Wavelength Dependent Trans to Cis and Quantum Chain Isomerizations of Anthrylethylene Derivatives

Gopal, V. Raj; Reddy, A. Mahipal; Rao, V. Jayathirtha

doi:10.1021/jo00129a043

Cited by 47 publications

(42 citation statements)

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“…On the other hand, according to Rao and coworkers (23), the quantum chain isomerization can also originate from the singlet excited state of trans isomer, provided that the excited singlet possesses charge transfer character. This mechanism involves an adiabatic isomerization ( trans *→ cis *) with the subsequent energy transfer to a ground state molecule ( cis *+ trans → cis + trans *), leading to a cis isomer‐rich pss and an increase in φ TC and φ CT as ligand concentration increases.…”

Section: Resultsmentioning

confidence: 98%

“…One should consider other factors that could increase quantum yield of photoisomerization and change the composition of pss. Quantum chain process is known to be responsible for high quantum yields of photoisomerization of some arylstilbene derivatives (20,22,23). Most reports concern the quantum chain mechanism that involves triplet energy transfer, excitation energy of a triplet state‐excited trans isomer, 3 trans *, which isomerizes into a new 3 trans *.…”

Section: Resultsmentioning

confidence: 99%

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Photoisomerization of Arylstilbazolium Ligands in the Presence of DNA^¶

Juskowiak¹,

Chudak²

2004

Photochem & Photobiology

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The ability of the DNA duplex to behave as an efficient organized medium for trans‐cis photoisomerization has been explored. The presence of DNA affected isomerization in a variety of ways depending on the aryl moiety properties of the ligand and its DNA‐binding mode. Contrary to intercalating ligands, 9‐[2‐(N‐methylpyridinium‐4‐yl)vinyl)phenanthrene (2) and 9‐[2‐(N‐methylpyridinium‐4‐yl)vinyl]anthracene (3), which gave only cis and trans isomers, the additional products‐cyclobutane photodimers‐were detected for 2‐[2‐(N‐methylpyridinium‐4‐yl)vinyl]naphthalene (1), which binds cooperatively to the minor groove of DNA. Photostationary states (pss) for all ligands were seriously affected by the presence of DNA. A trans isomer‐rich pss and restriction of trans→cis process, observed for ligands 1 and 2, were explained in terms of a different binding affinity of DNA toward particular isomers. On the contrary, 9‐anthryl derivative 3 isomerized against the isomer‐binding preferences, showing cis isomer‐rich pss and enhanced quantum yield of isomerization. The unique behavior of ligand 3‐DNA complex was attributed to different isomerization mechanism that consists in quantum chain isomerization from an excited singlet state possessing a charge transfer character. This is the first example of ligand, which undergoes DNA‐mediated cis‐trans isomerization in the opposite direction than expected from DNA‐binding preferences. The analysis of pss data based on two alternative pathways of photoisomerization showed that investigated ligands follow the model that allows isomerization of both free and DNA‐bound ligands.

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Section: Resultsmentioning

confidence: 98%

Section: Resultsmentioning

confidence: 99%

Photoisomerization of Arylstilbazolium Ligands in the Presence of DNA^¶

Juskowiak¹,

Chudak²

2004

Photochem & Photobiology

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“…The Horner–Wadsworth–Emmons olefinating reagent was prepared as described previously (27). Anthryl acrylate (28), pyrenyl carboxaldehyde (29), 4‐methylnaphthyl acrylate (30), 4‐methoxynaphthyl acrylate (30) and naphthyl acrylate (30) were prepared by adopting published procedures. Arylallyl alcohols were prepared by reducing the corresponding arylacrylates using di‐isobutylaluminiumhydride.…”

Section: Methodsmentioning

confidence: 99%

Ionic Photodissociation in Arylallyl Acetates¶

Srinivas

Reddy

et al. 2007

Photochemistry and Photobiology

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We have synthesized several 3‐arylallyl acetates 1, 2, 3, 5 and 6, and E‐3‐(1‐naphthyl)‐2‐propene‐1‐ol 4 for studying ionic photodissociation. Compounds 1, 2 and 3 underwent an efficient ionic photodissociation in polar solvents like acetonitrile and methanol leading to the formation of rearranged acetate and methyl ether products, as well as undergoing an E–Z isomerization. The arylallyl alcohol 4 and the two arylallyl acetates 5 and 6 did not undergo ionic photodissociation. Quantum yields of product formation, quantum yields of fluorescence, solvent polarity effects and triplet‐sensitization studies indicated that a highly polarized excited singlet state is responsible for the ionic photodissociation. Both the singlet‐ and triplet‐excited states are effective in displaying E–Z isomerization in 1, 2, 3 and 4. Compounds 5 and 6 are highly fluorescent, and the fluorescence may be the excited state deactivation pathway along with internal conversion.

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“…The broad structureless shape of the emission spectra and the solvent dependence of emission spectra indicate strong ICT in the excited state in case of CF5. The solvatochromic behavior is accompanied by a decrease of the fluorescence quantum yield when the polarity of the solvent increases (Table S1 in supporting information) is also an indication that the excited state possesses ICT [40].…”

Section: One-photon Absorption and Emission Spectramentioning

confidence: 96%

“…It is well established that d for the lowest lying twophoton state of quadrupolar molecules increases with the extent of the ICT up to the saturation limit [39]. Although the double bond (C]C) is an excellent conjugated bridge for the enhanced ICT from donor(s) to acceptor(s), it readily undergoes cis-trans photoisomerization [40,41], which may hamper the efficiency and the stability of the materials. This problem could be avoided if one uses triple bonds (C^C) as the conjugated bridge, since the conjugation through triple bonds are less sensitive to torsion than double bonds.…”

Section: Introductionmentioning

confidence: 99%