Applications of CDs in spectroscopy

The high electron density existing inside the CD cavity can grip the electrons of the encapsulated guest molecules, and result in a various spectral properties of both the guest and host [61]. This effect of CDs on the spectral properties of guest molecules has led to their utilization in various spectrometric analyses, such as UV/VIS spectrophotometric analysis, fluorescence and luminescence spectroscopy and NMR spectroscopy. 

CDs could effectively change UV/VIS spectral properties of guest by complexing the guest. Usually, the intensity and position of the absorption bands in the spectrum are varied after the formation of an inclusion complex. Due to the hydrophobic 

It has been reported that y3-CD could improve the selectivity of the color reactions of various metal ions with triphenylmethane, xanthene acid dyes and some other coloring reagents. The effect of fi-CD on the association compound system of metal (Mo, Zn, Co)-thiocyanate basic dyes such as malachite green, crystal violet, rhodamine B, rhodamine 6G and butyhhodamine B, has been investigated and the result shows that /3-CD could contribute to a more sensitive and stable system which improve the solubility of the basic dyes and produce a favorable microenviromnent for the color reactions [63]. /3-CD could be employed to solubilize the 1,2-amino anthraquinone in water due to the formation of inclusion complex which acts as a ligand for metal ions could be used for the determination of palladium at trace levels by spectrophotometry. In the spectrophotometric determination of microamounts of Zn based on the Zn-dithizone color reaction, -CD could increase the apparent molar absorptivity at 538 nm by 8.37 times. In the presence of cr-CD, the determination sensitivity of copper in leaves based on the color reaction of Cu(II) and mesotetrakis (4-methoxy-3-sulfophenyl) porphyrin was enhanced by 50% in the spectrophotometric analysis [64,65]. 

CDs also can be used as stabihzersfor color indicators to increase the stability of indicators used for the spectrophotometric determination of hydrogen peroxide in body fluids. In addition, CDs and their derivatives also have applications in enzyme assays and enzyme activity measurement. For example, glucosyl- or maltosyl-a-CD have been used to increase the accuracy and sensitivity of the assay of amylase. 

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