Solid-state synthesis of highly conducting polyphenylene from crystalline oligomers

Abstract

Paraphenylene oligomers (biphenyl, p-terphenyl, p-quaterphenyl, p-quinquephenyl, p-sexiphenyl) form electrically conducting complexes with AsF5. Prolonged exposure to AsF5 causes a polymerization of these p-phenylene oligomers to give highly conducting charge-transfer complexes of poly(p-phenylene). Conductivities as high as 50 S/cm have been measured. Powders, thin films, and single crystals of p-phenylene oligomers have been reacted with AsF5. The undoped oligomers and the doped, compensated, and annealed products have been investigated by means of x-ray diffraction, and UV-visible and IR transmission spectroscopy. The x-ray diffraction studies give evidence for a change in lattice spacings to those characteristic of the crystalline polymer. The spectroscopic measurements during AsF5 doping reveal shifts in absorption bands in the UV and the IR to those characteristic of poly(p-phenylene). Paraoligophenylenes have also been reacted with elemental potassium in THF solution with trace amounts of naphthalene. Highly conducting complexes were formed (0.5 S/cm for sexiphenyl) but there is no evidence for further polymerization.

Resolving Band-Structure Evolution and Defect-Induced States of Single Conjugated Oligomers by Scanning Tunneling Microscopy and Tight-Binding Calculations

“…Assuming the VB is described by EðkÞ ¼ À" À 2 þ 2t cosðkaÞ, where defines the shifting of the Fermi level away from the middle of the band gap, the band gap can be expressed as ð" þ Þ À 4t cosð N Þ. Using the reported band gap value of sexiphenyl 3.9 eV (or 3.1 eV) [28,29], we found ¼ 0:42 eV (or 0.38 eV). Figure 3(b) (squares) summarizes the band gap of different oligomers.…”

Standard molar enthalpies of formation and of sublimation of the terphenyl isomers

“…Some of these terphenyl derivatives have quite relevant biological activities, behaving as immune suppressants, antioxidants, neuroprotectives, cytotoxic, anti-thrombosis and anticoagulants [1]. Terphenyls have been the object of extensive research over the years, enhancing their characteristics and applications such as, the ability to form polyphenylene conducting polymers [2][3][4][5], use in organic light emitting diodes (OLEDs), field-effect transistors (FETs) and nonlinear optical devices [6][7][8][9], usage as ultraviolet organic lasers [10], host organic material for dopants [11][12][13][14][15][16], in catalysis [17,18], enzyme simulation [19], metal-organic frameworks [20] and modelling glass forming systems [3,21,22]. These vast applications require the knowledge of the energetics involving these polyphenyl oligomers as well as its relation with their structures.…”

Chemisorption of Benzene on Cu-Montmorillonite as Characterized by FTIR and 13C MAS NMR

“…The 980 and 1180 cm 1 bands in doped polyp-phenylene would be masked by those of the clay matrix in the benzene-Cu-montmorillonite system. The doping of poly-p-phenylene using an electron acceptor (e.g., AsFs) has been shown to result in further polymerization (Shacklette et al, 1980) of parent oligomers. In a photoacoustic infrared study of doped and undoped poly-p-phenylene, Yaniger et al (1984) suggested that the Raman-active 1598 and 1216 cm modes in undoped poly-p-phenylene become IR active in doped poly-p-phenylene as a result of symmetry breaking.…”