A novel synthetic path to a luminescent,dimeric samarium complex induced by the hydrolysis of methyl pyridine-3-carboxylate

A novel path to lanthanide complexes of aromatic carboxylates controlled by the hydrolysis of the corresponding aromatic carboxylate ester has been discovered. A dimeric samarium complex of pyridine-3-carboxylate (NIC) has been obtained using methyl pyridine-3-carboxylate (MNIC) as the starting ligand. With the hydrolysis of MNIC to NIC in the presence of sodium hydroxide, samarium ions coordinate to HNIC to form [Sm(NIC)₃(H₂O)₂]₂. X-ray analysis reveals the dimeric structure formed through bridging oxygen atoms of carboxylate groups. The complex crystallizes in the monoclinic space group P2₁/c with a?=?9.668(3), b?=?11.807(3), c?=?17.512(5)?Å, β?=?92.361(3)°, V?=?1997.3(10)?ų, D _c?=?1.838?Mg?m^?3, Z?=?2, R ₁?=?0.0225. The complex exhibits strong luminescence.     

Different crystal structure and photophysical properties of lanthanide complexes with 5-bromonicotinic acid

Five novel lanthanide (Eu³⁺ (1), Tb³⁺ (2), Sm³⁺ (3), Dy³⁺ (4) and Gd³⁺ (5)) complexes with 5-Bromonicotinic acid (5-Brnic) were synthesized and two of them (Tb³⁺, Sm³⁺) were characterized by X-ray diffraction. The results reveal that {[Tb(5-Brnic)₃(H₂O)₃]·H₂O}_n (2) and [Sm(5-Brnic)₃(H₂O)₂·H₂O]₂ (3) exhibit different coordination geometries and crystal structures. Complex 2 has a one-dimensional chain-like polymeric structure through the bridged 5-Brnic anions which links up two neighboring terbium ions, while Complex 3 forms a dimeric molecular structure. The lowest triplet state energy of 5-Brnic was determined to be 24 330 cm⁻¹ corresponded to the 0-0 transition in the phosphorescence spectrum of its gadolinium complex at 411 nm. The strong luminescent emission intensities of these complexes indicated that the triplet state energy of 5-Brnic is suitable for the sensitization of luminescence of Eu³⁺, Tb³⁺, Sm³⁺ and Dy³⁺, especially for that of Tb³⁺ and Dy³⁺.     

Hydrothermal synthesis and crystal structure of a novel luminescent europium complex of 2,5-pyridinedicarboxylic acid

A novel europium complex, Eu(Hdinic)(dinic)(H₂O)₅·4H₂O (dinic = 2,5-pyridinedicarboxylic acid), has been synthesized under hydrothermal conditions and characterized structurally by X-ray diffraction methods. The complex has a mononuclear molecular structure, is monoclinic, space group C2/c, with a?=?13.877(5), b?=?9.632(3), c?=?32.991(11)?Å, β?=?93.414(4)°, V?=?4402(2)?ų, D _c?=?1.948?Mg?m^?3, Z?=?8, F(000)?=?2576, R ₁?=?0.0320. Its photophysical properties are reported.     

Synthesis,crystal structure,and photophysical properties of a double open cubane-like Cd(II) complex based on 2-substituted-8-hydroxyquinoline

A 2-substituted-8-hydroxyquinoline (E)-2-[2-(3-thienyl)ethenyl]-8-quinolinol (HL) was synthesized and characterized by ESI-MS, NMR spectroscopy, and elemental analysis. Using solvothermal method, a tetranuclear complex [Cd₄L₆Br₂]·6DMF (1) was fabricated by assembly of Cd(II) with HL. X-ray structural analysis shows that 1 exhibits a double open cubane-like core structure, which is bridged by six 8-hydroxyquinolinate-based ligands. The supramolecular structure of 1 features a 3-D porous solid constructed by aromatic stacking interactions, C–H···π interactions and C–H···O hydrogen bonds. The assembly of cadmium salts and HL in solution was investigated by UV–vis and photoluminescence. We also studied the thermal stability and photophysical properties (fluorescent emission, lifetime, and quantum yield) of 1. The results show that 1 emits yellow luminescence in the solid state.     

