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Wortmann S, Schloeglmann S, Nuernberger P. Sensitivity of Isomerization Kinetics of 1,3,5-Triphenylformazan on Cosolvents Added to Toluene. J Org Chem 2021; 87:1745-1755. [PMID: 34843237 DOI: 10.1021/acs.joc.1c01928] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Formazan molecules exhibit photochromism because isomerization processes following excitation may occur in both the azo group and the hydrazone group; thus, each formazan may be present in various forms with different colors. The ratio of these forms depends on the illumination conditions and the environment of the formazan with a most incisive sensibility of the thermal anti-syn relaxation of the C═N toward slight traces of impurities in toluene solutions, as reported most prominently for 1,3,5-triphenylformazan. Here, we study the latter compound with transient absorption spectroscopy to investigate the role of these traces by adding small amounts of both protic and aprotic cosolvents. Whereas the activation barrier decreases if the binary solvent mixture has a higher polarity, the role of hydrogen bonding can have a reverse impact on the thermal isomerization rate. Both the addition of an aprotic cosolvent and the addition of a protic cosolvent can slow the reaction due to their hydrogen-bond accepting and hydrogen-bond donating properties, respectively. In the case of methanol as a cosolvent, this effect outweighed that of the polarity increase for small concentrations, which was not observed for the fluorinated alcohol hexafluoroisopropanol. The results are explained in the context of a competition between solute-cosolvent and cosolvent-cosolvent hydrogen bonding.
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Affiliation(s)
- Svenja Wortmann
- Institut für Physikalische und Theoretische Chemie, Universität Regensburg, 93040 Regensburg, Germany
| | - Sylvia Schloeglmann
- Institut für Physikalische und Theoretische Chemie, Universität Regensburg, 93040 Regensburg, Germany
| | - Patrick Nuernberger
- Institut für Physikalische und Theoretische Chemie, Universität Regensburg, 93040 Regensburg, Germany
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2
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Photoinduced double proton transfer in the glyoxal-methanol complex along T1 reaction path – a quantum chemical topological study. J Mol Struct 2021. [DOI: 10.1016/j.molstruc.2020.129426] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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3
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Photoinduced Double Proton Transfer in the Glyoxal-Methanol Complex Revisited: The Role of the Excited States. J Chem Theory Comput 2020; 16:3273-3286. [PMID: 32275423 DOI: 10.1021/acs.jctc.0c00007] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Under irradiation in the visible range, the glyoxal-methanol complex in a cryogenic argon matrix undergoes a double proton transfer (DPT) reaction through which the glyoxal molecule isomerizes into hydroxyketene. In this work, we employ electronic structure simulations in order to shed more light on the underlying mechanism. Rewardingly, we find that the lowest singlet excited state (S1) of the complex acts as a gateway to two previously unknown isomerization pathways, of which one takes place entirely in the singlet manifold and the other also involves the lowest triplet state (T1). Both of these pathways are fully compatible with the available experimental data, implying that either or both are operative under experimental conditions. In either pathway, the methanol molecule acts as a proton shuttle between the proton-donating and proton-accepting sites of glyoxal, resulting in a dramatic lowering of the potential energy barrier to isomerization with respect to the case of isolated glyoxal. The occurrence of DPT in the singlet manifold is demonstrated directly with the use of nonadiabatic molecular dynamics simulations at the spin-flip time-dependent density functional theory level.
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4
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Mena LD, Vera DMA, Baumgartner MT, Jimenez LB. Adiabatic deprotonation as an important competing pathway to ESIPT in photoacidic 2-phenylphenols. Phys Chem Chem Phys 2019; 21:12231-12240. [PMID: 31134981 DOI: 10.1039/c9cp02028d] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
ESIPT (Excited State Intramolecular Proton Transfer) to C atom in 2-phenylphenol is known to be an intrinsically inefficient process. However, to the best of our knowledge, a structure-ESIPT efficiency relationship has not been elucidated yet. Here, we show that there exists a competitive interplay between photoacidity and ESIPT efficiency for the 2-phenylphenol system. The attachment of electron withdrawing groups to the phenol moiety promotes adiabatic deprotonation in the excited state and diminishes the charge transfer character of the excitations, and both these factors contribute in decreasing the ESIPT reaction yield. On the other hand, unfavorable conformational distribution in the ground state also appears as another important aspect responsible for the low ESIPT extent of 2-phenylphenol. A new derivative bearing electron donating, bulky substituents at ortho and para positions of the phenol ring shows an outstanding ESIPT performance, which demonstrates that the efficiency of the process can be significantly enhanced by modifying the substitution pattern. We anticipate that our results will help to guide the molecular designing of new compounds with high ESIPT efficiency.
