Spectra of p-Benzoquinone, studied with ham/3

Åsbrink, L.; Bieri, Gerhard; Fridh, C.; Lindholm, E.; Chong, Delano P.

doi:10.1016/0301-0104(79)85187-3

Cited by 44 publications

(22 citation statements)

References 48 publications

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“…It was shown that good agreement between theory and experiment for ionization events that originate from non-bonding orbital of carbonyl oxygen and π orbital in C=C bonds were found. Excitation energies calculated by the HAM/3 method reproduce observed spectra fairly satisfactory [5][6][7][8][9][10] . The method is also capable of calculating electron affinity 4,11 .…”

Section: Introductionmentioning

confidence: 91%

Ionization energies, electron affinities and excitation energies of some steroid hormones calculated with the semiempirical HAM/3 method

Takahata¹,

Vendrame²

2001

J. Braz. Chem. Soc.

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Potenciais de ionização, afinidades eletrônicas e energias de excitação de hormônios sexuais humanos, tais como testosterona, estradiol, além de outros hormônios relacionados foram calculados pelo método semiempírico HAM/3. O espectro fotoeletrônico observado de um esteróide, a androst-4-eno-3,17-diona, foi analisado por comparação com as energias de ionização calculadas. Os espectros eletrônicos de excitação na região entre 50 e 350 nm foram simulados utilizando os valores calculados. Existe uma banda de excitação característica, de alta intensidade, na região entre 75 e 100 nm em todos os esteróides estudados. Os espectros de transição na região acima de 150 nm são diferentes de uma molécula para outra.Ionization energies, electron affinities and excitation energies of human sexual hormones such as testosterone, estradiol and related hormones were calculated with the semiempirical HAM/ 3 method. Observed photoelectron spectrum of androst-4-ene-3,17-dione was assigned using the calculated ionization energies. Spectra of electronic excitations in the region between 50 and 350nm of the molecules were simulated using the calculated values. There is a characteristic, high intensity, excitation band in the region between 75nm and 100nm in all of the steroids studied. The transition spectra above 150nm region are different from molecule to molecule.

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Section: Introductionmentioning

confidence: 91%

Ionization energies, electron affinities and excitation energies of some steroid hormones calculated with the semiempirical HAM/3 method

Takahata¹,

Vendrame²

2001

J. Braz. Chem. Soc.

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“…Based on the vibronic characteristics and differential sensitivities to chemical substitutions on the benzoid ring, an assignment for this region has been made as n, n, ~, ~r in the increasing order of the ionization energy. Asbrink et al [12] finally measured the PE spectra of PBQ and tetrafluoro PBQ up to 25 eV and interpreted them using the semiempirical HAM/3 MO method, giving n, n, ~r, ~r for the first four PES bands.…”

Section: Et(scf)/ehmentioning

confidence: 99%

“…The low-lying singlet and triplet n-~* and ~¢r* excited states of PBQ have recently been reported by several authors [3][4][5][6][7][8], and the ionization potentials have been measued by the photoelectron spectroscopy (PES) [9][10][11][12][13]. Several ab initio [14][15][16][17][18] and semiempirical MO studies [11][12][13][19][20][21] are also available in the literature.…”

Section: Introductionmentioning

confidence: 97%

“…Several ab initio [14][15][16][17][18] and semiempirical MO studies [11][12][13][19][20][21] are also available in the literature.…”

Section: Introductionmentioning

confidence: 99%

“…A comparison of the calculated ionization potentials in the SCF and CI levels with experiment[12]. ~, orbital energy ; A SCF, SCF energy difference between the cations and the ground state ; ACI, CI energy difference between the cations and the ground state.…”

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confidence: 99%

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An ab initio CI study of the ground and excited states of p-benzoquinone

1983

Molecular Physics

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Configuration interaction (C I) studies of ground, n ~r*, ~ ~r* electronically excited singlet and triplet states and of the ionized states (cations) are reported for p-benzoquinone. The splittings between two nrt* states, both for singlet and triplet, are shown to be very small confirming recent experimental results. A lower lying ~rTr* triplet state (aBz.) has been thereby assigned. The photoelectron spectra (PES) for the low-energy ionization region have been assigned. Contrary to the MO ordering, 2b3g(Tr.), lbtg(~g), 4b3g(n~), 5b:u(n.), the CI result predicts that the four first PES bands may be assigned to ~B3g(ng), 2B~u(n.), ~B3. (~.) and 2Blg(lrg) in order of increasing energy.

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Proximitätseffekte in der Organischen Chemie — Die photoelektronenspektroskopische Untersuchung nichtbindender und transanularer Wechselwirkungen

Martin

Mayer

1983

Angewandte Chemie

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Klassische Strukturformeln vermitteln hiiufig die Vorstellung, einzig und a h i n jene Beziehungen zwischen den Atomen seien von Bedeutung, welche fur den Zusammenhalt des Molekiils sorgen und durch Bindungsstriche wiedergegeben werden. Viele Wechselwirkungen zwischen Atomen oder Atomgruppen werden jedoch durch diese Schreibweise nicht erfaBt. Ihre Anwesenheit hat dennoch mitunter wichtige Konsequenzen fiir Grundzustandsenergien (cis-Difluorethylen ist stabiler als trans-Difluorethylen), Konformationen (syn-Methylvinylether ist stabiler als die anti-Form), Reaktiuituten (ein endo-standiger Cyclopropanring in 7anti-Norbornylderivaten beschleunigt die Solvolyse um den Faktor IOl4), UV-Spektren (die n-Systeme von Acridin und Purindurch eine viergliedrige Kette verbundenergeben beim ,,Ubereinanderlegen" Hypochromie), CD-Spektren (der inhiirent symmetrische, dissymmetrisch gestarte Chromophor von 2-Deuterionorbornadien IiiBt drei Ubergiinge im nahen UV erkennen) und ESR-Spektren (die Fernkopplung mit H-4 im Briickenkopf-Radikal Bicyclo[2.l.l]hex-l-yl betriigt 22.5 G). An den meisten intramolekularen Effekten dieser Art sind Orbitalwechselwirkungen beteiligt ; die Photoefektronenspektroskopie hat sich wie erwartet als aussagekraftige und wertvolle Erganzung der anderen Methoden erwiesen.

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Spectra of p-Benzoquinone, studied with ham/3

Cited by 44 publications

References 48 publications

Ionization energies, electron affinities and excitation energies of some steroid hormones calculated with the semiempirical HAM/3 method

Ionization energies, electron affinities and excitation energies of some steroid hormones calculated with the semiempirical HAM/3 method

An ab initio CI study of the ground and excited states of p-benzoquinone

Proximitätseffekte in der Organischen Chemie — Die photoelektronenspektroskopische Untersuchung nichtbindender und transanularer Wechselwirkungen

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