY. The reference compounds with dimethylaniline directly attached to the C8-position were also synthesized and besides photoinduced electron transfer also showed a charge-transfer emission. Their photophysical properties were investigated by steady-state fluorescence, time-correlated single-photon counting and femtosecond fluorescence up-conversion. Time-dependent density functional (TD-DFT) electronic-structure calculations on the properties of the excited states corresponding to local excitation of the BODIPY core and to charge transfer were conducted. Upon addition of trifluoroacetic acid in toluene and ethanol, the partial fluorescence intensity recovery was at least an order of magnitude more efficient with the newly synthesized sensors compared to the traditional reference sensors. The improved sensitivity of these novel BODIPY-based pH sensors was attributed to less efficient proton-coupled electron transfer of the protonated species.
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Affiliation(s)
- Hui Chong
- Division of Polymer Chemistry and Materials, Department of Chemistry, Katholieke Universiteit Leuven, Celestijnenlaan 200F, 3001, Leuven, Belgium
| | - Eduard Fron
- Division of Molecular Imaging and Photonics, Department of Chemistry, Katholieke Universiteit Leuven, Celestijnenlaan 200F, 3001, Leuven, Belgium
| | - Zhen Liu
- Division of Quantum Chemistry and Physical Chemistry, Department of Chemistry, Katholieke Universiteit Leuven, Celestijnenlaan 200F, 3001, Leuven, Belgium
| | - Stijn Boodts
- Division of Molecular Design and Synthesis, Department of Chemistry, Katholieke Universiteit Leuven, Celestijnenlaan 200F, 3001, Leuven, Belgium
| | - Joice Thomas
- Division of Molecular Design and Synthesis, Department of Chemistry, Katholieke Universiteit Leuven, Celestijnenlaan 200F, 3001, Leuven, Belgium
| | - Jeremy N Harvey
- Division of Quantum Chemistry and Physical Chemistry, Department of Chemistry, Katholieke Universiteit Leuven, Celestijnenlaan 200F, 3001, Leuven, Belgium
| | - Johan Hofkens
- Division of Molecular Imaging and Photonics, Department of Chemistry, Katholieke Universiteit Leuven, Celestijnenlaan 200F, 3001, Leuven, Belgium
| | - Wim Dehaen
- Division of Molecular Design and Synthesis, Department of Chemistry, Katholieke Universiteit Leuven, Celestijnenlaan 200F, 3001, Leuven, Belgium
| | - Mark Van der Auweraer
- Division of Molecular Imaging and Photonics, Department of Chemistry, Katholieke Universiteit Leuven, Celestijnenlaan 200F, 3001, Leuven, Belgium
| | - Mario Smet
- Division of Polymer Chemistry and Materials, Department of Chemistry, Katholieke Universiteit Leuven, Celestijnenlaan 200F, 3001, Leuven, Belgium
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Safko TM, Jiang S, Zhang L, Zhang Q, Weiss RG. Proton-coupled charge-transfer reactions and photoacidity of N,N-dimethyl-3-arylpropan-1-ammonium chloride salts. Photochem Photobiol Sci 2017; 16:972-984. [DOI: 10.1039/c7pp00044h] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Excited-state, intermolecular proton-transfers of aromatics tethered to ammonium groups are solvent mediated and coupled to either the formation of an exciplex or a solvent-separated ion pair.
