Organic conjugated chains

In the following section, step by step a qualitative picture is formed describing the impact of intcrmolecular interactions oil the absorption and luminescence of organic conjugated chains. The present calculations do not distinguish between dimers and aggregates (for which the wavefunctions of adjacent chains interact in the ground state, due to, for instance, solid-state effects) and excimers (where overlap occurs only upon photoexcitation) [29]. 

Color in Organic Compounds. In organic molecules, particularly those containing conjugated chains of alternating single and double... 

By extension one may say that the power laws (5-7) which determine the magnitude of the linear and nonlinear optical coefficients are consequences of this strong electron-lattice coupling. We now make the conjecture that the time response of these coefficients is severely affected by the dynamics of the electron-lattice coupling in conjugated chains when two or more resonant chemical structures can coexist this is the case for many of the organic chains of Figure 2. 

There was no published discussion at that time of the rules of dye chemistry and how the purported material rhodopsin would exhibit compliance with these rales. As indicated above, the most widely used class of dyes incorporates two polar atoms connected to each other by a conjugated carbon chain, and generally named a chromophoric system. The presence of a conjugated carbon chain is required as a minimum in nearly all organic material exhibiting a color in the visual band. Lack of such a conjugated chain leads to a colorless material. The proteins are such an unconjugated and inherently colorless family of materials. It was proposed that rhodopsin was formed by a... 

The conductivity is a solid-state phenomenon, and, as pointed out already, conductivity is not a single chain phenomenon. The band-gap description of a conjugated chain is a one-dimensional model. Additionally, considerably interchain charge transport is necessary to describe a metal-like behavior in the highly doped three-dimensional sample and further transfer mechanisms across the polymer chains have to be discussed. What one actually needs to know in explaining conductivity of organic polymers is how the charge transport proceeds... 

Two basic approaches have been taken. The first consists in grafting organometallic donor and acceptor groups, such as ferrocene [as in [84] (Calabrese et al, 1991)] ruthenium derivatives [as in [83] (Whittall et al, 1996)] and tungsten carbonyl, instead of their organic counterparts on tt-conjugated chains. Quite successful in this respect, although not truly org nometallic, are zwitterions based on borate donors and ammonium acceptors [86] (Lambert et ah, 1996) and Lewis acid complexation as in [85] (Kammler et al, 1996). 

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