14 research outputs found
Etude théorique des complexes mono et dinucléaires du ruthénium à liaisons (sigma)-silane
TOULOUSE3-BU Sciences (315552104) / SudocSudocFranceF
Rationalization of the Solvation Effects on the AtO+ Ground-State Change
International audience211At radionuclide is of considerable interest as a radiotherapeutic agent for targeted alpha therapy in nuclear medicine, but major obstacles remain because the basic chemistry of astatine (At) is not well understood. The AtO+ cationic form might be currently used for 211At-labeling protocols in aqueous solution and has proved to readily react with inorganic/organic ligands. But AtO+ reactivity must be hindered at first glance by spin restriction quantum rules: the ground state of the free cation has a dominant triplet character. Investigating AtO+ clustered with an increasing number of water molecules and using various flavors of relativistic quantum methods, we found that AtO+ adopts in solution a Kramers restricted closed-shell configuration resembling a scalar-relativistic singlet. The ground-state change was traced back to strong interactions, namely, attractive electrostatic interactions and charge transfer, with water molecules of the first solvation shell that lift up the degeneracy of the frontier Ï* molecular orbitals (MOs). This peculiarity brings an alternative explanation to the highly variable reproducibility reported for some astatine reactions: depending on the production protocols (with distillation in gas-phase or âwet chemistryâ extraction), 211At may or may not readily react
RĂ©arrangement thermique de <i>N</i>-acyl-2,2-dimĂ©thylaziridines substituĂ©esâ: Une Ă©tude mĂ©canistique
Rationalization of the Solvation Effects on the AtO<sup>+</sup> Ground-State Change
<sup>211</sup>At radionuclide is
of considerable interest as a
radiotherapeutic agent for targeted alpha therapy in nuclear medicine,
but major obstacles remain because the basic chemistry of astatine
(At) is not well understood. The AtO<sup>+</sup> cationic form might
be currently used for <sup>211</sup>At-labeling protocols in aqueous
solution and has proved to readily react with inorganic/organic ligands.
But AtO<sup>+</sup> reactivity must be hindered at first glance by
spin restriction quantum rules: the ground state of the free cation
has a dominant triplet character. Investigating AtO<sup>+</sup> clustered
with an increasing number of water molecules and using various flavors
of relativistic quantum methods, we found that AtO<sup>+</sup> adopts
in solution a Kramers restricted closed-shell configuration resembling
a scalar-relativistic singlet. The ground-state change was traced
back to strong interactions, namely, attractive electrostatic interactions
and charge transfer, with water molecules of the first solvation shell
that lift up the degeneracy of the frontier Ï* molecular orbitals
(MOs). This peculiarity brings an alternative explanation to the highly
variable reproducibility reported for some astatine reactions: depending
on the production protocols (with distillation in gas-phase or âwet
chemistryâ extraction), <sup>211</sup>At may or may not readily
react
211 At-labeled agents for alpha-immunotherapy: On the in vivo stability of astatine-agent bonds
International audienceThe application of 211 At to targeted cancer therapy is currently hindered by the rapid deastatination that occurs in vivo. As the deastatination mechanism is unknown, we tackled this issue from the viewpoint of the intrinsic properties of At-involving chemical bonds. An apparent correlation has been evidenced between in vivo stability of 211 At-labeled compounds and the AtĂR (R ÂŒ C, B) bond enthalpies obtained from relativistic quantum mechanical calculations. Furthermore, we highlight important differences in the nature of the AtĂC and AtĂB bonds of interest, e.g. the opposite signs of the effective astatine charges, which implies different stabilities with respect to the biological medium. Beyond their practical use for rationalizing the labeling protocols used for 211 At, the proposed computational approach can readily be used to investigate bioactive molecules labeled with other heavy radionuclides