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dc.contributor.authorTong, Liu
dc.date.accessioned2020-12-16T15:59:35Z
dc.date.available2020-12-16T15:59:35Z
dc.date.issued2020-06-04
dc.identifier.citationTong, Liu. 2020. Structural Studies of Fullerene Derivatives [60]PCBM and All 19 Isomers of Bis[60]PCBM. Queen Mary University of London.en_US
dc.identifier.urihttps://qmro.qmul.ac.uk/xmlui/handle/123456789/69348
dc.descriptionPhD Thesisen_US
dc.description.abstractBis[60]PCBM is a molecule with two identical asymmetric addends bridging double bonds on the fullerene C60, giving rise to 58 nominal structural isomers. However, symmetry, chirality and steric hindrance reasons leave 19 possible isomers. Considering bond-type involved gives one C1 and one C2 isomers for the cis-3, trans-3 and trans-2 bonds; one C1 and two Cs isomers for the cis-2 and trans-4 bonds; two C1 isomers for the e bonds; one isomer of C2v and C2h symmetry for the trans-1 bonds. The mixture of bis[60]PCBM was separated into individual components through high-pressure liquid chromatography. An initial single-pass HPLC treatment separated the mixture into 7 resolved fractions, of which three comprised a single isomer. A multi-stage peak-recycling HPLC process which involved several complimentary columns was devised to separate all isomers. The mixture was purified into 19 isomers (same number as possible isomers). Characterisation by UV-Vis absorption spectroscopy showed that some were similar, while others were different. This placed the isomers into 7 groups, two of which contained two isomers and the other five contained three isomers – the same in number and size for each bond-type as identified from the molecular structures, suggesting that there is a link between the shape of the spectra and the bond type of the isomer. A similar link was reported in the literature for symmetric fullerene bis-adducts, allowing assignment of the 7 isomer groups to their respective bond types. 13C NMR spectroscopy allowed for the C2v, C2h, and the unique (C1) isomers in each of the five three-membered bond-type groups to be associated with their corresponding ACKNOWLEDGMENTS 6 HPLC fraction. This left 6 groups, each two unidentified isomers with both being either C1, C2, or Cs, which cannot be distinguished by 13C NMR spectra. HPLC retention times for members of the three-membered groups had the order of symmetric-asymmetric-symmetric. Hence, the two same-symmetry isomers in each group had widely spaced retention times. As HPLC columns separate based on molecular polarity. By arranging the same-symmetry isomers in order of polarity inversely orders then in HPLC retention time, which allowed for their identification. By these analyses, every one of the 19 purified HPLC fractions was associated with its corresponding structural isomer. Structural identification via 13C NMR spectroscopy was aided by benchmarking several DFT methods against the spectrum of [60]PCBM. The B97X method performed particularly well, and Dunning-type, outperformed Pople-type, basis sets. Agreement between experiment and simulation allowed all resonances to be assigned to their corresponding carbon atoms with high confidence.en_US
dc.language.isoenen_US
dc.publisherQueen Mary University of Londonen_US
dc.titleStructural Studies of Fullerene Derivatives [60]PCBM and All 19 Isomers of Bis[60]PCBMen_US
dc.typeThesisen_US
rioxxterms.funderDefault funderen_US
rioxxterms.identifier.projectDefault projecten_US


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