Resonance of poly

C Spin-Lattice Relaxation-Times and n.O.e. Values of Resonance of Poly(n-butyl methacrylate) as 50% (w/w) Solution in Toluene-2H8... 

The temperature dependence of the chemical shifts of the base and sugar resonances of poly(dA-dT) in 0.1 M phosphate buffer is plotted in Figure 3. There are upfield and downfield shifts associated with the noncooperative premelting transition between 5 and 55°C while only downfield shifts are observed for most of the base and sugar protons on raising the temperature above 65°C in the noncooperative postmelting transition temperature range. 

Figure 13. The temperature dependence of the base and sugar proton resonances of poly(dA-dT) in 1M NaCl, lOmM cacodylate solution (O), and in IM (2HtC),-NCI, lOmM phosphate solution (0). (2H C).NCI was purchased from Merck and used without further purification.

Base Proton Complexation Shifts The complexation shifts of certain nucleic acid base resonances of poly(dA-dT) on formation of the daunomycin neighbor exclusion complex reflect the shielding contribution due to the anthracycline ring less the contribution from one neighboring base pair which is displaced following intercalation. Thus, the adenosine H-2 resonance remains unperturbed (Figure 27) while the thymidine exchangeable H-3 proton... 

Synthetic polypeptides have been studied in some detail [126] as model protein systems. The a-CH and NH proton resonances of poly(y-benzyl... 

Li et al. (10) used HCF triple resonance 3D NMR to assign the H, and " F resonances of poly(l-chloro-l-fluoroethylene) (PCFE). Figure 8 shows the ID NMR spectra of this polymer. The H spectrum contains very little useful information and the C spectrum shows essentially two clusters of resonances firom C-F and CHa groups. The F spectrum contains three groups of resonances in ca. 1 2 1 ratio, fi om mm, nor/rm and rr triad stereosequences. Application of HCF triple resonance 3D-NMR is particularly usefiil in this case, since has a natural abundance of 100% and an enormous chemical shift dispersion. The sensitivity of this erqreriment is comparable to that of a simple double resonance H C -HMQC experiment. 

Hz), is very close to that (190 Hz) determined for the CF carbon resonances of polydtFS, Since the CF carbon resonances of poly-aFS occur at 6 =92,1 and 6 =101 6 ppm and are not split appreciably by stereosequence effects, it seems that the CF carbon resonance patterns of the copolymers may be useful for sequence distribution measurements CF-carbon resonances of SSS and MSM triads should be observed at (6 =92.4 and 101.9 ppm) and (6 =94.3 and 103.2 ppm), respectively those associated with (MSS + SSM) triads should be observed in the vicinity of 6 =93 and 102,5 ppm. As can be seen in Figure 10, this seems to be the case for the copolymer containing 48 mole percent aFS the observed CF-carbon resonance pattern seems to be consistent with aFS triad fractions calculated for this sample, which are (SSM4MSS) > SSS" ... 

Fig. 42. The methylene resonance of poly(isobutylene) displays a y-gauche effect, i.e. a correlation of S with + t 4. The spread within the horizontal clusters is again...

The nmr spectmm of PVAc iu carbon tetrachloride solution at 110°C shows absorptions at 4.86 5 (pentad) of the methine proton 1.78 5 (triad) of the methylene group and 1.98 5, 1.96 5, and 1.94 5, which are the resonances of the acetate methyls iu isotactic, heterotactic, and syndiotactic triads, respectively. Poly(vinyl acetate) produced by normal free-radical polymerization is completely atactic and noncrystalline. The nmr spectra of ethylene vinyl acetate copolymers have also been obtained (33). The ir spectra of the copolymers of vinyl acetate differ from that of the homopolymer depending on the identity of the comonomers and their proportion. 

ADMET polymers are easily characterized using common analysis techniques, including nuclear magnetic resonance ( H and 13C NMR), infrared (IR) spectra, elemental analysis, gel permeation chromatography (GPC), vapor pressure osmometry (VPO), membrane osmometry (MO), thermal gravimetric analysis (TGA), and differential scanning calorimetry (DSC). The preparation of poly(l-octenylene) (10) via the metathesis of 1,9-decadiene (9) is an excellent model polymerization to study ADMET, since the monomer is readily available and the polymer is well known.21 The NMR characterization data (Fig. 8.9) for the hydrogenated versions of poly(l-octenylene) illustrate the clean and selective nature of ADMET. 

In our tip-enhanced near-field CARS microscopy, two mode-locked pulsed lasers (pulse duration 5ps, spectral width 4cm ) were used for excitation of CARS polarization [21]. The sample was a DNA network nanostructure of poly(dA-dT)-poly(dA-dT) [24]. The frequency difference of the two excitation lasers (cOi — CO2) was set at 1337 cm, corresponding to the ring stretching mode of diazole. After the on-resonant imaging, CO2 was changed such that the frequency difference corresponded to none of the Raman-active vibration of the sample ( off-resonant ). The CARS images at the on- and off- resonant frequencies are illustrated in Figure 2.8a and b, respectively. 

