Synthesis and properties of novel magnetic nanoparticles grafted with nitropyridine-substituted calix[4]arene derivative as Cr^6+ extractant

A new calix[4]arene derivative, 3, which functionalized at the lower rim with 2-(2-aminoethyl amino)-5- nitropyridine, was synthesized and characterized by a combination of FTIR, 1H NMR, 13C NMR, and elemental analysis. Then the calix[4]arene 3 was grafted onto [3-(2,3-epoxypropoxy)propyl]trimethoxysilane-modified Fe3O4 – nanoparticles (EPPTMS-MN) to produce new calixarene-adorned magnetic nanoparticles (MN-DiNoPy-Calix (4)). The structure of the calixarene-adorned magnetic nanoparticles 4 was determined by a combination of FTIR, TEM, and elemental analysis. Moreover, a study regarding the removal of toxic HCr2O_7^− anion from aqueous solution was also carried out with the calixarene-adorned magnetic nanoparticles in solid–liquid extraction studies.