Fluorescence modulation of cadmium sulfide quantum dots by azobenzene photochromic switch

wallpapers Industry 2021-04-29
Fluorescence modulation of cadmium sulfide quantum dots by azobenzene photochromic switch
Semiconductor quantum dots (QDs) are inorganic particles with nanoscale properties that reveal a variety of photophysical and photoelectronic properties, which could lead to a wide range of future applications in biomedical imaging and photodetectors. In the last few decades, great progress has been made in this field. These miniaturized particles exhibit clear emission bands, precisely located in the visible and near-infrared regions of the electromagnetic spectrum. They also have large extinction coefficients in the UV-vis region. Their long luminous lifetime and photobleaching resistance make them a potential alternative to organic dyes.
The adhesion of azobenzene photochromic switch on CdS (CdS) quantum dots was studied. The size of CdS quantum dots is controlled by changing the concentration of the capping agent (thioglycolic acid) and NH3. X-ray diffraction studies show that the grain size of CdS quantum dots is in the range of 6 ~ 10 nm. Fluorescent photochromic CdS-(I) and CdS-(II) dicads were synthesized by combining azobenzene photochromic derivatives bis (4-hydroxy-benzene-1-azo)4,4 '(1,1 'diphenyl methane)(I) and 4,4' -diazobenzene dibenzoic acid (II) with surface-modified CdS QDS. Under ultraviolet irradiation, the photochromic compounds (I) and (II) undergo reversible trans-cis isomerization. The photochromic compounds (I) and (II) of the photo-induced trans-cis transformation contribute to the transfer of photo-excited cis isomers of the conduction band Cd of the quantum dot electrons in the lowest occupied molecular orbital. Thus, the fluorescence of Cd - (I) and Cd (II) is doubly suppressed approximately five times compared to the quantum dots of Cd. Fluorescence modulation in such a system can aid in the design of fluorescent probes for biological imaging applications.