Anthracene-labeled

Incubation of Pseudomonas putida with anthracene-labeled carbon-base ferrichrome analog Fe(lll) complex 173 resulted in cellular iron uptake and the appearance of anthracene fluorescence in the culture medium identical to the Fe-ferrichrome uptake. Incubation with the alanyl analog 174 failed to show any significant iron uptake or fiuorescence. This is consistent with the tests described above on the unlabeled analogs. Remarkably, other strains such as Pseudomonas fluorescens S680 or WCS3742 also did not show any iron uptake or culture fluorescence. 

Fig.21. Ic/Ia for carbazole-labeled PS(OH) and anthracene-labeled PMMA in toluene as a function of the hydroxyl content in PS(OH) corresponding data taken after a small amount of THF had been added [143]...

Support for direct initiation by PS+ was recently obtained by experiments on the polymerization of cyclohexene oxide using anthracene labelled polytet-rahydofuran as the sensitizer. In this case poly(tetrahydrofuran-b-cyclo-hexeneoxide) is formed [66]. 

There are some special methods of chemical synthesis recoiling phenomenon (recoil synthesis). For example anthracene labelled with " C is synthesised by irradiating acridine with neutrons through N(n,p) C reaction. Similarly labelling is realised with the use of He( ,p) H or Li(n,a) H. For this purpose the compound to be labelled is mixed with He gas or Li,COj and then irradiated with neutrons. 

Mw = 4.1.10 was used as a matrix for FAD experiments. An anthracene labeled polybutadiene with the same microstructure was synthetized by anionic polymerization as... 

A detailed study of the FAD of anthracene labeled polybutadiene in a matrix of Diene 45 NF has been performed in the temperature range 240K-353K ( 2 ). 

In this paper, we report measurements of the orientation autocorrelation function of a backbone bond in dilute solutions of anthracene-labeled polyisoprene. The anthracene chromophore was covalently bonded into the chain such that the transition dipole for the lowest electronic excited state lies along the chain backbone. This assures that only backbone motions are detected. 

Figure 2. Transient grating decays for 9,lO-bis(methylene)-anthracene labeled polyisoprene in dilute hexane solution. Tg and Tx are the diffraction efficiencies of the grating for the probe beam polarized parallel and perpendicular to the excitation beams (see Equations 1 and 2). The two curves are initially different because the excitation beams create an anisotropic orientational distribution of excited state transition dipoles. As backbone motions occur, the transition dipoles randomize and the two curves coalesce. Both curves eventually decay due to the excited state lifetime. The structure of the anthracene-labeled polyisoprene is also displayed, with the position of the transition dipole Indicated by a double arrow. (Reproduced from Ref. 7. Copyright 1986 American Chemical Society.)...

Figure 3. Time-dependent anisotropy for anthracene-labeled polyisoprene in dilute hexane solution. The experimental anisotropy was obtained by setting the delay between the excitation and probe pulses to a given position and then varying the polarization of the probe beam. In the bottom portion of the figure, the smooth curve through the data is the best fit to the Hall-Helfand model(Ti=236 ps, t2=909 ps, and r(0)=0.250). Unweighted residuals for the best fit to this model are shown along with the experimental error bars in the top portion of the figure. Note that the residuals are shown on an expanded scale (lOx). The instrument response function is indicated at the left.

Figure 4. Time-dependent anisotropy for anthracene-labeled polyisoprene in dilute cyclohexane solution. The smooth curve through the data is the best fit to the Bendler-Yaris model(Ti=210 ps, t2=2750 ps, and r(0)=0.243).

Viovy, Monnerie, and Brochon have performed fluorescence anisotropy decay measurements on the nanosecond time scale on dilute solutions of anthracene-labeled polystyrene( ). In contrast to our results on labeled polyisoprene, Viovy, et al. reported that their Generalized Diffusion and Loss model (see Table I) fit their results better than the Hall-Helfand or Bendler-Yaris models. This conclusion is similar to that recently reached by Sasaki, Yamamoto, and Nishijima 3 ) after performing fluorescence measurements on anthracene-labeled polyCmethyl methacrylate). These differences in the observed correlation function shapes could be taken either to reflect the non-universal character of local motions, or to indicate a significant difference between chains of moderate flexibility and high flexibility. Further investigations will shed light on this point. 

It takes a finite time for the process to be completed the composition o slowly changes to the coexistent compositions (t>a and b- The process is illustrated by the horizontal arrow in Fig. 10.28. Kinetics of phase separation in a blend has recently gained considerable interest from both a theoretical and experimental point of view. Several experimental examinations were carried out to determine the concentration fluctuation during the phase-separation process taking PS/PVME as a model, which exhibits a LCST phase diagram. For example, Larbi et al. [168] observed fluorescence emission of anthracene-labeled PS in PS/PVME to investigate kinetics of both spinodal decomposition and nucleation growth. 

Table 6.1 Critical overlap concentration, C, for polystyrene coils in solution measured by energy transfer between carbazole- and anthracene-labeled polystyrene chains...

Experiments on temporally forcing of phase separation were performed using mixtures of poly(vinyl methyl ether) (PVME) and anthracene-labeled polystyrene (PSA). The phase diagram of this PSA/PVME blend is illustrated in Figure 1 together with the composition dependence of its glass transition... 

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