Three new multidimensional organic-inorganic hybrids based on polyoxometalates and copper coordination polymers with 4,4′-bipyridine ligands

Three new organic-inorganic hybrid materials with 4,4′-bipy ligands and copper cations as linkers, [Cu^II(H₂O)(4,4′-bipy)₂][Cu^II(H₂O)(4,4′-bpy)₂]₂H[Cu^IIP₈Mo₁₂O₆₂H₁₂] · 5H₂O (1), [Cu^I(4,4′-bipy)][Cu^II(4,4′-bipy)]₂ (BW₁₂O₄₀) · (4,4′-bipy) · 2H₂O (2) and [Cu^I (4,4′-bipy)]₃ (PMo₁₂O₄₀) · (pip) · 2H₂O (3) (pip = piperazine; 4,4′-bipy = 4,4′-bipyridine), have been hydrothermally synthesized. The single X-ray structural analysis reveals that the structure of 1 is constructed from [Cu(H₂O)(4,4′-bipy)₂] complexes into a novel, three-dimensional supermolecular network with 1-D channels in which Cu[P₄Mo₆]₂ dimer clusters reside. To the best of our knowledge, compound 1 is the first complex in which the [P₄Mo₆] clusters have been used as a non-coordinating anionic template for the construction of a novel, three-dimensional supermolecular network. Compound 2 is constructed from the six-supported [BW₁₂O₄₀]⁵⁻ polyoxoanions and [Cu^I(4,4′-bipy)] and [Cu^II(4,4′-bipy)] groups into a novel, 3-D network. Compound 3 exhibits unusual 3-D supramolecular frameworks, which are constructed from tetrasupporting [PMo₁₂O₄₀]³⁻ clusters and [Cu^I (4,4′-bipy)_n] coordination polymer chains. The electrochemical properties of 2 and 3 have been investigated in detail.     

Two new organic-inorganic hybrid materials based on the polyoxotungstoaluminates

Two new organic-inorganic hybrid compounds, {[Cu(2,2′-bipy)₂]₂(Hbpy)[α-AlW₁₂O₄₀]}·H₂O (1) and {[H₂en][Cu^I(4,4′-bipy)]₃(α-AlW₁₂O₄₀)}·4H₂O (2) (2,2′-bipy = 2,2′-bipyridine, 4,4′-bipy = 4,4′-bipyridine, py = pyridine, en = ethylene dimine) based on Keggin-type α-[AlW₁₂O₄₀]⁵⁻ polyoxoaions and transition-metal organoamine subunits, have been hydrothermally synthesized and characterized by elemental analysis, IR spectroscopy, thermal gravimetric analysis (TG), and single-crystal X-ray diffraction. In addition, the electrochemical properties and photocatalytic activity of compound 1 were studied. The structural analysis reveals that 1 shows a 1D infinite chain structure constructed from [α-AlW₁₂O₄₀]⁵⁻ polyoxoanions and {[Cu^II(2,2′-bipy)₂][Cu^II(2,2′-bipy)(py)]}⁴⁺ fragments, in which the remarkable aspect is that [α-AlW₁₂O₄₀]⁵⁻ polyoxoanion is modified in a fascinating symmetrical mode. Compound 2 displays an unprecedented 2D extended structure constructed from [α-AlW₁₂O₄₀]⁵⁻ polyoxoanions and 4,4′-bipy-Cu^I-4,4′-bipy linear chains, in which three - chain belts formed by three linear chains arranged Cu parallel connect alternately with [α-AlW₁₂O₄₀]⁵⁻ polyoxoanions. As far as we know, compounds 1 and 2 represent the first 1D and 2D extended hybrid materials constructed from 3d transition metals and polyoxotungstoaluminates linked through covalent bonds.     

