ChemInform Abstract: THE PHOTOCHEMICAL REACTIVITY OF SOME BENZOYLTHIOPHENES PART 3, THE EFFECT OF AN ADJACENT METHYL GROUP ON THE EXCITED STATE REACTIVITY OF 2-BENZOYLTHIOPHENE

1975 ◽  
Vol 6 (17) ◽  
pp. no-no
Author(s):  
D. R. ARNOLD ◽  
B. M. JUN. CLARKE
Keyword(s):  
Excited State ◽  
Photochemical Reactivity ◽  
Methyl Group

scholarly journals The Photochemical Reactivity of Some Benzoylthiophenes. III. The Effect of an Adjacent Methyl Group on the Excited State Reactivity of 2-Benzoylthiophene

1975 ◽  
Vol 53 (1) ◽  
pp. 1-11 ◽  
Author(s):  
D. R. Arnold ◽  
B. M. Clarke Jr.
Keyword(s):  
Excited State ◽  
Carbonyl Group ◽  
Emission Spectra ◽  
Ultraviolet Absorption ◽  
Photochemical Reactivity ◽  
Methyl Group ◽  
Partial Energy ◽  
Phosphorescence Emission ◽  
Π State

The ultraviolet absorption and phosphorescence emission spectra of 2-(2-methylbenzoyl) thiophene (1), 2-benzoyl-3-methylthiophene (2), 2-benzoyl-4-methylthiophene (3), and 2-benzoyl-5-methylthiophene (4) are reported and analyzed. Partial energy diagrams are constructed. The lowest triplet is assigned as a π,π* state of the 2-thienoyl chromophore in every case. Photocycloaddition of isobutylene to the carbonyl group was observed with 1 and 2. The oxetanes are thermally unstable; olefins 1-(2-thienyl)-1-(2-methylphenyl)-2-methylpropene (from 1) and 1-phenyl-1-(2-(3-methylthienyl))-2-methylpropene (from 2) were formed and characterized. Irradiation of 1 and 2 in O-deuteromethanol did not lead to incorporation of deuterium; no reaction was observed. These results are discussed in terms of the existing generalizations potentially useful for predicting photochemical reactivity.

The photochemical reactivity of some benzoylthiophenes. IV. The effect of an adjacent methyl group on the excited state reactivity of 3-benzoylthiophene

1978 ◽  
Vol 56 (15) ◽  
pp. 1970-1984 ◽  
Author(s):  
D. R. Arnold ◽  
C. P. Hadjiantoniou
Keyword(s):  
Hydrogen Abstraction ◽  
Thiophene Ring ◽  
Emission Spectra ◽  
Photochemical Reactions ◽  
Triplet States ◽  
Photochemical Reactivity ◽  
Methyl Group ◽  
State Diagrams ◽  
Phosphorescence Emission ◽  
Intramolecular Hydrogen

The electronic absorption and phosphorescence emission spectra and the photochemical reactivity of several methyl-3-benzoylthiophenes (2- and 4-methyl-3-benzoylthiophene (1, 2), 2,5-dimethyl-3-benzoylthiophene (3), and 3-(2-methylbenzoyl)thiophene (4)) have been studied. Partial state diagrams have been constructed. The lowest energy absorption in hexane solution in every case is the carbonyl n → π* transition. The two lowest triplet states of these ketones are close in energy and, in fact, the nature of the emitting triplet (n,π* or π,π*) depends upon the position of methyl substitution and upon the solvent. The photochemical reactions studied include intramolecular hydrogen abstraction (revealed by deuterium exchange in the adjacent methyl group upon irradiation in perdeuteriomethanol solution), photocycloaddition of dimethyl acetylenedicarboxylate to the thiophene ring, and photocycloaddition of isobutylene to the carbonyl group. Generalizations, potentially useful for predicting photochemical reactivity of these and other aromatic ketones are summarized.

Millimeter-Wave Spectrum of Ethyl Acetylene Centrifugal Distortion, Coriolis Interaction and Internal Rotation

1983 ◽  
Vol 38 (4) ◽  
pp. 447-451 ◽  
Author(s):  
J. Demaison ◽  
D. Boucher ◽  
J. Burie ◽  
A. Dubrulle
Keyword(s):  
Excited State ◽  
Internal Rotation ◽  
Plane Deformation ◽  
Wave Spectrum ◽  
Rotational Spectrum ◽  
Centrifugal Distortion ◽  
Coriolis Interaction ◽  
Methyl Group ◽  
First Excited State ◽  
Methyl Torsion

The rotational spectrum of ethyl acetylene has been investigated between 70 and 320 GHz. A Coriolis interaction has been found between the first excited state of the methyl torsion and the C - C = C in plane deformation. Splittings of transitions in the first excited torsional state show that the barrier hindering internal rotation of the methyl group amounts to 3271 cal/mole.

