Ketocalix[3]carbazole: facile synthesis, rigid conformation and baicalin-selective sensing

Abstract

The detection of baicalin is an important issue as far as food safety and human health are concerned, but remains less investigated. Up to now, there is no molecular fluorescent probe available for specific recognition of baicalin in water. In this study, a readily accessible method is described to prepare a conformation-locked diketocalix[3]carbazole (3). The hydrolysis of 3 generates a more rigid compound 5, which can specifically detect baicalin in water. Moreover, low toxicity of 5 toward both tumour and normal cells makes it promising for biological applications. Our work provides a facile method of preparing a conformation-frozen macrocyclic fluorescent probe for baicalin.