Construction of one-, two- and three-dimensional Cu(I) polymeric architectures containing bis(diphenylphosphino)acetylene and 4,4′-bipyridine linking ligands

One-dimensional {[Cu₂(dppa)₂(4,4′-bipy)(CH₃CN)₂](BF₄)₂ · 2CH₃CN}_n (1), two-dimensional {[Cu₂(dppa)(4,4′-bipy)₂(CH₃CN)₂](BF₄)₂ · 4CH₂Cl₂ · 4H₂O}_n (2) and three-dimensional {[Cu₂(dppa)(4,4′-bipy)₃](BF₄)₂ · 2CH₂Cl₂ · 3CH₃CN · 3H₂O}_n (3) polymeric complexes have been prepared by self-assembly of [Cu(MeCN)₄]BF₄, Ph₂PCCPPh₂ (dppa) and 4,4′-bipyridine (4,4′-bipy) in a 2:2:1, 1:1:1 and 2:2:3 molar ratio, respectively. The structures of 1-3, determined by an X-ray diffraction study, reveal a linear spring-like architecture for 1, a planar honeycomb grid for 2 and an interlocked adamantoid network for 3.     

Hydrothermal syntheses, crystal structures and characterizations of three new copper coordination polymers

Three new copper complexes, [Cu^IICu^I(ip)(ipH)(4,4′-bipy)_3/2]_n (1), [Cu(ip)(4,4′-bipy)]_n · 3nH₂O (2), and [Cu(ipH)₂(4,4′-bipy)]_n (3), have been hydrothermally synthesized by the reaction of Cu(NO₃)₂ · 3H₂O with isophthalic acid (ipH₂) and 4,4′-bipyridine (4,4′-bipy) under different reaction conditions. Complex 1, a mixed-valence copper(I,II) complex, exhibits a 2-D interpenetrating grid framework, in which five-coordinated Cu^II and three-coordinated Cu^I environments are established. The oxidation states of center Cu atoms have been confirmed by X-ray photoelectron spectroscopy (XPS) and electron paramagnetic resonance spectra (EPR). Complex 2 features a 2-D box-like bilayer architecture, in which Cu^II atoms are linked by ip ligands to form a 1-D double-chain and the resulting chains are further strutted by the 4,4′-bipy ligands. In complex 3, two bridging 4,4′-bipy ligands and two terminal ipH ligands confine the Cu^II center in a square plane coordination geometry. The whole molecule of 3 was arranged into a 1-D linear chain structure. Additionally, the thermogravimetric analyses (TGA) for complexes 1-3 are also discussed in this paper.     

Diverse dimensionalities and structures in copper coordination polymers incorporating substituted aliphatic dicarboxylate ligands and 4,4′-bipyridine

Hydrothermal synthesis has afforded a series of divalent copper coordination polymers with substituted glutarate ligands and the rigid rod tether 4,4′-bipyridine (bpy): {[Cu(Hdmg)₂(bpy)]·H₂O}_n (1, dmg = 3,3-dimethylglutarate), {[Cu₂(dmg)(bpy)₂](ClO₄)]_n (2), [Cu₂(emg)₂(bpy)]_n (3, emg = 3-ethyl, 3-methylglutarate) and [Cu₂(cda)₂(bpy)]_n (4, cda = 1,1-cyclopentanediacetate). All materials were characterized by single-crystal X-ray diffraction. Compound 1 manifests μ₂-oxygen bridged [Cu₂(Hdmg)₄] “X”-patterns connected into a ribbon motif by bpy linkers. On the other hand, 2 possesses mixed-valence [Cu^ICu^IICu^IICu^I] tetrameric clusters bridged by dmg ligands and pillared into an 8-connected body-centered cubic (bcu) cationic lattice by bpy linkers. Compounds 3 and 4 are structurally very similar, displaying chain motifs with {Cu₂(CO₂)₄} paddlewheels connected by dicarboxylates, in turn conjoined into (4,4)-grid coordination polymer layers by bpy tethers. Variable temperature magnetic data indicate the presence of very strong antiferromagnetic coupling within the {Cu₂(CO₂)₄} paddlewheels in the latter two complexes, with g = 2.30(2) and J = −352(3) cm⁻¹ for 3 and g = 2.35(2) and J = −352(5) cm⁻¹ for 4. Significant structural contrasts are evident when compared to previously reported divalent copper/4,4′-bipyridine coordination polymers with unsubstituted or 2-methyl substituted glutarate ligands.     