Synthesis and spectroscopic properties of benzo- and naphthofuryl-3-hydroxychromones

2001 ◽  
Vol 79 (4) ◽  
pp. 358-363 ◽  
Author(s):  
Andrey S Klymchenko ◽  
Turan Ozturk ◽  
Vasyl G Pivovarenko ◽  
Alexander P Demchenko
Keyword(s):  
Excited State ◽  
Proton Transfer ◽  
Spectroscopic Properties ◽  
Molecular Probe ◽  
Absorption Bands ◽  
Methyl Group ◽  
Long Wavelength ◽  
Excited State Proton Transfer ◽  
Wavelength Absorption ◽  
Long Wavelength Absorption Band

With the focus of designing new fluorescent probes, four new 3-hydroxy-chromone derivatives bearing benzofuran and naphthofuran groups were synthesized. They show bathochromic absorption shifts relative to 3-hydroxyflavone with the ability of retention to display the excited-state proton transfer. Disruption of the planarity by the methyl group in the furan ring leads to a decrease of both the extinction coefficient and the contribution of long wavelength absorption band, while molecules without a methyl group showed two distinct absorption bands. Shifts to longer wavelengths are also observed in fluorescent spectra, and the absence of the methyl group results in a dramatic increase of fluorescence quantum yield and lifetime. Of the extended 3-hydroxychromone derivatives, 3-hydroxy-2-naphtho[2,1-b]furan-2-yl-chromone has shown comparable, and in some cases better, absorption and fluorescence properties than the 3-hydroxychromones synthesized so far, which make it a highly promising candidate as molecular probe for analytical chemistry, biophysics, and cellular biology.Key words: benzo- and naphthofuryl-3-hydroxyflavone, synthesis, electronic spectra, fluorescence, excited state proton transfer.

Triphenylpyrazine: methyl substitution to achieve deep blue AIE emitters

2019 ◽  
Vol 7 (42) ◽  
pp. 13047-13051 ◽  
Author(s):  
Haozhong Wu ◽  
Jiajie Zeng ◽  
Zeng Xu ◽  
Bing Zhang ◽  
Han Zhang ◽  
...  
Keyword(s):  
Excited State ◽  
Phenyl Group ◽  
Decay Process ◽  
Methyl Group ◽  
Methyl Substitution ◽  
State Decay ◽  
Deep Blue

Based on our deep comprehension of the unique excited state decay process of tetraphenylpyrazine derivatives, triphenylpyrazine-3-carbazole (TrPP-3C) was designed by replacing the phenyl group with a methyl group at the 3-position of pyrazine.

Theoretical Study on the Excited-State Deactivation Paths for A-5FU Dimer

2021 ◽  
Author(s):  
Xue-Fang Yu ◽  
Ting-he Fu ◽  
Bo Xiao ◽  
Hong-yuan Yu ◽  
Qingzhong Li
Keyword(s):  
Excited State ◽  
Base Pair ◽  
Theoretical Study ◽  
Normal Function ◽  
Methyl Group

DNAs’ photostability plays a key role on the normal function of organisms. A-5FU is a base pair derivative of A-T dimer where the methyl group is replaced by a F...

Site-dependent effects of methylation on the electronic spectra of jet-cooled methylated xanthine compounds

2017 ◽  
Vol 19 (33) ◽  
pp. 22375-22384 ◽  
Author(s):  
Doory Kim ◽  
Key Young Yang ◽  
Hyung Min Kim ◽  
Tae-Rae Kim ◽  
Nam Joon Kim ◽  
...  
Keyword(s):  
Excited State ◽  
Ground State ◽  
Electronic Spectra ◽  
Methyl Group ◽  
Torsional Barrier

The torsional barrier of methylated xanthine compounds is affected by a methyl-adjacent carbonyl or methyl group in the ground state, whereas it is governed in the excited state by the hyperconjugation interaction in the LUMO.

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