Poly structural analysis

Fig. 13. (g+aaaag aaa) conformation of crystalline erythrodiisotactic poly(l,2-dimethyltetra-methylene) according to an X-ray structural analysis of Natta el al., Ref. z8>)... 

After the first report on the crystal structure correlation between 2,5-DSP and poly-2,5-DSP crystals, a different crystallographic result was reported on a poly-2,5-DSP crystal (Meyer et al., 1978). It was reconfirmed, however, that the first structural analysis was correct (Nakanishi et al., 1979a). 2,5-DSP, crystallized from benzene solution, is highly photoreactive (a-form), while the same compound, sublimed at a rather high temperature... 

BD Barr-Howell, NA Peppas. Structural analysis of poly(2-hydroxyethyl methacrylate) microparticles. Eur Polym J 23 591-596, 1987. 

M. Leclerc, F.M. Diaz, and G. Wegner, Structural analysis of poly(3-alkylthiophenes), Makromol. Chem., 190 3105-3116, 1989. 

Diederich and coworkers [10] synthesized so-called dendrophanes (Figure 13.6) containing a paracyclophane core embedded in dendritic poly(ether-amide) shells. X-ray crystal-structure analysis indicated that these dendrimers had an open cavity binding site in the center, suitable for the binding of aromatic guests. NMR and fluorescence titration experiments revealed a site specific binding between these dendrimers and 6-(p-toluidino)naphthalene-2-sulfonate (TNS) with a 1 1 association. Also, the fluorescence spectral shift of TNS, which is... 

Crystal structure analysis of poly(p-xylylene) (PPX) P-form [2,25]... 

Crystal structure analysis for poly(p-benzoic acid) whisker [40] and stmctural study of stacking faults in s5mdiotactic pol5 ropylene [41] were carried out. 

A study of methods for controlling the grafting sites of polystyrene polymers may serve as an example for the quantitative and structural analysis of the site of lithiation. Trimethylsilyl chloride serves as the quenching agent owing to the low incidence of side reactions besides metal replacement. Thus, on varying the conditions of metallation of low molecular weight polystyrene (409) and poly(4-methylstyrene) (410), aromatic and... 

Lang M, Wong RP, Chu C-C (2002) Synthesis and structural analysis of functionalized poly (s-caprolactone)-based three arm star polymers. J Polym Sci A Polym Chem 40 1127-1141... 

Matsumoto K, Kondo K., Ota T., Kawashima A., Kitamura, K, Ishida T. (2006) Binding model of novel 1-substituted quinazoUne derivatives to poly (ADP-ribose) polymerase-catalytic domain, revealed by X-ray crystal structure analysis of complexes. Biochi. et Biophy. Acta. 1764,913-919. 

Few neutron or electron diffraction studies have been reported, although the neutron structure analysis of substituted poly(benzobisthiazole) and poly(benzobisoxazole) derivatives of 19 and 5 has been reported and the torsion angle between the benzobisthiazole and phenyl rings was shown to be 7.2° larger than that determined from X-ray methods <1999MM4010, 2001MM2012>. 

Infrared and Raman spectra are useful, of course, in determining the symmetry of poly(nitrile) complexes. An example is dichlorobis(benzonitrile)platinum, a versatile starting material in platinum chemistry. There is a dispute in the literature as to whether it has a cis or trans configuration. (There is a general agreement that the corresponding Pd complex is trans.) It has recently been shown by X-ray structure analysis that both cis and trans complexes exist, and their vibrational spectra have been discussed.21... 

Polyanilines. Initial preparations of polyaniline (PANI) led to insoluble materials that were difficult to characterize. Use of model compounds and polymers (124,125) allowed for definitive structural analysis. Poly(/>-phenylene amineimine) (PPAI) was synthesized direcdy to demonstrate that PANI is purely para-linked (126). The synthesis was designed so as to allow linkage through the nitrogen atoms only (eq. 9). Comparison of the properties of PPAI and PANI showed PPAI to be an excellent model both structurally and electronically. 

The 13C chemical shift contour map for the Cp carbon of the L-alanine residue in peptides and polypeptides was made as a function of the dihedral angles(, W) by using the experimental data. Also, the corresponding calculated map was made by using the ab initio coupled Hartree-Fock method with the gauge included atomic orbitals(GIAO-CHF). From these results, it was found that the calculated map explains the chemical shift behavior of the a-helix and p-sheet forms in poly(L-alanine) and some proteins. This suggests that the calculated map is applicable to the structural analysis of proteins with complicated structure. 

From these results, it was found that the calculated map explains well the chemical shift behavior of the a-helix and p-sheet forms in poly(L-Ala) and some proteins. This suggests that the calculated map is applicable to the structural analysis of proteins with complicated structure. 

