Conjugated patterns

Given these surprising experimental facts, it is obviously important to inquire why the cyclic conjugation patterns (3.122) and (3.123) should lead to such diametrically opposite changes in conjugative stability compared with acyclic analogs. A... 

Quinone, 22, represents a six-membered carbon ring system with a conjugation pattern quite unlike that of benzene. As shown by its leading Lewis structure (of... 

Aniline and nitrobenzene electrophilic substitution reactivity We briefly consider the effect of pi-donor or pi-acceptor substituents on aromatic conjugation patterns for two representative examples aniline (23) and nitrobenzene (24). The leading NBO interactions between ring and substituent in these species are depicted in Fig. 3.47. 

When two trans-polyacetylene chains with different phases are put together, an obvious disturbance occurs in the standard conjugation pattern. The bond alternation defect that appears is known as a neutral soliton (Fig. 1.7). This kind of quasi-particle has an unpaired electron but is electrically neutral and is isoenergetically mobile along the polymer chain in both directions. This soliton gives rise to a state in the middle of the otherwise empty energy gap that can be occupied by zero, one or two electrons (Fig. 1.8). 

Reactions used to transform hydroporphyrins into porphyrinoids of different conjugation pattern are covered in Section IV. 

In most cases the ef-values closely follow the conjugation pattern anticipated by the Clar aromatic sextet theory [12, 126], Three typical examples of this kind are perylene (1), dibenzo[g,p]chrisene (2) and coronene (3) ... 

The effect of the biphenyl rule is small and is usually screened by much stronger conjugation modes (e.g. those taken into account by resonance, conjug-ated-circuit and/or Clar-aromatic-sextet theories [64]), In some exceptional cases, however, the biphenyl rule can completely invert the conjugation pattern anticipated by the classical theories. This particularly occurs in benzenoid... 

Figure 3a. Conjugated pattern solvent composition, 27.0/73.0 cellulose concentration, 12g/100mL DP, 210 storage time at 25"C, 14 days.

Figure 3b c. Conjugated patterns formed at relatively high cellulose concentration solvent composition, 24.5/75.5 cellulose concentration, 18g/100mL (b), 20g/100mL (c) DP, 210 storage time at 25 C, 10 days, with 1" red plate , direction of the highest refractive index of the 1 red plate. 

Hardison, W. G-, and Grundy, S. M. l 83). tffcci of bile acid conjugation pattern on bile acid metabolism in normal humans. GusfrOfMffwtogy 84, 617-620. 

If now the tube bears defects-either vacancies or sp -hybridized carbon atoms generated by the attachment of functional groups-the complete conjugation of TT-electrons is broken and the aromatic character decreases. In detail, the defects give rise to finite sections within the tube that exhibit different conjugation patterns similar to those in short nanotubes. Then transition to another structural type is observed at the latitude of the defect. 

Egbe DAM, BaderC, KlemmE, Ding L, Karasz FE, Grvunmt UW, et al. Influence of the conjugation pattern on the photophysical properties of alkoxy-substituted PE/PV hybrid polymers. Macromolecule 2003 36(25) 9303-l 2. 

Harrison, K., P Cawood, A. Iverson, and T. Dormandy, Diene Conjugation Patterns in Normal Human Serum, Life Chem. Rep. 3 A — 44 (1985). 

A series of fused two-ring systems (77) containing pyrrole, thiophene and selenophene rings has been investigated [329,330]. Of these only the 3,2- systems polymerize to conjugated polymers since only their conjugation pattern allows an effective delocalization. The conductivity of the doped materials is, in any case, low (5 X 10 S cm ). 

In general, bridged methano[10]annulene derivatives are a very attractive class of compounds for investigating non-trivial aromatic systems. Being quite easy to be synthesized and showing a somewhat tunable conjugation pattern [84] due to the... 

N., and Wharton, B. A., 1978, Duodenal bile acid conjugation patterns and dietary sulphur amino acids in the newborn. Gut 19 95. 

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