Structural characterization of copper (II) tetradecanoate with 2,2′-bipyridine and 4,4′-bipyridine to study magnetic properties

This paper presents synthesis, structural characterization and spintronic applications of copper (II) tetradecanoate derived magnetic complexes. The complexes were prepared by a chemical reaction between [Cu₂(CH₃(CH₂)₁₂COO)₄](EtOH)₂ and 2,2′-bipyridine-4,4′-bipyridine ligands respectively. The complexes were further reacted between the product of the first reaction and 4,4′-bipyridine-2,2′-bipyridine respectively. The structural characterization techniques included elemental analysis, Fourier transformed infrared spectroscopy (FTIR), Ultra-violet–Visible (UV–Vis) spectroscopy, polarized optical microscopy, magnetic moment and thermogravimetric analysis. The structural and characterization results suggested that the synthesized complexes were binuclear and mononuclear covalent complexes of copper(II) with structural formulas [Cu₂(η²-(OOCR)₄](4,4′-bpy)2H₂O] and [Cu(η¹-(OOCR)₂(2,2′-bpy) (4,4′-bpy)] respectively.     

The Synthesis of a New Dumbbell-shaped Compound of Bis-4, 4′-bipyridine Bridged by 2, 2′-Bipyridine

The title compound 5 was synthesized in 45% yield by the reaction of compound 3 with α,α′-bis (bromomethyl)-2, 2′-bipyridine in CH3CN at 70℃ for 24 h.     

Crystal Structure of infin; 2[Cu2I2(μ-4-4′-bipyridine)] and Investigations on the Thermal Decomposition of CuX-4,4′-bipyridine Coordination Polymers

Summary.  The inorganic-organic coordination polymer _infin; ²[Cu₂I₂(μ-4-4′-bipyridine)] was prepared by the reaction of Cu(I)I and 4,4^′-bipyridine in acetonitrile. Its structure consists of staircase-like CuX double chains which are connected to sheets by the 4,4^′-bipyridine ligands. The thermal decomposition of the corresponding 1:1 copper(I) halide-4,4^′-bipyridine compounds _infin; ²[CuX(μ-4-4′-bipyridine)] (X = Cl, Br, I) was investigated using simultaneous difference thermal analysis and thermogravimetry (DTA-TG), thermomicroscopy, and temperature resolved X-ray powder diffraction in air or argon. Upon heating _infin; ²[CuX(μ-4-4′-bipyridine)], several changes in sample mass are observed which correspond to a stepwise loss of the organic ligands. Temperature-resolved X-ray powder diffraction proves that _infin; ²[CuX(μ-4-4′-bipyridine)] transforms to _infin; ²[Cu₂ X ₂(μ-4-4′-bipyridine)] during the decomposition; the latter looses the remaining ligands when heated further, forming the corresponding copper(I)halides. When the experiments were performed under an argon atmosphere, the 2:1 coordination polymers were obtained as phase-pure compounds. Received March 1, 2001. Accepted April 11, 2001     

Structural diversity of homochiral cadmium-camphorates with 2,2′-bipyridine

Homochiral framework materials are of current interest due to their potential applications in asymmetric catalysis and enantioselective separation. Four new Cd(II) camphorates (1–4) with 2,2′-bipyridine ligand (= 2,2′-bipy) are successfully synthesized and show distinct structural features. Such rich Cd-cam-2,2′-bipy system is composed of four compounds, [Cd(d-cam)(2,2′-bipy)(DMF)]_n (1), [Cd(d-cam)(2,2′-bipy)(H₂O)]_n (2), [Cd₂(d-cam)₂(2,2′-bipy)₂]_n (3) and [Cd₂Cu₂(d-cam)₄(2,2′-bipy)₂]_n·4nH₂O (4), which are obtained under different conditions. Both compounds 1 and 2 show infinite homochiral Cd-camphorate chain, while compounds 3 and 4 exhibit homochiral layered structures based on different dinuclear units. The results demonstrate the rich coordination chemistry of the enantiopure d-camphorate ligand and the structural diversity of metal-camphorate compounds.     

Adsorption and redox chemistry of cis-RuLL'(SCN)2 with L=4,4′-dicarboxylic acid-2,2′-bipyridine and L'=4,4′-dinonyl-2,2′-bipyridine (Z907) at FTO and TiO2 electrode surfaces

The electrochemical and spectroelectrochemical properties of the sensitizer dye Z907 (cis-RuLL'(SCN)₂ with L=4,4′-dicarboxylic acid-2,2′-bipyridine and L'=4,4′-dinonyl-2,2′-bipyridine) adsorbed on fluorine-doped tin oxide (FTO) and TiO₂ surfaces have been investigated. Langmuirian binding constants for FTO and TiO₂ are estimated to be 3 × 10⁶ M⁻¹ and 4 × 10⁴ M⁻¹, respectively. The Ru(III/II) redox process is monitored by voltammetry and by spectroelectrochemistry. For Z907 adsorbed onto FTO, a slow EC-type electrochemical reaction is observed with a chemical rate constant of ca. k = 10⁻² s⁻¹ leading to Z907 dye degradation of a fraction of the FTO-adsorbed dye. The Z907 adsorption conditions affect the degradation process. No significant degradation was observed for TiO₂-adsorbed dye. Degradation of the Z907 dye affects the electron hopping conduction at the FTO–TiO₂ interface.     

Enantioselective palladium catalyzed allylic substitution with 2,2′-bipyridine ligands

A number of chiral C₁-symmetric 2,2′-bypyridines were prepared and assessed in the enantioselective palladium catalyzed allylic substitution of 1,3-diphenylprop-2-enyl acetate with dimethylmalonate. Enantioselectivity up to 89% was obtained.     

Single-crystal X-ray diffraction analysis of arylamine-containing 2,2′-bipyridine derivatives

The structures of six 2,2′-bipyridine derivatives containing aromatic amine moieties, namely N-aryl-4-aryl-1-(pyridin-2-yl)-6,7-dihydro-5H-cyclopenta[c]pyridine-3-amines, were studied by single-crystal X-ray diffraction. The molecular structures and the effect of the substituents of these compounds on the crystal packing are discussed.

     

The electron-donating properties of 2,2′-bipyridine. Charge-transfer studies

Molecular charge-transfer complexes of 2,2′-bipyridine with iodine and tetracyanoethylene have been investigated. The formation constants of these complexes were determined at different temperatures and the thermodynamic functions, ΔH_f and ΔS_f were calculated. The spectra and stability of the complexes were discussed and interpreted.     

Cyclopalladated 2-phenyldihydrooxazole complexes with ethylenediamine, 2,2′-bipyridine,and bridging acetate ligands

The ¹H NMR, electronic absorption, and luminescence spectra, as well as voltammograms of the reduction and oxidation of the complexes [Pd(C∧N)(N∧N)]ClO₄ and [Pd(C∧N)(μ-OOCCH₃)]₂ [where (C∧N)⁻ is deprotonated 2-phenyl-4,5-dihydro-1,3-oxazole, and N∧N is ethylenediamine or 2,2′-bipyridine (bpy)] were compared. Magnetic nonequivalence of protons in the dihydrooxazole ring and upfield shift of the corresponding signals were observed as a result of anisotropic effect of the ring current in palladated phenyl substituents in the [Pd(C∧N)(μ-OOCCH₃)]₂ complex having a C ₂ symmetry. One-electron reduction wave of [Pd(C∧N)bpy]⁺ was assigned to ligand-centered electron transfer to the π* orbital of 2,2′-bipyridine, and two oxidation waves of [Pd(C∧N)(μ-OOCCH₃)]₂ were attributed to successive one-electron oxidations of the palladium centers. Low-temperature (77 K) phosphorescence of [Pd(C∧N)En]⁺ and [Pd(C∧N)bpy]⁺ was ascribed to optical transition localized on the metal-complex fragment {Pd(C∧N)} and to interligand charge transfer between the chelating and cyclopalladated ligands. The formation of metal-metal bond in the complex [Pd(C∧N)(μ-OOCCH3₎]₂ gives rise to radiative decay of photoexcitation energy from two electronically excited states, one of which is localized on the {Pd(C∧N)} fragment, and the second corresponds to the charge transfer metal-metal-cyclopalladated ligand.     

A Novel Method for Synthesizing 4,4′-Bis(hydroxymethyl)-2,2′-bipyridine

IntroductionSince C. W. Tang firstly reported theelectroluminescence of 8- hydroxyquinolinealuminium[1] ,much attention has been paid to themetal complexes as electro- luminescent materials.Based on a series of experimental data,it has beenknown that the electroluminescence of metalcomplexes with heterocyclic ligands containing Nand O elements mainly results from the tripletstatetransition.For some transitional metal complexes,there exist the transitions from metal to ligand( MLCT) at thei…     

Two supramolecular structures constructed from Keggin-type polyoxometalates and 4,4′-bipyridine

Two supramolecular compounds based on Keggin-type polyoxometalates (POMs), (4,4′-H₂bpy)(4,4′-Hbpy)[PMo₁₂O₄₀] (1) and (4,4′-H₂bpy)(4,4′-Hbpy)₂[SiW₁₂O₄₀]?·?4H₂O (2), have been synthesized hydrothermally and characterized by elemental analyses, IR, UV-Vis, XPS spectra, thermogravimetric analyses, and single-crystal X-ray diffraction analyses. The two compounds consist of 4,4′-bipyridine (4,4′-bpy) ligands and different Keggin-type POMs which are [PMo₁₂O₄₀]^3? for 1 and [SiW₁₂O₄₀]^4? for 2. There are hydrogen-bonding interactions between the POMs, 4,4′-bipyridine, and/or water in 1 and 2. In addition, 2 contains an uncommon (H₂O)₂ water cluster.     

