Effect of the [2-(diphenylphosphorylmethoxy)phenyl]diphenylphosphine oxide derivative structures on the extraction and ion-selective properties toward rare-earth elements

The effect of structures of the derivatives of [2-(diphenylphosphorylmethoxy)phenyl]-diphenylphosphine oxide (L 1 ) on the complexation properties toward rare-earth elements (REE) was studied. A new structural analogue of L 1 , isopropyl 2-(diphenylphosphorylmethoxy)benzoate (L 3 ), was synthesized. The extraction of REE by the carboxylated podand L 3 in a 1,1,7-trihydrododecafluoroheptanol—water system with the HNO 3 concentration varied in a range from 1 to 6 mol L −1 was studied. The stability constants of the neodymium(iii) and erbium(iii) nitrate complexes with L 3 and 1-(methoxydiphenylphosphoryl)-2-diphenylphosphoryl-4-ethylbenzene (L 2 ) and of lutetium(iii) nitrate and chloride complexes with L 2 in 1,1,7-trihydrododecafluorheptanol were determined. The properties of the membranes of the ion-selective electrodes based on L 1 , L 2 , and L 3 toward REE cations were tested. The crystal structures of L 3 and [NdL 3 (NO 3 ) 3 (DMSO) 2 ] were determined by X-ray diffraction analysis.