Conjugated materials

Polyfpyridine vinylene) 55 may also be prepared by the Wessling route (Scheme 1 -19) [95]. Fully conjugated material may be obtained by thermal elimination of the sulfonium salt 61 or the halide 62. The method, however, does not... 

Whereas XRD patterns of the thin crystalline films provide information on the orientation and lattice distances perpendicular to the substrate, AFM has proven to be a powerful technique for obtaining structural information of thin-lilm surfaces of conjugated materials 195 j. AFM imaging of the surface of a thin (10 nm) annealed film of Ooct-OFV5 confirmed the domain structure of the annealed Ooct-... 

Other poly(2,5-dialkoxy-1,4-phenylene vinylene)s have been prepared in a similar fashion [34, 35, 40, 41]. Alternatively, a soluble a-halo precursor polymer 17 may be obtained by using less than one equivalent of base (Scheme 1-6). This may then be converted into fully conjugated material 16 by thermal treatment. This halo-precursor route may be preferred if the fully conjugated material has limited solubility or if incomplete conversion is desired. 

Parent polyfthicnylene vinylene) has also been synthesized by an aldol precursor route [122]. In this method, 5-methyl-2-thiophenecarbaldehyde 76 is treated with a base and the monomer polymerizes yielding a precursor 77 which is soluble in water. Thermal treatment in an acidic solution at 80 nC yields the fully conjugated material. Alternatively, the solid polymer may be healed to 280 C to effect elimination of water. Fully conjugated material exhibits low conductivity (10 8 S cm"1) in its pristine stale. 

In order to study the chaiged photoexcitalions in conjugated materials in detail their contribution to chaige transport can be measured. One possible experiment is to measure thermally stimulated currents (TSC). Next, we will compare the results of the TSC-expcrimenls, which are sensitive to mobile thermally released charges trapped after photoexcilation, to the temperature dependence of the PIA signal (see Fig. 9-17) which is also due to charged states as discussed previously. 

The Rise of Organophosphorus Derivatives in n-Conjugated Materials Chemistry... 

This account will summarise results in the development of n-conjugated materials incorporating phosphorus moieties with emphasis on the conceptual design and specific properties that result directly from the presence of the P-atom. Polyphosphazenes, which are the most familiar synthetic polymers incorporating phosphorus [8], will not be included in this review since they do not display the type of n-conjugation as sought in systems (A)-(D). 

The extraordinary impact of thiophene and pyrrole derivatives for the engineering of 7i-conjugated materials, naturally led to the consideration of phos-pholes as potential building blocks. However, phosphole exhibits electronic... 

Two types of symmetric fused dithienophospholes exist, which differ according to the position of the S atoms as illustrated by compounds (53) [54] and (54) [50] (Scheme 15). The a A -dithieno[3,2-fo 2, 3 -d]phosphole (55) has recently been considered as a potential subunit for the construction of n-conjugated materials [55] (Scheme 15). Exploitation of the reactivity of the nucleophilic P-atom of (55) allows access to derivatives (56) and complexes (57) (Scheme 15). The absorption and emission behaviour of these species varies with the nature of the P-moieties. Upon oxidation of the P-centre of (55),bathochromic shifts of Ajnax Aejn were observed Aj ax 344 nm for (55) and ca. 373 nm for (56), and Agjn 422 nm for (55) and ca. 460 nm for (56) [55]. These results nicely illustrate... 

Replacement of the para-substituted phenyl unit of alternating phosphine-ary-lene polymers by an ethynyl group, gives rise to a new family of 71-conjugated materials. Indeed, compounds (77) and (78) were prepared in 53% and 3% iso-... 

Hirsch A, Vostrowsky O (2001) Dendrimers with Carbon Rich-Cores. 217 51-93 Hirsch A, Vostrowsky O (2005) Functionalization of Carbon Nanotubes. 245 193-237 Hissler M, Dyer PW, Reau R (2005) The Rise of Organophosphorus Derivatives in p-Conjugated Materials Chemistry. 250 127-163 Hiyama T, Shirakawa E (2002) Organosilicon Compounds. 219 61-85 Holmberg K, see Hager M (2003) 227 53-74... 

Poly(para-phenylenevinylene)s (PPVs) represent one of the most intensively investigated classes of rr-conjugated materials. Many synthetic procedures to generate unsubstituted and substituted PPVs have been developed. They include 1,6-polymerizations of 1,4-xylylene intermediates as well as several polycondensation methods. Parallel to the polymer syntheses, several series of PPV oligomers (OPVs) have been synthesized and characterized. Such model oligomers of different molecular size allow for a study of the dependence of electronic and optical properties on the length of the conjugated Ti-system. 

Keywords Molecular Wires a Molecular Devices a Alligator Clips a Conjugated Materials... 

Sum Over States [3] (SOS) approaches constitute one of the most commonly used class of methodologies for theoretical estimation of hyperpolarizabilities. The strength of this approach is related to the fact that for many compounds of interest, only a few excited states make a major contribution. The simplest scheme, proposed by Oudar and Chemla [4—5] to analyze variations of p among push-pull conjugated materials, restricts the summation to a unique excited state. In this resulting two-state approximation (TS A), the static longitudinal electronic first hyperpolarizability, Pl, is given by ... 

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