Synthesis and luminescent properties of polymeric metal complexes containing bis(8-hydroxyquinoline) group

A novel ligand: 4,4′-bis(8-hydroxyquinoline-5-propenyl)-biphenyl (B8QPB) (1), has been synthesized by Witting-Horner reaction, and the corresponding two polymeric metal complexes were also prepared by polynuclear of the ligand with aluminium (III) (2) and zinc (II) (3) halides, respectively. The structure of the ligand was characterized by ¹H NMR, FT-IR and elemental analysis techniques; polymeric metal complexes were characterized by FT-IR, UV-vis, elemental analysis techniques, conductivity measurements and gel permeation chromatography (GPC). The results indicate that the stoichiometry of polymeric metal complexes is [(C₃₄H₂₄O₂N₂)₁₁Al₁₂Cl₂₈] and [(C₃₄H₂₄O₂N₂)₃₂(ZnCl₂)₃₃]. B8QPB coordinated with metal ions to form polymers. The luminescence properties of the complexes 1-3 were investigated by UV-vis and fluorescence spectra at room temperature. The experimental results show that polymeric metal complexes 2 and 3 emit blue/green luminescence at 514 and 504 nm in the solid state and at 470 and 507 nm in DMSO solution. Thermal properties measurement and analysis show that they have good thermal stabilities.     

Synthesis and luminescence of polymeric metal complexes based on 1,10-phenanthroline and 8-hydroxyquinoline

A ligand containing different coordination groups, 5-([1,10]phenanthroline-[4,5-f]imidazo-2-yl)-8-hydroxyquinoline (PhenI8Q) has been synthesized and two corresponding polymeric metal complexes Cu(II) (1) and Zn(II) (2) were prepared by coordination polymerization of the ligand with copper(II) and zinc(II) halides, respectively. The ligand was characterized by ¹H-NMR, ¹³C-NMR, and Fourier transform-infrared (FT-IR) and its corresponding polymeric metal complexes 1 and 2 were characterized by FT-IR, UV-Vis, elemental analysis, thermal gravimetric analysis, and conductivity measurements. The absorption spectra and luminescence of the ligand, 1, and 2 were investigated by UV-Vis and fluorescence spectroscopy at room temperature. Compared with the ligand, the fluorescence spectra of the polymeric metal complexes exhibit blue shifts in dimethyl sulfoxide (DMSO) solution and bathochromic shifts in the solid state. Complexes 1 and 2 emit blue light with emission maximum (λ _{f max}) at 449 and 431 nm in DMSO solution and at 485 and 484 nm in the solid state, respectively.     

Synthesis and luminescent properties of Zn complex based on 8-hydroxyquinoline group containing 3,5-bis(trifluoromethyl) benzene unit with unique crystal structure

The use of a novel 2-substituted-8-hydroxyquinoline ligand (E)-2-{2-[3,5-bis (trifluoromethyl)phenyl]ethenyl}-8-hydroxyquinoline(4, BFHQ) characterized by EIMS, ¹H NMR spectroscopy, elemental analysis, and FTIR spectroscopy enabled the isolation of a trimeric Zn(II) complex with the formula Zn₃(BFHQ)₆ (5, Scheme 1). X-ray structural analysis shows that 5 exhibits a trinuclear core, which is bridged by four 8-hydroxyquinoline rings. The trinuclear core is surrounded by three pairs of BFHQ ligands with offset π-π stacking, showing propeller-like molecular structure. The aggregation behavior of Zn(AcO)₂ and the ligand 4 in solution was investigated by UV-vis. The luminescence properties of compound 5 were investigated by UV-vis and fluorescence spectra at room temperature. The experimental results show that the complex 5 emits yellow luminescence at 553 nm (λ_{em, max}) in DMSO solution and at 610 nm (λ_em, max) in solid state. The thermogravimetric analysis was carried out to examine the thermal stability.     

Synthesis and characterization of 5-substituted 8-hydroxyquinoline derivatives and their metal complexes

5-Aminomethyl-8-hydroxyquinoline (QN) was synthesized as a scaffold to generate dimers, trimers, and tetramer metalloquinolates. Starting from QN, a series of 5-substituted 8-hydroxyquinoline derivatives conjugated with small bioactive molecules were synthesized. Absorption and emission spectra indicate that these QN derivatives chelate well with metal ions, which may serve as a new platform to explore the applications of metalloquinolates for a variety of potential applications.     

