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Structures And Stabilities Of Praseodymium-Containing Endohedral Metallofullerenes And Their Derivatives

Posted on:2017-02-16Degree:DoctorType:Dissertation
Country:ChinaCandidate:Y L ZhaoFull Text:PDF
GTID:1221330485992634Subject:Inorganic Chemistry
Abstract/Summary:PDF Full Text Request
Several praseodymium-containing endohedral metallofullerenes were successfully prepared using a modified arc-discharge method. After extraction from soot with 1,2,4-trichlorobenzene and multi-stage separation via preparative high performance liquid chromatography, we obtained monometallofullerene derivatives Pr@C72(C6H3Cl2), Pr@C74(C6H3Cl2), and Pr2@C72. The purities of the three isolated products were confirmed by analytical high performance liquid chromatography. The molecular composition of the products were determined by matrix-assisted laser desorption ionization time-of-flight mass spectrometry and laser desorption ionization time-of-flight mass spectrometry. By combined UV-visible-near-infrared absorption spectroscopy and quantum mechanics characterization, the molecular structure of Pr@C72(C6H3Cl2), Pr@C74(C6H3Cl2), and Pr2@C72 and the addition positions of substituent group at carbon cages were verified.Using quantum-mechanics methods, we detailedly discussed the isomeric structures, relative stabilities, thermodynamic distributions of Pr@C72, Pr@C74, and Pr2@C72. Furthermore, the formal charge states of the encapsulated Pr atom in Pr@C72, Pr@C74, and Pr2@C72 were confirmed by a comparasion with the reference molecules. Additionaly, the metal-to-cage electron transfers and metal-cage interactions of Pr@C2(10612)-C72, Pr@C2v(11188)-C72, Pr@D3h(14246)-C74, and Pr@D3h(14246)-C74(C6H3Cl2) were studied detailedly by the fragmental electron density difference method. Using the molecular bandgaps and free radical characteristics, the relative activities and the possibility of experimental separation of the fullerenes, endohedral metallofullerenes, and metallofullerene derivatives were explicated.Based on the computed quantum mechanics data, why the D2(10611)-C72 can be used as the endohedral cage of two Pr atoms were analyzed in detail. In addition, the addition reaction of Pr2@D2(10611)-C72 and Ad N2 was conducted. The molecular composition of adducts were confirmed by matrix-assisted laser desorption ionization time-of-flight mass spectrometry, and the isomeric structures and thermodynamic distribution of monoadduct were further discussed by theoretical chemistry methods.
Keywords/Search Tags:praseodymium-containing endohedral metallofullerenes, C72, C74, absorption spectra, quantum-mechanics computation
PDF Full Text Request
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