Synthesis, radii dependent self-assembly crystal structures and luminescent properties of rare earth (III) complexes with a tripodal salicylic derivative.

Five new rare earth complexes with a new flexible tripodal salicylic ligand (H(3)L), 2,2'-(2-((2-carboxyphenoxy)methyl)-2-(4-methylphenylsulfonamido)propane-1,3-diyl)bis(oxy)dibenzoic acid, of formulae [La(2)L(2)(DMF)(4)]·4DMF·4EtOH·2H(2)O (1), [Eu(2)L(2)(DMF)(4)]·2DMF (2), {[GdL(DMF)(H(2)O)(2)]·DMF}(∞) (3), {[TbL(DMF)(H(2)O)(2)]·DMF}(∞) (4) and {[YL(DMF)(H(2)O)(2)]·DMF}(∞) (5) (DMF = N,N-dimethylformamide) have been prepared. The single-crystal X-ray diffraction analysis revealed that complexes 1 and 2 present a cage-like homodinuclear species, while 3-5 show a helical one-dimensional coordination polymer. All these complexes are further connected by hydrogen bonds or π-π interactions, resulting in 3D supramolecular structures. The photophysical properties of the Eu and Tb complexes are investigated in the solid state at room temperature.

Olive-shaped chiral supramolecules: simultaneous self-assembly of heptameric lanthanum clusters and carbon dioxide fixation.

Cluster's last stand: Six chiral reduced Schiff base ligands containing amino acids and seven La(III) ions self-assemble to form a novel heptameric lanthanum supramolecule with the aid of the CO(3)(2-) ion (see picture). The cluster exists as a single chiral triple helix. The CO(3)(2-) ion, which is derived from atmospheric CO(2) , adopts a rare mu(3)-tridentate bridging mode that links three La(III) ions, thus allowing the cluster to efficiently fix CO(2).

Design of a semirigid molecule as a selective fluorescent chemosensor for recognition of Cd(II).

A new 8-hydroxyquinoline-based chemosensor possessing a semirigid structure was designed, and its fluorescent sensing behavior toward metalions was investigated. A prominent fluorescence enhancement only for Cd(2+) was found in aqueous methanol solution. The results clearly suggest that the specific semirigid structure could selectively accommodate Cd(2+) according to ionic radius, which would effectively suppress the intramolecular radiationless transitions from the n pi* state to enhance the fluorescence response.

Synthesis and novel fluorescence phenomenon of terbium complex with a new Schiff base ligand derived from condensation of triaminotriethylamine and 3-indolemethanal.

A new Schiff base ligand with tripodal structure, N,N',N''-tri-(3-indolemethanal)-triaminotriethylamine (L), and its complex with terbium was synthesized. The complex was characterized by element analysis, IR spectra, mass spectra, thermal analysis and molar conductivity. The terbium ion was found to coordinate to the Schiff base nitrogen atoms and the bridgehead nitrogen atom. The fluorescence properties of the complex in aqueous solutions were studied. Under the excitation of UV light, the complex exhibits characteristic fluorescence of terbium ion. H(+) concentration could strongly enhance the luminescence of terbium complex with L in aqueous solutions. This phenomenon will make the new complex favorable to be used in the fluorescence switches and sensors. The mechanism of the fluorescence enhancement by protonation of the indole nitrogen atoms is due to the suppressed photoinduced electron transfer (PIET) fluorescence quenching when adding acid.

Synthesis and infrared and fluorescence spectra of new europium and terbium polynuclear complexes with an amide-based 1,10-phenanthroline derivative.

An amide-based 1,10-phenanthroline (phen) derivative and its complexes with europium(III) and terbium(III) ions were synthesized. The complexes were characterized by elemental analysis, infrared spectra and conductivity. The europium and terbium ions were coordinated by O atoms of C=O, Ar-O-C and N atoms of phen. The fluorescence properties of the complexes in THF, dioxane, MeCN and DMF were investigated. Under the excitation of UV light, these complexes exhibited characteristic fluorescence of europium and terbium ions. The solvent factors influencing the fluorescent intensity were discussed.

Studies on synthesis and infrared and fluorescence spectra of new europium and terbium complexes with an amide-based open-chain crown ether.

An amide-based open-chain crown ether ligand and its complexes with europium and terbium were synthesized. The complexes were characterized by elemental analysis, infrared spectra and conductivity. The europium and terbium ions were found to coordinate to the C=O oxygen atoms and pyridine nitrogen atoms. The fluorescence properties of these complexes in DMF and CH3OH/CHCl3 were studied. Under the excitation of UV light, these complexes exhibit characteristic fluorescence of europium and terbium ions. The solvent factors influencing the fluorescent intensity are discussed.