Photolysis of r-1,c-2,t-3,t-4-tetraphenylcyclobutane: quantum yield determinations via high performance liquid chromatography

Frings, R.B.; Schnabel, W.

doi:10.1016/0047-2670(83)80067-7

Cited by 4 publications

(1 citation statement)

References 5 publications

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“…Exposure of tetraphenylcyclobutane, the dimerization product of E -stilbene, to wavelengths shorter than 300 nm leads to cycloreversion. − With different wavelengths this reaction may be driven either toward cyclization or cycloreversion. The refractive index n of a material is depending on physical properties like density, molecular weight, molar refraction and relative permittivity.…”

Section: Introductionmentioning

confidence: 99%

Selective [2 + 2]-Cycloaddition in Methacrylic Stilbene Polymers without Interference from E/Z-Isomerization

2011

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Stilbene is known to undergo two different reactions upon photochemical excitation. The first is an E/Z isomerization and the second is a [2 + 2]-cycloaddition of two stilbene molecules. Because both reactions occur in parallel their use is limited. Here we report on photorefractive polymers with a methacrylate backbone and covalently attached 4-hydroxy-(E)-stilbene or 3,5-dimethoxy-4-hydroxy-(E)-stilbene units in the side chain which show [2 + 2]-cycloaddition only. Both polymers, poly(4-methacryloyloxy-(E)-stilbene) (PMAES) and poly(4-methacryloyloxy-3,5-dimethoxy-(E)-stilbene) (PMADMES), show very high initial refractive indices of 1.6533 for PMAES and 1.6288 for PMADMES. The photochemical reaction upon laser irradiation with 355 nm was monitored by UV/vis, fluorescence, and IR spectroscopy. The light-induced changes of the refractive index at 633 nm measured by surface plasmon resonance (SPR) were found to be Δn > 0.05 for PMAES and Δn > 0.04 for PMADMES. The sensitivity of PMADMES is enhanced compared to PMAES due to the electron donating groups (EDG) as the direct comparison of both polymers shows. Both polymers are useful for optical devices because they do not show any absorption in the visible range and are noncrystalline as determined by wide-angle X-ray scattering (WAXS) and differential scanning calorimetry (DSC).

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Section: Introductionmentioning

confidence: 99%

Selective [2 + 2]-Cycloaddition in Methacrylic Stilbene Polymers without Interference from E/Z-Isomerization

2011

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Structure and Photochemical Properties of r‐1, c‐2, t‐3, t‐4‐l, 3‐Bis [2‐ (5‐R‐benzoxazolyl) ] −2,4‐di (4‐R' ‐phenyl) cyclobutane

Zhang

Zhuang

et al. 2001

Chin. J. Chem.

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molecule of IIc is centmsymmetric, which indicates that the dimerization process is a head-btail fahion. The selectivity of the photodimerization of Ia-Ic has been enhanced by using acidic solvent and the reaction speed would be decreased when electron donating gnxlp was introduced in the Qposition of the phenyl group. That the photodimerization is not affected by the presence of oxygen as well as its high stereo-selectivity demonstrated that the reaction proceeded through an excited singlet state. It was also found that under irradiation of short wavelength U V , these dimers underwent photolysis completely to reproduce its bnns-monomers, and then the new formed species changed into their ck-isomers through m -c k isomehtion.

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Chemical actinometers in the 250–270 nm region

Murata

Yoshinari

Yamaguchi

et al. 1991

Journal of Photochemistry and Photobiology A: Chemistry

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Photolysis of r-1,c-2,t-3,t-4-tetraphenylcyclobutane: quantum yield determinations via high performance liquid chromatography

Cited by 4 publications

References 5 publications

Selective [2 + 2]-Cycloaddition in Methacrylic Stilbene Polymers without Interference from E/Z-Isomerization

Selective [2 + 2]-Cycloaddition in Methacrylic Stilbene Polymers without Interference from E/Z-Isomerization

Structure and Photochemical Properties of r‐1, c‐2, t‐3, t‐4‐l, 3‐Bis [2‐ (5‐R‐benzoxazolyl) ] −2,4‐di (4‐R' ‐phenyl) cyclobutane

Chemical actinometers in the 250–270 nm region

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