A benzimidazolyl terpyridine-Fe2+ system and its recognition driven molecular model of a traffic light†
A new benzimidazolyl terpyridyl ligand (BIT) selectively detects Fe2+, F− and CN− ions in acetonitrile. The Fe2+ complex [Fe(H-BIT)2]·(ClO4)4 (1) displays the fast and selective detection of 2,4,6-trinitrophenol (TNP) with strong binding (log β = 8.51 ± 0.24) and a low limit of detection (1.4 × 10−7 M) among several nitroaromatics. The color of complex 1 changes from purple to red, yellow, and green upon the separate addition of 2,4,6-trinitrophenol and tetrabutylammonium salts of fluoride and cyanide, respectively. The overall color changes thus display a model of a traffic light. The structures of BIT, 1 and [Fe(BIT)2]·(TNP)2 (2) have been well characterized using spectroscopic techniques and single crystal X-ray crystallography.