Acetato and formato copper(II) complexes with 4,4′-dimethyl-2,2′-bipyridine and 5,5′-dimethyl-2,2′-bipyridine: Synthesis, crystal structure, magnetic properties and EPR results. A new 1D polymeric water chain

By the reactions of Cu(AcO)₂·H₂O and Cu(HCOO)₂·4H₂O with 4,4′-dimethyl-2,2′-bipyridine and 5,5′-dimethyl-2,2′-bipyridine the compounds [Cu(AcO)₂(4,4′-Me₂-2,2′-bipy)]·1/2H₂O (1), [Cu(AcO)₂(5,5′-Me₂-2,2′-bipy)(H₂O)] (2), [Cu(HCOO)(μ-HCOO)(4,4′-Me₂-2,2′-bipy)]_n·nH₂O (3) and [Cu(HCOO)(μ-HCOO)(5,5′-Me₂-2,2′-bipy)]_n·2nH₂O (4) were obtained. In the acetate complexes, 1 and 2, the geometry around copper is distorted octahedral and square pyramidal, respectively. Dimeric units of different geometry are formed in both cases through hydrogen bonds in which non-coordinated (in 1) and coordinated (in 2) water molecules are involved. The structures of 3 and 4 consist of polymeric monodimensional chains of square pyramidal copper units linked by axial-equatorial syn-anti (3) or anti-anti (4) bridging formate groups. Water molecules form hydrogen bonds with formate groups of the same chain in compound 3. In compound 4 the water molecules link the polymeric contiguous chains of complex through hydrogen bonds with oxygen atoms of formate groups and they are also linked between them, forming monodimensional water chains which run parallel to the complex chains. Sheets parallel to the ac plane are formed by alternating chains of water and polymeric complex. Magnetic properties and EPR spectra for these compounds have been studied.     

A new 3D transition-metal complex-templated framework based on Wells-Dawson polyoxometalate and copper(I)-pyrazine moieties

A new Wells-Dawson polyoxometalate-based compound, [Cu^II(2,2′-bipy)₂(H₂O)]₃[Cu^I₆(pz)₆(P₂W₁₈O₆₂)₂] (2,2′-bipy = 2,2′-bipyridine, pz = pyrizine) (1), has been hydrothermally synthesized and characterized by routine physical methods. Compound 1 exhibits a [Cu^II(2,2′-bipy)₂(H₂O)]²⁺ complex-templated 3D (3,4)-connected framework with the topology of (6³)(6²8⁴), which is built up by the cross-linking of porous P₂W₁₈-Cu layers and Cu^I-pz chains with Cu2 atoms as intersections. The transition-metal complex cation [Cu^II(2,2′-bipy)₂(H₂O)]²⁺ acts not only as a template locating in the voids of inorganic layers, but also as a charge-balance complex to make the 3D structure more steady. The electrochemistry property of compound 1 has also been discussed.     

Solution and solid-state complexes of the potentially tetradentate pyridyl-thiazole ligand 6,6′-bis(4-methylthiazol-2-yl)-2,2′-bipyridine with Co, Ni, Cu, Cd, Hg, Cu and Ag

