Picolinamide calixarenes

Distribution Ratios3 and Selectivity for the Extraction of Am and Eu from Aqueous Solutions 10 3 M HN03 into a NPHE/3 10 3 M [Bromocosan] Solution of Picolinamide Calixarenes... 

Under the same conditions, in contrast to what is observed for calix[4]arene-bearing CMPO moieties, with CPil2, distribution ratios of lanthanides increase from the lightest lanthanide, lanthanum, to europium. Americium can be easily separated from the lightest lanthanides (separation factor DAm/La > 20, DAm/Ce =15, /lAlll,Nd = 10, UAi /si = 7.5, DAm/Eu = 6), which are the most abundant lanthanides in fission-product solution. Cavitands bearing picolinamide (Cv5) or thiopicolin-amide (Cv6) residues seems much less selective than their calixarene counterparts, giving SAm/Eu < 2.18... 

Picolinamide and thiopicolinamide have been introduced on the lower rims of calixarene scaffolds of various sizes in order to study whether the size of the macrocycle, the cooperation and stereochemical disposition of these binding groups affect the efficiency of extraction and selectivity in the actinide/lanthanide separation. Thus, picolinamide conjugates of calix[4]arene 38-40 and those of calix[6]arene 42-44 and of calix[8]arene 45 and 46 have been formed from appropriate amino derivatives of the corresponding calixarenes and picolinic acid pentafluorophenyl ester. The thiopicolinamide analog 41 has been synthesized from 40 and Lawesson s reagent (2005EJO2338). 

STRUCTURE 19.3 (a) Tetrafunctionalized cavitands (tetrakis(diphenyl-(N-methylcarbamoyl) methyl phosphine oxide) cavitand for IR = H, 2R = Ph), (b) calixarene-based picolinamides (5,11,17,23,29,35, 41,47-octakis(phenylmethoxy)-49,50,51,52,53,54,55,56-octakis 3-[(pyridine-2-carboxy)amino]propoxy calix[8]arene for n = S,m = 3,R = OBn). 

Casnati, A., Della Ca , N., Fontanella, M. et al. 2005. Calixarene-based picolinamide extractants for selective An/Ln separation from radioactive waste, Eur. J. Org. Chem. 2338-2348. 

Galletta, M., Macerata, E., Mariani, M. et al. 2006. A study on synergistic effects and protonation of a selected calixarene based picolinamide ligand used in the An/Ln separation. Czech. J. Phys. 56 D453-D458. 

---