Coumarin, molecular formula: C9H6O2, relative molecular weight 146.15, white crystalline solid, melting point 68 ~ 70 ° C, boiling point 298°C/266Pa, relative density 0.9350. It is naturally found in black fragrant beans, cockleburs, wild vanilla, orchids, and has fresh hay and fragrant fragrant incense. In general, it is not edible, and tobacco and external use are allowed. On October 27, 2017, the list of carcinogens published by the International Agency for Research on Cancer of the World Health Organization has initially compiled and referenced, and coumarin is in the list of 3 types of carcinogens.
Figure 1. Chemical structure of Coumarin.
Coumarins inhibit the synthesis of coagulation factors in the liver. Coumarins are similar in structure to vitamin K. Coumarins bind to vitamin K epoxide reductase in the liver, inhibit the conversion of vitamin K from epoxide to hydroquinone, and inhibit the circulation of vitamin K. Coumarins can be said to be vitamin K antagonists or competitive inhibitors (see enzymes). The carboxylation of coagulation factors II, IX, IX, X, and X containing glutamic acid residues is inhibited, and its precursors are not coagulant, so the coagulation process is suppressed. But it has no effect on established clotting factors.
Coumarin compounds are an important component of fluorescent dyes. They can be used in the fields of fluorescent dyes, laser dyes, and optoelectronic materials. They are a class of benzopyran structures with high fluorescence quantum yield (φf). Stokes with large displacement (Stokes, Chinese translation Stokes, unit of dynamic viscosity, equal to cm / s), compounds with adjustable photophysics and photochemistry, and good light stability, have become the preferred fluorescent group in the molecular design of fluorescent sensors. From the perspective of molecular structure, the coumarin compound inhibits the rotation of the double bond through the lactone structure and improves the light stability. Studies on the relationship between the structure and fluorescence properties of coumarin compounds have shown that the fluorescence of coumarin compounds is related to the intramolecular charge transfer from the 7-position electron-donor group to the hydroxyl group in the lactone bond in the coumarin ring. Moreover, various functions can be achieved by slightly changing the donor-acceptor portion of the substituent on the coumarin parent. Changes in the properties of the 7-position electron donor group and the 3- and 4-position electron withdrawing group on the coumarin molecular structure can cause the coumarin compound to change from yellow, red to blue-green and different fluorescent properties. The function of coumarins depends to a large extent on the nature of the substituents at each position of the coumarin ring, especially the effects of the substituents at the 3- and 4-positions are more pronounced. In 1868, Perkin first used salicylaldehyde and acetic anhydride as raw materials. Cycloaddition in the presence of sodium acetate yielded coumarin. This method has been the main method for the industrial production of coumarin. The 3-aryl substituted coumarin is obtained by adding salicylaldehyde and benzoic acid derivatives as raw materials and heating and cycloaddition under basic conditions such as pyridine or triethylamine.