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Affiliation(s)
| | - Shenlong Jiang
- Hefei National Laboratory for Physical Sciences at the Microscale
- Department of Chemical Physics
- Synergetic Innovation Center of Quantum Information and Quantum Physics
- University of Science and Technology of China
- Hefei
| | - Lei Zhang
- Hefei National Laboratory for Physical Sciences at the Microscale
- Department of Chemical Physics
- Synergetic Innovation Center of Quantum Information and Quantum Physics
- University of Science and Technology of China
- Hefei
| | - Qun Zhang
- Hefei National Laboratory for Physical Sciences at the Microscale
- Department of Chemical Physics
- Synergetic Innovation Center of Quantum Information and Quantum Physics
- University of Science and Technology of China
- Hefei
| | - Richard G. Weiss
- Department of Chemistry
- Georgetown University
- Washington
- USA
- Institute for Soft Matter Synthesis and Metrology
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Safko TM, Faleiros MM, Atvars TDZ, Weiss RG. Intramolecular, Exciplex-Mediated, Proton-Coupled, Charge-Transfer Processes in N,N-Dimethyl-3-(1-pyrenyl)propan-1-ammonium Cations: Influence of Anion, Solvent Polarity, and Temperature. J Phys Chem A 2016; 120:3983-91. [PMID: 27268751 DOI: 10.1021/acs.jpca.6b01519] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
An intramolecular exciplex-mediated, proton-coupled, charge-transfer (PCCT) process has been investigated for a series of N,N-dimethyl-3-(1-pyrenyl)propan-1-ammonium cations with different anions (PyS) in solvents of low to intermediate polarity over a wide temperature range. Solvent mediates both the equilibrium between conformations of the cation that place the pyrenyl and ammonium groups in proximity (conformation C) or far from each other (conformation O) and the ability of the ammonium group to transfer a proton adiabatically in the PyS excited singlet state. Thus, exciplex emission, concurrent with the PCCT process, was observed only in hydrogen-bond accepting solvents of relatively low polarity (tetrahydrofuran, ethyl acetate, and 1,4-dioxane) and not in dichloromethane. From the exciplex emission and other spectroscopic and thermodynamic data, the acidity of the ammonium group in conformation C of the excited singlet state of PyS (pKa*) has been estimated to be ca. -3.4 in tetrahydrofuran. The ratios between the intensities of emission from the exciplex and the locally excited state (IEx/ILE) appear to be much more dependent on the nature of the anion than are the rates of exciplex formation and decay, although the excited state data do not provide a quantitative measure of the anion effect on the C-O equilibrium. The activation energies associated with exciplex formation in THF are calculated to be 0.08 to 0.15 eV lower than for the neutral amine, N,N-dimethyl-3-(1-pyrenyl)propan-1-amine. Decay of the exciplexes formed from the deprotonation of PyS is hypothesized to occur through charge-recombination processes. To our knowledge, this is the first example in which photoacidity and intramolecular exciplex formation (i.e., a PCCT reaction) are coupled.
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Affiliation(s)
- Trevor M Safko
- Department of Chemistry and cInstitute for Soft Matter Synthesis and Metrology, Georgetown University , 37th and O Streets NW, Washington, DC 20057-1227, United States
| | - Marcelo M Faleiros
- Instituto de Química, Universidade Estadual de Campinas , Caixa Postal 6154, Campinas, Sao Paulo13083-970, Brasil
| | - Teresa D Z Atvars
- Instituto de Química, Universidade Estadual de Campinas , Caixa Postal 6154, Campinas, Sao Paulo13083-970, Brasil
| | - Richard G Weiss
- Department of Chemistry and cInstitute for Soft Matter Synthesis and Metrology, Georgetown University , 37th and O Streets NW, Washington, DC 20057-1227, United States
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Yan N, Xu Z, Diehn KK, Raghavan SR, Fang Y, Weiss RG. How Do Liquid Mixtures Solubilize Insoluble Gelators? Self-Assembly Properties of Pyrenyl-Linker-Glucono Gelators in Tetrahydrofuran–Water Mixtures. J Am Chem Soc 2013; 135:8989-99. [DOI: 10.1021/ja402560n] [Citation(s) in RCA: 139] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Ni Yan
- Key Laboratory
of Applied Surface
and Colloid Chemistry (Ministry of Education), School of Chemistry
and Chemical Engineering, Shaanxi Normal University, Xi’an 710062, P. R. China
| | - Zhiyan Xu
- Key Laboratory
of Applied Surface
and Colloid Chemistry (Ministry of Education), School of Chemistry
and Chemical Engineering, Shaanxi Normal University, Xi’an 710062, P. R. China
| | - Kevin K. Diehn
- Department
of Chemical and Biomolecular
Engineering, University of Maryland, College
Park, Maryland 20742-2111, United States
| | - Srinivasa R. Raghavan
- Department
of Chemical and Biomolecular
Engineering, University of Maryland, College
Park, Maryland 20742-2111, United States
| | - Yu Fang
- Key Laboratory
of Applied Surface
and Colloid Chemistry (Ministry of Education), School of Chemistry
and Chemical Engineering, Shaanxi Normal University, Xi’an 710062, P. R. China
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