Naphthalene doped conductivity

Many expensive reductions such as the Birch reduction of naphthalene to isotetralin, benzene to cyclohexene, with metallic sodium and liquid ammonia, or reduction with LiAlHa, can generally be carried out electrochemically at much lower cost and under safe conditions. Electrochemical processes allow fluorinations to be carried out without using fluorine gas. Conducting polymers have been made by electrochemical processes which operate under ambient conditions, and the polymer can be synthesized, doped and shaped in film form in a single step. 

Johnson and Willson interpreted the main feature of the observations on solid polyethylene doped with aromatic solutes in terms of an ionic mechanism it was analogous to that proposed for irradiated frozen glassy-alkane-systems in which ionization occurred with G = 3 — 4 [96], The produced charged species, electron and positive hole, were both mobile as indicated by the radiation-induced conductivity. The production of excited states of aromatic solutes was caused mainly by ion-electron neutralization. The ion-ion recombination was relatively slow but it might contribute to the delayed fluorescence observed. On the basis of Debye-Simoluchovski equation, they evaluated the diffusion coefficients of the radical anion of naphthalene and pyrene as approximately 4 x 10 12 and 1 x 10 12 m2 s 1 respectively the values were about three orders of magnitude less than those found in typical liquid systems. 

Poly(arylenevinylene)s based on naphthalene (JJ7) and thiophene (118, 119) have been reported. When naphthalene was substituted for benzene in the polymer structure, the resulting conductivity for the AsFs-oxidized polymer was 10 S/cm. Orientation of the polymer via stretch alignment has not been reported. The thiophene derivative, however, was stretch aligned (118) and doped with iodine and FeCl3. Conductivities of2700 were obtained with iodine-doped samples having elongation ratios of 6. The anisotropy of the conductivity was 35. 

Figure 8.24. Conductivity versus doping level, for potyaniline samples doped with three different acids hydrochloric acid (HCl) ( ), p-tolucnc sulphonic acid (PTSA) (O) and naphthalene 1,5-disulphonlc acid (NDSA) ( ).

Electron-donating dopants may reduce polyacetylene or other conjugated polymers giving rise to -type conductivity. Doping occurs when the polymer is immersed in a tetrahydrofuran solution of radical anion/alkalide where the alkalide components can be Li, Na, K, Cs, or Rb, and the radical anion can be naphthalene, anthracene, or benzo-phenone. A doping reaction such as the following occurs (Nph = naphthalene) ... 

Shen, Y, and M. Wan. 1997. Soluble conductive polypyrrole synthesized by in situ doping with P-naphthalene sulphonic acid. J Polym Sci A Polym Chem 35 3689. 

Another view has recently been proposed by Wegner.Naphthalene and other simple aromarics can be oxidize electrochemi-cally to form monomelic radial cat n salts (Ar. X ) which have conductivities of 10 to 10 s/cm. The crystal structures of these reveal that the aromatic moieties form stacks, along which the charges and the electrons are presumably delocalized. The structure is formally analogous to that deduced for oxidized (doped) polyacetylene in which the polyene chains are arranged in stacks. This leads to the idea that intermolecular delocalization is the important feature which leads to high conductivity. Other data are consistent with this rationale. Biphenyl and terphenyl radical cation salts have crystal structures very similar to that of oxidized (doped) poly(p-phenylene lO). In the older literature oligoanilines (26) are reported upon iodine treatment to yield conductivities up to 1 s/cm the aniline moieties are stacked in these materials as well. Poly(N-vinyl-carbazole) (27) forms radical cation structures by oxidation with... 

In the following we want, therefore, to describe first the structure of the simplest organic metal derived from as simple molecules as naphthalene or other arenes. These structures help to understand the type of intermolecular interactions necessary to produce a quasi-metallic state in organic systems. The structure and the structural changes upon oxidation ("doping") of poly(acetylene) will then be described. A description of these chemical reactions and their implications for the electronic and vibronic spectra will follow. Finally, some other conducting polymers or oligomers will be described and the use of such materials in electrochemical cells will be discussed as well. 

In the language common to the field of conductive polymers going from neutral naphthalene (Fig. 1A) to the cation radical complex (Fig. IB) may be called "doping of naphthalene. In fact, the same type of complexes are obtained, if solid... 

Demonstrating that these low oxidation potential aromatic amines are very easy to polymerize, the Dao group subsequently reported [410] chemical polymerization with Cu(Bp4)2 xH20 oxidant/dopant for a series of Poly(N-alkyl-Diphenylamine) s. A 4-4 C-C (phenyl-phenyl) coupling mechanism was claimed for tWs polymerization. These CPs showed poor conductivities (10 S/cm) and a yellow-to-violet electrochromism. In a variant of diis syntliesis, Poly(N-alkyl-diaryl amines), i.e. with a naphthalene group replacing one of the phenyls in DPA, were chemically synthesized by Dao et al. [586]. These polymers however showed poor conductivity (10 S/cm) even in their highly doped form. The spectroelectrochemical characterization of these (see Chapter 3) showed broad-band responses characteristic of P(DPA) and its derivatives. 

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