1
|
Shin HS, Moon DY, An S, Park BS. Solvent assisted photochemical formation of a new keto[3,3]paracyclophane. Org Biomol Chem 2022; 20:4303-4308. [PMID: 35575223 DOI: 10.1039/d2ob00660j] [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
Photolysis of a phenacyl benzoate tethered with a phenol leads to a very efficient release of benzoic acid, which is suggested to occur by electron transfer and/or proton transfer from the remote phenol moiety to the triplet excited carbonyl. Photolysis of the compound in protic solvents forms a new keto[3,3]paracyclophane.
Collapse
Affiliation(s)
- Ho Suk Shin
- Department of Chemistry, Dongguk University, Seoul 04620, Korea.
| | - Da Yoon Moon
- Department of Chemistry, Dongguk University, Seoul 04620, Korea.
| | - Sejin An
- Department of Chemistry, Dongguk University, Seoul 04620, Korea.
| | - Bong Ser Park
- Department of Chemistry, Dongguk University, Seoul 04620, Korea.
| |
Collapse
|
2
|
Jin P, Long J, Du Y, Zheng X, Xue J. Hydrogen bond configuration and protonation of ground and lowest excited triplet states of 4‑amino‑4'‑nitrobiphenyl based on nanosecond transient absorption spectroscopy. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2019; 217:44-50. [PMID: 30927570 DOI: 10.1016/j.saa.2019.03.054] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2018] [Revised: 01/19/2019] [Accepted: 03/17/2019] [Indexed: 06/09/2023]
Abstract
Intramolecular charge transfer (ICT) is an important photochemical process. In contrast to those in singlet manifold, triplet ICT states were less studied. In this paper, the lowest excited triplet state (T1) of 4‑amino‑4'‑nitrobiphenyl (NH2-Bp-NO2) was recorded with nanosecond transient absorption spectroscopy in acidic acetonitrile and alcoholic solutions. By employing the Kamlet-Taft model to analyze the correlation between absorption maxima and alcohol solvent properties including polarity/polarizability, abilities of hydrogen bond donating and hydrogen bond accepting, hydrogen bond configuration in the ground state (S0) and T1 was resolved. The results suggest that the hydrogen bond between amino H and alcohol is dominant in S0, while in T1, hydrogen bonds between amino H and alcohol, between nitro O and alcohol have comparable contribution. By examination of the 1‑naphthol quench effect on T1, the hydrogen bond between nitro O and alcohol was confirmed present. Theoretical calculation results on the model of NH2-Bp-NO2-(MeOH)3 also indicate that hydrogen bonds between amino H and alcohol, between nitro O and alcohol are both much stronger in T1 than in S0. In acidic acetonitrile solution, in S0 of NH2-Bp-NO2 the amino group is protonated with pKa of 4.5, meanwhile in T1 the nitro group is much easier to be protonated than in S0. Its conjugated acid was measured to have a pKa of 3.1.
Collapse
Affiliation(s)
- Peipei Jin
- Department of Chemsitry, Zhejiang Sci-Tech University, Hangzhou 310018, China
| | - Jing Long
- Department of Chemsitry, Zhejiang Sci-Tech University, Hangzhou 310018, China
| | - Yong Du
- Center for THz Research, China Jiliang University, Hangzhou 310018, China
| | - Xuming Zheng
- Department of Chemsitry, Zhejiang Sci-Tech University, Hangzhou 310018, China
| | - Jiadan Xue
- Department of Chemsitry, Zhejiang Sci-Tech University, Hangzhou 310018, China.
| |
Collapse
|
3
|
Ma C, Ou YQ, Chan CTL, Wong AKW, Chan RCT, Chung BPY, Jiang C, Wang ML, Kwok WM. Nonradiative dynamics determined by charge transfer induced hydrogen bonding: a combined femtosecond time-resolved fluorescence and density functional theoretical study of methyl dimethylaminobenzoate in water. Phys Chem Chem Phys 2018; 20:1240-1251. [DOI: 10.1039/c7cp05140a] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Hydrogen bonding with water alters nonradiative pathway of a twisted charge transfer state in methyl dimethylaminobenzoate.
