Luminescent chromophores

We have studied two types of polymers that both belong to the second case those in which luminescent chromophores (typically K-coujugatcd oligomers) are separated by higher-energy-gap blocks (see Fig. 16-1 a) and those in which the chromophores are linked to each other in a non-coplanar way (sec Fig. 16-lb). 

CPL and CD are based upon similar aspects of molecular structure. It is important to realize, however, that, even if the same states are involved, these measurements do not usually supply redundant information. From the Franck-Condon principle, CPL is a probe of excited state geometry, and CD is a probe of ground state geometry. CPL measurements have some advantages over the measurement of CD, as well as some inherent limitations. The most serious limitation is, quite obviously, that the optically active molecule under study must contain a luminescent chromophore with a reasonable quantum yield. Although this severely limits the range of possible applications of CPL, it does result in a specificity and selectivity that is not present in CD or absorption experiments. 

The photophysics and photochemistry of bis-2-(9-anthryl)-ethyl glutamate and pivalate have been employed as a pair of models of different polymeric systems with the same luminescent chromophores.An ingenious method which has been used successfully to enhance excitation transfer in solid polymer is the introduction of intervening anthryl groups along a polymer chain... 

Examples of type B polymers include aromatic polyesters and polyether-sulphones in which the luminescent chromophores have been identified as the aromatic ester carbonyl [81, 82, 547] and sulphonyl groups [4, 79]. 

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