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Affiliation(s)
- Leandro D Mena
- INFIQC, Departamento de Química Orgánica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba Ciudad Universitaria, Córdoba, Argentina.
| | - D M A Vera
- QUIAMM-INBIOTEC-Departamento de Química, Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, Mar del Plata, Argentina
| | - Maria T Baumgartner
- INFIQC, Departamento de Química Orgánica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba Ciudad Universitaria, Córdoba, Argentina.
| | - Liliana B Jimenez
- INFIQC, Departamento de Química Orgánica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba Ciudad Universitaria, Córdoba, Argentina.
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5
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Bull JN, Silva GD, Scholz MS, Carrascosa E, Bieske EJ. Photoinitiated Intramolecular Proton Transfer in Deprotonated para-Coumaric Acid. J Phys Chem A 2019; 123:4419-4430. [DOI: 10.1021/acs.jpca.9b02023] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- James N. Bull
- School of Chemistry, University of Melbourne, Parkville, VIC 3010, Australia
- School of Chemistry, Norwich Research Park, University of East Anglia, Norwich NR4 7TJ, United Kingdom
| | - Gabriel da Silva
- Department of Chemical Engineering, University of Melbourne, Parkville, VIC 3010, Australia
| | - Michael S. Scholz
- School of Chemistry, University of Melbourne, Parkville, VIC 3010, Australia
| | - Eduardo Carrascosa
- School of Chemistry, University of Melbourne, Parkville, VIC 3010, Australia
| | - Evan J. Bieske
- School of Chemistry, University of Melbourne, Parkville, VIC 3010, Australia
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6
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Kluczyk D, Matwijczuk A, Górecki A, Karpińska MM, Szymanek M, Niewiadomy A, Gagoś M. Molecular Organization of Dipalmitoylphosphatidylcholine Bilayers Containing Bioactive Compounds 4-(5-Heptyl-1,3,4-thiadiazol-2-yl) Benzene-1,3-diol and 4-(5-Methyl-1,3,4-thiadiazol-2-yl) Benzene-1,3-diols. J Phys Chem B 2016; 120:12047-12063. [PMID: 27798830 DOI: 10.1021/acs.jpcb.6b09371] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
This article presents the results of spectroscopic studies of two compounds from the 1,3,4-thiadiazole group, that is, 4-(5-methyl-1,3,4-thiadiazole-2-yl)benzene-1,3-diol (C1) and 4-(5-heptyl-1,3,4-thiadiazole-2-yl)benzene-1,3-diol (C7), present at different molar concentrations in 1,2-dipalmitoyl-sn-glycero-3-phosphatidylcholine (DPPC) liposome systems. In the case of both investigated compounds, fluorescence measurements revealed the presence of several emission bands, whose appearance is related to the molecular organization induced by changes in the phase transition in DPPC. On the basis of the interpretation of Fourier transform infrared spectra, we determined the molecular organization of the analyzed compounds in multilayers formed from DPPC and the 1,3,4-thiadiazoles. It was found that the compound with a longer alkyl substituent both occupied the lipid polar head region in the lipid multilayer and interacted with lipid hydrocarbon chains. In turn, the compound with a shorter alkyl substituent interacted more strongly with the membrane polar region. On the basis of the knowledge from previous investigations conducted using different solvents, the fluorescence effects observed were related to the phenomenon of molecular aggregation. The effects were strongly influenced by the structure of the compound and, primarily, by the type of the alkyl substituent used in the molecule. The substantial shortening of fluorescence lifetimes associated with the effect of long-wave emission (with a maximum at 505 nm) decay also confirms the model of aggregation effects in the analyzed systems. Similar effects can be very easily distinguished and associated with respective forms of the compounds in biologically relevant samples.