Synthesis,characterization, crystal structure and biological activities of supramolecular compounds of Mn(II) and Zn(II) with dipicolinic acid and 8-hydroxyquinoline

Two compounds, (8-H₂Q)₂[Mn(dipic)₂] · 6H₂O (1) and (8-H₂Q)₂[Zn(dipic)₂] · 6H₂O (2) (8-HQ = 8-hydroxyquinoline (oxine), H₂dipic = dipicolinic acid), have been prepared and characterized by elemental, spectroscopic (IR and UV–Vis), and thermal analyses, magnetic measurements and single crystal X-ray diffraction techniques. Compounds 1 and 2 consist of two 8-hydroxyquinolinium cations, one bis(dipicolinato)M(II) anion (M = Mn(II) and Zn(II)) and six uncoordinated water molecules. Both 1 and 2 crystallize in the monoclinic space group C2/c. In the complex anion, each dipic ligand is tridentate through N of pyridine and oxygens of the carboxylate groups. Crystal packing of 1 and 2 is a composite of intermolecular hydrogen bonding interactions. The in vitro antibacterial and antifungal activities of 1 and 2 were evaluated by the agar well diffusion method by MIC (Minimal Inhibition Concentration), looking for compounds which display high-inhibitory effect against gram positive bacteria and fungi. No growth inhibition was observed against tested gram negative bacteria.     

Syntheses,crystal structures,and properties of four transition metal complexes based on 5-nitro-8-hydroxyquinoline

Four new complexes, [M(C₉H₅N₂O₃)₂(H₂O)₂]·CH₃OH (M?=?Zn(II), Cd(II) and Mn(II)) (1–3) and [Cu(C₉H₅N₂O₃)₂] (4), have been synthesized by reactions of 5-nitro-quinoline-8-yl acetate (NQA) and corresponding metal salts at room temperature and characterized by elemental analysis, IR, thermal gravimetric analysis (TGA), fluorescence measurement and single crystal X-ray diffraction. 1–3 are mononuclear, further extended to 2-D layers by hydrogen bonds. For 4, Cu²⁺ is coordinated by two N atoms and two O atoms from two NQ ligands. TGA indicates that 1–4 have good thermal stabilities. Furthermore, 1 and 2 show excellent luminescence in the solid state at room temperature.     

Synthesis of 5-alkoxymethyl- and 5-aminomethyl-substituted 8-hydroxyquinoline derivatives and their luminescent Al(III) complexes for OLED applications

Several 5-alkoxymethyl- and 5-aminomethyl-substituted 8-hydroxyquinolines were synthesised. Their coordination complexes with Al(III) were also synthesised. These complexes are soluble and stable in common organic solvents and show green luminescence with high quantum yields.     

Novel polymeric metal complexes as dye sensitizers for Dye-sensitized solar cells based on poly thiophene containing complexes of 8-hydroxyquinoline with Zn(II),Cu(II) and Eu(III) in the side chain

Novel polymeric metal complexes as dye sensitizer for dye-sensitized solar cells (DSSCs) based on poly thiophene containing complexes of 8-hydroxyquinoline with Zn(II),Cu(II), and Eu(III) in the side chain have been synthesized according to the Stille coupling method and characterized by FTIR, GPC, and Elemental analysis. The UV-vis absorption spectroscopy, photoluminescence spectroscopy, cyclic voltammetry, and the applications in dye-sensitized solar cells (DSSCs) are also determined and studied. The DSSCs fabricated by PZn(Q)₂-co-3MT, PCu(Q)₂-co-3MT, and PEu(Q)₃-co-3MT exhibit good device performance with a power conversion efficiency of up to 0.56%, 0.78%, and 1.16%, respectively, under simulated AM 1.5 G solar irradiation (100 mW/cm²). They possess excellent stabilities and their thermal decomposition temperatures are 340 °C, 400 °C, and 540 °C, respectively, indicating polymeric metal complexes are suitable for the fabrication processes of optoelectronic devices.     

