Iron compounds luminol chemiluminescence

Ironically, the synthesis and chemiluminescent properties of some of these important compounds were first reported in the 1920s i.e., acridine-9-carboxylic acid, a precursor of acridinium esters, was synthesized in 1928 (L7), which was the same year that Albrecht described the chemiluminescence of luminol (A8). The emission from lucigenin, a 6is-acridinium analog, was reported 7 years later by Gleu and Petsch (G7). 

Luminol (LOO-min-ol) is a substance that glows when it come in contact with blood. It was discovered in the late nineteenth century, but chemists found little use for the compound for half a century. Then, in 1928, the German chemist H. 0. Albrecht found that the addition of hydrogen peroxide to luminol produces a bluish-green glow, an example of the phenomenon known as chemiluminescence. Chemiluminescence is the process by which light is emitted as the result of a chemical reaction. Albrecht found that the reaction between hydrogen peroxide and luminol required a catalyst, a small amount of a metal such as copper or iron. 

The reaction process is considered to be the same for similar compounds, but the sensitivity of chemiluminescence has been suggested to be structure-dependent. The reactivity of a compound contributes to its sensitivity. Phenacylalcohol derivatives have been detected with different sensitivities in chemiluminescence analysis.In radical reactions, the reaction proceeds as follows in buffered solutions, a compound such as phenacylalcohol is easily attacked by oxidation if traces of a copper or iron salt are present, and the superoxide reacts with luminol or lueigenin to produce chemiluminescence as shown in Figure 11.7. 

A further example is the well-known chemiluminescent compound lumi-nol [436] Luminol reacts with the iron in hemoglobin and is used in forensics to detect traces of blood its pK s are reported to be 6.74 and 15.1 [436], The first ionization takes place at the lower of the two ring N-H groups. 

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