Synthesis, Crystal Structure and Optical Properties of 2-(3-(Hexyloxy)-5-Methylphenoxy)-N-(4-Nitrophenyl)acetamide for Anion Detection

Abstract

In this study, 2-(3-(hexyloxy)-5-methylphenoxy)-N-(4-nitrophenyl)acetamide (sensor L1) was synthesized and characterized by FT–IR, ESI–MS, 1H and 13C NMR spectroscopy, elemental analysis, and single crystal X-ray techniques. The crystal structure and space group of sensor L1 was monoclinic and P21, respectively. The crystal packing of sensor L1 was dominantly linked by two strong hydrogen bonds forming a six membered ring pattern. The binding properties of sensor L1 and various anions (F−, Cl−, Br−, CH3COO−, C6H5COO−, and H2PO4−) were investigated by UV–Vis and 1H NMR spectroscopy in DMSO. The proton resonance signals of sensor L1 and F− greatly changed positions when compared to those of anions. The solution color of sensor L1 changed from pale yellow to orange in the presence of F−. The UV–Vis results indicate that sensor L1 and F− ions underwent an internal charge transfer process. The stoichiometric complex was confirmed by Job’s method, revealing a 1:1 formation for sensor L1 and fluoride. Our results show that sensor L1 is highly selective for fluoride ions over other anions.