Nuclear magnetic resonance has proved to be a valuable tool in determination of configurational sequences in poly(MMA) (14). In Figure 3 is shown the NMR of poly(MMA) synthesized with an anionic polymerization catalyst known to produce predominantly isotactic sequences. In these polymers, the NMR spectrum of the methylene units In the polymer backbone gives an unequivocal determination of tacticity. The methylene signal, occurring about 1.8... 

R.J. Lehnert, P.J. Hendra, N. Everall and N.J. Clayden, Comparative quantitative study on the crystallinity of poly(tetrafluoroethylene) including Raman, infra-red and F nuclear magnetic resonance spectroscopy, Polymer, 38(7) (1997) 1521-1535. 

Similarly, blocking MVE from quasiliving poly(IBVE) dications was accomplished. The products were fractionated with a heterogeneous mixture of n-heptane and water (5/2, v/v) the former is a good solvent for poly(IBVE) only, the latter a good solvent for poly(MVE) only. The 1H NMR spectra of the n-heptane-soluble fractions exhibited a sharp resonance at 6 3.3 ppm (-OCH3), characteristic of MVE units, and a doublet at 6 0.9 ppm (—i (CH3)2), characteristic of IBVE units. The presence of poly(MVE) segments in these fractions indicates the formation of IBVE-MVE block polymers. 

The closest physical realization of the system examined above would be a polymer such as poly(vinyl fluoride) doped into poly(ethylene) (observing the r resonance) or poly(trifluoroethylene) doped into poly(tetra-fluorethylene), observing H. Neither of these systems is likely to be sufficiently miscible, and there is the possibility of significant proportions of head-to-head linkages, which would dominate the experimental M2 because of the proximity of the spins on adjacent backbone atoms. 

Cheng et al. [116] reported that the structure of primaquine phosphate irradiated with 0.7—10 Mrad remained unchanged. The energy transfer action of the quinolyl group was considerable due to its resonance stabilization. Radiation-induced degradation of polyl(vinyl alcohol) decreased in the presence of primaquine phosphate but the degradation mechanism was unaffected. The content of primaquine phosphate showed linear relationship with degradation parameters of poly(vinyl alcohol). 

An illustrative example is the work of Clark et al, on the conformation of poly(vinyl pyrrolidone) (PVP) adsorbed on silica 0). These authors determined bound fractions from magnetic resonance experiments. In one instance they added acetone to an aqueous solution of PVP in order to achieve theta conditions for this polymer. They expected to observe an increase in the bound fraction on the basis of solvency effects as predicted by all modern polymer adsorption theory (2-6), but found exactly the opposite effect. Their explanation was plausible, namely that acetone, with ability to adsorb strongly on silica due to its carbonyl group, would be able to partially displace the polymer by competing for the available surface sites. 

L.S. Swanson, J. Shinar, Y.W. Ding, and T.J. Barton, Photoluminescence, electroluminescence, and optically detected magnetic resonance study of 2,5-dialkoxy derivatives of poly(p-phenylene acetylene) (PPA) and PPA-based light-emitting diodes, Synth. Met., 55 1-6, 1993. 

Dynamics of Poly(oxyethylene) Melts Comparison of 13C Nuclear Magnetic Resonance Spin-Lattice Relaxation and Dielectric Relaxation as Determined from Simulations and Experiments. 

The H- and C-NMR spectroscopic data support the proposed primary structure of poly(Lys-25). The amide carbonyl resonances are particularly informative as these signals are well resolved in the C-NMR spectrum of poly(Lys-25) (Figure 4). An amide carbonyl resonance is observed at 174.9 ppm for poly(Lys-25) that does not appear in the spectrum of poly(Val-Pro-Gly-Val-Gly) [13]. The position and relative intensity of this resonance are consistent with a lysine amide carbonyl group within a peptide bond [14]. Moreover, the resonances of the amide carbonyl groups for other residues in the pentapeptide repeat are split due to the substitution of a lysine residue at position 4 in every fifth pentapeptide in Lys-25. In addition, the absence of splitting in amide carbonyl group of valine in position 4 (174.5 ppm) supports this assignment, as this residue is replaced by lysine in the fifth pentapeptide of the Lys-25 repeat. The presence of other resonances attributable to the lysine residue can be detected in the H- and C-NMR spectra of the Lys-25 polymer at levels commensurate with its... 

Figure 4 Detail of the amide carbonyl resonances in the C-NMR spectrum (100 MHz) of poly (Lys-25) in 70% H2O/30% D2O solution. The spectrum was recorded on a Varian INOVA 400 NMR spectrometer. Chemical shifts were referenced to external tetramethylsilane.

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