Optical systems more promising

In contrast, the use, in chromatography, of poly(trityl methacrylate) appears much more promising. Both the insoluble polymer and macroporous silica gel coated with a soluble polymer have been used. The latter system gives better results, especially with regard to elution time. The columns have proved quite efficient in resolution of a great variety of chiral organic compounds (365, 388). Other examples of usefiil chiral polymer supports are the substituted polyacrylamides (389). Earlier used adsorbents obtained by reacting optically active amines with polyacryloyl chloride have been superseded by new chiral phases prepared by direct polymerization of optically active acrylamides. 

In order to uncover the photophysical processes and the loss mechanism in polymeric solar cells, two main approaches can be distinguished electrical measurements and time-resolved optical spectroscopy. Electrical measurements have the fundamental disadvantage that they lack time and spatial resolution to probe the processes that occur directly after exciton ionization. To investigate these dynamics, time-resolved spectroscopy is a much more promising approach, because ultrafast laser systems allow observing these proeesses directly with subpicosecond time resolution. 

Early attempts using unidentate phosphines gave only low optical yield. Bidentate systems are more promising but there is still a problem of flexibility and rapid interconversion ... 

A significant improvement was achieved when Shvo s Ru-catalyst 2 (Fig. 12b) was employed in combination with the addition of DMP to suppress dehydrogenation reactions [106]. Poly-(R)-6-MeCL, with a promising ee of 86% and Mp of 8.2 kDa, was obtained after workup starting from optically pure (5 )-6-MeCL. The low rate of reaction compared to DKR (typically complete after 48 h with the Shvo catalyst) is attributed to the low concentration of the terminal alcohol as well as to the iterative nature of the system. Racemic 6-MeCL showed comparable rates of reaction for both enantiomers, which polymerized within 220 h with complete conversion of both enantiomers, yielding polymers of high ee (92%) and Mp (9.4 kDa). Successful polymerizations with more than 100 consecutive and iterative enzymatic additions and Ru-catalyzed racemizations on one polymer chain were realized. 

Most recently, an in vivo investigation of a NIR Con A RET system was reported and the host response characterized.114 In this work, Cy-7-labeled Con A and Alexa Flour 647-labeled dextran system were entrapped with a hollow microdialysis fiber immobilized on the tip of an optical fiber. The device was characterized in vitro, the result of which indicated a response range of 36 150 mg/dL. More important, the device was implanted subcutaneously and evaluated in vivo for 16 days. Results were promising, as the implant readout retained a high degree of correlation with blood glucose fluctuations (as measured by blood-draw methods). An increase in response time was observed at the end of the experimental period, with fibrous encapsulation cited as the cause. 

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