Collapse
Affiliation(s)
- Chensheng Ma
- College of Chemistry and Environmental Engineering
- Shenzhen University
- Shenzhen
- P. R. China
| | - Yue-Qun Ou
- College of Chemistry and Environmental Engineering
- Shenzhen University
- Shenzhen
- P. R. China
| | - Chris Tsz-Leung Chan
- College of Chemistry and Environmental Engineering
- Shenzhen University
- Shenzhen
- P. R. China
| | - Allen Ka-Wa Wong
- Department of Applied Biology and Chemical Technology
- The Hong Kong Polytechnic University
- Kowloon
- P. R. China
| | - Ruth Chau-Ting Chan
- Department of Applied Biology and Chemical Technology
- The Hong Kong Polytechnic University
- Kowloon
- P. R. China
| | - Bowie Po-Yee Chung
- Department of Applied Biology and Chemical Technology
- The Hong Kong Polytechnic University
- Kowloon
- P. R. China
| | - Chao Jiang
- College of Chemistry and Environmental Engineering
- Shenzhen University
- Shenzhen
- P. R. China
| | - Ming-Liang Wang
- College of Chemistry and Environmental Engineering
- Shenzhen University
- Shenzhen
- P. R. China
| | - Wai-Ming Kwok
- Department of Applied Biology and Chemical Technology
- The Hong Kong Polytechnic University
- Kowloon
- P. R. China
| |
Collapse
|
4
|
Qiao E, Zheng H. Raman spectroscopic study of cyclohexane at pressures below 1000MPa. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2017; 185:52-54. [PMID: 28535461 DOI: 10.1016/j.saa.2017.05.033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Revised: 05/13/2017] [Accepted: 05/15/2017] [Indexed: 06/07/2023]
Abstract
At present, the room temperature freezing pressure of cyclohexane is still uncertain, and the phase transition pressure of solid I - solid III is not reliable at ambient temperature. In this work, we have performed a Raman spectroscopic study of cyclohexane in a Moissanite anvil cell at pressures below 1000MPa at 25°C, and analyzed the characteristic of Raman brands νs(CH2), νas(CH2) and νb(Ring). Two phase transition pressures 80MPa and 550MPa were determined by a quartz pressure gauge, and they are the room temperature freezing pressure of cyclohexane and the phase transition pressure of solid I to solid III, respectively. Furthermore, from the phase diagram of cyclohexane, it is inferred that pressure plays an important role on the stability of cyclohexane as the main constituent of oil, and it can be beneficial to understanding the formation, migration and preservation of petroleum in subterranean rock strata.
Collapse
Affiliation(s)
- Erwei Qiao
- Key Laboratory of Neotectonic Movement and Geohazard, Ministry of Land and Resources, Institute of Geomechanics, Chinese Academy of Geological Sciences, Beijing 100081, China.
| | - Haifei Zheng
- Laboratory of Orogenic Belts and Crustal Evolution, Ministry of Education, School of Earth and Space Sciences, Peking University, Beijing 100871, China
| |
Collapse
|
5
|
Narra S, Shigeto S. Direct observation of the solvent effects on the low-lying nπ* and ππ* excited triplet states of acetophenone derivatives in thermal equilibrium. J Phys Chem B 2015; 119:3808-14. [PMID: 25686256 DOI: 10.1021/jp512494m] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Low-lying excited triplet states of aromatic carbonyl compounds exhibit diverse photophysical and photochemical properties of fundamental importance. Despite tremendous effort in studying those triplet states, the effects of substituents and solvents on the energetics of the triplet manifold and on photoreactivity remain to be fully understood. We have recently studied the ordering of the low-lying nπ* and ππ* excited triplet states and its substituent dependence in acetophenone derivatives using nanosecond time-resolved near-IR (NIR) spectroscopy. Here we address the other important issue, the solvent effects, by directly observing the electronic bands in the NIR that originate from the lowest nπ* and ππ* states of acetophenone derivatives in four solvents of different polarity (n-heptane, benzene, acetonitrile, and methanol). The two transient NIR bands decay synchronously in all the solvents, indicating that the lowest nπ* and ππ* states are in thermal equilibrium irrespective of the solvent polarity studied here. We found that the ππ* band increases in intensity relative to the nπ* band as solvent polarity increases. These results are compared with the photoreduction rate constant for the acetophenone derivatives in the solvents to which 2-propanol was added as a hydrogen-atom donor. Based on the present findings, we present a comprehensive, solvent- and substituent-dependent energy level diagram of the low-lying nπ* and ππ* excited triplet states.
