Colorimetric “naked eye” detection of CN−, F−, CH3COO− and H2PO4− ions by highly nonplanar electron deficient perhaloporphyrins

Abstract

Highly nonplanar perhaloporphyrin-based receptors have been synthesized and characterized by various spectroscopic techniques. Nonplanar and electron deficient nature was authenticated by electronic spectral, electrochemical redox and protonation–deprotonation studies. The colorimetric “naked eye” anion sensing ability of these sensors was probed by spectroscopic and electrochemical studies. These receptors were found to be highly selective and sensitive for the basic anions, such as CN⁻, F⁻, OAc⁻ and H₂PO₄⁻, over the tested anions and were able to detect these anions even at nanomolar concentrations via anion induced deprotonation. These perhaloporphyrin receptors have been recovered from receptor–anion host–guest complexes formed during sensing events by acid treatment and were reused for the detection of basic anions without loss of their sensing ability.