Reaction of the potentially tetradentate N-donor ligand 6,6′-bis(4-methylthiazol-2-yl)-2,2′-bipyridine (L¹) with the transition metal dications Co^II, Ni^II, Cu^II, Cd^II and Hg^II results in the formation of mononuclear [M(L¹)]²⁺ complexes, in which a planar ligand coordinates to the metals via all four N-donors. In contrast, reaction of L¹ with Cu^I and Ag^I monocations, affords dinuclear double stranded helicate species [M₂(L¹)₂]²⁺ (where M = Cu^I or Ag^I), in which partitioning of the ligand into two bis-bidentate pyridyl-thiazole chelating units allows each ligand to bridge both metal centres. X-Ray crystallography, electrospray mass spectroscopy and NMR spectroscopy reveal that the complexes [M_n(L¹)_m]^z+ (where n = 1, m = 1 and z = 2, when M = Co^II, Ni^II, Cu^II, Cd^II and Hg^II; n = 2, m = 2 and z = 2, when M = Cu^I), retain their solid-state structures in solution. Conversely, whilst ¹H NMR studies suggest that combination of equimolar amounts of Ag(X)(where ) and L¹ (in either nitromethane or acetonitrile) results in the formation of a helicate in solution, in the solid-state, an anion-templating effect gives rise to either mononuclear or dinuclear helicate structures [Ag_n(L¹)_n][X]_n (where n = 2 when X = OTf⁻; n = 1 when ).     

Preparation and photophysical studies of copper(I) and ruthenium(II) complexes of 4,4′-bis(3,5-dimethoxyphenyl)-6,6′-dimethyl-2,2′-bipyridine

We report the synthesis of a new ligand, 4,4′-bis(3,5-dimethoxyphenyl)-6,6′-dimethyl-2,2′-bipyridine, optimised for binding to copper(I) and with pendant functionality that can eventually be developed into metallodendritic structures. The synthesis and photophysical properties of complexes with copper(I) and ruthenium(II) are reported. The solid state structure of the complex [Cu(1)₂][PF₆] · MeCN (1 = 4,4′-bis(3,5-dimethoxyphenyl)-6,6′-dimethyl-2,2′-bipyridine) is also described.     

Syntheses and characterization of luminescent dinuclear and polynuclear Cu(I) complexes containing 4,4′-bis(diphenylphosphino)biphenylene bridge

The dinuclear complex [Cu₂(dpbp)₂(NCMe)₄][BF₄]₂ (1) has been prepared by treating [Cu(NCMe)₄][BF₄] with 4,4′-bis(diphenylphosphino)biphenylene (abbreviated as dpbp). Reactions of 1 with 2,2′-bipyridine and 1,1′-bis(diphenylphosphino)ferrocene (abbreviated as dppf) afford [Cu₂(dpbp)₂(2,2′-bipy)₂][BF₄]₂ (2) and [Cu₂(dpbp)(dppf)₂][BF₄]₂ (3), respectively. In contrast, compound 1 reacts with tetra(2-pyridyl)ethyl-1,4-diaminobutane (abbreviated as tpyda) to produce the polymeric complex {[Cu₂(dpbp)(tpyda)][BF₄]₂}_n (4). Compounds 1-4 are photoluminescent with the emission band (λ_max) in the range 510-554 nm. The crystal structures of 1 and 4 have been determined by an X-ray diffraction study.     

Syntheses, spectroscopic properties and crystal structures of two organoruthenium (II) complexes of bipyridines: [{Cp*Ru(2,2′-bipy)}2(μ-Cl)][PF6] and [{(η-p-cymene)Ru}2(μ-OH)2(4,4′-bipy)]2[BF4]4

