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The electronic structures and spectra of proflavine, acridine orange, and their DNA complexes
Author(s) -
Ito Hirotoshi,
I'Haya Y. J.
Publication year - 1968
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.560020102
Subject(s) - proflavine , acridine orange , acridine , chemistry , stacking , crystallography , molecule , chromophore , intercalation (chemistry) , intermolecular force , dipole , exciton , photochemistry , computational chemistry , dna , physics , inorganic chemistry , apoptosis , biochemistry , organic chemistry , quantum mechanics
The electronic structure of the proflavine cation is studied by the SCF – ASMO – CI method using the Pariser–Parr–Pople approximations. It is shown that the band at 445 mμ may be assigned to the 1 A 1 → 1 B 1 , transition polarized along the long axis of the molecule. The bands in the neighbourhood of 260 mμ, which are composed of three absorption bands, are tentatively assigned to the 1 A 1 → 1 B 1 , 1 A 1 → 1 B 1 , and 1 A 1 → 1 A 1 transitions, respectively, in order of decreasing wavelength. The spectrum of the acridine orange cation may be understood to have the same assignment as that of the proflavine cation. The acridine dye cations are well known for their dimerization with concentration. The intermolecular distances in these dimers are estimated from the band shifts due to the formation of dimers, using the exciton theory. The main contribution to the molecular interaction is shown to be the electrostatic dipole–dipole interaction. Since the first excitation band of the dye molecule which exhibits a remarkable change due to the formation of the DNA–acridine dye complex, is suggested to be polarized along the long axis, preference of the outside stacking or the intercalation model is qualitatively discussed from the spectral shift of the acridine dye bound to the DNA, assuming simple models.