Structural design, X -ray characterization, and photochemical investigation of organic molecules in highly ordered media: Organic molecular rotors and reactive intermediates in crystals

Organic crystals are viewed by many as long rows of molecules trapped in a rigid geometric arrangement, lifeless compared to the molecular freedom that may be possible in solution. The idea that atoms and molecules move in crystals has long been viewed as outrageous until the discovery of X-ray diffraction, which provides an average unit cell or the time and space average of the distribution of atoms over the entire crystal. Crystalline organic molecules are not stationary; they move appreciably about their mean positions in the crystal lattice. The idea of molecular motions in crystals is the main theme in this dissertation, which will focus on molecules in crystals and their fate upon external stimuli (i.e. photochemical, electrical, or magnetic).;Chapter 1 outlines the introduction for the three main projects in this dissertation: (1) The current developments in the design and synthesis of organic molecules with rotary motion serve as the justification for the design, synthesis, and X-ray characterizations of molecular "compasses" and "gyroscopes" (Chapter 2). (2) The second part of the introduction focuses on the reported methods for the preparation of aceanthrylenes (Chapter 3) and other higher order cyclopentafused polycyclic aromatic hydrocarbons (CP-PAHs) (Chapter 4). (3) The last section of the introduction will focus on the photochemistry of reactive intermediates such as biradicals, carbenes, and ionic intermediates (Chapter 5) in solution and organic crystals.;Chapter 2 describes the current developments within the past three years of intense research on the design, synthesis, and X-ray characterizations of molecular "compasses" and "gyroscopes" with polar phenylene groups that can be influenced by external stimuli (i.e. electric or magnetic fields).;Chapter 3 details the palladium(0)-catalyzed methodology for the synthesis of aceanthrylenes. Chapter 4 presents the synthesis, X-ray characterization, and photophysical measurements of cyclopent[hi]aceanthrylene, a nonalternant cyclopentafused polycyclic aromatic hydrocarbon, by a similar Pd(0)-catalyzed methodology described in Chapter 3.;Chapter 5 reports the synthesis, photochemical generation, and product analysis of ionic intermediates (oxonium ylides) in solution, low-temperature organic glasses, and crystals. The first spectroscopic detection of oxonium ylides from a triplet carbene is presented.