Photochemical hydrogen abstraction as a radiationless transition in the photoketonization of β-dicarbonyl compounds

Nikolov, Geno; Markov, P.

doi:10.1016/0047-2670(81)80023-8

Cited by 11 publications

(8 citation statements)

References 8 publications

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“…The agreement with the experimental bond lengths in the enol form [12,14] and slightly better with 6-21G ÃÃ than with 6-311G ÃÃ . The differences of the results with the two basis sets, however, are much greater for the valence angles, especially for the transition state, where differences for the dihedral angles of up to 40 degrees were observed.…”

Section: Resultssupporting

confidence: 71%

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Ab initio Study of the Keto-Enol Equilibriumof Malonaldehyde

Delchev

Nikolov

2000

Monatshefte fuer Chemie

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The mechanism of the keto-enol tautomerism of malonaldehyde was studied by ab initio methods using 6-21G ÃÃ and 6-311G ÃÃ basis functions at the HF level. Two separate mechanisms were examined: through-space proton transfer in the 3-shaped form and through-space proton transfer in a sickle-shaped form obtained from the 3 form by rotation. The transition state structure of the 3 form is non-planar, whereas that of the sickle form is planar. The sickle form is connected with a 2 nd order saddle, indicating that there should exist a lower energy barrier, i.e. that the throughbond mechanism may be preferred. The calculated energy barriers of keto-enol tautomerism for the sickle form is twice as high as those for the omega form.

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Section: Resultssupporting

confidence: 71%

“…The two forms may interconvert through two possible mechanisms: through-space or through-bonds [10]. It has been proven theoretically that in the 3-shaped form the proton transfer takes place through space [8,11,12].…”

Section: Introductionmentioning

confidence: 99%

Ab initio Study of the Keto-Enol Equilibriumof Malonaldehyde

Delchev

Nikolov

2000

Monatshefte fuer Chemie

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“…Then the transfer of the the UV light the process of cis-enol r trans-enol is possible. hydrogen atom to the carbon atom can be explain through quantum mechanical tunnelling, 11 on acIt is also probably that the photoisomerization enol r enol involves intersystem crossing.…”

Section: Resultsmentioning

confidence: 99%

Photochemical behavior of poly(ethylacryloylacetate) and poly(acryloylacetone) films

Masuda

Sertova

Петков

1997

J. Polym. Sci. A Polym. Chem.

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“…The relative contributions of the keto and enolic tautomers depend on several factors such as solvent characteristics, temperature and substitution on curcumin. In general, many of the diketones exist in solutions predominantly in the enolic form at room temperature 42,44. The enolic form can exist in different cis and trans isomeric forms depending on the temperature, polarity or hydrogen bonding nature of the solvents 45,46.…”

Section: Resultsmentioning

confidence: 99%

Binding of curcumin and its long chain derivatives to the activator binding domain of novel protein kinase C

Majhi

Rahman

Panchal

et al. 2010

Bioorganic & Medicinal Chemistry

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Protein Kinase C (PKC) is a family of serine/threonine kinases that play a central role in cellular signal transduction. The second messenger diacylglycerol having two long carbon chains acts as the endogenous ligand for the PKCs. Polyphenol curcumin, the active constituent of Curcuma longa is an anticancer agent and modulates PKC activity. To develop curcumin derivatives as effective PKC activators, we synthesized several long chain derivatives of curcumin, characterized their absorption and fluorescence properties and studied their interaction with the activator-binding second cysteinerich C1B subdomain of PKCδ, PKCε and PKCθ. Curcumin (1) and its C16 long chain analog (4) quenched the intrinsic fluorescence of PKCδC1B, PKCεC1B and PKCθC1B in a manner similar to that of PKC activator 12-O-tetradecanoylphorbol 13-acetate (TPA). The EC 50 s of the curcumin derivatives for fluorescence quenching varied in the range of 4-11 μM, whereas, EC 50 s for TPA varied in the range of 3-6 μM. Fluorescence emission maxima of 1 and 4 were blue shifted and the fluorescence anisotropy values were increased in the presence of the C1B domains similar to that shown by the fluorescent analog of TPA, sapintoxin-D, confirming that they were bound to the proteins. Molecular docking of 1 and 4 with novel PKC C1B revealed that both the molecules form hydrogen bonds with the protein residues. The present result shows that curcumin and its long chain derivatives bind to the C1B subdomain of novel PKCs and can be further modified structurally to improve its binding and activity.

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Photochemical hydrogen abstraction as a radiationless transition in the photoketonization of β-dicarbonyl compounds

Cited by 11 publications

References 8 publications

Ab initio Study of the Keto-Enol Equilibriumof Malonaldehyde

Ab initio Study of the Keto-Enol Equilibriumof Malonaldehyde

Photochemical behavior of poly(ethylacryloylacetate) and poly(acryloylacetone) films

Binding of curcumin and its long chain derivatives to the activator binding domain of novel protein kinase C

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