Photosensitive Dyes And ¦Â-cyclodextrin Research

The cyanine dyes have evoked great interest primarily because of their unrivalled ability to impart light sensitivity to silver halide emulsions in a region of the spectrum to which the silver halide is normally not sensitive. Recently, with the development of relative technology, it is found that cyanine dyes have some good optical properties, such as high extinction coefficient, wide spectrum, good fluorescence quantum yield and high spectral sensitivity. Just because of these properties, they are widely used as new fluorescent probes in labeling the biologic macromolecules, and used as recording media, et al.In this paper, the structure and quality of cyanine dyes as well as their synthesis and new applications are briefly reviewed. In recent years, microwave-assisted reactions have attracted much interest because of the simplicity in operation and the rapid synthesis of a variety of compounds. The notable features of the microwave approach are enhanced reaction rates, formation of pure products in high yields and the ease of manipulation. With the assistance of microwave irradiation, four series of photosensitive dyes are synthesized in higher yield. Meanwhile, all of them have been characterized by 1H NMR, MS, IR and UV spectra. The approach provides an attractive and environmentally friendly pathway to several useful photosensitive dyes.Despite the popularity of cyanine dyes as a class of functional compounds, there are several practical considerations that limit efficient use of these dyes. Photodecomposition and self aggregation are common phenomena associated with cyanine dyes. It is urgent to resolve these practical problems. In this paper, the inclusion phenomena of cyanine dyes and β-cyclodextrin has been investigated by UV-Vis spectrometry. The results show that the presence of β-cyclodextrin, in general, can increase the absorbance and the photostability of cyanine dyes in aq. solution and for the same series of asymmetric monomethine thiacyanine dyes, thedye with greater substituents attached to aromatic ring reveals the more enhancementin photostability. The supramolecular control of photostability of cyanine dyes isachieved through their inclusion action with β-cyclodextrin.