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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Investigation of higher fullerenes

Chang, Kai-Chin 21 February 2013 (has links)
Trifluoromethylierung von Mischungen hoeherer Fullerene mit CF3I wurde in Ampullen bei 400-420 Grad Celsius und 500-600 Grad Celsius durchgefuehrt. Die Produktmischungen wurden mittels mehrstufiger HPLC getrennt. In mehreren Versuchen konnten aus den isolierten HPLC-Fraktionen Kristalle fuer die Roentgenstrukturanalyse gewonnen werden. Die folgenden Strukturen der CF3-Derivate der Fullerene C84, C86 und C88 wurden bestimmt: 1 Isomer von C84(4)(CF3)12, C84(11)(CF3)10, C84(11)(CF3)12, C84(11)(CF3)16, C84(16)(CF3)8, C84(16)(CF3)14, C84(18)(CF3)10, C84(18)(CF3)12, C84(22)(CF3)20, C84(23)(CF3)8, C84(22)(CF3)10, C84(22)(CF3)12, C84(22)(CF3)18, C86(17)(CF3)10, C86(17)(CF3)16, C88(33)(CF3)16, C88(33)(CF3)18 und C88(33)(CF3)20. 2 Isomere von C84(22)(CF3)12, C84(22)(CF3)14 und C84(23)(CF3)14. 3 Isomere von C84(11)(CF3)14. 4 Isomere von C84(22)(CF3)16. Die Additionsmuster der Strukturen wurden diskutiert. Die experimentell nachgewiesenen Strukturen wurden mit berechneten Modellstrukturen verglichen. Dabei wurde auch die Stabilitaet der experimentellen Strukturen vorausgesagt. Zusaetzlich wurden die moeglichen Reaktionspfade fuer die Bildung hoeherer Derivate ausgehend von niedrigen Derivaten diskutiert. Sie zeigen, dass die Regioselektivitaet der Addition vom Kaefigisomer abhaengig ist. Die Reaktionspfade von vier Fullerenkaefigen werden in dieser Arbeit vorgestellt. C84(11)(CF3)10 --> C84(11)(CF3)16 C84(22)(CF3)2 --> C84(22)(CF3)20 C84(23)(CF3)10 --> C84(23)(CF3)18 C86(17)(CF3)10 --> C86(17)(CF3)16 / Trifluoromethylation of higher fullerene mixtures with CF3I was performed in ampoules at 400 to 420 degree Celsius and 500 to 600 degree Celsius. The obtained product mixtures were separated by multistep HPLC. Subsequent crystal growth and X-ray diffraction measurements allowed for structural characterization of the CF3 derivatives of fullerenes C84, C86 and C88 listed as the following. 1 isomer of C84(4)(CF3)12, C84(11)(CF3)10, C84(11)(CF3)12, C84(11)(CF3)16, C84(16)(CF3)8, C84(16)(CF3)14, C84(18)(CF3)10, C84(18)(CF3)12, C84(22)(CF3)20, C84(23)(CF3)8, C84(22)(CF3)10, C84(22)(CF3)12, C84(22)(CF3)18, C86(17)(CF3)10, C86(17)(CF3)16, C88(33)(CF3)16, C88(33)(CF3)18 and C88(33)(CF3)20. 2 isomers of C84(22)(CF3)12, C84(22)(CF3)14 and C84(23)(CF3)14. 3 isomers of C84(11)(CF3)14. 4 isomers of C84(22)(CF3)16. The molecular structures of isolated isomers were discussed in terms of their addition patterns and relative formation energies. DFT calculations were used to predict stable molecular structures of the CF3 derivatives. Calculated model structures have been compared with the experimental ones. In addition, the reaction pathways from the lower derivatives to higher ones of selected compounds were predicted. The pathways indicate the regioselectivity of additions depending on the fullerene cage isomer. Reaction pathways are presented for four fullerene cages in this work. C84(11)(CF3)10 --> C84(11)(CF3)16 C84(22)(CF3)2 --> C84(22)(CF3)20 C84(23)(CF3)10 --> C84(23)(CF3)18 C86(17)(CF3)10 --> C86(17)(CF3)16

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