Classification main chain structure

The A-B type iniferters are more useful than the B-B type for the more efficient synthesis of polymers with controlled structure The functionality of the iniferters can be controlled by changing the number of the A-B bond introduced into an iniferter molecule, for example, B-A-B as the bifunctional iniferter. Detailed classification and application of the iniferters having DC groups are summarized in Table 1. In Eqs. (9)—(11), 6 and 7 serve as the monofunctional iniferters, 9 and 10 as the monofunctional polymeric iniferters, and 8 and 11 as the bifunctional iniferters. Tetrafunctional and polyfunctional iniferters and gel-iniferters are used for the synthesis of star polymers, graft copolymers, and multiblock copolymers, respectively (see Sect. 5). When a polymer implying DC moieties in the main chain is used, a multifunctional polymeric iniferter can be prepared (Eqs. 15 and 16), which is further applied to the synthesis of multiblock copolymers. 

For NMA it made sense to define CO ib (amide IV), CO ob (amide VI), CN t (amide VII), and C CN d and CNC d as characteristic modes. Such a classification is too simplistic for a polypeptide chain, where many of these modes, together with NC C d and C b, mix strongly and very differently depending on the main-chain conformation and the side-chain structure. 

The various orientations and conformations mesogenic groups can adopt in a layer has been studied extensively for low molar mass smectic materials, and the classification and terminology of smectic systems is entirely based on these studies. However, low molar mass smectic compound or smectic LC-side chain polymers do, of course, not allow one to elucidate the role spacers play in the layer structures of LC-main chain polymers. Therefore, poly(ester-imide)s, po-... 

Quite early on, structural investigations showed [17] that the mesogens in the main chain and the side chain orient parallel to one another. This was confirmed by electron microscopy [18], X-ray diffraction [6,7,13, 14, 17, 19, 20] and HNMR spectroscopy [21]. Following the general classification of LC side-chain polymers (Figure 2) [22], these polymers should be classified as type III. In these combined LC polymers, the polymer chains and mesogens orient parallel to one another to define the LC director. 

The sequences in PLC chains which cause the LC character can be of different shapes elongated (represented in the following by rectangles), approximately spherical (which will be represented by discs), or stars. The LC sequences can be placed in the main chain, or in side chains, or in both. To survey existing and possible structures, a comprehensive classification of PLCs based on their molecular structures was developed [25] and subsequently amplified [9,27] a recent version is shown in Table 41.1. 

In discussions of structure we must limit ourselves to the case of linear polymers, for with the branched polymers so far studied their complexity has defied analysis. Here, however, as I have discussed elsewhere [11], it is possible to draw up a rational classification of the types of structure as defined by the arrangements of hydrogen bonds taken as the main element in intra- and inter-chain linking. 

Based on spectroscopic properties, mainly electron paramagnetic resonance (EPR), the active sites of copper proteins have been classified into three groups, types I, II, and III. This nomenclature was originally applied to blue oxidases to distinguish the four copper ions contained in these proteins. The original classification has been extended to the copper sites of other proteins. The recent increase in structural information on the copper sites in proteins has, however, revealed greater diversity in the type of copper site. For instance, the type III and type II sites in ascorbate oxidase are in close proximity, forming a trinuclear site, in which all three copper ions are essential for the reactivity. Some proteins, once believed to contain a copper site with normal spectroscopic properties, and thus referred as type II, have been shown to contain copper coordinated by an unusual side chain. Therefore, in this review, new nomenclature is used to classify the copper sites more precisely with respect to their structural features and spectroscopic properties. The definitions are as follows ... 

The penicillins [pen i SILL in] are the most widely effective antibiotics and are among the least toxic drugs known the major adverse reaction to penicillins is hypersensitivity. The members of this family differ from one another in the R substituent attached to the 6-aminopenicillanic acid residue. The nature of this side chain affects their antimicrobial spectrum, stability to stomach acid, and susceptibility to bacterial degradative enzymes (P-lactamases). Figure 30.1 shows the main structural features of the penicillins. Figure 30.2 shows the classification of agents affecting cell wall synthesis. 

---