Bifunctional Co(II)-porphyrin 1D-coordination polymer for selective cyanide sensing in tobacco smoke and efficient solid-liquid extraction

Abstract

Selective chromogenic sensing and extraction of cyanide (CN⁻) is a central issue of supramolecular chemistry and analytical sciences that impact biological and environmental chemistry. In this work, we reported a 1D coordination polymer [Co(TPyP)] (TPyP= dianion of 5,10,15,20-tetrapyridylporphyrin) that contains an open coordination site on Co(II) atom that acts as a high-affinity binding point for CN⁻ recognition. This Co(II)-polymer was structurally described by X-ray diffraction and Hirschfeld surfaces. Also, it was thoroughly characterized by several spectroscopic tools and scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDS). [Co(TPyP)] was found to be an exceptionally high overall binding constant for CN⁻ (log β= 10.04) with an equilibrium model 1:2 in CH₃CN and highly selectivity over common interfering anions including halides and basic oxyanions. Under these conditions, CN⁻ can be sense with a limit of detection of 5.40 μM by UV–Vis and visual change of the solution. On the basis of analytical tools (electrospray ionization mass spectrometry, X-ray single-crystal diffraction, infrared spectroscopy, UV–Vis) and time-dependent density functional theory (TD-DFT) calculations the spectrophotometric change is attributed to the coordination of two CN⁻ ions in the axial positions of the Co(II) atom, with simultaneous formation of anionic complex [Co(TPyP)(CN)₂]⁻².

[Co(TPyP)] can operate efficiently as an optical selective sensor for CN⁻ in commercial cigarettes in the micromolar concentration range. Additionally, this Co(II)-polymer can capture selectively CN⁻ in solid-liquid extractions. The development of bifunctional molecules able to visually sense CN⁻ ions and extract them from solid crystalline salts has not been explored until now.