Structural and spectroscopic studies of binuclear Cu2+ and Co2+ complexes with an amide-based naphthalenophane

Evaluation of exchange interaction in binuclear copper(II) chelates of amide-based cyclophanes

“…The J value evaluated in such a way is found to be about 22 cm -'. The X-ray study of the Cu(II) chelate has shown that the distance between the two Cu(II) ions is 0.83 nm [7]. Since the dipolar interaction predicted for the Cu-Cu distance is very weak in comparison with the observed J value, antiferromagnetic interaction operative through the bridging n-electron system is predominant.…”

“…Among numerous examples in this field, binuclear copper(II) chelates of amide-based cyclophanes (shown in Fig. 1) provide an interesting system for the investigation of the peculiarities of exchange interactions because two Cu(II) ions are bridged by aromatic groups which can be readily replaced and are separated so distant that the dipolar interaction is very weak [6,7]. Electron paramagnetic resonance (EPR) is a powerful tool for studying exchange interactions between magnetic centers because it provides information on the value of both the isotropic exchange interactions J in their ground states (described by the Hamiltonian JS, S2) and the anisotropic exchange interactions Dex which are due to the isotropic exchange interactions J' between the ground state of one metal ion and the excited states of the other [8,9].…”

Bichromophoric Naphthalene Derivatives of Ethylenediaminetetraacetate: Fluorescence from Intramolecular Excimer, Protonation and Complexation with Zn2+and Cd2+

“…In this work, we have designed bichromophores 1 and 2 shown in Scheme 1, abbreviated as (edta1nap)H 2 and (edta2nap)H 2 , respectively, with acidic protons; in each compound, two naphthalene units are linked by amide bonds to an ethylenediaminetetraacetate (edta) chain, which contains amino nitrogen atoms as electron-donating sites. The amide groups are predicted to define the effective length and conformation of the interlinking chain because of their planarity [15,16]. As a result of the combined effects of these functional groups, two naphthyl groups in a molecule are expected to have a mutual geometrical relation favorable for forming an excimer under specific conditions.…”

19 Coordination chemistry of macrocyclic ligands

“…Binuclear Cu II complexes of the naphthalenophane H 8 L 268 can be isolated in varying degrees of protonation depending on the pH of the reaction medium. 200 The complex [Cu II 2 (H 4 L 268 )] crystallises from acidic solution, each metal centre adopts a square pyramidal coordination geometry with an amide oxygen atom, two amino nitrogen atoms and two carboxylate donor oxygen atoms. Crystallisation from basic solution affords [Cu II 2 (L 268 )] 4Ϫ in which the metal centres are square planar with deprotonated amide groups and amine donors making up the coordination sphere.…”