The host-guest system of resorcinolcalix[4]arene and pyridine-containing compounds: their syntheses, structures, antioxidant and antibacterial activity analyses

Abstract

Self-assembly of C-iso-butyl-resorcinolcalix[4]arene (CBCR) with 4-aminopyridine (4-AP) or 3-dimethylaminopyridine (3-DMAP) in ethanol afforded two host-guest complexes CBCR4-AP (1) and CBCR2(3-DMAP) (2), respectively. Complexes 1 and 2 were characterized by FT-IR, 1H NMR spectroscopies and single crystal X-ray diffraction analysis. The antioxidant and antibacterial experiments were conducted on complexes 1 and 2. The DPPH and ABTS free radical scavenging rate could reach 91.73% and 98.55% when the concentration of complex 2 was 500 and 31.25 mg/mL, respectively. The clearance rate of complex 1 for both free radicals is weaker than 2. When the concentration of 1 was 31.25 mg/mL, the ABTS free radical scavenging rate was 74.60%. The antibacterial test of complexes 1 and 2 showed that the antibacterial circle diameter of complex 1 against Escherichia coli was 10.25 mm, with a MIC value of 12.5 mg/mL, and the antibacterial circle diameter against Staphylococcus aureus was 14.33 mm with a MIC value of 3.12 mg/mL; complex 2 has a diameter of 11.27 mm and a MIC value of 12.5 mg/mL for Escherichia coli, and a diameter of 16.40 mm and a MIC value of 1.56 mg/mL for Staphylococcus aureus. Co-crystallization of pyridine-containing compounds and CBCR might enhance antioxidant and antibacterial activity.