Collapse
Affiliation(s)
- Sudhakar Narra
- Department of Applied Chemistry and Institute of Molecular Science, National Chiao Tung University , 1001 Ta-Hsueh Road, Hsinchu 30010, Taiwan
| | | |
Collapse
|
6
|
Senadheera SN, Yousef AL, Givens RS. Photorelease of phosphates: Mild methods for protecting phosphate derivatives. Beilstein J Org Chem 2014; 10:2038-54. [PMID: 25246963 PMCID: PMC4168878 DOI: 10.3762/bjoc.10.212] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2014] [Accepted: 08/07/2014] [Indexed: 12/17/2022] Open
Abstract
We have developed a new photoremovable protecting group for caging phosphates in the near UV. Diethyl 2-(4-hydroxy-1-naphthyl)-2-oxoethyl phosphate (14a) quantitatively releases diethyl phosphate upon irradiation in aq MeOH or aq MeCN at 350 nm, with quantum efficiencies ranging from 0.021 to 0.067 depending on the solvent composition. The deprotection reactions originate from the triplet excited state, are robust under ambient conditions and can be carried on to 100% conversion. Similar results were found with diethyl 2-(4-methoxy-1-naphthyl)-2-oxoethyl phosphate (14b), although it was significantly less efficient compared with 14a. A key step in the deprotection reaction in aq MeOH is considered to be a Favorskii rearrangement of the naphthyl ketone motif of 14a,b to naphthylacetate esters 25 and 26. Disruption of the ketone-naphthyl ring conjugation significantly shifts the photoproduct absorption away from the effective incident wavelength for decaging of 14, driving the reaction to completion. The Favorskii rearrangement does not occur in aqueous acetonitrile although diethyl phosphate is released. Other substitution patterns on the naphthyl or quinolin-5-yl core, such as the 2,6-naphthyl 10 or 8-benzyloxyquinolin-5-yl 24 platforms, also do not rearrange by aryl migration upon photolysis and, therefore, do not proceed to completion. The 2,6-naphthyl ketone platform instead remains intact whereas the quinolin-5-yl ketone fragments to a much more complex, highly absorbing reaction mixture that competes for the incident light.
Collapse
Affiliation(s)
| | - Abraham L Yousef
- Department of Chemistry, University of Kansas, Lawrence, Kansas 66045, U.S.A
| | - Richard S Givens
- Department of Chemistry, University of Kansas, Lawrence, Kansas 66045, U.S.A
| |
Collapse
|
7
|
Senadheera SN, Evans AS, Toscano JP, Givens RS. 2-Diazo-1-(4-hydroxyphenyl)ethanone: a versatile photochemical and synthetic reagent. Photochem Photobiol Sci 2013; 13:324-41. [PMID: 24305682 DOI: 10.1039/c3pp50305d] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
α-Diazo arylketones are well-known substrates for Wolff rearrangement to phenylacetic acids through a ketene intermediate by either thermal or photochemical activation. Likewise, α-substituted p-hydroxyphenacyl (pHP) esters are substrates for photo-Favorskii rearrangements to phenylacetic acids by a different pathway that purportedly involves a cyclopropanone intermediate. In this paper, we show that the photolysis of a series of α-diazo-p-hydroxyacetophenones and p-hydroxyphenacyl (pHP) α-esters both generate the identical rearranged phenylacetates as major products. Since α-diazo-p-hydroxyacetophenone (1a, pHP N2) contains all the necessary functionalities for either Wolff or Favorskii rearrangement, we were prompted to probe this intriguing mechanistic dichotomy under conditions favorable to the photo-Favorskii rearrangement, i.e., photolysis in hydroxylic media. An investigation of the mechanism for conversion of 1a to p-hydroxyphenyl acetic acid (4a) using time-resolved infrared (TRIR) spectroscopy clearly demonstrates the formation of a ketene intermediate that is subsequently trapped by solvent or nucleophiles. The photoreaction of 1a is quenched by oxygen and sensitized by triplet sensitizers and the quantum yields for 1a-c range from 0.19 to a robust 0.25. The lifetime of the triplet, determined by Stern-Volmer quenching, is 31 ns with a rate for appearance of 4a of k = 7.1 × 10(6) s(-1) in aq. acetonitrile (1 : 1 v : v). These studies establish that the primary rearrangement pathway for 1a involves ketene formation in accordance with the photo-Wolff rearrangement. Furthermore we have also demonstrated the synthetic utility of 1a as an esterification and etherification reagent with a variety of substituted α-diazo-p-hydroxyacetophenones, using them as synthons for efficiently coupling it to acids and phenols to produce pHP protect substrates.
Collapse
|
8
|
Givens RS, Rubina M, Stensrud KF. Stereochemically probing the photo-Favorskii rearrangement: a mechanistic investigation. J Org Chem 2013; 78:1709-17. [PMID: 23057737 PMCID: PMC3586294 DOI: 10.1021/jo301640q] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Using model (R)-2-acetyl-2-phenyl acetate esters of (S)- or (R)-α-substituted-p-hydroxybutyrophenones (S,R)-12a and (R,R)-12b, we have shown that a highly efficient photo-Favorskii rearrangement proceeds through a series of intermediates to form racemic rearrangement products. The stereogenic methine on the photoproduct, rac-2-(p-hydroxyphenyl)propanoic acid (rac-9), is formed by closure of a phenoxy-allyloxy intermediate 17 collapsing to a cyclopropanone, the "Favorskii" intermediate 18. These results quantify the intermediacy of a racemized triplet biradical (3)16 on the major rearrangement pathway elusively to the intermediate 18. Thus, intersystem crossing from the triplet biradical surface to the ground state generates a planar zwitterion prior to formation of a Favorskii cyclopropanone that retains no memory of its stereochemical origin. These results parallel the mechanism of Dewar and Bordwell for the ground state formation of cyclopropanone 3 that proceeds through an oxyallyl zwitterionic intermediate. The results are not consistent with the stereospecific S(N)2 ground state Favorskii mechanism observed by Stork, House, and Bernetti. Interconversion of the diastereomeric starting esters of (S,R)-12a and (R,R)-12b during photolysis did not occur, thus ruling out leaving group return prior to rearrangement.
