The low temperature radiolysis of cis-syn-cis- dicyclohexano-18-crown-6 complexes with alkaline earth metal nitrates: An evidence for energy transfer to the macrocyclic ligand

Zakurdaeva, Olga A.; Нестеров, С. В.; Shmakova, N. A.; Соколова, Н. А.; Feldman, Vladimir I.

doi:10.1016/j.radphyschem.2015.07.004

Cited by 5 publications

(2 citation statements)

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“…Taking into account reactions and –, the radiolysis of 18C6·Sr(XF n ) 2 complexes should be a rather complicated process with a significant contribution of the intermediates resulted from BF 4 – and PF 6 – anions to the total yield of the stabilized radical species. Similar situation has been found previously for the radiolysis of dicyclohexano-18-crown-6 (DCH18C6) complexes with alkaline earth metal nitrates . Despite the significant electron fractions of macrocycle in those complexes (e.g., ε DCH18C6 = 0.67 in DCH18C6·Sr(NO 3 ) 2 complex), NO 3 2– dianions were revealed to be predominant radical species stabilized under irradiation in the dose range below 40 kGy.…”

Section: Resultssupporting

confidence: 82%

“…Similar situation has been found previously for the radiolysis of dicyclohexano-18-crown-6 (DCH18C6) complexes with alkaline earth metal nitrates. 34 Despite the significant electron fractions of macrocycle in those complexes (e.g., ε DCH18C6 = 0.67 in DCH18C6•Sr(NO 3 ) 2 complex), NO 3 2− dianions were revealed to be predominant radical species stabilized under irradiation in the dose range below 40 kGy. The observed effect has been attributed to the absorbed energy transfer from the macrocycle to nitrate-anions at the early stages of radiolysis.…”

Section: ■ Experimental Sectionmentioning

confidence: 93%

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Evidence for Indirect Action of Ionizing Radiation in 18-Crown-6 Complexes with Halogenous Salts of Strontium: Simulation of Radiation-Induced Transformations in Ionic Liquid/Crown Ether Compositions

et al. 2018

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Ionic liquid/crown ether compositions are an attractive alternative to traditional extractants in the processes for spent nuclear fuel and liquid radioactive wastes reprocessing. These compositions are exposed to ionizing radiation, and their radiation stability, especially in the presence of metal salts, is a crucial issue. In the present study, the macrocyclic 18C6·Sr(BF) and 18C6·Sr(PF) complexes simulating the components of metal loaded ionic liquid/crown ether extractants were synthesized and their structures were characterized by FTIR spectroscopy and single-crystal X-ray diffraction analysis. Inclusion of Sr cation into the 18C6 cavity resulted in more symmetric D conformations of the macrocycle. The structural transformations of the crown ether were accompanied by an elongation of polyether C-O bonds that could increase the possibility of radiolytic cleavage of the macrocycle. However, EPR study of the synthesized compounds subjected to X-ray irradiation revealed predominant formation of macrocyclic -CH-ĊH-O- radicals. This result demonstrated an evidence for indirect action of ionizing radiation on individual components of the complexes and was reasonably described by a positive "hole" transfer from primary macrocyclic radical cation to fluorous anion at the primary stages of radiolysis and a subsequent interaction of fluorine atom with 18C6 macrocycle in secondary radical reactions. The observed effects may be partially responsible for enhanced sensitivity of the ionic liquid/crown ether extractants to ionizing radiation due to chemical blocking of the crown ether with radiolytic HF, radiation-chemical degradation of the 18C6, and precipitation of a low-soluble SrF.

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Section: Resultssupporting

confidence: 82%

Section: ■ Experimental Sectionmentioning

confidence: 93%