Two 5-tetrazolylazo-8-hydroxyquinoline-based Zn(II) and Mn(II) complexes: syntheses,structures and optical properties

Two 5-tetrazolylazo-8-hydroxyquinoline (TTHQ) Zn²⁺ and Mn²⁺ complexes, [Zn(TTHQ)(en)]·2H₂O (en = ethylenediamine) (1) and [Mn₂(TTHQ)₂(H₂O)₆]·2H₂O (2), were synthesized and characterized by single-crystal X-ray diffraction analysis. Stacking (π–π) and hydrogen-bonding interactions are responsible for the stabilization of the supramolecular structures. UV–vis spectral changes and photoluminescent properties of TTHQ, 1 and 2 were investigated and a red emission was found. The hydrogen-bonding interaction energies in 1 and 2 were calculated using density functional theory at the WB97XD/6-31++G level.     

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.     

Efficient Synthesis of 2-(8-Quinolinoxy)-4H-imidazolin-4-ones

IntroductionMany N- heterocycles including 4H - imidazolin-4- ones show bactericidal and fungicidal activities,especially those with a 2 - alkoxyl substituent[1— 5] .The efforts to discover the new biologically activederivatives reflected by the still important numberof publications and patents have been devoted tothe subject[6— 11] .For example,some 2 - amino or 2 -alkylthio substituted 4H- imidazolin- 4- ones showsignificant antifungal and antibacterial activi-ties[7— 9] ,whereas others …     

Influence of Poly(methylmethacrylate) on 8-hydroxyquinoline Derivative-Metal Complexes Electroluminescence

A new method is presented of enhancing the organic electroluminescent(EL) efficiency by using poly (methylmethacrylaie) (PMMA) as barrier layers which play the role of controlling the electron-hole recombination in the organic EL materials. The organic EL device with one layer of 8-hydroxyquinoline derivalive-metal complexes-(Alq3, Znq2) as the EL-emitting layers, and two layers of EL emitting materials deposited on PMMA Langmuir-Blodgett films (PMMA/Alq3, PMMA/Znq2) sandwiched between indium/tin oxide (ITO) and aluminum electrodes have been fabricated, respectively. The evidence reveals that the LB film takes an importance to raising the 8-hydroxyquinoline derivative-metal complexes EL efficiency.     

Synthesis of light-emmting materials bis-[2′-2″-(9H-fluoren-2-yl)-vinyl-8-hydroxyquinoline] zinc(II) and bis-[2′-4″-(4,5-diphenyl-1H-imidazol-2-yl)styryl-8-hydroxyquinoline] zinc(II)

Two novel light-emitting materials bis-[2′-2″-(9H-fluoren-2-yl)-vinyl-8-hydroxyquinoline] zinc(II) (3) and bis-[2′-4″-(4,5-diphenyl-1H-imidazol-2-yl)styryl-8-hydroxyquinoline] zinc(II) (4) containting 8-hydroxyquinoline and fluorene or imidazole moieties have been synthesized. The optical properties of these complexes were influenced by the styryl substituents, and exhibited orange-emission. They have higher fluorescence quantum yields than Alq₃, and good stabilities with thermal decomposition temperatures 395 °C and 435 °C. The single-layer OLED fabricated by 3 emitted lemon-yellow, and exhibited good device performance with a maximum luminance of 489 cd m⁻², and luminance efficiency of up to 0.41 cd A⁻¹. The single-layer OLED fabricated by 4 emitted yellow-green, and exhibited good device performance with a maximum luminance of 323 cd m⁻², and luminance efficiency of up to 0.54 cd A⁻¹.     

Synthesis and photoluminescence properties of 8-hydroxyquinoline derivatives and their metallic complexes

Three new 8-hydroxyquinoline derivatives, i.e. 5-[(4-styryl-benzylidene)-amino]-quinolin-8-ol (1), 5-[(4-bromo-2-fluoro-benzylidene)-amino]-quinoline-8-ol (2) and 2-[2-(9-ethyl-9H-carbazol-2yl)-vinyl]-quinolin-8-ol (3), and their metallic complexes were synthesized and identified by ultraviolet-visible (UV-Vis), ¹H nuclear magnetic resonance (¹H NMR), Fourier transform infrared spectrometer (FTIR), mass spectrometry (MS) spectra and elemental analyses. Their fluorescence properties were studied by photoluminescence, which indicated that the luminescence wavelength of 5-and 2-substitued-8-hydroxyquinoline derivatives shifted to red in comparison with that of 8-hydroxyquinoline. Meanwhile, the fluorescence lifetime of 2-[2-(9-ethyl-9H-carbazol-2yl)-vinyl]-quinolin-8-ol and its zinc complex showed long lifetime in benzene solution. __________ Translated from Chinese Journal of Organic Chemistry, 2007, 27(3): 402–408 [译自: 有机化学]     

8-hydroxyquinoline based neutral tripodal ionophore as a copper (II) selective electrode and the effect of remote substitutents on electrode properties

New PVC membrane ion selective electrodes based on 1,3,5-Tris(8-quinolinoxymethyl)-2,4,6-trimethylbenzene (MO8HQ) are reported. The basic sensing material belongs to the group of tripodal ionophores. Also their derivatives prepared by placing suitable substitutents at fifth position of 8-oxine moiety, i.e, 1,3,5-Tris(5-chloro-8-quinolinoxymethyl)-2,4,6-trimethylbenzene (5CHQ), 1,3,5-Tris(5-benzoyl-8-quinolinoxymethyl)-2,4,6-trimethylbenzene (5BHQ) and 1,3,5-Tris[(5-phenylhydroxymethylene)-8-quinolinoxymethyl]-2,4,6-trimethylbenzene (HYD-8HQ) ionophores have also been used to make copper-selective membrane electrodes. Among all the four electrodes, MO8HQ and HYD-8HQ ionophores based electrodes show excellent response towards Cu (II) ions. The electrodes having composition 33% PVC, 4% MO8HQ and 63% dibutyl phthalate (DBP) and 33% PVC, 6% HYD-8HQ, 63% dibutyl phthalate (DBP) exhibit a good Nernstian response to Cu (II) ions in the range of 1.0 × 10⁻⁶ to 1 × 10⁻¹ M. The electrode shows a reasonably fast response time of 15 s. The effect of pH and electrode response is also reported. It shows good selectivity for Cu (II) ions in comparison to heavy metal ions, transition metal ions and for alkali and alkaline earth metal ions. The electrode response and selectivity remains unchanged for at least 5 months. The electrode can be used as an indicator electrode in the potentiometric titration of Cu (II) ions with EDTA.     

Molecular fluorescent probe for Zn based on 2-(2-nitrostyryl)-8-methoxyquinoline

A fluorescent Zn²⁺ sensor based on the 2-(2-nitrostyryl)-8-methoxyquinoline (2-nitroSQ) has been designed, synthesized, and characterized by various spectral techniques. The designed fluorophore displays high selectivity, sensitive fluorescence enhancement (13-fold), and strong binding affinity toward Zn²⁺ among the various biologically significant metal ions examined in ACN-H₂O (9:1, v/v).     

Preparation of cobalt and nickel complexes of 8-hydroxyquinoline with nanobelt structure via one-step,low-heating,solid-state reactions

Two nano-structural complexes, bis-(8-hydroxyquinoline) cobalt and bis-(8-hydroxyquinoline) nickel, have been prepared by one-step, low-heating, solid-state reaction, a simple, safe, economical and environmentally-friendly method. TEM and SEM images show that the complexes are composed of nanobelts with width ranging from 100 to 300?nm and a length of up to 1?µm. The technique offers a new way for fabricating coordination compounds with one-dimensional nanostructure.     

