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Ultraviolet photoelectron studies of 5‐halouracils
Author(s) -
Padva A.,
Peng S.,
Lin J.,
Shahbaz M.,
Lebreton P. R.
Publication year - 1978
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.1978.360170611
Subject(s) - chemistry , lone pair , electronegativity , valence (chemistry) , atomic orbital , halogen , ionization energy , ultraviolet photoelectron spectroscopy , x ray photoelectron spectroscopy , molecular orbital , atom (system on chip) , ionization , atomic physics , crystallography , computational chemistry , electronic structure , molecule , ion , nuclear magnetic resonance , physics , organic chemistry , alkyl , quantum mechanics , computer science , embedded system , electron
Ultravoilet photoelectron spectroscopy has been employed to exmamin the valence electronic structure of 5‐fluorouracil, 5‐chlorouracil, 5‐bromouracil, and 5‐iodouracil. Photoelectron bands associted with the three highest π orbitals and the two oxygen atom lone‐pair orbitals were assigned by a comparison to similar bands observed in the photoelectron spectrum of uraciul. Bands arising from the halogen atom lone‐pair orbitals were assigned by comparing the present results with photoelectron spectra measured for halobenzenes, and by considering the linear dependence of halogen atom lone‐pair ionization potentials upon halogen atom electronegativities. The present spectroscopic results have been compared with results from studies of association constants of 5‐halouracil–adenine complexes. This examination in dicates that the complex association constants incresase as the ionization potentials of the highest occupied π orbital and the halogen atom lone‐pair orbitals of th halouracils decrease.