Synthesis of sulfonylcalix[4]arene complexes and research on electrochemical detection of rutin by the composites of the complexes with multi-walled carbon nanotubes

In this study, three sulfonylcalix[4]arene complexes of [Co2TBSC(en)3]·2CH3OH (Co-TBSC), [Mn2TBSC(DMA)2(en)2] (Mn-TBSC) and [Zn2TBSC(en)2] (Zn-TBSC) were synthesized by solvothermal method with sulfonylcalix[4]arene and three different metal salts. Then multi-walled carbon nanotubes (MWCNTs) was introduced into complexes to form composites of Co-TBSC/MWCNTs(1:2), Mn-TBSC/MWCNTs(1:2) and Zn-TBSC/MWCNTs(1:2), respectively. Various physical characterizations illustrated the successful preparation of three composites. The electrochemical properties of the composites were characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The results show that they have good electrocatalytic activity and conductivity. The sensors based on the three composites were applied to determine the rutin under the optimal experimental conditions. The results showed that the detection ranges and limits of detection of three kinds of composites for detecting rutin were similar, but the sensitivities of Co-TBSC/MWCNTs(1:2) and Zn-TBSC/MWCNTs(1:2) (9.43 and 9.30 μA·μM−1) are larger than that of Mn-TBSC/MWCNTs(1:2) (5.34 μA·μM−1). Since the three composites were all obtained by mixing three complexes with MWCNTs in a mass ratio of 1:2, the different detection sensitivities may be caused by the different crystal structures of the complexes. The conclusion was further proved by density functional theory (DFT) calculation.