Trimer molecules approach

Hexa(oligophenyl)benzenes (e. g. 31 or 33) present one possible approach to the realization of this aim. Two efficient synthetic routes have been elaborated for the preparation of hexa(terphenyl)- and hexa(quaterphenyl)benzene. The first, involving palladium-catalyzed trimerization of diarylacetylenes [54] as the key step, was demonstrated by the synthesis of a hexakis-alkylated hexa(terphenyl)benzene derivative 31 from the corresponding bis(terphenyl) acetylene (32). The peripheral tert-alkyl substituents serve to solubilize the molecule. 

Various spectroscopic approaches applied to the 510 nm transition indicate an unusual environment for the redshifted lutein (Figures 7.5 and 7.7a). Interaction with the Chi a603 could force lutein 2 molecule to adopt a twisted configuration. In addition, strong interaction with a number of aromatic residues, in particular tryptophan and phenylalanine, which possess relatively large surface areas, could further promote this distortion. It is reasonable to assume that the energy required to produce this distortion comes from the forces involved in the stabilization of LHCII trimers. 

Two theoretical approaches for calculating NMR chemical shift of polymers and its application to structural characterization have been described. One is that model molecules such as dimer, trimer, etc., as a local structure of polymer chains, are in the calculation by combining quantum chemistry and statistical mechanics. This approach has been applied to polymer systems in the solution, amorphous and solid states. Another approach is to employ the tight-binding molecular orbital theory to describe the NMR chemical shift and electronic structure of infinite polymer chains with periodic structure. This approach has been applied to polymer systems in the solid state. These approaches have been successfully applied to structural characterization of polymers... 

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