Collapse
Affiliation(s)
- Richard S Givens
- Department of Chemistry, The University of Kansas, 1251 Wescoe Hall Drive, 5010 Malott Hall, Lawrence, Kansas 66045, United States.
| | | | | |
Collapse
|
9
|
Klán P, Šolomek T, Bochet CG, Blanc A, Givens R, Rubina M, Popik V, Kostikov A, Wirz J. Photoremovable protecting groups in chemistry and biology: reaction mechanisms and efficacy. Chem Rev 2013; 113:119-91. [PMID: 23256727 PMCID: PMC3557858 DOI: 10.1021/cr300177k] [Citation(s) in RCA: 1248] [Impact Index Per Article: 113.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2012] [Indexed: 02/06/2023]
Affiliation(s)
- Petr Klán
- Department of Chemistry, Faculty of Science, Masaryk University, Kamenice 5, 625 00 Brno, Czech Republic.
| | | | | | | | | | | | | | | | | |
Collapse
|
10
|
Ngoy BP, Sebej P, Solomek T, Lim BH, Pastierik T, Park BS, Givens RS, Heger D, Klán P. 2-Hydroxyphenacyl ester: a new photoremovable protecting group. Photochem Photobiol Sci 2012; 11:1465-75. [PMID: 22766787 DOI: 10.1039/c2pp25133g] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A 2-hydroxyphenacyl moiety absorbing below 370 nm is proposed as a new photoremovable protecting group for carboxylates and sulfonates. Laser flash photolysis and steady-state sensitization studies show that the leaving group is released from a short-lived triplet state. In addition, DFT-based quantum chemical calculations were performed to determine the key reaction steps. We found that triplet excited state intramolecular proton transfer represents a major deactivation channel. Minor productive pathways involving the triplet anion and quinoid triplet enol intermediates have also been identified.
Collapse
Affiliation(s)
- Bokolombe Pitchou Ngoy
- Department of Chemistry, Faculty of Science, Masaryk University, Kamenice 5, 625 00, Brno, Czech Republic
| | | | | | | | | | | | | | | | | |
Collapse
|
11
|
Zhang J, Zhao G, Li R, Hou D. Time-Dependent Density Functional Theory Study on the Electronic Excited State of Hydrogen-Bonded Clusters Formed by 2-Hydroxybenzonitrile (o-Cyanophenol) and Carbon Monoxide. J CLUST SCI 2011. [DOI: 10.1007/s10876-011-0406-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
12
|
Miao C, Shi Y. Reconsideration on hydrogen bond strengthening or cleavage of photoexcited coumarin 102 in aqueous solvent: A DFT/TDDFT study. J Comput Chem 2011; 32:3058-61. [DOI: 10.1002/jcc.21888] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2011] [Revised: 06/10/2011] [Accepted: 06/22/2011] [Indexed: 12/26/2022]
|
13
|
Wang D, Hao C, Wang S, Dong H, Qiu J. Time-dependent density functional theory study on the electronic excited-state hydrogen bonding of the chromophore coumarin 153 in a room-temperature ionic liquid. J Mol Model 2011; 18:937-45. [DOI: 10.1007/s00894-011-1131-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2011] [Accepted: 05/15/2011] [Indexed: 12/15/2022]
|
14
|
Givens RS, Stensrud K, Conrad PG, Yousef AL, Perera C, Senadheera SN, Heger D, Wirz J. p-Hydroxyphenacyl photoremovable protecting groups - Robust photochemistry despite substituent diversity. CAN J CHEM 2011; 89:364-384. [PMID: 24436496 PMCID: PMC3891043 DOI: 10.1139/v10-143] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A broadly based investigation of the effects of a diverse array of substituents on the photochemical rearrangement of p-hydroxyphenacyl esters has demonstrated that common substituents such as F, MeO, CN, CO2R, CONH2, and CH3 have little effect on the rate and quantum efficiencies for the photo-Favorskii rearrangement and the release of the acid leaving group or on the lifetimes of the reactive triplet state. A decrease in the quantum yields across all substituents was observed for the release and rearrangement when the photolyses were carried out in buffered aqueous media at pHs that exceeded the ground-state pKa of the chromophore where the conjugate base is the predominant form. Otherwise, substituents have only a very modest effect on the photoreaction of these robust chromophores.
