Delangle, P
Declercq, Jean-Paul
[UCL]
Mulatier, JC
Tinant, Bernard
[UCL]
Dutasta, JP.
Syntheses and host-guest properties of tetrabridged phosphorylated cavitands in their iiii (4i) configurations are described, The tetraphosphonato cavitands 2 and 3, with the four P=O bonds oriented inwards (4i stereoisomer) were prepared in 25% and 53% yields respectively, from the corresponding resort[4]arenes, dichloro(phenyl)phosphane oxide and base. The formation of the 4i stereoisomers is solvent-dependent and is attributable to the capability of an ammonium guest to form an inclusion complex. Only the iiio (3io) stereoisomer of 3 was isolated otherwise, in low yield. These phosphonato cavitands, in their 4i configurations, are particularly efficient extractants for metal ions. The free energies of complexation of 3 with alkali metal and ammonium cations in chloroform solution are in the range from -43.3 (Li+) to -52.4 kJ mol(-1) (CH3NH3+). High binding constants, H-1, P-31 and Cs-133 NMR studies in solution and single-crystal X-ray analysis clearly demonstrated that the aromatic cavity of the host and the four hard donor P=O groups act cooperatively to ensure the encapsulation of the cationic guests. In the solid, the 2 . Cs+ complex showed the Cs' ion inside the aromatic cavity, interacting strongly with the four phosphoryl groups. The 2 . CH3NH3+ complex showed the methyl group of the guest oriented inside the cavity, with the stability of the complex supported by a complex H bond pattern involving H2O molecules and the anion.
Bibliographic reference |
Delangle, P ; Declercq, Jean-Paul ; Mulatier, JC ; Tinant, Bernard ; Dutasta, JP.. Synthesis and binding properties of iiii (4i) stereoisomers of phosphonato cavitands - Cooperative effects in cation complexation in organic solvents. In: European Journal of Organic Chemistry, , no. 19, p. 3695-3704 (2001) |
Permanent URL |
http://hdl.handle.net/2078.1/42477 |