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Catalán J, Martin-Somer A, Hopf H. Evidence of the torsion of a polyene chain in a strongly hindered molecular environment: The ttbP4 crystal. J Photochem Photobiol A Chem 2023. [DOI: 10.1016/j.jphotochem.2023.114679] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/13/2023]
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2
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Krishnan SB, Clark RJ, Lin X, Dmitrenko O, Hilinski EF, Kuhn LR, Alabugin IV, Saltiel J. α-Methylstilbene Isomers: Relationship of Structure to Photophysics and Photochemistry. J Phys Chem A 2022; 126:8976-8987. [PMID: 36414392 DOI: 10.1021/acs.jpca.2c06319] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Significant differences in the photochemical and photophysical behavior of trans-α-methylstilbene and trans-stilbene have been attributed to structural changes caused by the steric requirements of the methyl group. We present here the X-ray structures of cis- and trans-α-methylstilbene (c- and t-MeSt). This is the first X-ray structure of a cis-stilbene. Despite the pronounced departure from phenyl group coplanarity, the solid-state packing of t-MeSt resembles that of trans-stilbene in that both exhibit disorder with a bicycle pedal structural relationship, dynamic in t-St but static in t-MeSt. We compare the X-ray structures with calculated structures. We also compare our steady state and transient photochemical and spectroscopic results with predictions in a recent theoretical paper that anticipated some of our experiments. Deviations from planarity imposed by the methyl substitution account for the shorter lifetimes of the trans excited states. The rapid torsional relaxation of 1t-MeSt* to the twisted intermediate 1p*, ktp = 2.9 × 1012 s-1, observed using fs transient absorption spectroscopy, explains the sharp decrease in the fluorescence quantum yield of t-MeSt. We correct misconceptions that have appeared in the literature concerning the shape of the stilbene potential energy surface in S1. The nonplanarity due to methyl substitution leads to chirality issues that are relevant in biological molecules such as the protonated Schiff bases of retinal in the opsins.
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Affiliation(s)
- Sumesh B Krishnan
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306-4390, United States
| | - Ronald J Clark
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306-4390, United States
| | - Xinsong Lin
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306-4390, United States
| | - Olga Dmitrenko
- Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, United States
| | - Edwin F Hilinski
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306-4390, United States
| | - Leah R Kuhn
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306-4390, United States
| | - Igor V Alabugin
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306-4390, United States
| | - Jack Saltiel
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306-4390, United States
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Aldaz CR, Martinez TJ, Zimmerman PM. The Mechanics of the Bicycle Pedal Photoisomerization in Crystalline cis,cis-1,4-Diphenyl-1,3-butadiene. J Phys Chem A 2020; 124:8897-8906. [PMID: 33064471 DOI: 10.1021/acs.jpca.0c05803] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Direct irradiation of crystalline cis,cis-1,4-diphenyl-1,3-butadiene (cc-DPB) forms trans,trans-1,4-diphenyl-1,3,-butadiene via a concerted two-bond isomerization called the bicycle pedal (BP) mechanism. However, little is known about photoisomerization pathways in the solid state and there has been much debate surrounding the interpretation of volume-conserving isomerization mechanisms. The bicycle pedal photoisomerization is investigated using the quantum mechanics/molecular mechanics complete active space self-consistent field/Amber force-field method. Important details about how the steric environment influences isomerization mechanisms are revealed including how the one-bond flip and hula-twist mechanisms are suppressed by the crystal cavity, the nature of the seam space in steric environments, and the features of the bicycle pedal mechanism. Specifically, in the bicycle pedal, the phenyl rings of cc-DPB are locked in place and the intermolecular packing allows a passageway for rotation of the central diene in a volume-conserving manner. In contrast, the bicycle pedal rotation in the gas phase is not a stable pathway, so single-bond rotation mechanisms become operative instead. Furthermore, the crystal BP mechanism is an activated process that occurs completely on the excited state; the photoproduct can decay to the ground state through radiative and non-radiative pathways. The present models, however, do not capture the quantitative activation barriers, and more work is needed to better model reactions in crystals. Last, the reaction barriers of the different crystalline conformations within the unit cell of cc-DPB are compared to investigate the possibility for conformation-dependent isomerization. Although some difference in reaction barriers is observed, the difference is most likely not responsible for the experimentally observed periods of fast and slow conversion.
