香豆素-3-羧酸制备实验的改进与拓展设计

香豆素-3-羧酸的制备是一个经典实验,一般是以水杨醛和丙二酸二乙酯为原料,在哌啶催化下加热回流2 h,经过两步完成。我们对该实验进行了以下改进与拓展:1)以水杨醛和米氏酸为原料,水为溶剂,在90℃下加热搅拌30 min,即可得到香豆素-3-羧酸;同时改变底物实现7-(二乙氨基)香豆素-3-羧酸的制备;2)通过观察香豆素-3-羧酸和7-(二乙氨基)香豆素-3-羧酸与稀土离子Eu^(3+)混合溶液的荧光,引入计算化学验证香豆素-3-羧酸和7-(二乙氨基)香豆素-3-羧酸对Eu^(3+)的能量转移性质。本实验涉及多个学科的重要知识点,具有较强的模块性、综合性、趣味性、教学可行性,有利于培养学生的创新能力与综合应用能力。

Growth response and toxic effects of three antibiotics on Selenastrum capricornutum evaluated by photosynthetic rate and chlorophyll biosynthesis

The effects of three types of antibiotics （erythromycin,ciprofloxacin and sulfamethoxazole） on the photosynthesis of freshwater algae,Selenastrum capricornutum Printz,were investigated by determining the growth rate,chloroplast pigments content,seven main precursors （including δ-aminolevulinic acid,porphobilinogen,uroporphyrinogen III,coproporphyrinogen III,protoporphyrin IX,Mg-proporphyrin IX and protochlorophyllide）,and photosynthetic rate during chlorophyll biosynthesis.The antibiotics significantly decreased the growth rate,chlorophyll content,and photosynthetic rate.Erythromycin induced a decreasing effect at a concentration of 0.06 mg/L,while ciprofloxacin and sulfamethoxazole achieved the same results at concentrations higher than 1.5 mg/L.Only erythromycin significantly inhibited chlorophyll biosynthesis,which indicated that it was considerably more toxic to S.capricornutum than ciprofloxacin and sulfamethoxazole,and may pose a high potential risk to aquatic ecosystems.