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Affiliation(s)
- Dariusz Kluczyk
- Department of Cell Biology, Institute of Biology and Biochemistry, Maria Curie-Skłodowska University , 20-033 Lublin, Poland
| | | | - Andrzej Górecki
- Department of Physical Biochemistry, Faculty of Biochemistry, Biophysics and Biotechnology of the Jagiellonian University , Gronostajowa 7, 30-387 Krakow, Poland
| | - Monika M Karpińska
- Institute of Industrial Organic Chemistry , Annopol 6, 03-236 Warsaw, Poland
| | | | - Andrzej Niewiadomy
- Institute of Industrial Organic Chemistry , Annopol 6, 03-236 Warsaw, Poland
| | - Mariusz Gagoś
- Department of Cell Biology, Institute of Biology and Biochemistry, Maria Curie-Skłodowska University , 20-033 Lublin, Poland
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7
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Das A, Banerjee T, Hanson K. Protonation of silylenol ether via excited state proton transfer catalysis. Chem Commun (Camb) 2016; 52:1350-3. [PMID: 26502917 DOI: 10.1039/c5cc08081a] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We demonstrate the photocatalytic protonation of a silylenol ether using 7-bromo-2-naphthol as an ESPT catalyst with phenol as the sacrificial proton source. Greater than 95% conversion is achieved with 1 mol% catalyst. The reaction cycle is dependent on the significantly increased acidity of the catalyst in the excited state as well as the long lifetime for the triplet excited state of 7-bromo-2-naphthol. The reaction does not occur in the absence of light (367 nm) and can readily be controlled by light intensity modulation. We also demonstrate that a 72% reaction yield can be obtained with unsubstituted naphthol as the catalyst by coupling triplet energy transfer, via a visible light absorbing (445 nm) sensitizer, into the catalytic cycle. These results open the door to an entirely new class of sensitized photocatalytic reactions that harness the excited state acidity of ESPT dyes.
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Affiliation(s)
- Anjan Das
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306, USA.
| | - Tanmay Banerjee
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306, USA.
| | - Kenneth Hanson
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306, USA.
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8
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Xia SH, Xie BB, Fang Q, Cui G, Thiel W. Excited-state intramolecular proton transfer to carbon atoms: nonadiabatic surface-hopping dynamics simulations. Phys Chem Chem Phys 2016; 17:9687-97. [PMID: 25711992 DOI: 10.1039/c5cp00101c] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Excited-state intramolecular proton transfer (ESIPT) between two highly electronegative atoms, for example, oxygen and nitrogen, has been intensely studied experimentally and computationally, whereas there has been much less theoretical work on ESIPT to other atoms such as carbon. We have employed CASSCF, MS-CASPT2, RI-ADC(2), OM2/MRCI, DFT, and TDDFT methods to study the mechanistic photochemistry of 2-phenylphenol, for which such an ESIPT has been observed experimentally. According to static electronic structure calculations, irradiation of 2-phenylphenol populates the bright S1 state, which has a rather flat potential in the Franck-Condon region (with a shallow enol minimum at the CASSCF level) and may undergo an essentially barrierless ESIPT to the more stable S1 keto species. There are two S1/S0 conical intersections that mediate relaxation to the ground state, one in the enol region and one in the keto region, with the latter one substantially lower in energy. After S1 → S0 internal conversion, the transient keto species can return back to the S0 enol structure via reverse ground-state hydrogen transfer in a facile tautomerization. This mechanistic scenario is verified by OM2/MRCI-based fewest-switches surface-hopping simulations that provide detailed dynamic information. In these trajectories, ESIPT is complete within 118 fs; the corresponding S1 excited-state lifetime is computed to be 373 fs in vacuum. Most of the trajectories decay to the ground state via the S1/S0 conical intersection in the keto region (67%), and the remaining ones via the enol region (33%). The combination of static electronic structure computations and nonadiabatic dynamics simulations is expected to be generally useful for understanding the mechanistic photophysics and photochemistry of molecules with intramolecular hydrogen bonds.
