Cycloparaphenylenes (CPPs) represent the unit-cycles of conductive armchair carbon nanotubes (CNTs). In addition to their utility for the bottom-up synthesis of CNTs with discrete diameter and chirality, these strained hydrocarbon macrocycles have attractive properties of their own for material science and organic electronics. Herein I report research focused on advancing the synthetic technology behind CPPs, culminating in the synthesis of [5]CPP, the smallest and most highly-strained member of the CPP series to date, as well as the derivitization of the CPP platform to include chiral nanohoops with a spiral carbon backbone and photoswitchable nanohoops based on azobenzene incorporation into the CPP architecture. The synthesis and characterization of [5]CPP, 1,5-naphthyl[6]CPP, azo[11]CPP, and azo[9]CPP are reported along with advanced intermediates towards rotationally restricted 2,6-naphthyl[6]CPP and preliminary photoisomerization results for azo[11]CPP and azo[9]CPP. This dissertation contains both previously published and unpublished co-authored material.

For the past three decades, newly discovered carbon nanostructures such as fullerenes, graphene and carbon nanotubes (CNTs) have revolutionized the field of nanoscience, introducing many practical and potential applications pertaining to their exceptional structural, mechanical, thermal, and optoelectronic properties. Raman spectroscopy has been an instrumental technique for characterizing these materials due to its non-destructive nature and high sensitivity to the material responses. While Raman spectroscopy is broadly used for identifying specific material types and quality, it has also been increasingly useful as a tool for probing the electronic and excitonic properties, as well as their interplay with the vibrational properties in the aforementioned carbon nanomaterials. In this dissertation, we present our Raman-related research on carbon nanotubes and a new member of the nano-carbon family - carbon nanohoops (cycloparaphenylenes, or CPPs). We discuss our new findings on the resonance Raman spectroscopy (RRS) of various semiconducting CNTs, with the focus on the Raman excitation profiles (REPs) for the G-band. The asymmetric lineshapes observed in the G-band REPs for the second excitonic (E22) transition of these CNTs contradict a long-held approximation, the Franck-Condon principle, for the vibronic properties of the carbon nanotubes. In addition, the G-band REPs from the closely spaced E33 and E44 transitions are investigated, and we demonstrate that these excitonic levels exhibit significant quantum interference effects between each other. We also present the first comprehensive study of Raman spectroscopy of CPPs. Analogously to CNTs, we show that Raman spectroscopy can be used to identify CPPs of different sizes. A plethora of Raman modes are observed in these spectra, including modes that are comparable to those of CNTs, such as the G-band, as well as Raman peaks that are unique for CPPs. Calculated Raman spectra using density functional theory (DFT) are compared with the experimental results for the assignment of different modes. Furthermore, we refine our knowledge of the CPP Raman modes by concentrating on the even-numbered CPPs. By taking advantage of the symmetry arguments in the even [n]CPPs, we are able to utilize group theory and accurately identify the size dependences of different Raman-active modes.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第22661号 / 工博第4745号 / 新制||工||1741(附属図書館) / 京都大学大学院工学研究科高分子化学専攻 / (主査)教授 山子 茂, 教授 田中 一生, 教授 村田 靖次郎 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第18298号 / 工博第3890号 / 新制||工||1597(附属図書館) / 31156 / 京都大学大学院工学研究科高分子化学専攻 / (主査)教授 山子 茂, 教授 中條 善樹, 教授 村田 靖次郎 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM