The Role of a Nitro Substituent in C-Phenylcalix[4] resorcinarenes to Enhance the Adsorption of Gold(III) Ions

摘要

Nitro-substituted C-phenylcalix[4]resorcinarene derivatives were synthesized and evaluated for gold(III) ions adsorption. All the nitro-substituted C-phenylcalix[4]resorcinarenes showed higher maximum adsorption capacity as compared to the bare C-phenylcalix[4]resorcinarene. A remarkable high adsorption capacity of up to 272.70 mg g~(-1) was obtained after 2 h on the C-2-nitrophenylcalix[4]resorcinarene (Calix-2NO2), which was two times higher than that of the C-phenylcalix[4] resorcinarene. The adsorption capacity was affected by the position of the nitro group. The highest adsorption capacity observed on the Calix-2NO2 was closely related to the strongest supramolecular interactions between the gold(III) ions and the Calix-2NO2, as supported by Fourier transform infrared (FTIR) and proton nuclear magnetic resonance (~1H-NMR) spectroscopies as well as the desorption study. This study demonstrated that the macrocyclic material, namely nitro-substituted C-phenylcalix[4]resorcinarenes, were effective adsorbents having good reusability, and thus, applicable for gold(III) ions recovery.