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Affiliation(s)
- Cody R Aldaz
- Department of Chemistry, University of Michigan, 930 N University Ave., Ann Arbor, Michigan 48109-1055, United States
| | - Todd J Martinez
- Department of Chemistry and the PULSE Institute, Stanford University, Stanford, California 94305, United States
| | - Paul M Zimmerman
- Department of Chemistry, University of Michigan, 930 N University Ave., Ann Arbor, Michigan 48109-1055, United States
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Sonoda Y, Goto M, Ichimura K. Solid-state one-way photoisomerisation of Z,E,Z-1,6-(4,4'-diphenyl)hexa-1,3,5-triene dicarboxylate examined using higher-order derivative spectra and powder XRD patterns. Photochem Photobiol Sci 2018; 17:271-280. [PMID: 29364307 DOI: 10.1039/c7pp00247e] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Higher order derivative spectra were applied at first to one-way ZEZ-to-EEE photoisomerisation of dimethyl ester (ZEZ-DPH1) of the titled compound in a methylcyclohexane solution. Many common crossing points emerged in UV-induced derivative-spectral changes to reveal the direct ZEZ-to-EEE photoisomerisation without the transient formation of an intermediate to suggest the bicycle-pedal mechanism. The solid-state photoisomerisation was subsequently monitored by tracing changes in the fourth-order derivatives of absorption spectra of a thin crystalline layer of ZEZ-DPH1 prepared by the drop-casting method, because the distortion of absorption spectra due to light scattering is cancelled. It was suggested that the solid-state photochemical event consists of three steps: fast ZEZ-to-EEE photoisomerisation, a subsequent slow ZEZ-to-EEE photoisomerisation and very slow disappearance of the EEE-isomer. Studies on powder XRD were also carried out for a drop-cast solid layer of ZEZ-DPH1 to disclose the coexistence of a crystal form other than the original one, and the former exhibited faster ZEZ-to-EEE photoisomerisation when compared with the original crystal form. The results revealed by XRD analysis are in line with those obtained by higher-order derivative spectra, confirming the solid-state one-way photoisomerisation to take place through the bicycle-pedal process.
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Affiliation(s)
- Yoriko Sonoda
- Electronics and Photonics Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Higashi 1-1-1, Tsukuba, Ibaraki 305-8565, Japan
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Horino Y. Novel Carbon-Carbon Bond Forming Reactions by Allylpalladium Intermediates Possessing Silyl, Boryl, or Stannyl Groups. J SYN ORG CHEM JPN 2017. [DOI: 10.5059/yukigoseikyokaishi.75.24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Yoshikazu Horino
- Department of Environmental Applied Chemistry, University of Toyama
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Mondal B, Captain B, Ramamurthy V. Volume demanding geometric isomerization of cis-4-stilbazole. HCl salts in the crystalline state: Probing the role of a metastable dimer. J Photochem Photobiol A Chem 2016. [DOI: 10.1016/j.jphotochem.2015.07.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Ichimura K. Solid-StateE-to-ZPhotoisomerization of 4-Dimethylaminoazobenzene Examined by Higher-Order Derivative Spectra. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2016. [DOI: 10.1246/bcsj.20160180] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Veerakanellore GB, Captain B, Ramamurthy V. Solid-state photochemistry of cis-cinnamic acids: a competition between [2 + 2] addition and cis–trans isomerization. CrystEngComm 2016. [DOI: 10.1039/c6ce00682e] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Horino Y, Takahashi Y, Koketsu K, Abe H, Tsuge K. Practical and Convenient Synthesis of 1,6-Di- or 1,2,5,6-Tetra-arylhexa-1,3,5-trienes by the Dimerization of Pd(0)-Complexed Alkenylcarbenes Generated from π-Allylpalladium Intermediates. Org Lett 2014; 16:3184-7. [DOI: 10.1021/ol501643x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Yoshikazu Horino
- Department of Applied Chemistry and ‡Department of Chemistry, Graduate School of
Science and Engineering, University of Toyama, Gofuku, Toyama 930-855, Japan
| | - Yu Takahashi
- Department of Applied Chemistry and ‡Department of Chemistry, Graduate School of
Science and Engineering, University of Toyama, Gofuku, Toyama 930-855, Japan
| | - Kaori Koketsu
- Department of Applied Chemistry and ‡Department of Chemistry, Graduate School of
Science and Engineering, University of Toyama, Gofuku, Toyama 930-855, Japan
| | - Hitoshi Abe
- Department of Applied Chemistry and ‡Department of Chemistry, Graduate School of
Science and Engineering, University of Toyama, Gofuku, Toyama 930-855, Japan
| | - Kiyoshi Tsuge
- Department of Applied Chemistry and ‡Department of Chemistry, Graduate School of
Science and Engineering, University of Toyama, Gofuku, Toyama 930-855, Japan
