202865-84-7

Rhomboidal macrocyclic subunits of graphdiyne-like nanoribbon (GDNR) bearing both alkyne and diyne units, allowing for multichannel π-conjugation, were synthesized using an oxidative Glaser-type ring closing reaction. These subunits, called the "meshes" of the nanoribbon, possess phenyl groups with decyloxy solubilizing chains on each corner. The yields of the ring closing reaction highly depend on the metal (Cu or Pd) catalyst used for the macrocyclization step. Increasing the width of the meshes from one macrocycle to two fused macrocycles resulted in a decrease of the bandgap by 0.23 eV as shown by optical spectroscopy. The optimized geometries of the meshes alongside their HOMO and LUMO orbitals were calculated using DFT calculations at the B3LYP/6-31+G? level of theory. The results showed a nearly planar conformation for both meshes with HOMO and LUMO orbitals entirely delocalized over the molecules.

The COGEF technique (COnstrained Geometries simulating External Force) was used to investigate the effects of macroscopic forces on cyclic enediynes, which can undergo Bergman Cyclization (BC). Because the forces needed to activate BC were found to be less than the forces needed for chain scission in?polymer backbones, the calculations suggest that enediynes are potentially useful mechanophores. Three enediynes studied computationally were synthesized. The thermal BC reactions for these compounds were studied by DSC and found to be consistent with the predicted thermal sensitivity based on known substituent effects. However, upon incorporation of the enediynes into a polymer matrix as crosslinks, no definitive mechanical activation was observed, and conclusions about the stress-sensitivity of enediynes were unable to be drawn. Model studies suggest that insufficient force was applied to the crosslinks for mechanical activation to be observable by DSC.

The oxidative photocyclization reactions of olefins that contain 1H-phosphindole or dibenzophosphole substituents have been applied to the synthesis of P/N-bi-heterosubstituted dimeric helicenes, as well as of new [6]- and [8]phosphahelicenes. In these photocyclization processes, the configuration of the stereogenic phosphorus center dictates the sense of helical chirality. Thus, by starting from enantiomerically pure P-menthylphosphole-oxide units, this method affords enantiopure helical compounds. The helical phosphine oxides were characterized by X-ray diffraction. After reduction of the phosphine-oxides, the corresponding helical phosphines have been used as ligands in transition-metal complexes. The X-ray crystal structure of a gold chloride complex of a [6]helicene is reported. From phosphindoles to helicenes: Olefins with 1H-phosphindole or dibenzophosphole substituents are suitable precursors for P/N-bi-heterosubstituted dimeric helicenes, as well as for new [6]- and [8]phosphahelicenes. The highly diastereoselective oxidative photocyclization of these olefins opens up access to enantiomerically pure helical derivatives. The structural characterization of a helical phosphine oxide, sulfide, and gold complex is reported. Copyright