Interaction of [Cp*RuCl(μ-Cl)]₂ with 2,2′-bipyridine (2,2′-bipy) in the presence of Na[PF₆] gave a chloride bridging dinuclear complex [{Cp*Ru(2,2′-bipy)}₂(μ-Cl)][PF₆] (1). In the crystal structure, the cation [{Cp*Ru(2,2′-bipy)}₂(μ-Cl)]⁺ contains a bent Ru-Cl-Ru linkage with an angle of 141.87(12)°. The tris(μ-hydroxo)diruthenium complex [{(η⁶-p-cymene)Ru}₂(μ-OH)₃][BF₄] in acetone solution was treated by 4,4′-bipyridine (4,4′-bipy) to give a hydroxo-bridged tetranuclear complex [{(η⁶-p-cymene)Ru}₂(μ-OH)₂(μ-4,4′-bipy)]₂[BF₄]₄ (2). Complex 2 consists of four (η⁶-p-cymene)Ru moieties connected by two 4,4′-bipy and four hydroxo-bridging groups, forming a novel metallomacrocycle with alternating hydroxyl and 4,4′-bipy bridges between the ruthenium atoms. Spectroscopic properties along with electrochemistry of two organoruthenium (II) complexes 1 and 2 are reported.     

Synthesis and structural characterization of three hydrogen-bonding connected supramolecular complexes of nickel, zinc and copper with 1,3-diphenyl-4-(salicylidene hydrazide)-acetyl-pyrazolone-5 and 2,2′-bipyridine

A new set of supramolecular complexes, [Ni(DPAP-SHZ)(2,2′-bipy)CH₃OH] (1), [Zn(DPAP-SHZ)(2,2′-bipy)CH₃OH] (2) and [Cu(DPAP-SHZ)(2,2′-bipy)] · 2CH₂Cl₂ (3) (DPAP-SHZ = 1,3-diphenyl-4-(salicylidene hydrazide)-acetyl-pyrazolone-5, 2,2′-bipy = 2,2′-bipyridine) have been synthesized and characterized by elemental analysis, TG-DTA, IR spectroscopy and X-ray crystallography. The X-ray diffraction analyses of the complexes show that the Ni(II) ion and Zn(II) ion centers are six-coordinated while the Cu(II) ion center is five-coordinated. The three supramolecular complexes contain the same ligands, namely DPAP-SHZ and 2,2′-bipy. However, their hydrogen bonds are significantly different, and this variation apparently is responsible for the dissimilar structures of the three supramolecular complexes.     

In situ 5-sulfosalicylate decarboxylation or dimethylformamide hydrolysis generating supramolecular assembly architectures

Six transition-metal complexes, {[Co(4,4′-bipy)(H₂O)₄](Hbs)₂ · 3H₂O}_n (1), [Mn(4,4′-bipy)₂(H₂O)₄](Hbs)₂ · 2H₂O (2), {[Mn(HCOO)(H₂O)₂(4,4′-bipy)]₂[Mn(4,4′-bipy)(Hssal)₂(H₂O)₂]}_n (3), [Cd(4,4′-bipy)₂(H₂O)₄](Hbs)₂ · 2H₂O (4), {[Cd₃(CH₃COO)₄(4,4′-bipy)₄](Hbs)₂ · 10H₂O}_n (5), and {[Cd(HCOO)(H₂O)₂(4,4′-bipy)]₂[Cd(4,4′-bipy)(Hssal)₂(H₂O)₂]}_n (6), have been synthesized by hydrothermal or reflux synthetic method and characterized by single-crystal X-ray diffraction, IR, elemental analysis, thermogravimetric analysis and fluorescence analysis, where Hssal²⁻ is doubly deprotonated 5-sulfosalicylate, Hbs⁻ is 4-hydroxybenzenesulfonate and 4,4′-bipy is 4,4′-bipyridine. The structural analyses showed that all of the six complexes are cation-anion species containing in situ synthesized ligands, Hbs⁻ or HCOO⁻, and the former arises from the decarboxylation of 5-sulfosalicylic acid under the hydrothermal conditions. The formate anions derived from the hydrolysis of DMF. A series of supramolecular compounds show that the structural diversity is strongly associated with their properties.     