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Saltiel J, Krishna TRS, Laohhasurayotin K, Ren Y, Phipps K, Davis PH, Yee WA. Medium Effects on the Direct Cis−Trans Photoisomerization of 1,4-Diphenyl-1,3-butadiene in Solution. J Phys Chem A 2011; 115:2120-9. [DOI: 10.1021/jp111482m] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Jack Saltiel
- Departments of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306-4390, United States
| | - Talapragada R. S. Krishna
- Departments of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306-4390, United States
| | - Kritapas Laohhasurayotin
- Departments of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306-4390, United States
| | - Yanjun Ren
- Departments of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306-4390, United States
| | - Kathleen Phipps
- Departments of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306-4390, United States
| | - Paul H. Davis
- Santa Clara University, Santa Clara, California 95053-0365, United States
| | - W. Atom Yee
- Santa Clara University, Santa Clara, California 95053-0365, United States
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Das S, Varghese S, Kumar NSS. Butadiene-based photoresponsive soft materials. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2010; 26:1598-1609. [PMID: 19627077 DOI: 10.1021/la901962k] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The creation of stimuli-responsive materials offers considerable challenges in the area of material science. The use of light as an external stimulus has particular advantages because it can bring about rapid transformations in remote regions in a very precise manner. Naturally occurring photoresponsive systems provide the motivation for developing corresponding artificial systems using molecular self-assembly to address issues such as quantum efficiency, selectivity, and amplification. A practical strategy for developing photoresponsive materials is to utilize molecules that can undergo considerable change in shape on photoisomerization. Although the photoisomerization of polyenes between their linear all-trans isomer and bent cis isomers has been extensively investigated in solution and in organized media because of its relevance to naturally occurring photoresponsive systems, its use in developing artificial photoresponsive systems has not been well explored. This feature article provides an overview of photoresponsive soft materials such as liquid crystals and gels with special emphasis on our recent studies related to the use of the butadiene chromophore for the design of such materials. The role of molecular self-assembly in controlling the photochemical and photophysical properties of these molecules is also discussed.
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Affiliation(s)
- Suresh Das
- Photosciences and Photonics Section, Chemical Sciences and Technology Division, National Institute for Interdisciplinary Science and Technology, Trivandrum-695 019, Kerala, India
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Saltiel J, Papadimitriou D, Krishna T, Huang ZN, Krishnamoorthy G, Laohhasurayotin S, Clark R. Photoisomerization of All-cis-1,6-diphenyl-1,3,5-hexatriene in the Solid State and in Solution: A Simultaneous Three-Bond Twist Process. Angew Chem Int Ed Engl 2009; 48:8082-5. [DOI: 10.1002/anie.200902724] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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14
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Photoisomerization of All- cis-1,6-diphenyl-1,3,5-hexatriene in the Solid State and in Solution: A Simultaneous Three-Bond Twist Process. Angew Chem Int Ed Engl 2009. [DOI: 10.1002/ange.200902724] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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15
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Sonoda Y, Goto M, Tsuzuki S, Akiyama H, Tamaoki N. [2+2] Photodimerization and photopolymerization of diphenylhexatriene crystals utilizing perfluorophenyl–phenyl stacking interactions. J Fluor Chem 2009. [DOI: 10.1016/j.jfluchem.2008.09.010] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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16
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Sonoda Y, Yoshida M, Goto M. (Z,E,Z)-1,6-Di-1-naphthyl-hexa-1,3,5-triene. Acta Crystallogr Sect E Struct Rep Online 2009; 65:o294. [PMID: 21581904 PMCID: PMC2968162 DOI: 10.1107/s1600536809000592] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2008] [Accepted: 01/07/2009] [Indexed: 11/24/2022]
Abstract
The title compound, C26H20, lies about an inversion centre. The naphthalene unit and the hexatriene chain are each approximately planar (maximum deviations of 0.0143 and 0.0042 Å, respectively), and are inclined to one another at a dihedral angle of 49.20 (4)°. The dihedral angle between the two naphthalene ring systems of neighboring molecules is 85.71 (4)°.