Fluorine-19 NMR spectroscopy has had widespread use in the structural analysis of polymers. This is because the presence of a fluorine in a monomer leads to a polymer where the fluorine may be in a range of environments, leading to a range of peaks which are not obscured by other resonances from elsewhere in the molecule as they are for proton and carbon NMR. Figure 5 shows the fluorine-19 spectrum of poly(tetrafluoroethene), 11. Each carbon in the chain can have the R or S configuration with respect to each end of the chain, such that pairs of adjacent centres can be meso, m, or racemic, r. Depending upon the configuration of the two carbons to either side of the fluorine, different resonances are... 

The structural analysis has been carried out right up to the recognition of molecular Level (i, 2). a-Chymotrypsin is poly(amino acid) consisting of 245 amino adds, having relatively deep grooves. It catalyzes the hydrolysis of carboxylic acid derivatives such as protein, simple amides, esters, etc. The active site is composed of aspartic add, Asp (102). .. histidine, His (57). .. serine, Ser (195), and the distances between Asp. .. His and His... Ser are 2.8 A and 3.0 A, respectively. Electronic structures of these moieties depend on the pH of the reaction system. In the range of pH > 7 at which a-chymotrypsin is active, —COO" of Asp attracts N4 proton in imidazolyl of His, and Nj in the imidazolyl of His attracts the proton in OH of Ser. It is called charge-relay system . 

After completion of the calculations182 on poly(Gly-Pro-Pro), it was learned that Okuyama et al.187 had carried out a single-crystal X-ray structure analysis of (Pro—Pro—Gly)10. The calculated structure (Figure 25) is in agreement with theirs, with a root-mean-square deviation of 0.3 A for all (nonhydrogen) atoms, based on a comparison between the X-ray coordinates (kindly provided by Professor M. Kakudo) and the computed coordinates. 

The reactions of alkynes or alkenes with Ni-R bonds are important in organic synthesis, particularly when they involve metallacyclic precursors because these reactions lead to synthetically valuable poly- or heterocyclic derivatives. A crucial question in this context is the regioselectivity of the insertion reaction. To address this issue, a systematic study has been carried out on the insertion of various unsymmetrical alkynes into the Ni-C(sp ) bond of the nickellacycle (8) (Scheme 14) structural analysis of the fairly stable 7-membered ring Ni-aUcenyl products (9) indicates that the insertions are primarily governed by electronic factors. ... 

Fundamental to the formation of pigment clusters are the structure and organization of the antenna polypeptides [2,3,9]. As structural analysis has shown to date, all pigment molecules are bound at defined binding sites (not covalently bound Chi, BChl, carotenoids covalently bound bilins) to relatively small poly-... 

Products 82 are of low chemical stability and rapidly decompose (several minutes) in air decomposition is slower (several days) in the absence of water and oxygen. Thus, these investigations have defined general limitations for poly(arylenemethide) synthesis, set by their chemical instability. A structural analysis of a decomposed ladder-type poly(arylenemethide) 76 has clearly shown that the bridge (methide position) is the site of attack with formation of hydroxyl- or hydroperoxyl-groups [102]. 

When BuSi(0SiMe20H)3 is heated, poly-condensation is immediately started, forming many different products. In order to synthesize low-molecular condensates, we have reacted BuSi(OSlMe2Cl)3 with one equivalent of the triol BuSi(0H)3 using triethylamine as HCl captor (compare also Eq. 2) the cage like BuSi(0SiMe20)3Si Bu is formed in 60% yield. In Fig. 3 the result of an X-ray structure analysis is depicted. Bicyclic molecules with the same skeleton of atoms but with different substituents are known [20,21]. 

Six spin-coupling pathways are subtended by typical glycosidic linkages, and in the structural analysis of oligo- and poly-saccharides, it would clearly be advantageous to use as many of these coupling constants as possible for the definition of molecular geometry, particularly in view of the limited number of NOEs observed in these systems. 

The angle between the NH and the fiber axis, was calculated as well as the angle, 0nc - These coincide with data from an X-ray diffraction analysis 0nh = 68° and c = 49° from NMR and 0nh = 66° and 0nc = 49° from X-ray diffraction analysis. A similar structural analysis with solid-state NMR was performed for poly(m-xylene-a,a -diyladipamide) and nylon 66 [28]. 

In practice the type of support used most widely is a lightly crosslinked poly(styrene-divinylbenzene) system usually in the form of spherical beads —50-500 pm in diameter produced by suspension polymerisation [51]. Typically the level of the crosslinking comonomer divinylbenzene used is only —0.5-2.0 vol%. This is crucial in terms of structural analysis by NMR, since such lightly crosslinked systems can swell considerably in suitable solvents (up to —15 fold), such that the local environment around a functional group attached to the polymer network can approach closely to that in isotropic solution (see later). 

The structural analysis using high resolution solid-state NMR has been successfully performed on other conducting polymers such as polyphenylene vinylene [21], polyaniline [22-24], polyphenylene sulphide [25, 26] and poly-p-phenylene [27-29]. 

Brand F, Dautzenberg H. Structural analysis in interpolyelectrolyte complex formation of sodium poly(styrenesulfonate) and diallyldimethylammonium chloride-acrylamide copolymers by viscometry. Langmuir 1997 13(11) 2905-2910. 

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