• 제목/요약/키워드: electronic bulletin

검색결과 486건 처리시간 0.02초

Benzoin Condensation Reactions of 5-Membered Heterocyclic Compounds Catalyzed by Thiazolium Salts

  • Chang Kiu Lee;Jin Soon Gong;Sin Kwan Seog;Jong-Gab Jun
    • Bulletin of the Korean Chemical Society
    • /
    • 제14권1호
    • /
    • pp.29-31
    • /
    • 1993
  • Benzoin condensation reactions of furfurals and thiophenecarboxaldehydes in the presence of substituted benzyl and alkyl thiazolium salts were examined in order to improve the yield of the reaction and to examine the effect of the electronic nature of the catalysts. Thiophene derivatives gave thenils as the major products in low yields while furan derivatives gave only furoins in moderate to high yields.

Dichlororhodium(Ⅲ) Complexes of N,N$^\prime$-Dimethylethylenediamine-N,N$^\prime$-diacetic Acid

  • Kim, Chang-Hwan;Jun, Moo-Jin;Jun, Jin-Seung
    • Bulletin of the Korean Chemical Society
    • /
    • 제7권2호
    • /
    • pp.145-147
    • /
    • 1986
  • Dichlororhodium(Ⅲ) complexes of a flexible quadridentate ligand, N,N'-dimethylethylenediamine-N,N'-diacetic acid (dmedda), have been prepared. Both cis-${\alpha}$ and cis-${\beta}$ isomers have been yielded in the $K[Rh(dmedda)Cl_2]$ complexes, which were characterized with elemental analyses, electronic absorption and proton nuclear magnetic resonance spectroscopic data.

Theoretical Analysis of Dipole Moment Derivatives in Fluoromethanes. (II) Difluoromethane

  • Kim, Kwan
    • Bulletin of the Korean Chemical Society
    • /
    • 제8권1호
    • /
    • pp.10-15
    • /
    • 1987
  • The results of an ab initio (6-31G) molecular orbital calculation of the dipole moment derivatives and gas phase IR intensities of difluoromethane are reported. The results are compared with corresponding values obtained from a CNDO calculation. The directions of the dipole derivatives calculated by the two methods agree very well, whereas the intensities differ significantly. The results are also analyzed for the charge-charge flux-overlap electronic contributions to the dipole derivatives.

Theoretical Studies on the Photo-Skinsensitizing Psoralens (I)

  • Ja-Hong Kim;Sang-Chul Shim
    • Bulletin of the Korean Chemical Society
    • /
    • 제1권2호
    • /
    • pp.71-73
    • /
    • 1980
  • The electronic structure of photo-skinsensitizing psoralens has been investigated by the FMO method. On the basis of theoretical calculations, optimum value of indices (Ft=0.33) has been proposed which corresponds to the sum of frontier electron density. The results indicate that this index is closely correlated with photo-skinsensitizing carcinogenic activity. The formations of molecular complexes between DNA and photo-skinsensitizing carcinogens is discussed in terms of charge transfer interactions.

Analysis of Rotationally Cooled Vibronic Emission Spectra ($1^2A_2→1^2B_2$) of m-Xylyl Radical

  • 최익순;이상국
    • Bulletin of the Korean Chemical Society
    • /
    • 제17권8호
    • /
    • pp.749-753
    • /
    • 1996
  • The rotationally cooled but electronically excited m-xylyl radical has been generated in a jet from the gas mixture of precursor m-xylene and buffer gas He by a technique of corona excited supersonic expansion. The visible vibronic emission spectra in the transition of 12A2→12B2 of m-xylyl radical in the gas phase have been recorded using a Fourier transform spectrometer. The spectra have been analyzed for the assignments of the vibrational frequencies in the electronic ground state with combination of the torsional frequencies reported previously.

Synthesis and Reaction of Novel Tricyclic Dynemicin A Models with Methyl Group

  • 류훈한;홍용표
    • Bulletin of the Korean Chemical Society
    • /
    • 제17권9호
    • /
    • pp.831-835
    • /
    • 1996
  • New dynemicin A mimics with methyl group 2a and 2b were synthesized, and acid-induced hydrolyzed to see an electronic effect of substituent for epoxide opening. The model 2a with methyl group at C3 position was more rapidly transformed to diol 16a than 2b with methyl group at C2. This result suggests that any substituent at C3 position plays more important role than any substituent at C2 position in the dynemicin A mimic activation.

Rotational Contour Analysis of the Vibronic Bands in the High Resolution Emission Spectra of the Benzyl Radical

  • 최익순;한명선;이상국
    • Bulletin of the Korean Chemical Society
    • /
    • 제17권10호
    • /
    • pp.882-885
    • /
    • 1996
  • The 6a10 and 6b10 vibronic bands in the 12A2-12B2 electronic transition of the emission spectra of the benzyl radical obtained using a high resolution Fourier transform spectrometer are rotationally analyzed. The observed rotational contours were fitted by computer simulated rotational contours, providing determination of the variations, ΔA, ΔB, and ΔC of the rotational constants accompanying the vibronic transitions corresponding to each band. The molecular rotational constants A, B, and C are revised for the upper state and for the two lower states, respectively.