This thesis describes the synthesis of polyyne rotaxanes and an investigation of their excited state photophysical properties. The threading of dumbbell-shaped carbon chains with macrocyclic components is a way to mechanically insulate and control the environment around the carbon chains. The resulting polyyne rotaxanes can serve as model compounds for insulated carbyne. Different strategies have been tested for the synthesis of polyyne rotaxanes with different topologies and structures. Study of rotaxanes in the excited states reveals strong electronic communication between an acetylenic thread and a macrocycle. Chapter 1 summarizes the field of acetylene scaffolding, introducing some recent achievements in acetylene chemistry. General synthetic methods for polyynes are discussed, and an introduction to active metal template synthesis of rotaxanes is given. Chapter 2 describes the synthesis of a family of polyyne rotaxanes with different axle lengths and macrocycles, prepared by homocoupling of terminal alkynes. Synthesis of hexayne rotaxane with functional pyridine end-group is presented and a number of crystal structures of polyyne rotaxanes are analyzed. Chapter 3 demonstrates the use of acetylene cross-coupling in the synthesis of rotaxanes. Synthesis of rotaxanes with different topological structure is provided. Chapter 4 details the excited state properties of polyynes studied by time -resolved spectroscopy. The complexes of rhenium(I) carbonyls with rotaxanes is presented and the excited state energy transfer in rotaxanes is studied. Chapter 5 explores new synthetic strategies for polyyne rotaxanes, using "masked" precursors. It also highlights the potential of carbenoid rearrangement of alkyliden es for the construction of linear and cyclic architectures. Chapter 6 is the summary of the project and general discussion of future directions. There are two appendices in the end of thesis: Appendix A covers the photophysics of rhenium tricarbonyl complex of the hexayne rotaxane with a small macrocycle and Appendix B reports work towards the synthesis of rotaxanes with platinum(II)-alkyne complexes.

Nous devions fournir des résultats théoriques aux expérimentateurs du LISA (Paris XII) pour les aider dans les identications spectroscopiques de polyynes de l'atmosphère de Titan. Puis nous nous sommes intéressés à des problèmes plus théoriques concernant la nature des liaisons chimiques (alternance simple/triple liaison). Nous avons ensuite étudié le produit de cyclisation de C4H2, ainsi que les réactions de formation à partir de molécules de l'atmosphère de Titan et des réactions d'isomérisation. Puis, nous avons essayé d'étendre notre étude au terme suivant, C6H2. Les méthodes classiques ne nous permettaient pas d'identier clairement l'état fondamental, donc nous avons utilisé des méthodes QMC. Nous avonségalement entrepris le développement d'une méthode permettant de décrire l'appariement électronique (EPLF), et d'une méthode de localisation basée sur les distributions de probabilités. Ces deux méthodes ont été testées puis appliquées à la forme cyclique de C6H2.

Polyyne molecules were produced as a result of the femtosecond laser irradiation of liquid acetone (CH3)2CO and alkane molecules hexane C6H14 and octane C8H18 using 800 nm, 100 fs duration pulses. These polyynes have been detected as a Raman band in irradiated liquid from 1800 to 2200 cm−1. Polyyne molecules generally detected as a Raman band in SERS experiment are C8H2, C10H2, C12H2 and C14H2. Two well established experimental techniques, time of flight mass spectrometry and surface enhanced Raman spectrometry were used to identify positively polyyne formation as a result of femtosecond laser irradiation of acetone and alkane liquids. Small polyynes C2H2, C4H2, and C6H2 were positively detected in the time of flight mass spectrometer TFMS, while longer polyynes from C6H2, C8H2, C10H2, C12H2 and C14H2 were detected by surface enhanced Raman spectroscopy SERS. Intensity capping occurs in a liquid due to filamentation, and the resulting intensity in a liquid is s 1013 W/cm2 during irradiation. This results in main process of ionization in the larger part of the laser focus as multiphoton ionization MPI. Focal volume increase in a liquid provides a larger volume where ions C+, C+2 and C2+are produced to initiate chemical reactions outside the laser focus. The current work established positively, that the longer polyyne formation does not occur by dehydrogenation of alkane molecules by only breaking the C-H bonds as was previously anticipated. It is proposed in this work that lengthening of polyyne chains occurs due to addition reaction of species of C+, C+2 and C2+ to double bonded species themselves produced as a result of the breaking down of the parent molecules in the laser focus. The carbon addition reactions occur outside the laser focus due to the close proximity of molecules in the liquid phase.

Polyyne molecules were produced as a result of the femtosecond laser irradiation of liquid acetone (CH3)2CO and alkane molecules hexane C6H14 and octane C8H18 using 800 nm, 100 fs duration pulses. These polyynes have been detected as a Raman band in irradiated liquid from 1800 to 2200 cm−1. Polyyne molecules generally detected as a Raman band in SERS experiment are C8H2, C10H2, C12H2 and C14H2. Two well established experimental techniques, time of flight mass spectrometry and surface enhanced Raman spectrometry were used to identify positively polyyne formation as a result of femtosecond laser irradiation of acetone and alkane liquids. Small polyynes C2H2, C4H2, and C6H2 were positively detected in the time of flight mass spectrometer TFMS, while longer polyynes from C6H2, C8H2, C10H2, C12H2 and C14H2 were detected by surface enhanced Raman spectroscopy SERS. Intensity capping occurs in a liquid due to filamentation, and the resulting intensity in a liquid is s 1013 W/cm2 during irradiation. This results in main process of ionization in the larger part of the laser focus as multiphoton ionization MPI. Focal volume increase in a liquid provides a larger volume where ions C+, C+2 and C2+are produced to initiate chemical reactions outside the laser focus. The current work established positively, that the longer polyyne formation does not occur by dehydrogenation of alkane molecules by only breaking the C-H bonds as was previously anticipated. It is proposed in this work that lengthening of polyyne chains occurs due to addition reaction of species of C+, C+2 and C2+ to double bonded species themselves produced as a result of the breaking down of the parent molecules in the laser focus. The carbon addition reactions occur outside the laser focus due to the close proximity of molecules in the liquid phase.