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Saltiel J, Bremer M, Laohhasurayotin S, Krishna T. Photoisomerization ofcis,cis- andcis,trans-1,4-Di-o-tolyl-1,3-butadiene in Glassy Media at 77 K: One-Bond-Twist and Bicycle-Pedal Mechanisms. Angew Chem Int Ed Engl 2008. [DOI: 10.1002/ange.200704465] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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18
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Saltiel J, Bremer M, Laohhasurayotin S, Krishna T. Photoisomerization ofcis,cis- andcis,trans-1,4-Di-o-tolyl-1,3-butadiene in Glassy Media at 77 K: One-Bond-Twist and Bicycle-Pedal Mechanisms. Angew Chem Int Ed Engl 2008; 47:1237-40. [DOI: 10.1002/anie.200704465] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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Furukawa D, Kobatake S, Matsumoto A. Direct observation of change in the molecular structure of benzyl (Z,Z)-muconate during photoisomerization in the solid state. Chem Commun (Camb) 2008:55-7. [DOI: 10.1039/b714792a] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Saltiel J, Krishna TSR, Laohhasurayotin S, Fort K, Clark RJ. Photoisomerization of cis,cis- to trans,trans-1,4-Diaryl-1,3-butadienes in the Solid State: The Bicycle-Pedal Mechanism. J Phys Chem A 2007; 112:199-209. [DOI: 10.1021/jp077342c] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Jack Saltiel
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306-4390
| | | | - Somchoke Laohhasurayotin
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306-4390
| | - Katy Fort
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306-4390
| | - Ronald J. Clark
- Department of Chemistry and Biochemistry, Florida State University, Tallahassee, Florida 32306-4390
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Sonoda Y, Goto M, Tsuzuki S, Tamaoki N. Fluorescence Spectroscopic Properties and Crystal Structure of a Series of Donor−Acceptor Diphenylpolyenes. J Phys Chem A 2006; 110:13379-87. [PMID: 17165862 DOI: 10.1021/jp064937j] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A series of p-nitro-p'-alkoxy(OR)-substituted (E,E,E)-1,6-diphenyl-1,3,5-hexatrienes (1a, R = Me; 1b, R = Et; 1c, R = n-Pr; 1d, R = n-Bu) were prepared. The absorption and fluorescence spectra in solution were almost independent of the alkoxy chain length. The absorption maximum showed only a small dependence on the solvent polarity, whereas the fluorescence maximum red-shifted largely as the polarity increased. The solid-state absorption and fluorescence spectra were red-shifted relative to those in low polar solvents and were clearly dependent on the alkoxy chain length. The fluorescence maxima for the crystals of 1b and 1d were observed at 635-650 nm, which were red-shifted by 40-50 nm relative to those for 1a and 1c. The Stokes shifts were all relatively small (3000-3500 cm-1). For all four compounds, the fluorescence decay curves in the solid state were able to be analyzed by single-exponential fitting to give the lifetimes of 1.1-1.3 ns. This indicates that the emission of 1a-d is not originated from an excimer or molecular aggregates, but from only one emitting monomeric species. The fluorescence quantum yields of 1a-d were considerably high compared with the values for organic solids, which is consistent with their monomeric origin of emission. Single-crystal X-ray structure analyses of 1a, 1c, and 1d showed that the crystal packing was dependent on the alkoxy chain length. The crystals of 1a and 1c had herringbone structure, whereas that of 1d had pi-stacked structure. Strong pi-pi interaction in the crystal of 1d would be the cause of the spectral red shifts relative to those for 1a and 1c. No observation of excimer fluorescence from crystal 1d can be attributed to the limited overlap between the pi-planes of the molecules due to its "slipped-parallel" structure.
