Oligo substitution patterns

The large amount of work devoted to the synthesis of oligo-p-peptides has created a need for some standardization in nomenclature. The proposals of Seebach 5 will be used throughout this section, i.e. the P-peptides will be named according to their substitution pattern with the superscript representing the position of the substituent on the peptide backbone (Scheme 1) the prefix H to the three-letter code for amino acids has been used throughout to denote a homoamino acid, e.g. HLeu is homoleucine, HVal is homovaline, etc. 

A series of PAI have been condensed using trimellitic acid and also 3-amino-4-methylbenzoic acid and various diamines. It was found that the permeability or helium increases with increasing fluorine content. In addition, nonlinear moieties contribute to the permeability. In PAI with oligo(tetrafluoroethene) segments, the substitution patterns of the phenyl group in the diamine moieties do not notably influence the diffusivity." ... 

Thermochromism. Neutral poly(3-alkylthiophene)s and poly(3-alkoxy-4-metiiylthiophene)s exhibit strong chromic effect upon heating both in the solid state and in solution[25-2P]. Two types of thermochromic behavior can be observed and are correlated to the substitution pattern of the polymers. As an example of the first type (the two-phase behavior), the temperature dependence of the absorbance of a thin film of poly[3-oligo(oxyethylene)-4-methylthiophene] [57] is shown in Figure 4. 

We now illustrate the impact of cyano functionalization on the electronic properties of oligo thiophenes. This issue is of prime interest in the context of organic light-emitting diodes, as demonstrated before in the case of PPV [72-74] the goal is to uncover the substitution patterns that lead to devices with enhanced efficiencies. In the following, we focus on cyano-substituted bi- and terthiophene derivatives that have been synthesized and characterized both electrochemically and optically by the Thiais group, see Fig. 6 [75]. 

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