Collapse
Affiliation(s)
- Richard S. Givens
- Department of Chemistry, University of Kansas Lawrence, Lawrence, KS 66045, USA
| | - Kenneth Stensrud
- Department of Chemistry, University of Kansas Lawrence, Lawrence, KS 66045, USA
| | - Peter G. Conrad
- Department of Chemistry, University of Kansas Lawrence, Lawrence, KS 66045, USA
| | - Abraham L. Yousef
- Department of Chemistry, University of Kansas Lawrence, Lawrence, KS 66045, USA
| | - Chamani Perera
- Department of Chemistry, University of Kansas Lawrence, Lawrence, KS 66045, USA
| | | | - Dominik Heger
- Research Centre for Toxic Compounds in the Environment (RECETOX) and Department of Chemistry, Faculty of Science, Masaryk University, Kamenice3, 625 00 Brno, Czech Republic
| | - Jakob Wirz
- Department of Chemistry, University of Basel, Klingelbergstrasse 80, CH-4056 Basel, Switzerland
| |
Collapse
|
15
|
Liu YH, Mehata MS, Liu JY. Excited-state proton transfer via hydrogen-bonded acetic acid (AcOH) wire for 6-hydroxyquinoline. J Phys Chem A 2010; 115:19-24. [PMID: 21141974 DOI: 10.1021/jp1101626] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Spectroscopic studies on excited-state proton transfer (ESPT) of hydroxyquinoline (6HQ) have been performed in a previous paper. And a hydrogen-bonded network formed between 6HQ and acetic acid (AcOH) in nonpolar solvents has been characterized. In this work, a time-dependent density functional theory (TDDFT) method at the def-TZVP/B3LYP level was employed to investigate the excited-state proton transfer via hydrogen-bonded AcOH wire for 6HQ. A hydrogen-bonded wire containing three AcOH molecules at least for connecting the phenolic and quinolinic -N- group in 6HQ has been confirmed. The excited-state proton transfer via a hydrogen-bonded wire could result in a keto tautomer of 6HQ and lead to a large Stokes shift in the emission spectra. According to the results of calculated potential energy (PE) curves along different coordinates, a stepwise excited-state proton transfer has been proposed with two steps: first, an anionic hydrogen-bonded wire is generated by the protonation of -N- group in 6HQ upon excitation to the S(1) state, which increases the proton-capture ability of the AcOH wire; then, the proton of the phenolic group transfers via the anionic hydrogen-bonded wire, by an overall "concerted" process. Additionally, the formation of the anionic hydrogen-bonded wire as a preliminary step has been confirmed by the hydrogen-bonded parameters analysis of the ESPT process of 6HQ in several protic solvents. Therefore, the formation of anionic hydrogen-bonded wire due to the protonation of the -N- group is essential to strengthen the hydrogen bonding acceptance ability and capture the phenolic proton in the 6HQ chromophore.
Collapse
Affiliation(s)
- Yu-Hui Liu
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | | | | |
Collapse
|
16
|
Zhao GJ, Northrop BH, Han KL, Stang PJ. The Effect of Intermolecular Hydrogen Bonding on the Fluorescence of a Bimetallic Platinum Complex. J Phys Chem A 2010; 114:9007-13. [DOI: 10.1021/jp105009t] [Citation(s) in RCA: 208] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Guang-Jiu Zhao
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China, and Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, USA
| | - Brian H. Northrop
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China, and Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, USA
| | - Ke-Li Han
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China, and Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, USA
| | - Peter J. Stang
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China, and Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, USA
| |
Collapse
|
17
|
An HY, Kwok WM, Ma C, Guan X, Kan JTW, Toy PH, Phillips DL. Photophysics and Photodeprotection Reactions of p-Methoxyphenacyl Phototriggers: An Ultrafast and Nanosecond Time-Resolved Spectroscopic and Density Functional Theory Study. J Org Chem 2010; 75:5837-51. [DOI: 10.1021/jo100848b] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Hui-Ying An
- Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong S. A. R., P. R. China
| | - Wai Ming Kwok
- Department of Applied Biology and Chemical Technology, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong S. A. R., P. R. China
| | - Chensheng Ma
- Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong S. A. R., P. R. China
| | - Xiangguo Guan
- Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong S. A. R., P. R. China
| | - Jovi Tze Wai Kan
- Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong S. A. R., P. R. China
| | - Patrick H. Toy
- Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong S. A. R., P. R. China
| | - David Lee Phillips
- Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong S. A. R., P. R. China
| |
Collapse
|
18
|
