Homologous oligomers

Reaction of l.l -dimercapto-ferrocene with succinc acid chloride and sebacinic acid chloride yielded polymers with molar masses of = 12000 g moP which were determined by end group analysis assuming OCH3 end groups and by GPC calibrated with a series of homologous oligomers identified in the GPC graph [25],... 

A closely related case is the synthesis of so-called polyrylenes 6 in which naphthalene repeat units are fused via their four peri-positions. Polymer 6 has played an important role in the electronic study of low band gap polymers [131]. We first synthesized the homologous oligomer series 7 and 8 comprising an increasing number of naphthalene units [132-134] (Figure 3). 

Atmospheric pressure chemical ionization. APCI-MS analysis in positive ion mode gives only one major ion for each homolog/oligomer, corresponding to loss of the sulfate group [R(OCH2CH2) OH + H]" (32). 

Polymers from either of these homologous series can be made to predominate by usiag a small excess of the diamine or diacid, respectively. In addition to these linear polymers, cycHc oligomers are also formed, though ia this case n... 

Voltammetric measurements on defined soluble oligomers in the homologous series of the p-phenylenevinylenes and the p-phenylenes have finally ended specu-... 

Butadiene and isoprene give rise to mixtures of what are usually called telom-ers, namely 1 1 telomers between the amine and the 1,3-diene (trae hydroamination products), 1 2 telomers and even higher homologs together with oligomers of the diene as exemplified in Eq. (4.41). 

C-termini and a large glycosylated extracellular loop between transmembrane domains 3 and 4. The proteins show the most homology in their transmembrane spanning domains, particularly domains 1, 2, and 4-8, which may be involved in moving the transmitter across the membrane. The transporters are substrates for PKC-dependent phosphorylation, which reduces their activity. The dopamine transporter is phosphorylated on the extreme end of the N-terminal tail, and consensus phosphorylation sites for various other kinases are present in the intracellular loops and domains [20-22] (Fig. 12-4). The dopamine and norepinephrine transporters form functional homo-oligomers, although it is not known if this is required for transport activity, and the transporters also interact with many other membrane proteins that may control their cell-surface expression or other properties. 

The major components are series of homologous trimers, tetramers, and pentamers of the three acids 44-46, along with smaller quantities of dimers, hexamers, and heptamers. Furthermore, the secretion contains several isomers of each oligomer, furnishing a combinatorial library of several hundred macro-cyclic polyamines [51, 52]. Using repeated preparative HPLC fractionation, the most abundant trimeric, tetrameric and pentameric earliest-eluting compounds were isolated. One and two-dimensional H NMR spectroscopic analyses showed that these molecules were the symmetric macrocyclic lactones 48, 49, and 50 (m, n, o, p, q=7) derived from three, four or five units, respectively, of acid 46. Moreover, using preparative HPLC and NMR methods, various amide isomers, such as 53,54, and 55 (Fig. 9) were also isolated and characterized [51,52]. 

---