Anion detection by fluorescent Zn(II) complexes of functionalized polyamine ligands

The Zn(2+) coordination chemistry and luminescent behavior of two ligands constituted by an open 1,4,7-triazaheptane chain functionalized at both ends with 2-picolyl units and either a methylnaphthyl (L1) or a dansyl (L2) fluorescent unit attached to the central amino nitrogen are reported. The fluorescent properties of the ZnL1(2+) and ZnL2(2+) complexes are then exploited toward detection of anions. L1 in the pH range of study has four protonation constants. The fluorescence emission from the naphthalene fluorophore is quenched either at low or at high pH values leading to an emissive pH window centered around pH = 5. In contrast, in L2 the fluorescence emission from the dansyl unit occurs only at basic pH values. In the case of L1, a red-shifted band appearing in the visible region was assigned to an exciplex emission involving the naphthalene and the tertiary amine of the polyamine chain. L1 forms Zn(2+) mononuclear complexes of ZnH(p)L1((p+2)+) stoichiometry with p = 1, 0, -1. Formation of the ZnL1(2+)species produces a strong enhancement of the L1 luminescence leading to an extended emissive pH window from pH = 5 to pH = 9. Addition of several anions to this last complex leads to a partial quenching effect. On the contrary, the fluorescence emission of L2 is partially quenched upon complexation with Zn(2+) in the same pH window (5 < pH < 9). The lower stability of ZnL2(2+) with respect to ZnL1(2+) suggests a lack of involvement of the sulfonamide group in the first coordination sphere. However, there is spectral evidence for an interesting photoinduced binding of the sulfonamide nitrogen to Zn(2+). While addition of diphosphate, triphosphate, citrate, and D,L-isocitrate to a solution of ZnL2(2+) restores the fluorescence emission of the system (lambda max ca. 600 nm), addition of phosphate, chloride, iodide, and cyanurate do not produce any significant change in fluorescence. Moreover, this system would permit one to differentiate diphosphate and triphosphate over citrate and d, l-isocitrate because the fluorescence enhancement observed upon addition of the first anions is much sharper. The ZnL2(2+) complex and its mixed complexes with diphosphate, triphosphate, citrate, and D,L-isocitrate have been characterized by (1)H, (31)P NMR, and Electrospray Mass Spectrometry.     

Synthesis, characterization and molecular structure of Ru(II) complex with 8-hydroxyquinoline derivative

The new (E)-8-hydroxyquinoline-2-carbaldehyde O-benzyl oxime ligand and its hydride-carbonyl complex of ruthenium was synthesized and characterized by infrared, proton and phosphorus nuclear magnetic resonance, electronic absorption and emission spectroscopy and X-ray crystallography. The experimental studies were complemented by theoretical calculations. From the electronic spectrum of the complex the Racah’s and nepheloauxetic parameters are calculated. The electronic structure of the complexes, presented in particular by the density of states diagram, have been correlated with its ability to fluoresce and used to analyze the UV-Vis spectra.     

Preparations and structures of titanium(IV) complexes containing 8-hydroxyquinolinate and a Schiff-base N-(2-oxyphenyl)salicylideneiminate

In methanol, the reaction of Ti(OⁱPr)₄, N-(2-hydroxyphenyl)salicylideneimine (H₂Sap) and 8-hydroxyquinoline (HQ) in stoichiometric ratio 1:1:x yielded Ti(Sap)₂ precipitate as initial product even when x was as high as 10. However, when the reaction mixture with x = 2 was left standing for 12 h or more, a small amount of red crystalline Ti(Sap)Q(OMe) was isolated. Addition of wet acetonitrile to the reaction mixture with x = 10, small amount of another red crystalline [Ti(Sap)Q]₂(μ-O) was obtained after standing for 2 days. The reaction between TiQ₂(OⁱPr)₂ and H₂Sap in methanol with stoichiometric ratio of y:1 also yielded Ti(Sap)₂ as initial product even for y as large as 10. ¹H NMR investigation of the reaction of TiQ₂(OMe)₂ with H₂Sap revealed that Ti(Sap)Q(OMe) was not detected initially. These experimental results can be explained based on a mechanism that includes: (i) rapid reaction of H₂Sap with Ti(IV) centers to form Ti(Sap)₂; (ii) equilibrium between TiQ₂(OMe)₂ and Ti(Sap)Q(OMe); (iii) equilibrium between Ti(Sap)Q(OR) and Ti(Sap)₂; and (iv) limited solubilities of Ti(Sap)Q(OR) and Ti(Sap)₂. The equilibrium constants and solubilities in the mechanism were determined by the ¹H NMR spectral method. The structures of Ti(Sap)Q(OMe) and [Ti(Sap)Q]₂(μ-O), consisting octahedrally coordinated Ti(IV), were determined by X-ray diffraction method.