Chalcogenide derivatives of 1,2,5-triphenyl-1H-phosphole: structure and photophysical properties

Chalcogenide derivatives of triphenylphosphole (oxide (1), sulfide (2) and selenide (3)) were synthesized and characterized by X-ray diffraction studies. Intermolecular interactions were observed in the bulk molecular packing in terms of hydrogen bonding for 1 or π–π stacking for 3. One of the useful applications of the chalcogenide derivatives of triphenylphosphole has been demonstrated utilizing the photophysical properties of 1 to detect aromatic nitro compounds through fluorescence quenching.     

Synthesis and photophysical properties of metal anthraquinone phthalocyanine

A novel anthraquinone phthalocyanine Al(Ⅲ) 4 and Co(Ⅱ) 5 were synthesized and characterized by elemental analysis, IR, UV/ vis, 1H NMR, HPLC and MS. The photophysical properties of the two metal complexes were studied and compared by ?uorescence spectrum method.     

Synthesis,crystal structure and properties of three ternary dysprosium 2-halogenated benzoic acid complexes

Three ternary dysprosium complexes [Dy(2-ClBA)₃?·?phen]₂ (1), [Dy(2-ClBA)₃?·?2,2′-bipy]₂ (2), and [Dy(2-BrBA)₃?·?phen]₂ (3) (where 2-ClBAH?=?2-ClC₆H₄COOH, 2-BrBAH?= 2-BrC₆H₄COOH, phen?=?1,10-phenanthroline, and 2,2′-bipy?=?2,2′-bipyridine) have been synthesized and characterized by X-ray single crystal diffraction. Complex 1 consists of two independent binuclear molecules, [Dy(2-ClBA)₃?·?phen]₂ (a) and [Dy(2-ClBA)₃?·?phen]₂ (b), in which the coordination environment is similar. Each Dy³⁺ is nine coordinate with two nitrogens from phen and seven oxygens from five 2-ClBA groups. 2-ClBA groups coordinate to Dy³⁺ in three ways, bidentate chelating, bidentate-bridging and terdentate-bridging. Complexes 2 and 3 consist of one binuclear molecule. The crystal structure of 2 is similar to that of binuclear molecule (a) or (b) of complex 1. In 3, each Dy³⁺ ion is eight-coordinate by two nitrogens from phen and six oxygens from five 2-BrBA groups. 2-BrBA groups coordinate to the Dy³⁺ ion in two ways, bidentate chelating and bidentate-bridging. The complexes were studied by UV, DTA-TG, and fluorescence spectrometry.     

Magnetic properties and structure of a CuDy heterodinuclear Schiff base complex

The crystal structure of a new heterodinuclear lanthanide complex, L²Cu(Me₂CO)Dy(NO₃)₃ (L²=N,N′-bis(2-hydroxy-3-methoxy-benzylidene)-ethylenediamine) has determined and the magnetic properties of the complex investigated. (C₁₈H₁₈N₂O₄)Cu(C₃H₆O)Dy(NO₃)₃, monoclinic, space group P2₁/c, with a=9.875(2), b=18.870(7), c=15.675(8) Å, β=95.45(3)°, V=2908(2) Å³, Z=4. The structure consists of ordered dinuclear units with Cu^II and Dy^III ions bridged by two phenolato oxygen atoms of the Schiff base ligand. The Cu^II ion has a square-pyramidal geometry involving the basal N₂O₂ donor atoms of the Schiff base ligands and one oxygen atom of the acetone molecule at the apex position. The Dy^III ion is decacoordinated by the four oxygen atoms of L² and six oxygen atoms from the three bidentate nitrate ions. The Cu?Dy separation is 3.461(2) Å. The χT versus T plots, χ being the molar magnetic susceptibility per Cu^IIDy^III unit and T the temperature, has been measured in the 4.5-300 K temperature range. The magnetic properties of the compound are dominated by the crystal field effect on the Dy^III site, masking the magnetic interaction between the paramagnetic centers.     

