Synthesis, Characterization, and Physical Properties of Monodisperse Oligo(p-phenyleneethynylene)s

Abstract

A new stepwise synthesis method for the preparation of precisely defined oligo(pphenyleneethynylene)s (OPEs) is described. High-purity monomer, trimer, pentamer, heptamer, and nonamer of OPEs with dihexyloxy side groups and trimethylsilyl (TMS) or thioacetyl (SAc) terminals have been synthesized. The structures of the oligomers were characterized by 1 H NMR, 13 C NMR, and elemental analysis. DSC studies show narrow and well-developed melting and crystallization peaks, indicating the high perfection of the crystals formed in these oligomers. Optical microscopy was used for investigating the supramolecular morphology of solid-state films of pentamer with TMS end groups, as an example. Numerous dendrites with a spherulitic size of ca. 50 µm were observed. UV-vis absorption and photoluminescence (PL) spectra in both dilute solution and films show a gradual red shift of the λ max from trimer to nonamer. At the nonamer stage, the optical maximum is approaching a limit of convergence.

The cationization mechanism study of novel oligo (p-phenyleneethynylene)s

“…Oligomers O1-O8 were synthesized by Pd/Cu-catalyzed coupling reaction and the synthetic details were reported previously [22]. The solvent, inhibitor-free tetrahydrofuran (Aldrich, Milwaukee, WI), stored in a Sure/Seal bottle, was used as received.…”

“…Hence, these oligomers did desorb and photoionize directly but not through the electrotransfer process by the matrix described in literature. Actually, the oligomers have strong absorption at the wavelength of nitrogen laser (337 nm) although the maximum is at a higher wavelength (UV spectra of O1-O4 shownäinäFigureä3)ä [22].äThus,ätheäoligomers undergo electron-transfer reactions yielding considerable amounts of radical cations. These multi-aromatic oligomers are good electron-transfer materials themselves.…”

Break-Junction Experiments on Acetyl-Protected Conjugated Dithiols under Different Environmental Conditions

“…Synthesis of the molecule was performed according to the procedure reported in the literature. 39 Solvents 1,2,4-trichlorobenze, mesitylene, and tetrahydrofuran, and the deprotection agent tetrabutylammonium hydroxide, Bu 4 NOH (as hydrated salt), were purchased from SigmaAldrich and used without further purification. Bu 4 NOH was kept in the refrigerator and under Ar atmosphere.…”

Morphology and photophysical properties of phenyleneethynylene oligomer

“…The oligo(p-phenyleneethynylene) pentamer with TMStermini was prepared by a stepwise synthetic method [26]. The films were prepared by spincoating the oligomer/xylene solution (ca.…”

“…Recently, we have developed a series of alkoxy substituted OPEs with different terminal groups and investigated their absorption and emission properties in solution and solid state. In addition, the selforganized crystalline morphology of trimethylsilyl (TMS)-terminated pentamer was studied [26]. In order to gain better understanding of the relationship between the microscopic organization and optical properties of OPEs in films, we examine the spincoated and thermally annealed films of TMSterminated pentamer using a combination of different characterization methods.…”