Ma C, Kwok W, An HY, Guan X, Fu M, Toy P, Phillips D. A Time-Resolved Spectroscopic Study of the Bichromophoric Phototrigger 3′,5′-Dimethoxybenzoin Diethyl Phosphate: Interaction Between the Two Chromophores Determines the Reaction Pathway. Chemistry 2010; 16:5102-18. [DOI: 10.1002/chem.200902891] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
|
19
|
Cao Q, Guan X, George MW, Phillips DL, Ma C, Kwok WM, Li M, Du Y, Sun XZ, Xue J. Ultrafast time-resolved transient infrared and resonance Raman spectroscopic study of the photo-deprotection and rearrangement reactions of p-hydroxyphenacyl caged phosphates. Faraday Discuss 2010. [DOI: 10.1039/b908188g] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
|
20
|
|
21
|
Stensrud K, Noh J, Kandler K, Wirz J, Heger D, Givens RS. Competing pathways in the photo-Favorskii rearrangement and release of esters: studies on fluorinated p-hydroxyphenacyl-caged GABA and glutamate phototriggers. J Org Chem 2009; 74:5219-27. [PMID: 19572582 PMCID: PMC3422889 DOI: 10.1021/jo900139h] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Three new trifluoromethylated p-hydroxyphenacyl (pHP)-caged gamma-aminobutyric acid (GABA) and glutamate (Glu) derivatives have been examined for their efficacy as photoremovable protecting groups in aqueous solution. Through the replacement of hydrogen with fluorine, e.g., a m-trifluoromethyl or a m-trifluoromethoxy versus m-methoxy substituents on the pHP chromophore, modest increases in the quantum yields for the release of amino acids GABA and glutamate as well as improved lipophilicity were realized. The pHP triplet undergoes a photo-Favorskii rearrangement with concomitant release of the amino acid substrate. Deprotonation competes with the rearrangement from the triplet excited state and yields the pHP conjugate base that, upon reprotonation, regenerates the starting ketoester, a chemically unproductive or "energy-wasting" process. When picosecond pump-probe spectroscopy is employed, GABA derivatives 2-5 are characterized by short triplet lifetimes, a manifestation of their rapid release of GABA. The bioavailability of released GABA at the GABA(A) receptor improved when the release took place from m-OCF3 (2) but decreased for m-CF3 (3) when compared with the parent pHP derivative. These studies demonstrate that pKa and lipophilicity exert significant but sometimes opposing influences on the photochemistry and biological activity of pHP phototriggers.
Collapse
Affiliation(s)
- Kenneth Stensrud
- Department of Chemistry,1251 Wescoe Hall Drive, University of Kansas, Lawrence, KS 66045
| | - Jihyun Noh
- Department of Otolaryngology, 3500 Terrace St., University of Pittsburgh, Pittsburgh, PA 15208
| | - Karl Kandler
- Department of Otolaryngology, 3500 Terrace St., University of Pittsburgh, Pittsburgh, PA 15208
| | - Jakob Wirz
- Departement Chemie, Universität Basel, Klingelbergstrasse 80, CH-4056 Basel, Switzerland
| | - Dominik Heger
- Department of Chemistry, Faculty of Science, Masaryk University, Brno, Czech Republic
| | - Richard S. Givens
- Department of Chemistry,1251 Wescoe Hall Drive, University of Kansas, Lawrence, KS 66045
| |
Collapse
|
22
|
Wang YT, Jin KJ, Leopold SH, Wang J, Peng HL, Platz MS, Xue J, Phillips DL, Glover SA, Novak M. Characterization of Reactive Intermediates Generated During Photolysis of 4-Acetoxy-4-aryl-2,5-cyclohexadienones: Oxenium Ions and Aryloxy Radicals. J Am Chem Soc 2008; 130:16021-30. [PMID: 18975865 DOI: 10.1021/ja805336d] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Yue-Ting Wang
- Department of Chemistry and Biochemistry, Miami University, Oxford, Ohio 45056, Department of Chemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, Department of Chemistry, University of Hong Kong, Hong Kong, P.R. China, and School of Biological, Biomedical, and Molecular Sciences, Division of Chemistry, University of New England, Armidale, 2351, New South Wales, Australia
| | - Kyoung Joo Jin
- Department of Chemistry and Biochemistry, Miami University, Oxford, Ohio 45056, Department of Chemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, Department of Chemistry, University of Hong Kong, Hong Kong, P.R. China, and School of Biological, Biomedical, and Molecular Sciences, Division of Chemistry, University of New England, Armidale, 2351, New South Wales, Australia
| | - Samuel H. Leopold
- Department of Chemistry and Biochemistry, Miami University, Oxford, Ohio 45056, Department of Chemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, Department of Chemistry, University of Hong Kong, Hong Kong, P.R. China, and School of Biological, Biomedical, and Molecular Sciences, Division of Chemistry, University of New England, Armidale, 2351, New South Wales, Australia
| | - Jin Wang
- Department of Chemistry and Biochemistry, Miami University, Oxford, Ohio 45056, Department of Chemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, Department of Chemistry, University of Hong Kong, Hong Kong, P.R. China, and School of Biological, Biomedical, and Molecular Sciences, Division of Chemistry, University of New England, Armidale, 2351, New South Wales, Australia