Hydrothermal synthesis of copper complexes of 4′-pyridyl terpyridine: From discrete monomer to zigzag chain polymer

Seven copper complexes [Cu(L1)I₂] (1), [Cu₂(L1)₂I₂]₂[Cu₂(μ-I)₂I₂] (2), [Cu(L2)I₂] (3), [Cu₂(L2)(μ-I)I(PPh₃)] (4), [Cu₄(L2)₂(μ-I)₂I₂] (5), {[Cu(L2)I]₂[Cu₂(μ-I)₂I₂]}_n (6) and [Cu₂(L2)(μ-I)₂]_n (7) have been prepared by reactions of ligands: 4′-(2-pyridyl)-2,2′:6′,2″-terpyridine (L1) and 4′-(3-pyridyl)-2,2′:6′,2″-terpyridine (L2) with CuI in hydrothermal conditions, respectively. By alternating the oxidations states of the metal centers, increasing stoichiometric metal/ligand ratio and introducing a second ligand, the compounds, were successfully developed from mononuclear (1 and 3) to multinuclear (2, 4 and 5) and polymers (6 and 7). The synthesis of these compounds may provide an approach for the construction of coordination compounds of 4′-pyridyl terpyridine with different nuclearity.     

Synthesis and characterisation of bis(2,2′-bipyridine)(4-carboxy-4′-(pyrid-2-ylmethylamido)-2,2′-bipyridine)ruthenium(II) di(hexafluorophosphate): Comparison of spectroelectrochemical properties with related complexes

The new complex, [Ru^II(bpy)₂(4-HCOO-4′-pyCH₂ NHCO-bpy)](PF₆)₂ · 3H₂O (1), where 4-HCOO-4′-pyCH₂NHCO-bpy is 4-(carboxylic acid)-4′-pyrid-2-ylmethylamido-2,2′-bipyridine, has been synthesised from [Ru(bpy)₂(H₂dcbpy)](PF₆)₂ (H₂dcbpy is 4,4′-(dicarboxylic acid)-2,2′-bipyridine) and characterised by elemental analysis and spectroscopic methods. An X-ray crystal structure determination of the trihydrate of the [Ru(bpy)₂(H₂dcbpy)](PF₆)₂ precursor is reported, since it represented a different solvate to an existing structure. The structure shows a distorted octahedral arrangement of the ligands around the ruthenium(II) centre and is consistent with the carboxyl groups being protonated. A comparative study of the electrochemical and photophysical properties of [Ru^II(bpy)₂(4-HCOO-4′-pyCH₂NHCO-bpy)]²⁺ (1), [Ru(bpy)₂(H₂dcbpy)]²⁺ (2), [Ru(bpy)₃]²⁺ (3), [Ru(bpy)₂Cl₂] (4) and [Ru(bpy)₂Cl₂]⁺ (5) was then undertaken to determine their variation upon changing the ligands occupying two of the six ruthenium(II) coordination sites. The ruthenium(II) complexes exhibit intense ligand centred (LC) transition bands in the UV region, and broad MLCT bands in the visible region. The ruthenium(III) complex, 5, displayed overlapping LC bands in the UV region and a LMCT band in the visible. 1, 2 and 3 were found, via cyclic voltammetry at a glassy carbon electrode, to exhibit very positive reversible formal potentials of 996, 992 and 893 mV (versus Fc/Fc⁺) respectively for the Ru(III)/Ru(II) half-cell reaction. As expected the reversible potential derived from oxidation of 4 (−77 mV (versus Fc/Fc⁺)) was in excellent agreement with that found via reduction of 5 (−84 mV (versus Fc/Fc⁺)). Spectroelectrochemical experiments in an optically transparent thin-layer electrochemical cell configuration allowed UV-Vis spectra of the Ru(III) redox state to be obtained for 1, 2, 3 and 4 and also confirmed that 5 was the product of oxidative bulk electrolysis of 4. These spectrochemical measurements also confirmed that the oxidation of all Ru(II) complexes and reduction of the corresponding Ru(III) complex are fully reversible in both the chemical and electrochemical senses.     

