Complexation of phosphoryl-containing mono-, bi- and tri-podands with alkali cations in acetonitrile. Structure of the complexes and binding selectivity

• DOI: 10.1039/a708245b
• Publication Date: 2002-07-26T09:21:54Z
• Authors: Vitaly P. Solov’ev; Vladimir E. Baulin; Nadezhda N. Strak...; Vladimir P. Kazac...; Vitaly K. Belsky; Alexandre A. Varnek; Tatiana A. Volkova; Georges Wipff
• Keywords: Phosphine oxide

We present experimental and theoretical studies on new ionophores (L) which possess a high complexation ability for Li+ or Na+ cations. Four tri-podands (R1–O–C2H4–)3N [R1 = –CH2–P(O)Ph2 (P1), –C2H4– P(O)Ph2 (P2), -o-C6H4P(O)Ph2 (P3) -o-C6H4–CH2–P(O)Ph2 (P4)], one bi-podand (R2–O–C2H4–)2N–CH3 [R2 (P5)] mono-podand [R2–O–(CH2–CH2–O)3–R2 (P6)] containing phosphine oxide terminal groups have been synthesised. Stability constants, enthalpies entropies of their with lithium, sodium potassium thiocyanates determined in acetonitrile at 298 K by calorimetric titration technique. find that form variety complexes [(M+)3L, (M+)2L, M+L M+L2)], whereas the bi- only Na+, M+L2 K+. Formation poly-nuclear (M+)nL solution has confirmed electro-spray mass spectrometry. At relatively small concentrations ligand (C 0L), P1 binds much better than Li+, P4 P5 display remarkable Li+/Na+ selectivity; large C0L selectivity decreases. X-Ray diffraction performed monocrystals NaNCS P2 P3 show is encapsulated inside 'basket-like' pseudocavity, coordinating all donor atoms tri-podand. Molecular dynamics simulations P2, 1∶1 M+ suggest structures are similar to those found solid state.