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Affiliation(s)
- Yoriko Sonoda
- Nanotechnology Research Institute and Technical Center, National Institute of Advanced Industrial Science and Technology (AIST), Higashi 1-1-1, Tsukuba, Ibaraki 305-8565, Japan.
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Fengqiang Z, Motoyoshiya J, Nakamura J, Nishii Y, Aoyama H. Photochemical Behavior of Some p-Styrylstilbenes and Related Compounds: Spectral Properties and Photoisomerization in Solution and in Solid State. Photochem Photobiol 2006. [DOI: 10.1111/j.1751-1097.2006.tb09825.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Fengqiang Z, Motoyoshiya J, Nakamura J, Nishii Y, Aoyama H. Photochemical behavior of some p-styrylstilbenes and related compounds: spectral properties and photoisomerization in solution and in solid state. Photochem Photobiol 2006; 82:1645-50. [PMID: 16879037 DOI: 10.1562/2006-01-17-ra-780] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The spectral properties and Z,E-photoisomerizations of three 4-styrylstilbenes, a 4,4'-bis(P-methylstyryl)benzene and a 4,4'-distyrylstilbene were investigated in solution and in the solid state. Some notable features of the absorption and fluorescence spectra due to the structures and the phases (solution or solid) were observed, especially the Stokes shifts. Interesting photochemical behaviors in solution and in the solid state were also found. While the (E,Z)-4-styrylstilbenes undergo a one-way photoisomerization to their E,E-isomers with almost equal rates in solution, their quantum yields in the solid state decrease with increasing substituent size at the terminal aromatic rings. On the other hand, the 4,4'-bis(beta-methylstyryl)benzene undergoes a mutual photoisomerization in solution, but its E,Z-isomer isomerizes in a one-way manner to the E,E-isomer in the solid state. Additionally, the (Z,E,Z)-4,4'-styrylstilbene was found to undergo a one-way photoisomerization to the E,E,E-isomer via the E,E,Z-isomer in solution and the crystalline E,E,Z-isomer to the E,E,E-isomer in the solid state.
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Affiliation(s)
- Zhu Fengqiang
- Department of Chemistry, Faculty of Textile Science and Technology, Shinshu University, Ueda, Nagano 386-8567, Japan
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Saltiel J, Krishna TSR, Clark RJ. Photoisomerization of cis,cis-1,4-Diphenyl-1,3-butadiene in the Solid State: The Bicycle-Pedal Mechanism. J Phys Chem A 2006; 110:1694-7. [PMID: 16450997 DOI: 10.1021/jp056700d] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The cis-trans photoisomerization of crystalline or powdered cis,cis-1,4-diphenyl-1,3-butadiene (cc-DPB) was studied at room temperature. The progress of the reaction was monitored by fluorescence spectroscopy, powder X-ray diffraction, 1H NMR and HPLC. High conversions (up to 90%) to the trans,trans isomer were observed in a crystal to crystal reaction. Formation of the cis,trans isomer, the sole product obtained in solution and in very viscous glassy media at 77 K is entirely suppressed in the solid state. The observed two-bond photoisomerization is explained by Warshel's bicycle-pedal photoisomerization mechanism (BP). The results are consistent with X-ray diffraction measurements, which have revealed that cc-DPB molecules exist in crystals in edge to face alternating arrays of two conformer structures whose phenyl rings deviate significantly from the plane of the central diene moiety ( approximately 40 degrees ). One of the conformers has the two phenyls in parallel planes and the other in roughly perpendicular planes. Least motion considerations suggest that the former should undergo the two-bond photoisomerization more easily, in agreement with observations that indicate that the reaction proceeds in discrete stages. Recently reported cis,cis- to trans,trans-muconate photoisomerizations in the solid state are proposed to also proceed via the BP mechanism. The reactions are consistent with the X-ray crystal structures of the cis,cis-muconate isomers.
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