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

Abstract

AbstractNitro‐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.