Poly -based indicators

The question mark ( ) indicates the hypothetical positions of Pt(poly) based on the Ea value given by Frumkin,10 and of Pt(l 11) based on the Eano value proposed by Iwasite.210... 

Homopolymers of simple alkyl and aryl isocyanides (Mv.p.osm > 1000-4000) are insoluble in all common solvents. This statement, however, requires elaboration of the fact that trichloroacetic acid successfully disperses these polymers. Observations with poly(cr-toluyl isocyanide) are informative, since the polymer is canary yellow in color, and turns to dark brown in trichloroacetic acid—acting in the manner of an acid-base indicator dye. Dilution with water of the trichloroacetic acid solution of poly(aqueous alkali produces the original yellow color. It appears that the polyisocyanide is dispersed in trichloroacetic acid as a pro-tonated species. Conductimetric experiments on poly(a-phenylethyl isocyanide) in dichloroacetic acid confirm this view (25). 

Poly (vinyl alcohol)-Based Indicators for Optical pH and Mg(II) Sensing... 

In contrast to polycarbodiimides having a rather dynamic helical structure, a stable, static helix can be obtained from a bulky monomer, 158, by polymerization with an achiral titanium(IV) salt. Poly-159 indicated a large dextrorotation ([a]o+791°) based on a single-handed helical structure. The single-handed helix remained stable even after heating at a high temperature for more than 34 h. 

The band structures of the periodic DNA models obtained with the aid of the PPP CO method can be divided into two groups. The five homopolynucleotides (also including poly and the two poly (base pairs) [poly(A-T) and poly(G-C)]< > possess rather broad bands (the widths of the valence bands are 0.2-0.3 eV, those of the conduction bands about 0.1 eV, and the widths of the lowest filled bands are in most cases approximately 1 eV). On the other hand, for the more complicated periodic DNA models, where we have two different base pairs in the unit cell, such as poly(Glc). the bands are very narrow (the widths of the valence bands are usually 0.01-0.03 eV, those of the conduction bands about 0.01 eV, and the widths of the lowest filled bands are approximately 0.1 eV). The CNDO/2 CO calculations of periodic base stacks and of the sugar-phosphate chain of DNA< > again give rather broad bands [valence bandwidths between 0.15 and 0.50 eV for the base stacks and 0.05 eV for poly(SP), and conduction bandwidths 0.1-0.25 eV for both kinds of system], while the MINDO/2 CO results for the base stacks indicate somewhat less-broad bands (widths of valence bands 0.03-0.30 eV and of conduction bands 0.03-0.17 eV). Further details of the PPP and all-valence-electron CO calculations of different periodic DNA models can be found in original papers " as well as in a review paper. ... 

C27H27Br2N07S M 669.387 Used as acid-base indicator (pH range 7.S-9.5 colour change yellow blue). Used attached to amino groups on the surface of poly(methylmethacrylate) fibre. Pink cryst. powder. Sol. EtOH, alkalis insol. H2O. 8.5. Puschett, J.B. et al, Talanta, 1991, 38, 335 synth, use)... 

Phosphaies are used in an astonishing variety of donicsiic and industrial applications but their ubiquitous presence and their substantial impact on everyday life is frequently overlo(4ted. It will be convenient first lo indicate the specihc uses of individual compounds and the properties on which ihey are based, then to conclude with a brief summary of many diffcreni types of application and their interrelation. TTie most widely used compounds are the various phosphate salts of Na, K. NH4 and Ca. TTie uses of di-. iri- and poly-phosphaie.s are mentioned on pp. 527-29. 

The important action of electrostatic forces between a cationic model and an anionic polynucleotide is clearly shown in Fig. 7. The hypochromicity sharply decreased with the ionic strength of the solution, which indicates that the base-base interactions between A12 and Poly U supported by the electrostatic attractive forces are weakened by the shielding effects of added salts. 

The thermal properties of tyrosine-derived poly(iminocarbonates) were also investigated. Based on analysis by DSC and thermogravi-metric analysis, all poly(iminocarbonates) decompose between 140 and 220 C. The thermal decomposition is due to the inherent instability of the iminocarbonate bond above 150°C and is not related to the presence of tyrosine derivatives in the polymer backbone. The molecular structure of the monomer has no significant influence on the degradation temperature as indicated by the fact that poly(BPA.-iminocarbonate) also decomposed at about 170 C, while the structurally analogous poly(BPA-carbonate) is thermally stable up to 350 C. 

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