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THEORETICAL INVESTIGATION OF EXCIMER AND EXCIPLEX STATES OF URACIL AND HALOGEN DERIVATIVES: EFFECT OF NONPARALLELISM OF BASES
Author(s) -
Pechenaya Vera I.,
Danilov Victor I.,
Slyusarchuk Oleg N.,
Alderfer James L.
Publication year - 1995
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1995.tb02341.x
Subject(s) - excimer , excited state , chemistry , singlet state , photochemistry , halogen , ground state , uracil , computational chemistry , atomic physics , fluorescence , physics , optics , organic chemistry , alkyl , dna , biochemistry
Theoretical modeling of initial steps of the photodimerization mechanism of uracil, 5‐methyl‐and 5‐halogen derivatives was performed. The interaction energy of bases in stacked dimers in the ground and lowest excited states was calculated as a function of the distance between the base planes and of the rotation angles within the perturbation theory for the extended Hückel treatment. The existence of excimer and exciplex region on the potential surface of the excited state was revealed. The excimer (exciplex) geometry has the planes nonparallel with more close contact of the C5‐C6 bonds as compared to the ground state of dimers. The results provide new information useful for understanding the photodimerization mechanism of bases and testifies that the singlet excimer state can be a precursor of the photodimerization reaction.