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Affiliation(s)
- Shu-Hua Xia
- Key Laboratory of Theoretical and Computational Photochemistry, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing 100875, China.
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9
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Guo WW, Liu XY, Chen WK, Cui G. Excited-state proton transfer in 4-2′-hydroxyphneylpyridine: full-dimensional surface-hopping dynamics simulations. RSC Adv 2016. [DOI: 10.1039/c6ra17827h] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
We have employed combined electronic structure calculations and “on-the-fly” fewest switches surface-hopping dynamics simulations to study the S1 excited-state intramolecular proton transfer (ESIPT) and decay dynamics of 4-(2′-hydroxyphenyl)pyridine.
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Affiliation(s)
- Wei-Wei Guo
- Key Laboratory of Theoretical and Computational Photochemistry
- Ministry of Education
- College of Chemistry
- Beijing Normal University
- Beijing 100875
| | - Xiang-Yang Liu
- Key Laboratory of Theoretical and Computational Photochemistry
- Ministry of Education
- College of Chemistry
- Beijing Normal University
- Beijing 100875
| | - Wen-Kai Chen
- Key Laboratory of Theoretical and Computational Photochemistry
- Ministry of Education
- College of Chemistry
- Beijing Normal University
- Beijing 100875
| | - Ganglong Cui
- Key Laboratory of Theoretical and Computational Photochemistry
- Ministry of Education
- College of Chemistry
- Beijing Normal University
- Beijing 100875
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10
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Yang Y, Liu Y, Yang D, Li H, Jiang K, Sun J. Photoinduced excited state intramolecular proton transfer and spectral behaviors of Aloesaponarin 1. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2015; 151:814-820. [PMID: 26172469 DOI: 10.1016/j.saa.2015.07.046] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2015] [Revised: 06/14/2015] [Accepted: 07/07/2015] [Indexed: 06/04/2023]
Abstract
The novel spectral behaviors of Aloesaponarin 1 (AS1) are investigated by studying the dynamics process of excited state intramolecular proton transfer (ESIPT). Two intramolecular hydrogen bonds (HB1 and HB2) are formed between hydroxyl and carbonyl groups of AS1. The calculated potential energy curves of AS1 demonstrate that the ESIPT process along HB1 is energy favorable while not along HB2. The analysis of potential energy curves describes clearly the dynamic behaviors of the proton transfer process from hydroxyl group to carbonyl group along HB1. The infrared spectra of AS1 confirm that the stretching absorption peak of hydroxyl group in HB1 disappears and that a new peak corresponding to hydroxyl group appears in the first excited state, which depicts the ESIPT process indirectly. The fluorescence peaks of AS1 (636nm), AS2 (Aloesaponarin 1 3-O-methyl ether, 629 nm) and AS3 (Aloesaponarin 1 8-O-methyl ether, 522 nm) demonstrate that the fluorescence behavior of AS1 is primarily effected by HB1 rather than HB2. The large Stokes shifts of AS1 (206 nm) indicate that the absorbed energy is partly transferred to non-harmful long fluorescence through ESIPT process, which plays important role in the explanation for the UV protection property of AS1. The inducement and influence factors of ESIPT process of AS1 are illustrated by analyzing electrostatic potential, molecular orbital and natural bond orbital.
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Affiliation(s)
- Yonggang Yang
- College of Physics and Information Engineering, Henan Normal University, Xinxiang 453007, China
| | - Yufang Liu
- College of Physics and Information Engineering, Henan Normal University, Xinxiang 453007, China.