A novel dinuclear cyclometalated iridium complex bridged with 1,4-bis[pyridine-2-yl]benzene: its structure and photophysical properties

The synthesis, structure, and photophysical properties of a new cyclometalated dinuclear iridium complex, (ppy)2Ir(mu-BPB)Ir(ppy)2 [ppy = 2-phenylpyridine, BPB = 1,4-bis(pyridin-2-yl)benzene], have been investigated.     

Supramolecular structure of the polymeric Eu(III) complex with pyridine-2,6-dicarboxylic acid

The europium complex with pyridine-2,6-dicarboxylic acid forms three-dimensional polymers in the solid state. The crystal structure of this assembly shows that europium cation is nine-coordinated and the first coordination sphere contains four water molecules. Mono(dipicolinate) structural units are interconnected by bridging carboxylate oxygens to provide a compact supramolecular structure with a high density.     

A novel triply bridged dinuclear four-coordinate copper(I) complex with sterically bulky bis(dicyclohexylphosphino)methane ligand

A novel triply bridged dinuclear copper(I) complex: Cu₂(μ-paa)(μ-dcpm)₂(BF₄)₂·2CH₂Cl₂ [ paa = pyridine-2-carbaldehyde azine (C₁₂H₁₀N₄) and dcpm = bis(dicyclohexylphosphino)methane(C₂₅H₄₆P₂) ] has been synthesized and structurally characterized. Crystallographic studies of the complex showed that two copper(I) ions were bridged by one paa ligand and two dcpm ligands. The paa ligand adopted the Z configuration at the partially double N-N bond and the two copper ions have distorted tetrahedral coordination geometry. Because of the steric effect of dcpm, the pyridine rings of the paa ligand are obviously not on the same plane (the dihedral angle is 43.61⁰). The interaction between neighboring ligands results in a N-N bond length (1.374(7) Å) contraction. The UV-vis spectra of the complex exhibited intense high-energy absorptions at λ_max < 340 nm and broad visible bands in a range of 380?550 nm, ascribed to intraligand (IL π-π*) transitions and metal-to-ligand charge-transfer (MLCT) transitions, respectively. Interestingly, the absorbtion peaks varied regularly with the solvent polarity. Although the complex has a rigid structure with the copper ions held firmly by triply bridged ligands, the emission and excitation spectra revealed that the complex exhibits weak fluorescence.

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A dimeric luminescent lanthanide complex [Eu(PAA)2(phen)(NO3)]2: hydrothermal synthesis,crystal structure and fluorescence

A lanthanide coordination complex [Eu(PAA)₂(phen)(NO₃)]₂ (PAA?=?phenylacetic acid, phen?=?1,10-phenanthroline) has been synthesized by the hydrothermal method. Single crystal X-ray diffractions show that it forms a dimeric molecular structure. The title complex crystallizes in the triclinic system, space group P 1, with lattice parameters a?=?8.9473(8)?Å, b?=?13.3659(12)?Å, c?=?13.4745(12)?Å, α?=?60.7590(10)°, β?=?89.5100(10)°, γ?=?71.9850(10)°, V?=?1317.3(2)?ų, D _c?= 1.675?Mg?m^?3, Z?=?1, F(000)?=?660, GOF?=?1.003, R ₁?=?0.0206, wR ₂?=?0.0575. The fluorescence excitation and emission spectra have been investigated.     

