Low-energy electron-induced decomposition of 5-trifluoromethanesulfonyl-uracil: A potential radiosensitizer

Abstract

5-trifluoromethanesulfonyl-uracil (OTfU), a recently proposed radiosensitizer, is decomposed in the gas-phase by attachment of low-energy electrons. OTfU is a derivative of uracil with a triflate (OTf) group at the C 5-position, which substantially increases its ability to undergo effective electron-induced dissociation. We report a rich assortment of fragments formed upon dissociative electron attachment (DEA), mostly by simple bond cleavages (e.g., dehydrogenation or formation of OTf −). The most favorable DEA channel corresponds to the formation of the triflate anion alongside with the reactive uracil-5-yl radical through the cleavage of the O-C 5 bond, particularly at about 0 eV. Unlike for halouracils, the parent anion was not detected in our experiments. The experimental findings are accounted by a comprehensive theoretical study carried out at the M06-2X/aug-cc-pVTZ level. The latter comprises the thermodynamic thresholds for the formation of the observed anions calculated under the experimental conditions (383.15 K and 3 × 10 −11 atm). The energy-resolved ion yield of the dehydrogenated parent anion, (OTfU-H) − , is discussed in terms of vibrational Feshbach resonances arising from the coupling between the dipole bound state and vibrational levels of the transient negative ion. We also report the mass spectrum of the cations obtained through ionization of OTfU by electrons with a kinetic energy of 70 eV. The current study endorses OTfU as a potential radiosensitizer agent with possible applications in radio-chemotherapy.

Uracil-5-yl O-Sulfamate: An Illusive Radiosensitizer. Pitfalls in Modeling the Radiosensitizing Derivatives of Nucleobases

“…In these calculations, the M06-2X 38 functional combined with the aug-cc-pVTZ 39 , 40 basis set has been used. This methodology was shown to be successful for this kind of calculation, 25 giving results comparable to those obtained with the G4 scheme. 41 …”

“…The decomposition of a potential radiosensitizer by LEEs can be studied in the gas phase using a crossed electron–molecular beam technique, which utilizes mass spectrometry for the analysis of fragment anions formed as a result of DEA. 25 , 26 …”

Studi Termodinamika Transpor Ionik Natrium Klorida Dalam Air dan Campuran Tertentu

“…Oleh karena itu, energi ionisas i (82)(83)(84)(85)(86) pertamanya cukup rendah yaitu pada 495,8 kj/mol. Sebaliknya, energi (87)(88)(89)(90)(91) ionisasi (92)(93)(94)(95)(96)(97)(98)(99)(100)(101) kedua sangat tinggi (4562 kj/mol), karna elektron pada kulit L lebih dekat ke ini atom. Akibatnya, natrium membentuk senyawa ionik (48) dengan bermuatan Na + .…”

Studi Termodinamika Transpor Ionik Natrium Klorida Dalam Air dan Campuran Tertentu

“…Oleh karena itu, energi ionisas i (82)(83)(84)(85)(86) pertamanya cukup rendah yaitu pada 495,8 kj/mol. Sebaliknya, energi (87)(88)(89)(90)(91) ionisasi (92)(93)(94)(95)(96)(97)(98)(99)(100)(101) kedua sangat tinggi (4562 kj/mol), karna elektron pada kulit L lebih dekat ke ini atom. Akibatnya, natrium membentuk senyawa ionik (48) dengan bermuatan Na + .…”