4,4′-Oxybis{N-[(E)-quinolin-2-yl­methyl­idene]aniline}

The title Schiff base compound, C32H22N4O, was prepared by a reaction of 4,4′-diamino­diphenyl ether and 2-quinoline­carboxaldehyde. The mol­ecule consists of two 4-{N-[(E)-quinolin-2-yl­methyl­idene]amino}­phenyl units linked by an oxygen bridge. The dihedral angles between two benzene rings and between the two quinoline ring systems are 53.81 (7) and 42.56 (4)°, respectively. Inter­molecular C—H⋯N hydrogen bonding is present in the crystal structure

4,4′-Methylenebis{N-[(E)-quinolin-2-yl­methylidene]aniline}

The title compound, C33H24N4, was prepared by the reaction of a bifunctional aromatic diamine (4,4′-diamino­diphenyl­methane) and an aldehyde (quinoline-2-carboxaldhyde). The mol­ecule consists of two nearly planar (or r.m.s. deviation = 0.017 Å) 4-methyl-N-[(E)-quinolin-2-yl­methyl­idene]aniline moieties, which are linked by the methyl­ene group. The angle between the mean planes of the two benzene rings connected to the methyl­ene group is 77.86 (11)°

1-{[4-(4-{[(2-Oxidonaphthalen-1-yl)methylidene]azaniumyl}phenoxy)phenyl]iminiumylmethyl}naphthalen-2-olate

The title Schiff base compound, C34H24N2O3, was prepared by a condensation reaction of bifunctional aromatic diamine (4,4′-diaminodiphenyl ether) with hydroxynaphtaldehyde. The asymmetric unit contains two independent molecules with similar conformations. The compound contains a central oxygen bridge and two functionalized [(E)-(phenyliminio)methyl]naphthalen-2-olate units. The dihedral angles between the benzene rings linking to the central O atom are 74.64 (19) and 69.85 (18)° in the two independent molecules. Intramolecular O—H...O hydrogen bonding occurs between the protonated imino N atoms and deprotonated hydroxy O atoms in both molecules. In the crystal, weak C—H...O hydrogen bonds are observed

Step by Step Assembly of Polynuclear Lanthanide Complexes with a Phosphonated Bipyridine Ligand

The synthesis of the octadentate ligand L (LH₈ = ((([2,2′-bipyridine]-6,6′-diylbis­(methylene))­bis­(azanetriyl))­tetrakis­(methylene))­tetrakis­(phosphonic acid)) is reported. The coordination of L with various lanthanide cations was monitored by absorption and luminescence spectrophotometric titration experiments (Ln = Tb, Yb), potentiometry (Ln = La, Eu, Lu), and mass spectrometry (Ln = Tb). It was found that L forms very stable mononuclear (LnL) species in aqueous solutions (log <i>K</i> = 19.80(5), 19.5(2), and 19.56(5) for La, Eu, and Lu, respectively) with no particular trend along the series. Spectroscopic data showed the Ln cations to be enclosed in the cavity formed by the octadentate ligand, thereby shielding the metal from interactions with water molecules in the first coordination sphere. When more than one equivalent of cations is added, the formation of polynuclear [(LnL)₂Ln_<i>x</i>] complexes (<i>x</i> = 1–3) can be observed, the presence of which could be confirmed by electrospray and MALDI mass spectrometry experiments. DFT modeling of the mononuclear (LnL) complexes indicated that the coordination of the cation in the cavity of the ligand results in a very asymmetric charge distribution, with a region of small negative electrostatic potential on the hemisphere composed of the chromophoric bipyridyl moiety and an electron-rich domain at the opposite hemisphere around the four phosphonate functions. DFT further showed that this polarization is most likely at the origin of the strong interactions between the (LnL) complexes and the incoming additional cations, leading to the formation of the polynuclear species. ¹H and ³¹P NMR were used to probe the possible exchange of the lanthanide complexed in the cavity of the ligand in D₂O, revealing no detectable exchange after 4 weeks at 80 °C and neutral pD, therefore pointing out an excellent kinetic inertness