Iodine complex structure

Miyasaka, K. PVA-Iodine Complexes Formation, Structure and Properties. Vol. 108, pp. 91-130. 

As shown in Fig. 5, the initial fast reaction is the association of bromine with the chalcogen atom to form the -complex of bromine with diphenylselenide, dicyanomethylidene telluropyran 20, and telluropyranone 22. These structures are analogous to the 1,4-diselenane iodine complex 15 (Fig. 3), whose structure has been characterized by X-ray crystallography. The second-order rate constants are on the... 

Although Schardinger did not propose a structure for his crystalline dextrins, he made several observations that can now be attributed to their cyclic structure. For example, he discovered their ability to engage in complex-formation "With various substances, the crystalline dextrins form loose complexes which, like those produced with alcohol, ether, and chloroform, are indeed partly decomposed by water, while the iodine complexes are more stable toward water. He also found, as previously mentioned, that the crystalline dextrins were nonreducing toward copper salts and nonfermentable by yeast. This last observation he considered was "... the most essential thing that I was able to mention concerning the formation of crystalline dextrins by microbes. Both of these observations can be explained by the lack of a chain termination. 

Among the widely studied [AuX(PR3)] (X = halogen, PR3 tertiary phosphine) [AuBrL] (L = 2-methylphenylphosphine) crystallizes as a folded chain [65]. Chains of the tetrahydrothiophene and tetrahydroselenophene complexes [AuX(EC4H8)] (E = S, X = Cl, Br or I E = Se, X = I) [66, 67] exhibit different patterns. In the crystal structure of the tetrahydrothiophene compounds [AuX(SC4H8)] (X = Cl, Br) neutral units associate, whereas the structure of the iodine complexes consists of Aul2 and... 

Matsuoka, H. and he, N. Small-Angle and Ultra-Small Angle Scattering Study of the Ordered Structure in Polyelectrolyte Solutions and Colloidal Dispersions. Vol. 114, pp. 187-232. Miyasaka, K PVA-Iodine Complexes Formation, Structure and Properties. Vol. 108, pp. 91-130. 

At room temperature pyridines react reversibly with halogens and interhalogens, e.g. IC1, to give unstable adducts, which behave as mild halogenating agents. X-Ray diffraction studies of the pyridine-iodine complex have given its structure (73). 

Figure 16-6 (a) Schematic structure of the starch-iodine complex. The amylose chain forms a helix around l6 units. [Adapted from A T. Calabrese and A. Khan, "Amylose-lodine Complex Formation with Kl Evidence for Absence of Iodide Ions Within the Complex." J. Polymer Sci. 1999, A37,2711.] (fc>) View down the starch helix. Showing iodine inside the helix.8 [Figure kindly provided by R. D. Hancock, [rower Engineering, Sett Lake City.]... 

While the range of copper(II) complexes involving Cu—Br bonds (Table 81c) is more limited than those for Cu—Cl bonds (Table 81b), the structures tend to be analogous, with short Cu—Br distances of 2.4 A and long distances of ca. 3.0 A. Simple iodine complexes of the copper(II) ion are unknown, in view of the ready reduction of copper(II) to copper(I) with the liberation of iodine, nevertheless, copper-iodine bonds are formed if the copper(II) ion is stabilized by complex formation, as in [Cu(bipy)2I]I (420),1299 the structure of which involved the first example of five-coordinate copper(II) stereochemistry.1300 Semi-coordinate iodide... 

The PVA-Iodine complexes formed in PVA films soaked in iodine-KI aqueous solutions without boric acid are studied from the structural point of view. First, iodine soaking at comparatively low iodine concentrations is studied where iodine sorption takes place mostly in the amorphous phase. There, our interest is concentrated on the following problems What happens in PVA films during iodine soaking How does the solid structure of PVA films affect the formation and properties of the complex How does the chain extension affect the complex formation and properties What is the structure of the complex formed in the amorphous phase Then iodine soaking at high iodine concentrations is studied where iodine sorption takes place in the crystal phase as well as in the amorphous phase. 

Structure of the PVA-Iodine Complex Formed in the Amorphous Phase of PVA Films. 110... 

The blue PVA-Iodine complex was first found by Herrmann et al [5] who first synthesized PVA, and by Staudinger et aL [6] as early as 1927. Since then, the complex has attracted the interest of many researchers, and many studies have been done from different points of view. Some studied the complex formed in PVA solutions, while others studied the complex formed in bulk (film and fibers) PVA. Some concentrated their attentions on the effects of the PVA molecular structure on the complex formation, i.e. the 1,2 glycol hetero structure content of the chain backbone [10-12], the stereoregularity [10,11,13-15], the degree of saponification [16-18] and the chemical modification such as formalization [18-20]. 

In this manuscript, the author would like to review the structural studies, made by his group, on the PVA-Iodine complexes formed in PVA films soaked in iodine-KI solutions. This review starts with what happens during soaking of PVA films in iodine, discusses next the effects of structure and extension of PVA films on the formation and properties of complexes, and ends with the structures of the complexes. 

Our structure studies on the PVA-Iodine complexes formed in PVA films soaked in iodine-KI solutions without Boric add have been reviewed in this paper. 

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