Polyacetylene magnetic properties

Five aspects of the preparation of solids can be distinguished (i) preparation of a series of compounds in order to investigate a specific property, as exemplified by a series of perovskite oxides to examine their electrical properties or by a series of spinel ferrites to screen their magnetic properties (ii) preparation of unknown members of a structurally related class of solids to extend (or extrapolate) structure-property relations, as exemplified by the synthesis of layered chalcogenides and their intercalates or derivatives of TTF-TCNQ to study their superconductivity (iii) synthesis of a new class of compounds (e.g. sialons, (Si, Al)3(0, N)4, or doped polyacetylenes), with novel structural properties (iv) preparation of known solids of prescribed specifications (crystallinity, shape, purity, etc.) as in the case of crystals of Si, III-V compounds and... 

Table 29. Electric and magnetic properties of substituted polyacetylenes (25 °C)...

Table VI includes the electrical and magnetic properties of the polymers studied. Polyacetylene is a semiconductor. In contrast, the conductivities of the Si-containing polyacetylenes are only in the order of S/cm,...

The unique properties of polymers such as polyacetylene, whose backbones consist of an alternating succession of single and double bonds, and most of which show extraordinary electrical, optical and magnetic properties including electrical conductivity when "doped" with electron donors or acceptors [35], are also outside the scope of this work. Sophisticated quantum mechanical treatments are required to predict these properties of such polymers. 

ESEEM has been applied to the study of surface complexes, coordination of water in metmyoglobin, the structures of ligands in a copper protein, magnetic properties of electronic triplet states, and solitons in polyacetylene. 

Tsukamoto, J. Takahashi, A., "Structure and Morphology of Metallic-Conductive Polyacetylene", p. 711 in Chiang, L.Y. Garito, A.F. Sandman, D.J. (Eds.), Mat. Res. Soc. Symp. Proc., Vol. 247 Electrical, Optical, and Magnetic Properties of Organic Solid State Materials, Materials Research Society, Pittsburgh, Pennsylvania, USA (1992). 

H. Nishide, N. Yoshioka, Y. Saitoh, R. Gotoh, T. Miyakawa, and E. Tsuchida, Synthesis and magnetic property of polyacetylene bearing p-conjugated bis(diphenylene)phenylallyl radicals, J. Macromol. Sci. Pure Appl. Chem., A-29, 775 (1992). 

Several experiments have been carried out to confirm the physical properties of solitons in mns-polyacetylene [27]. Lately, this excitation has also been studied in another degenerate ground state conjugate polymer, poly(l,6-heptadiene) [28]. The onedimensional spin diffusion and associated spin dynamics are verified from electron magnetic resonance spectroscopy, nuclear magnetic resonance (NMR) spectroscopy and electron nuclear double resonance (ENDOR) measurements [13]. The density of neutral solitons has been estimated by Motsovoy and co-workers [29]. For more details on the physical properties of solitons, the reader is referred to a review article by Heeger and co-workers [13]. However, more theoretical and experimental work is... 

It has been generally accepted that polyacetylene has a planar structure, irrespective of cis and trans forms, due to ir-conjugation between the sp hybridized carbon atoms in the polymer chain [1,4]. If it were possible to modify such a planar structure of pofyacetylene into a hehcal one [13], one might expect novel magnetic and optical properties [14]. Here, we report polymerization of acetylene in asymmetric reaction field constructed with chiral nematic LCs, and show that pofyacetylene films formed by helical chains and fibrils can be synthesized [15]. Polymerization mechanism giving hehcal structure from primary to higher order and hierarchical spiral morphology is discussed. 

A polymeric material that possesses the electronic, magnetic, electrical, and optical properties of a metal while retaining the processibility and mechanical properties usually associated with a conventional organic polymer is called a conducting pol ymer. Since the first demonstration of metallic conductivity in AsF5-doped polyacetylene by MacDiarmid and co-workers in 1977 [1], conducting polymers have become the main part of a larger class of materials commonly known as synthetic metals. 

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