A novel dimeric zinc(II) complex with a tripodal peptide ligand: a structure stabilized by ligand sharing

The crystal structure of a novel dimeric zinc(II) complex, [ZnL(H₂O)]₂(ClO₄)₂·4H₂O (L?=?N-(bis(2-pyridyl)methyl)-2-pyridinecarboxamide), has been determined by X-ray diffraction. In this complex each planar N_py–N_amido–N_py moiety of the ligand coordinates to one zinc ion and the pendant pyridine of one [ZnL] unit completes the coordination sphere of a [ZnL] neighbor. Units of the complex are connected in a two-dimensional network by intermolecular hydrogen bonds. The thermodynamic properties of the ligand with bivalent metal ions Co(II), Ni(II), Cu(II) and Zn(II) were studied by potentiometric titration and the order of the stability constants is in agreement with the Irving–Williams series. The dimeric complex is stabilized through ligand sharing, as confirmed by the crystal structure and thermodynamic properties.     

Covalently assembly and photophysical properties of novel lanthanide centered hybrid materials by functionalized thioacylureas bridge

A novel molecular precursor (abbreviated as TAM-Si) derives from thioacetaminde (TAM) modified by 3-(triethoxysilyl)-propyl isocyanate (TEPIC) though the hydrogen transfer addition reaction. Then TAM-Si behaves as functional molecular bridge which coordinates to RE³ (Eu³⁺, Tb³⁺) as well as form SiO network with inorganic precursor (TEOS) after a sol–gel process (cohydrolysis and copolycondensation reaction), resulting in the covalently bonded hybrid materials (RE–TAM-Si). On the other hand, the hybrid material of TAM-Si without introduction of RE³⁺ as well has been obtained. SEM pictures indicate that the TAM-Si show the sphere micromorphology with particle size of micrometer dimension while RE–TAM-Si hybrids present different nanometer particle, which suggests that lanthanide ions has influence on the microstructure of hybrid systems through its coordinated effect. The blue emission for TAM-Si hybrids and the narrow-width green and red emissions were achieved for Tb³⁺ and Eu³⁺ ions, respectively, indicating that the intramolecular energy transfer process take place from photoactive group to Tb³⁺ and Eu³⁺ ions in these hybrid microsphere systems. Especially the lifetime and quantum efficiency for europium hybrids have been determined.     

A one-dimensional azido-bridged manganese(III) complex with bidentate Schiff base: Crystal structure and magnetic properties

The synthesis, structural characterization, and magnetic behavior of a novel one-dimensional azido-bridged manganese(III) complex of formula [Mn(L)₂N₃] (1) is reported, where HL is the bidentate Schiff base obtained from the condensation of salicylaldehyde with 4-methoxy aniline. Complex 1 crystallizes in the monoclinic system, space group P2₁/n, with a=11.743(4) Å, b=24.986(9) Å, c=13.081(5) Å, β=95.387(7)° and Z=2. The complex is of one-dimensional chain structure with single end-to-end azido bridges and the manganese(III) ion has an elongated octahedral geometry. Magnetic studies show that the weak antiferromagnetic interaction is mediated by the single end-to-end azido bridge with the exchange parameter J=−5.84 cm⁻¹.     

Synthesis and evaluation of thermal, photophysical and magnetic properties of novel starlike fullerene–organosilane macromolecules

Thermal, photophysical and magnetic properties of some novel fullerenol–silane adducts are described. Excellent improvement of thermal stability and high char yield due to the presence of silicon is the key feature of these adducts. Highest luminescence quenching due to maximum π–π electronic interactions between phenyl ring and fullerene are observed in the aromatic-silane adducts and the quenching ability of the aromatic ring reduces with further delocalization of the π-electrons as in naphthyl silane. The alkyl vinyl silane, on the other hand, records better fluorescence intensity owing to increase population of the electron density (+I effect) and non-effective charge transfer complex formation between isolated vinylic double bond and fullerene. Emission peak positions of these adducts are comparable to fullerenol because of control derivatization of fullerene ring causing less perturbation of the symmetric π-electronic system. These adducts are paramagnetic in nature with peaks around 3515 G and higher g-values (2.005–2.009) compared to fullerenol (1.985). The fullerenol–silane adducts are synthesized using fullerenol as substrate and different chloro and alkoxy silanes as silylating agents adopting simple nucleophilic displacement and transesterification reactions. All the fullerenol–silane adducts are characterized spectroscopically.