The synthesis and characterization of Hno1pa2py, a new tacn-based ligand, is reported. The complexation process with Cu(2+) was proved to be very fast even in acidic medium. Potentiometric titrations allowed us to establish that Hno1pa2py exhibits an overall low basicity as well as a high selectivity for Cu(2+) over Zn(2+) cations. The copper(II) complex was synthesized and characterized using UV-vis and EPR spectroscopies and density functional theory (DFT) calculations. The studies clearly showed that the [Cu(no1pa2py)](+) complex is present in solution as a mixture of two isomers in which the ligand is coordinated to the metal center using a N5O donor set with the metal center in a distorted octahedral geometry. The very high kinetic inertness of the [Cu(no1pa2py)](+) complex was demonstrated by using acid-assisted dissociation assays as well as cyclic voltammetry. Preliminary investigations of (64)Cu complexation were performed to validate the potential use of such chelating agent for further application in nuclear medicine. The X-ray crystal structures of copper(II) complexes of L1, the ester derivative of Hno1pa2py, have been determined.

International audienceThree 1,4,7-triazacyclononane-based (tacn-based) ligands containing picolyl and picolinate pendant arms (no3py, no2pa1py, and no3pa) were synthesized, and their copper(II) complexation properties were studied to evaluate their potentials as chelators for copper radioisotopes. The thermodynamic stability constants of the complexes were determined by potentiometric titrations. These studies evidenced the formation of mononuclear species for no3py and mono- and dinuclear species for no2pa1py and no3pa. The pCu values decreased as the number of carboxypicolyl arms increased. The [Cu(no3py)]2+ complex presented a very high stability constant (log KCuL = 27.4) and a very high selectivity towards Zn2+ ions (log KZnL = 17.25). Vis/NIR (NIR = near-infrared) absorption and electron paramagnetic resonance (EPR) spectroscopy indicated that the three complexes present distorted octahedral geometries with two paramagnetic species, which were identified as the Δ(δδδ) and Λ(δδδ) isomers [and their corresponding enantiomeric forms Λ(λλλ) and Δ(λλλ)] by DFT calculations. The electrochemical properties were investigated by cyclic voltammetry, which revealed quasireversible behavior for the [Cu(no3py)]2+ complex but irreversible Cu2+/Cu+ systems for [Cu(no2pa1py)] and [Cu(no3pa)]–

International audienceCopper- and cobalt-based layered simple hydroxides (LSH) are successfully functionalized by a series of fluorene mono- and diphosphonic acids, using anionic exchange reactions and a preintercalation strategy. The lateral functionalization of the fluorene moieties has only little impact on the overall structure of the obtained layered hybrid materials but it influences the organization of the molecules within the interlamellar spacing. For bulky fluorene (9,9-dioctyl derivative), luminescence is preserved when inserted into copper and cobalt hydroxydes, whereas it is completely quenched for the other fluorenes. Detailed characterization of the internal structure and chemical bonding properties for copper- and cobalt-based hybrids is performed via ancillary experimental techniques. For the copper-based LSH class, for which more elusive findings are found, first-principles molecular dynamics simulations unravel the fundamental stabilizing role of the H-bonding network promoted within the local environments of the fluorene mono- and diphosphonic acids. The cobalt series of compounds constitute a new class of hybrid magnets, with ordering temperatures ranging from 11.8 to 17.8 K and show a clear magnetoelectric effect. This effect appears above a threshold magnetic field, which is null below the magnetic ordering temperature, and it persists in the paramagnetic regime till about 110 K