| Polydiacetylenes (PDAs) form one unique class of conjugated polymers which combine highly ordered and conjugated backbones with side chains bearing tunable functionalities. They exhibit interesting optical and electronic properties and find broad applications including photoelectrochemical cells, organic light-emitting diodes, chemical sensors and other areas. Preparation of PDAs requires appropriate packing of the monomers in order to induce a 1,4-topochemical polymerization.; In this project, we have successfully designed, synthesized and characterized an unique polydiacetylene, poly(diioddiacetylene) or PIDA, a nearly unadorned carbon chain substituted with only single-atom iodine. PIDA represents a possible solution to the problem of the PDAs synthesis PIDA may also act as a precursor to carbyne, the hypothesized linear sp-hybridized allotrope of carbon (-C=C-) n. We used a host-guest strategy to approach the target PIDA, in which both hydrogen bonding and halogen bonding play a key role in the alignment of the diodobutadiyne monomers. In co-crystals with one bis(nitrile) oxalamide host, the diyne undergoes spontaneous topochemcial polymerization to form PIDA, indicating the bis(nitrile) oxalamide host controls the spacing and alignment of the diynes properly for a 1,4-topochemcial polymerization. We have confirmed the structure of the copper-looking single-crystal PIDA through single-crystal x-ray diffraction, ultraviolet-visible absorption spectroscopy, scanning electron microscopy and Raman scattering spectroscopy. The physical properties including unique thermochromic behaviors and morphology investigation are also presented in this dissertation.; Another project is focused on investigation of self assembled monolayer films on the substrate via STM. Preliminary results are obtained from the steric acid and its complex with 4,4'bipyridine. The goal is to explore whether halogenated alkynes could assemble to form ordered alignment on suitable substrates. The final goal includes investigating ordered packing of the diyne compounds that can topochemcially polymerize, leading to conjugated monolayer polymer films. |