| | - Huo-Lei Peng
- Department of Chemistry and Biochemistry, Miami University, Oxford, Ohio 45056, Department of Chemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, Department of Chemistry, University of Hong Kong, Hong Kong, P.R. China, and School of Biological, Biomedical, and Molecular Sciences, Division of Chemistry, University of New England, Armidale, 2351, New South Wales, Australia
| | - Matthew S. Platz
- Department of Chemistry and Biochemistry, Miami University, Oxford, Ohio 45056, Department of Chemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, Department of Chemistry, University of Hong Kong, Hong Kong, P.R. China, and School of Biological, Biomedical, and Molecular Sciences, Division of Chemistry, University of New England, Armidale, 2351, New South Wales, Australia
| | - Jiadan Xue
- Department of Chemistry and Biochemistry, Miami University, Oxford, Ohio 45056, Department of Chemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, Department of Chemistry, University of Hong Kong, Hong Kong, P.R. China, and School of Biological, Biomedical, and Molecular Sciences, Division of Chemistry, University of New England, Armidale, 2351, New South Wales, Australia
| | - David Lee Phillips
- Department of Chemistry and Biochemistry, Miami University, Oxford, Ohio 45056, Department of Chemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, Department of Chemistry, University of Hong Kong, Hong Kong, P.R. China, and School of Biological, Biomedical, and Molecular Sciences, Division of Chemistry, University of New England, Armidale, 2351, New South Wales, Australia
| | - Stephen A. Glover
- Department of Chemistry and Biochemistry, Miami University, Oxford, Ohio 45056, Department of Chemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, Department of Chemistry, University of Hong Kong, Hong Kong, P.R. China, and School of Biological, Biomedical, and Molecular Sciences, Division of Chemistry, University of New England, Armidale, 2351, New South Wales, Australia
| | - Michael Novak
- Department of Chemistry and Biochemistry, Miami University, Oxford, Ohio 45056, Department of Chemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, Department of Chemistry, University of Hong Kong, Hong Kong, P.R. China, and School of Biological, Biomedical, and Molecular Sciences, Division of Chemistry, University of New England, Armidale, 2351, New South Wales, Australia
| |
Collapse
|
23
|
Givens RS, Heger D, Hellrung B, Kamdzhilov Y, Mac M, Conrad PG, Cope E, Lee JI, Mata-Segreda JF, Schowen RL, Wirz J. The photo-Favorskii reaction of p-hydroxyphenacyl compounds is initiated by water-assisted, adiabatic extrusion of a triplet biradical. J Am Chem Soc 2008; 130:3307-9. [PMID: 18290649 DOI: 10.1021/ja7109579] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Richard S Givens
- Department of Chemistry, University of Kansas, Lawrence, Kansas 66045, USA.
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
24
|
Clarke TM, Gordon KC, Chan WS, Phillips DL, Wagner P, Officer DL. Raman spectroscopy of short-lived terthiophene radical cations generated by photochemical and chemical oxidation. Chemphyschem 2007; 7:1276-85. [PMID: 16673432 DOI: 10.1002/cphc.200500680] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The Raman spectra of various terthiophene radical cations are investigated; namely those of unsubstituted terthiophene and two styryl-substituted terthiophenes. Transient pump-probe resonance Raman spectroscopy is used to measure the short-lived radical cation spectra of non-end-capped 2,2':5',2''-terthiophene (3T) and 3'-[(E)-2-(4-nitrophenyl)ethenyl]-2,2':5',2''-terthiophene (NO2-pe3T). For these two compounds, the radical cations are generated via either direct photogeneration or photochemically using the electron acceptor tetracyanoethylene. The radical cation of 5,5''-dimethyl-3'-[(E)-2-phenylethenyl]-2,2':5',2''-terthiophene (DM-pe3T) is stable for up to five minutes as a result of the two alpha end caps and continuous-wave resonance Raman spectroscopy and chemical oxidation is used to obtain the spectrum of this radical cation. The resonance Raman spectra of all three terthiophene radical cations are dominated by a group of very intense bands in the low-frequency region. These bands have been assigned, by density functional theory methods, to C-S stretching modes coupled to thiophene ring deformations. These modes are significantly less intense in the sigma-dimer of NO2-pe3T [i.e. the corresponding styryl sexithiophene (NO2-pe3T)2]. This observation is attributed to a smaller change in the C--S bond order in the sexithiophene compared to the analogous terthiophene. This bond order difference may be rationalised by consideration of the singly occupied molecular orbital and lowest unoccupied molecular orbital, which are involved in the electronic transition probed by the laser excitation wavelength.