Surface-enhanced Raman scattering of 4,4′-bipyridine on gold nanoparticle surfaces

The adsorption structure and mechanism of 4,4′-bipyridine (BiPy) on gold nanoparticle surfaces has been investigated by means of surface-enhanced Raman scattering (SERS). The aromatic ring of BiPy appeared to assume a perpendicular orientation with respect to the gold surface from the presence of the ν(CH) band at ∼3060 cm⁻¹. The SERS intensities of several vibrational modes of BiPy on Au were found to vary as the bulk concentration. The SERS intensities for BiPy on Au could be ascribed to both the electromagnetic (EM) and charge transfer (CT) enhancement mechanism.     

A novel electrolyte: CdS nanoparticle capped with 2,2′-bipyridine

The use of an electroneutral ligand modified the Cd²⁺-rich surface of CdS leads to the surrounding of CdS/2,2′-bpy by the counter ion (anion) to balance the charge of the Cd²⁺ ions, resulting in the CdS cluster with strong electrolyte behavior.     

New complexes of heavy lanthanides with 4,4′-bipyridine and trichloroacetates

Novel mixed-ligand complexes with empirical formula Ln(4-bpy)₂(CCl₃COO)₃·nH₂O [where Ln(III)?=?Dy, Ho, Er, Tm, Yb, Lu; 4-bpy?=?4,4??-bipyridine] were prepared and characterized by chemical and elemental analysis, infrared spectroscopy, and conductivity measurements (in methanol, dimethylformamide, and dimethyl sulfoxide). X-ray powder diffraction patterns indicate that the complexes are small crystalline compounds. IR spectra of complexes show that all carboxylate groups and 4-bpy are engaged in coordination of lanthanide ions. The thermal behavior of complexes was studied by means of TG, DTG, DTA techniques in the solid state under nonisothermal conditions in air atmosphere. During heating, the complexes decompose via intermediate products to the oxide Ln₂O₃. The combined TG?CFTIR technique was employed to study the decomposition pathway of the Ho(III) and Tm(III) complexes in flowing argon atmosphere.     

Photochemistry of tetramethyl(2,2′-bipyridine)platinum(IV)

It is shown that photolysis of [PtMe₄(bipy)] using incident radiation with λ 436 or 473 nm occurs with high quantum efficiency of 0.8–1.0 to give homolysis of a methylplatinum bond; this has allowed a study of the chemical reactions of the [PtMe₃(bipy)] radical.     

Picosecond fluorescence decays from electronic excited states of 2,2′-bipyridine solutions

The photophysics of 2,2′-bipyridine in solution has been studied using picosecond excitation and single photon counting detection technique. Excited state relaxations could occur through non reactive (internal conversion, radiative decay) and reactive (photoisomerization) channels. The solvent influences the decay both indirectly (energy ordering of states) or directly through the friction exerted on the isomerization coordinate.     

Synthesis of ruthenium tris(2,2′-bipyridine)-type complexes tethered to peptides at 5,5′-positions

Utilization of 5′-amino-2,2′-bipyridine-5-carboxylic acid allows molecular design of ruthenium tris(bipyridine)-type complexes bearing two different functional groups. In this study, a novel ruthenium tris(bipyridine) derivative bearing viologen and tyrosine as an electron acceptor and donor, respectively, is synthesized. This synthesis exemplifies the effectiveness of the molecular design for functionalizing ruthenium bipyridine-type complexes. The photophysical properties are discussed in comparison with a reference ruthenium complex which has neither the electron acceptor nor donor.     

Nickel(II) complex containing 5,5′-dimethyl-2,2′-bipyridine: Crystal structure and luminescent properties

[Ni(5,5′-dmbipy)₂Cl₂]·3H₂O (1) complex was obtained from the reaction of NiCl₂·6H₂O with 5,5′-dimethyl-2,2′-bipyridine (5,5′-dmbipy) in a mixture of CH₃OH/CH₃CN. This complex was characterized by elemental analysis, IR, UV-Vis and luminescence spectroscopy, and its structure was determined by the single-crystal diffraction method. The Ni atom has a distorted octahedral coordination by four N atoms from two 5,5′-dmbipy ligands and two Cl^– anions.     

Two transition metal coordination polymers constructed from 3-aminobenzoate and 4,4′-bipyridine

Two new transition metal coordination polymers, [Zn(abz)(bipy)](ClO₄) (1) and [Mn(bipy)₅(H₂O)₆](ClO₄)_2?·?2(abz)?·?2(H₂O) (2) (bipy?=?4,4′-bipyridine, abz?=?3-aminobenzoate), were prepared and characterized by elemental analysis, FTIR spectroscopy, and single-crystal X-ray diffraction. Complex 1 is a 2-D-layered network with a (4,4) net built up by bipy and 3-aminobenzoate ligands connecting two zinc nodes. Complex 2 is a 3-D supramolecular grid network constructed from close stacking bipy ligands of H-type cation units with large cavities hosting 3-aminobenzoate, perchlorate ions, and water. Solid state photoluminescence for 1 was also investigated.