Tuning the Stoichiometry of Lanthanide Complexes with Calixarenes: Bimetallic Complexes with a Calix[6]arene Bearing Ether‐Amide Pendant Arms

Abstract

A de-tert-butylated calix [6]arene (A 6 L 6 ) fitted with six etheramide pendant arms was synthesized and characterized in solution. NMR spectroscopic data point to the six phenoxide units adopting an average D 6h conformation on the NMR time scale. According to MM3 molecular mechanics, and MOPAC quantum mechanical calculations, A 6 L 6 is a ditopic ligand featuring two nonadentate coordination sites, each built from three pendant arms, and extending in opposite directions with one above, and the other under the main ring. A 6 L 6 reacts with Ln III ions (Ln = La, Eu) in acetonitrile to successively form 1:1 and 2:1 complexes. The isolated Eu III 2:1 complex is luminescent (quantum yield: 2.5% in acetonitrile, upon ligand excitation). In the solid state, the luminescence decay is bi-exponential, with lifetimes equal to 1.66 and 0.46 ms (upon direct metal excitation), pointing to the presence of two differently coordinated metal ions, one with essentially

Benefiting from the Unique Properties of Lanthanide Ions

“…Experimentally, this is substantiated by NMR data in solution and by the isolation of a bimetallic complex with Eu, [Eu 2 (OTf) 2 (A 6 L 6 )-(H 2 O) 2 ] 4+ , the calculated structure of which is shown in Figure 5. 33 Its quantum yield in acetonitrile (2.5%) is comparable to the one mentioned above for the 1:1 complex with A 4 bL. 4 Macrocycle B 4 bL 4 also adopts a cone conformation, both in the solid state and in solution.…”

Lanthanide-containing luminescent molecular edifices

“…Three consecutive phenol groups are positioned in such a way that the pendant arms form two predisposed cavities for metal ion co-ordination, each built up of three pendant arms, and extending on opposite sides of the macrocycle. Experimentally, this is substantiated by NMR data in solution, and by the isolation of a 2:1 complex with Eu [21]. The calculated structure of the latter is shown on Fig.…”

Uranyl complexes formed with a para-t-butylcalix[4]arene bearing phosphinoyl pendant arms on the lower rim. Solid and solution studies

“…1a) fitted with ether amide [34,35] and phosphinoyl pendant arms [6,[36][37][38] on the narrow rim. We have reported the structural and photophysical properties of their Brought to you by | New York University Bobst Library Technical Services Authenticated Download Date | 5/31/15 1:11 PM lanthanide complexes [34][35][36][37][38]. Recently, our work has been expanded to the study of actinide complexes formed with the phosphinoyl-derivatized calix [6]arene B 6 bL 6 , as well as to its extraction capability towards uranyl, thorium(IV), and representative trivalent rare earths (Y, La, Eu) [6].…”