Collapse
Affiliation(s)
- Tracey M Clarke
- Department of Chemistry and MacDiarmid Institute for Advanced Materials and Nanotechnology, University of Otago, PO Box 56, Dunedin, New Zealand
| | | | | | | | | | | |
Collapse
|
25
|
Ma C, Du Y, Kwok WM, Phillips DL. Femtosecond Transient Absorption and Nanosecond Time-Resolved Resonance Raman Study of the Solvent-Dependent Photo-Deprotection Reaction of Benzoin Diethyl Phosphate. Chemistry 2007; 13:2290-305. [PMID: 17154320 DOI: 10.1002/chem.200600893] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
A combined femtosecond transient absorption (fs-TA) and nanosecond time-resolved resonance Raman (ns-TR3) study was performed to directly detect the dynamics and elucidate the mechanism of the excited state deactivation and solvent-dependent photo-deprotection pathways for benzoin diethyl phosphate (BDP) in neat acetonitrile (MeCN) and 75 % H2O/25 % MeCN. Comparison of the TA spectral evolution observed in the two solvents provides explicit evidence that the photophysical deactivation of the BDP singlet excited state has little solvent dependence. The TA spectra also indicate the related internal conversion (IC) and intersystem crossing (ISC) processes occur rapidly on hundreds of femtoseconds and approximately 2-3 ps time scales, respectively. From this and in conjunction with a photochemistry study and ground state resonance Raman (RR) measurements, the TA results reveal that the phenacyl localized BDP triplet state (that is mainly npi* nature) is the common and immediate precursor to the photo-deprotection reaction in both solvents. However, the triplet deprotection follows different pathways in neat MeCN versus the largely water containing solvent. The deprotection reaction in MeCN was determined to occur with a approximately 11 ns time constant and the reaction was found to be an unimolecular process leading to elimination of the diethyl phosphoric acid apparently concurrent with cyclization to yield the benzofuran product. In the water mixed solvent, the triplet reaction was observed to proceed with a approximately 15 ns time constant and the reaction leads to not only the deprotection-cyclization but also a heterolytic dissociation to release the diethyl phosphate anion through a branching and competing mechanism. The ns-TR3 spectra combined with relevant DFT calculations have been used to characterize the dynamics, structure and vibrational frequencies to help identify the important intermediates as well as to explore the reaction pathway leading to formation of the solvolysis product in the largely water solvent. A consecutive mechanism has been revealed for the heterolysis-solvolysis reaction in the water mixed solvent. The present work provides direct and irrevocable evidence for the dynamics and mechanistic description of the overall photophysics and deprotection related photochemistry for BDP.
Collapse
Affiliation(s)
- Chensheng Ma
- Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong S.A.R., PR China
| | | | | | | |
Collapse
|
26
|
Lathioor EC, Leigh WJ. Bimolecular Hydrogen Abstraction from Phenols by Aromatic Ketone Triplets†. Photochem Photobiol 2006; 82:291-300. [PMID: 16042506 DOI: 10.1562/2005-06-20-ra-581] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Absolute rate constants for hydrogen abstraction from 4-methylphenol (para-cresol) by the lowest triplet states of 24 aromatic ketones have been determined in acetonitrile solution at 23 degrees C, and the results combined with previously reported data for roughly a dozen other compounds under identical conditions. The ketones studied include various ring-substituted benzophenones and acetophenones, alpha,alpha,alpha-trifluoroacetophenone and its 4-methoxy analog, 2-benzoylthiophene, 2-acetonaphthone, and various other polycyclic aromatic ketones such as fluorenone, xanthone and thioxanthone, and encompass n,pi*, pi,pi*(CT) and arenoid pi,pi* lowest triplets with (triplet) reduction potentials (E(red)*) varying from about -10 to -38 kcal mol(-1). The 4-methylphenoxyl radical is observed as the product of triplet quenching in almost every case, along with the corresponding hemipinacol radical in most instances. Hammett plots for the acetophenones and benzophenones are quite different, but plots of log k(Q) vs E(red)* reveal a common behavior for most of the compounds studied. The results are consistent with reaction via two mechanisms: a simple electron-transfer mechanism, which applies to the n,pi* triplet ketones and those pi,pi* triplets that possess particularly low reduction potentials, and a coupled electron-/proton-transfer mechanism involving the intermediacy of a hydrogen-bonded exciplex, which applies to the pi,pi* ketone triplets. Ketones with lowest charge-transfer pi,pi* states exhibit rate constants that vary only slightly with triplet reduction potential over the full range investigated; this is due to the compensating effect of substituents on triplet state basicity and reduction potential, which both play a role in quenching by the hydrogen-bonded exciplex mechanism. Ketones with arenoid pi,pi* states exhibit the fall-off in rate constant that is typical of photoinduced electron transfer reactions, but it occurs at a much higher potential than would be normally expected due to the effects of hydrogen-bonding on the rate of electron-transfer within the exciplex.
Collapse
Affiliation(s)
- Edward C Lathioor
- Department of Chemistry, McMaster University, 1280 Main Street West, Hamilton, ON, Canada
| | | |
Collapse
|
27
|
Yabumoto S, Sato S, Hamaguchi HO. Vibrational and electronic infrared absorption spectra of benzophenone in the lowest excited triplet state. Chem Phys Lett 2005. [DOI: 10.1016/j.cplett.2005.09.025] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
|