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Nguyen HD, Abe M. Crucial Roles of Leaving Group and Open-Shell Cation in Photoreaction of (Coumarin-4-yl)methyl Derivatives. J Am Chem Soc 2024; 146:10993-11001. [PMID: 38579283 DOI: 10.1021/jacs.4c02880] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/07/2024]
Abstract
Photoreactions of (coumarin-4-yl)methyl derivatives have been extensively studied in many fields of chemistry, including organic synthesis and photoinduced drug delivery systems. The identification of the reaction intermediates involved in the photoreactions is crucial not only for elucidating the reaction mechanism but also for the application of the photoreactions. In this study, the photoreactions of 7-diethylamino(coumarin-4-yl)methyl thioester 1a [-SC(O)CH3], thionoester 1b [-OC(S)CH3], and ester 1c [-OC(O)CH3] were investigated to clarify the intermediary species and their chemical behavior. While a radical pair [i.e., 7-diethylamino(coumarin-4-yl)methyl radical and CH3C(O)S•] plays an important role in the photoreactions of 1a and 1b, an ion pair [i.e., 7-diethylamino(coumarin-4-yl)methyl cation, and CH3CO2-] was the key in the photoreaction of 1c. 18O-isotope-labeling of 1c revealed a negligible recombination process within the ion pair. The unprecedented observation was rationalized by the open-shell character of the 7-diethylamino(coumarin-4-yl)methyl cation, whose formation was confirmed through product analysis and transient absorption spectroscopy.
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Affiliation(s)
- Hai Dang Nguyen
- Department of Chemistry, Graduate School of Advance Science and Engineering, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8526, Hiroshima, Japan
| | - Manabu Abe
- Department of Chemistry, Graduate School of Advance Science and Engineering, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8526, Hiroshima, Japan
- Hiroshima Research Center for Photo-Drug-Delivery Systems (Hi-P-DDS), Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8526, Hiroshima, Japan
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Wan Z, Yu S, Wang Q, Sambath K, Harty R, Liu X, Chen H, Wang C, Liu X, Zhang Y. Far-red BODIPY-based oxime esters: photo-uncaging and drug delivery. J Mater Chem B 2023; 11:9889-9893. [PMID: 37850246 PMCID: PMC10750304 DOI: 10.1039/d3tb01867a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2023]
Abstract
Far-red BODIPY-based oxime esters for photo-uncaging were designed to release molecules of interest with carboxylic acids. The low power red LED light breaks the N-O oxime ester bond and frees the caged molecules. We studied the mechanism and kinetics of the uncaging procedure using a 1H NMR spectrometer. Moreover, the drug delivery strategy to release valproic acid (VPA) on demand was tested in vitro using this far-red BODIPY photo-uncaging strategy to induce apoptosis in tumor cells.
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Affiliation(s)
- Zhaoxiong Wan
- Department of Chemistry and Environmental Science, College of Science and Liberal Arts, New Jersey Institute of Technology, 323 Martin Luther King Jr. Blvd., Newark, New Jersey 07102, USA.
| | - Shupei Yu
- Department of Chemistry and Environmental Science, College of Science and Liberal Arts, New Jersey Institute of Technology, 323 Martin Luther King Jr. Blvd., Newark, New Jersey 07102, USA.
| | - Qi Wang
- Department of Chemistry and Environmental Science, College of Science and Liberal Arts, New Jersey Institute of Technology, 323 Martin Luther King Jr. Blvd., Newark, New Jersey 07102, USA.
| | - Karthik Sambath
- Department of Chemistry and Environmental Science, College of Science and Liberal Arts, New Jersey Institute of Technology, 323 Martin Luther King Jr. Blvd., Newark, New Jersey 07102, USA.
| | - Roshena Harty
- Department of Chemistry and Environmental Science, College of Science and Liberal Arts, New Jersey Institute of Technology, 323 Martin Luther King Jr. Blvd., Newark, New Jersey 07102, USA.
