Interactions of α-, β- and γ-cyclodextrin with bicyclo[2.2.2]octane-1,4-derivatives in aqueous solution and in the gas phase A microcalorimetric and molecular modelling study

1998 ◽  
Vol 94 (12) ◽  
pp. 1737-1741 ◽  
Author(s):  
Magnus Stödeman ◽  
Ulf Berg ◽  
Anette Svensson
2005 ◽  
Vol 70 (11) ◽  
pp. 1769-1786 ◽  
Author(s):  
Luc A. Vannier ◽  
Chunxiang Yao ◽  
František Tureček

A computational study at correlated levels of theory is reported to address the structures and energetics of transient radicals produced by hydrogen atom abstraction from C-1, C-2, C-3, C-4, C-5, O-1, O-3, and O-5 positions in 2-deoxyribofuranose in the gas phase and in aqueous solution. In general, the carbon-centered radicals are found to be thermodynamically and kinetically more stable than the oxygen-centered ones. The most stable gas-phase radical, 2-deoxyribofuranos-5-yl (5), is produced by H-atom abstraction from C-5 and stabilized by an intramolecular hydrogen bond between the O-5 hydroxy group and O-1. The order of radical stabilities is altered in aqueous solution due to different solvation free energies. These prefer conformers that lack intramolecular hydrogen bonds and expose O-H bonds to the solvent. Carbon-centered deoxyribose radicals can undergo competitive dissociations by loss of H atoms, OH radical, or by ring cleavages that all require threshold dissociation or transition state energies >100 kJ mol-1. This points to largely non-specific dissociations of 2-deoxyribose radicals when produced by exothermic hydrogen atom abstraction from the saccharide molecule. Oxygen-centered 2-deoxyribose radicals show only marginal thermodynamic and kinetic stability and are expected to readily fragment upon formation.


2019 ◽  
Vol 34 (1) ◽  
pp. 1247-1258 ◽  
Author(s):  
Asmaa F. Kassem ◽  
Gaber O. Moustafa ◽  
Eman S. Nossier ◽  
Hemat S. Khalaf ◽  
Marwa M. Mounier ◽  
...  

Author(s):  
Branislav Milovanović ◽  
Jurica Novak ◽  
Mihajlo Etinski ◽  
Wolfgang Domcke ◽  
Nadja Doslic

Despite many studies, the mechanisms of nonradiative relaxation of uracil in the gas phase and in aqueous solution are still not fully resolved. Here we combine theoretical UV absorption spectroscopy...


2014 ◽  
Vol 15 (5) ◽  
pp. 7651-7666 ◽  
Author(s):  
Ivanka Tsakovska ◽  
Merilin Al Sharif ◽  
Petko Alov ◽  
Antonia Diukendjieva ◽  
Elena Fioravanzo ◽  
...  

2003 ◽  
Vol 101 (13) ◽  
pp. 1945-1953 ◽  
Author(s):  
FRANCESCO AQUILANTE ◽  
MAURIZIO COSSI ◽  
ORLANDO CRESCENZI ◽  
GIOVANNI SCALMANI ◽  
VINCENZO BARONE

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