| | - Dapeng Yang
- Physics Laboratory, North China University of Water Resources and Electric Power, Zhengzhou 450045, China
| | - Hui Li
- College of Physics and Information Engineering, Henan Normal University, Xinxiang 453007, China
| | - Kai Jiang
- College of Chemistry and Environmental Science, Henan Normal University, Xinxiang 453007, China
| | - Jinfeng Sun
- College of Physics and Information Engineering, Henan Normal University, Xinxiang 453007, China
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Lukeman M, Simon H, Wan P, Wang YH. Photocyclization and Photoaddition Reactions of Arylphenols via Intermediate Quinone Methides. J Org Chem 2015; 80:11281-93. [PMID: 26496171 DOI: 10.1021/acs.joc.5b01580] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
A series of five benzannelated derivatives of 2-phenylphenol were prepared, and their photochemistry was investigated. Two of these (3-phenyl-2-naphthol, 10, and 1-phenyl-2-naphthol, 11) were photoinert. For 2-(1-naphthyl)phenol (12) and 1-(1-naphthyl)-2-naphthol (13), ESPT took place to either the 2'-position or the 7'-position of the naphthalene ring to give quinone methides (QMs) that underwent either reverse proton transfer (RPT) or electrocyclic ring closure to give dihydrobenzoxanthenes. The intermediate QMs for 12 and 13 were detected and characterized by laser flash photolysis. For 2-(9-phenanthryl)phenol (14), ESPT took place either to the 5'-position to give a QM that underwent quantitative electrocyclic ring closure to give the corresponding benzoxanthene or to the 10'-position to give a QM that underwent RPT. If the solution contained methanol, the QM produced on ESPT to the 10'-position in 14 could be trapped as the photoaddition product. The compounds studied in this work demonstrate three possible reactions of QMs produced following ESPT to aromatic carbon atoms: (1) reverse proton transfer (RPT) to regenerate starting material; (2) addition of hydroxylic solvents to give the photoaddition product; and (3) electrocyclic ring closure to give benzoxanthene derivatives.
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Affiliation(s)
- Matthew Lukeman
- Department of Chemistry, Acadia University , 6 University Ave., Wolfville, NS, B4P 2R6, Canada
| | - Hilary Simon
- Department of Chemistry, Acadia University , 6 University Ave., Wolfville, NS, B4P 2R6, Canada
| | - Peter Wan
- Department of Chemistry, University of Victoria , Box 3065 Stn CSC, Victoria, BC, V8W 3V6, Canada
| | - Yu-Hsuan Wang
- Department of Chemistry, University of Victoria , Box 3065 Stn CSC, Victoria, BC, V8W 3V6, Canada
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12
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Ma J, Zhang X, Basarić N, Wan P, Phillips DL. Observation of excited state proton transfer reactions in 2-phenylphenol and 2-phenyl-1-naphthol and formation of quinone methide species. Phys Chem Chem Phys 2015; 17:9205-11. [PMID: 25760013 DOI: 10.1039/c4cp05061d] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The excited state intramolecular proton transfer (ESIPT) reactions from a phenol (naphthol) to a carbon atom in the adjacent aromatic ring of 2-phenylphenol (1) and 2-phenyl-1-naphthol (4) are prototypical examples of intramolecular proton transfer not mediated by solvent molecules. Femtosecond time-resolved transient absorption (fs-TA) studies are conducted for the first time to directly probe the formation of quinone methide (QM) species generated from the ESIPT pathways of 1 and 4. Steady-state absorption experiments demonstrated 1 exists mainly in its non-deprotonated form in neat MeCN and in water-MeCN solutions. Observation of the phenolate form in water-containing solution (MeCN-H2O, 1 : 1, v : v) in fluorescence spectra demonstrates the occurrence of an ESPT reaction between 1 and the surrounding water molecules. In neat MeCN a transient species that absorbs around 520 nm was detected in fs-TA spectra and was assigned to the QM species formed by ESIPT to the 2'-position. This transient signal is strengthened in cyclohexane. In a water-MeCN solution, an additional transient species assigned to the QM species at the 4'-position of 1 was also detected that absorbs around 485 nm. Similar results for 4 were observed, with the absorbance of the transient species being more intense, which suggests there is more efficient production of the QM species from 4, consistent with quantum yields for deuterium exchange in the distal ring reported for these compounds.
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Affiliation(s)
- Jiani Ma
- Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of Ministry of Education, College of Chemistry and Materials Science, Northwest University, Xi'an, P. R. China
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