| | - Xiangshan Liu
- Department of Chemistry and Environmental Science, College of Science and Liberal Arts, New Jersey Institute of Technology, 323 Martin Luther King Jr. Blvd., Newark, New Jersey 07102, USA.
| | - Hao Chen
- Department of Chemistry and Environmental Science, College of Science and Liberal Arts, New Jersey Institute of Technology, 323 Martin Luther King Jr. Blvd., Newark, New Jersey 07102, USA.
| | - Chen Wang
- Department of Chemistry and Biochemistry, Queens College, City University of New York, 65-30 Kissena Blvd., New York 11432, USA
| | - Xuan Liu
- Department of Electrical and Computer Engineering, New Jersey Institute of Technology, 323 Martin Luther King Jr. Blvd., Newark, New Jersey 07102, USA
| | - Yuanwei Zhang
- Department of Chemistry and Environmental Science, College of Science and Liberal Arts, New Jersey Institute of Technology, 323 Martin Luther King Jr. Blvd., Newark, New Jersey 07102, USA.
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Karas LJ, Wu CH, Wu JI. Barrier-Lowering Effects of Baird Antiaromaticity in Photoinduced Proton-Coupled Electron Transfer (PCET) Reactions. J Am Chem Soc 2021; 143:17970-17974. [PMID: 34672631 DOI: 10.1021/jacs.1c09324] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Many popular organic chromophores that catalyze photoinduced proton-coupled electron transfer (PCET) reactions are aromatic in the ground state but become excited-state antiaromatic in the lowest ππ* state. We show that excited-state antiaromaticity makes electron transfer easier. Two representative photoinduced electron transfer processes are investigated: (1) the photolysis of phenol and (2) solar water splitting of a pyridine-water complex. In the selected reactions, the directions of electron transfer are opposite, but the net result is proton transfer following the direction of electron transfer. Nucleus-independent chemical shifts (NICS), ionization energies, electron affinities, and PCET energy profiles of selected [4n] and [4n + 2] π-systems are presented, and important mechanistic implications are discussed.
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Affiliation(s)
- Lucas J Karas
- Department of Chemistry, University of Houston, Houston, Texas 77204, United States
| | - Chia-Hua Wu
- Department of Chemistry, University of Houston, Houston, Texas 77204, United States
| | - Judy I Wu
- Department of Chemistry, University of Houston, Houston, Texas 77204, United States
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Ganguly G, Pathak S, Paul A. Unraveling the stability of cyclobutadiene complexes using aromaticity markers. Phys Chem Chem Phys 2021; 23:16005-16012. [PMID: 34235525 DOI: 10.1039/d1cp01467f] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Cyclobutadiene (CBD) is the paradigmatic antiaromatic molecule but is known to form highly stable aromatic complexes, e.g. CBD-Fe(CO)3. This intriguing reversal of aromaticity from antiaromatic to aromatic terrain during the complexation process cannot be appropriately handled with single-reference-based theoretical techniques. We explore this aromaticity reversal, for the first time, by a detailed aromaticity analysis using magnetically induced current densities (MICD) and nucleus independent chemical shifts (NICS) using genuine ab initio multi-reference wavefunction-based theory. We trace the dramatic change of aromaticity for a prototypical cyclobutadiene complex, CBD-CH+ (CH+Fe(CO)3), considering a 3D potential energy surface for two independent parameters, namely the approach of CH+ and the automerization cross-section of cyclobutadiene. The 3D potential energy surfaces indicate the presence of a conical intersection/avoided crossing between the ground and the first excited state. The plot of aromaticity indices and the corresponding numerical values show that the change of aromaticity indices is drastic around the conical intersection/avoided crossing and automerization of cyclobutadiene plays a crucial role in the formation of cyclobutadiene complexes. Computations on analogous CBD-Be and CBD-CO systems (Be/COFe(CO)3) emphasize the generality of the conclusions drawn from the CBD-CH+ system.
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Affiliation(s)
- Gaurab Ganguly
- School of Chemical Sciences, Indian Association for the Cultivation of Science, 2A & 2B Raja S C Mullick Road, Kolkata 700032, India.
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