Rc-Conjugation

On the basis of a naive analogy with cyclopropenones, the ground-state aromatic stabilization of which has been recently reconfirmed, some kind of aromaticity can, in principle, be assigned to these systems when Z = SO or SOj, assuming a possibility for transmission of electronic effects via rc-conjugation. 

Disklike rc-conjugated mesogen Mesogenic side group Flexible spacer Solubilizing side chain... 

The imines 158 are in the s-trans form (75BSF1663), as are the corresponding formylaziridines, confirming the importance of rc-conjugative effects in determining the conformational preference of these derivatives. 

An extensive review of the synthesis of rc-conjugated polymers is presented using a tutorial approach to provide an introduction to the field intended for the undergraduate student and the experienced chemist alike. The many synthetic methodologies that have been used for the synthesis of conjugated polymers are outlined for each class of polymers with a focus on research from the 1990s. The effect of structure on electrical properties is detailed. Specific systems reviewed include the polyacetylenes, polyanilines, polypyrroles, polythiophenes, poly(arylene vinylenes), and polyphenylenes. 

The process now known as reductive alkylation of rc-conjugated anions (quenching of anions) is as old as the preparation of the ions themselves5). The highly colored solutions obtained by the addition of alkali metals to solutions of aromatic hydrocarbons in ether were reacted with electrohpiles such as protons or alkyl halides (Scheme 2). The products of such a process are reduced hydrocarbons. The Birch reduction is one example oT such a process, reaction of an anion with an alkyl halide leading to an alkylated reduced hydrocarbon is another example 165). The complexity of the quenching experiments is demonstrated by the naphthalene radical anion 150-1581... 

Polycyclic Anions From Doubly to Highly Charged rc-Conjugated Systems... 

Rabinovitz, M. Polycyclic Anions From Doubly to Highly Charged rc-Conjugated Systems. 146, 99— 170 (1988). 

The LQ for CdSe/ZnS nanocrystals passivated by various organic ligands (pyridyl-substituted porphyrins, pyridine, 2,2 -bipyridine, 1,10-phenathroline) has been studied by the use of steady-state and time resolved spectroscopic measurements in toluene at 295 K. It was shown that porphyrin rc-conjugated macrocycle (via mesomeric effects and possible partial overlap HOMO and LUMO of porphyrin and meso-pyridyl rings) plays the principal role in non-radiative exciton relaxation in NC-organic ligand composites. 

Dirty" conductors with electrical conductivities of the order of 10 S/cm or less Such systemsscan be achieved with relative ease all that is required is a moderately high density of carriers. Carrier delocalization is neither required nor implied by such values. In such cases, the heavily doped polymers are highly disordered systems which can be considered as examples of Ae "Fermi glass" concept. Indeed, rc-conjugation is not even needed to achieve this low level of conductivity in polymers. ... 

The existence of conformational polymorphs of 1 is evidently a result of interplay between the steric hindrance of the mesityl groups, the tendency of the whole molecule towards planarity which would maximize 7i-rc conjugation, and crystal forces favoring close packing. 

We investigated the charge transport properties of the rc-conjugated polymer poly (para-phenylenevinylene) and its soluble substituted derivative DPOP-PPV (Fig. 1.2). In... 

To establish that the oxidative stability of R)-5 and (5)-6 was indeed due to the extra rc-conjugation present as a result of the binaphthyl backbone, we undertook a comparative study of the sensitivity of the related phenyl-, naphthyl-and binaphthyl-substituted phosphines shown in Fig. 1.5. 

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