Polyiodine chains

The amylose-iodine interaction has a dipolar nature, as deduced from a distinct difference between the molecular coefficient of iodine in starch and in nonpolar solvents.123 The additional stabilization may result from the formation of resonating polyiodine chains at high dipolar interactions. The composition of the total energy of stabilization is shown5 in Table VI. 

It is clear from the accunulated evidence that the stabilization energy of the complex can be realized only if the triiodide ion is present. Moreover, I has a considerably higher affinity for the polysaccharide matrix than does I in the absence of cooperative interactions along the polyiodine chain (3, 2 ). These circumstances suggested to us that the complexation process is... 

Results are plotted as the dashed curve in Figure 4a. As expected, the average length of the polyiodine chains declines with increasing [l ] for fixed 9 = 1/2, because higher results in more chain initiations under conditions of fixed total bound iodine. When is converted to X using Equation 14,... 

X excitation as expected, but that the position of the 162 cm Raman line remains unchanged from DP 18 to 190. This invariance of the Raman band position with amylose chain length indicates, that this vibration mode is independent of the polyiodine chain length. 

There is a mar)ced difference in the CD spectra measured immediately after addition of iodine and after 24 hours. This is in contrast to only a minor change in the absorption spectrum, which indicates that little happens to the polyiodine chain. 

Resonance Raman measurements with iodine-complexed amyloses have shown that the vibration modes typical of the iodine species bound in the complex do not depend on the length of the polyiodine chain. Evidently these signals only give information about short sections of the polyiodine chain, as could be expected on the basis of Raman spectroscopy. Even at... 

Furthermore, it is reasonable to assume that a tie chain whose freedom of movement is highly restricted by crystal interfaces can hardly form a helix to surround a polyiodine for making a complex. These considerations and expert-... 

In addition to If there are numerous other polyiodine anions, especially those shown in Fig. 13-4. These are all formed by the relatively loose association of several I2 molecules with one or two I- ions.6566 For If there may be either discrete bent ions or infinite chains. The If ion can be described as an If ion to which two I2 molecules are attached, while If seems to be a very loose aggregation. The I4" ion has two 1 ions associated with an I2 molecule and Ican be described as I4 to which two more I2 molecules are attached. The well-known blue starch-iodine compound has linear If ions in the amylose helix. 

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