Synthesis, structural and spectroscopic characterization of mono- and binuclear copper(I) complexes with substituted diimine and phosphine ligands

The reaction of [Cu(CH₃CN)₄]BF₄, 6-(4-methoxyl)phenyl-2,2′-bipyridine (designated as MeO-CNN), and/or tricyclohexylphosphine (PCy₃) and diimine ligands derived from 4,4′-bipyridine gave four mono- and binuclear copper(I) complexes, [Cu(MeO-CNN)₂]BF₄ (1), [Cu₂(MeO-CNN)₂(PCy₃)₂(4,4′-bipy)](BF₄)₂ · 1.5CH₂Cl₂ (2) (bipy = bipyridine), [Cu₂(MeO-CNN)₂(PCy₃)₂(bpete)](BF₄)₂ · 4CH₂Cl₂ (3) (bpete = trans-1,2-bis(4-pyridyl)ethene) and [Cu₂(MeO-CNN)₂(PCy₃)₂(4,4′-azpy)] (BF₄)₂ · 1.5CH₂Cl₂ (4) (azpy = azobispyridine). Crystallographic studies of complexes 1-4 show that each copper(I) center adopts a pseudo-tetrahedral coordination geometry. Complexes 2-4 consists of -Cu(MeO-CNN)(PCy₃) units which are linked through 4,4′-bipy, bpete and 4,4′-azpy, respectively. The UV-Vis spectra of these four complexes all exhibit intense high-energy absorptions at λ_max < 340 nm and broad visible bands in a range of 430-550 nm, ascribed to intraligand (IL π → π^∗) transitions and metal-to-ligand charge-transfer (MLCT) transitions, respectively. The density functional theory calculation was used to interpret the absorption spectrum of 1, which further supports the assignment of MLCT character. The binuclear complexes 2 and 3 both display red solid-state emissions centred at 620 and 660 nm from metal-to-ligand charge-transfer excited state, respectively. Interestingly, the electron paramagnetic resonance (EPR) spectral measurements confirm copper(I) complexes oxidized to corresponding copper(II)-halide product upon excitation at 355 nm in dichloromethane solution.     

Syntheses, characterization and DNA binding of mono- and diruthenium(II) complexes containing 2,2′-bis(1,2,4-triazino[5,6-f]phenanthren-3-yl)-4,4′-bipyridine and 2,2′-bipyridine ligands

A novel bridging ligand 2,2′-bis(1,2,4-triazino[5,6-f]phenanthren-3-yl)-4,4′-bipyridine (btpb) and its mononuclear ruthenium(II) complex [Ru(bpy)₂(btpb)]²⁺ (Rubtpb; bpy = 2,2′-bipyridyl) and dinuclear ruthenium(II) complex [Ru(bpy)₂(btpb)Ru(bpy)₂]⁴⁺ (Ru₂btpb) have been synthesized and characterized by elemental analyses, fast atom bombardment or electrospray mass spectra, ¹H NMR, and electronic spectroscopy. Binding behaviors of the mono- and dinuclear complexes with calf thymus DNA (CT-DNA) have been investigated by absorption spectra, viscosity measurements, and equilibrium dialysis experiments. As the concentration of DNA is increased, the electronic absorption spectra bands at the metal-ligand charge transfer of the mononuclear complex Rubtpb at 501.0 nm exhibit hypochromism of about 17.4% and bathochromism of 2.0 nm, the dinuclear complex Ru₂btpb at 511.0 nm exhibits hypochromism of about 24.8% and bathochromism of 1.0 nm. The increasing amounts of the complexes on the relative viscosities of CT-DNA are much smaller than that of the classic intercalators. The experiments suggest that the Rubtpb and Ru₂btpb may be bound to DNA by non-intercalating binder.     

A series of metal-organic frameworks constructed with 2,2′-bipyridine-3,3′-dicarboxylate: Syntheses, structures, and physical properties

To determine the influence of metal ion and the auxiliary ligand on the formation of metal-organic frameworks, six new coordination polymers, {[Mn₂(bpdc)(bpy)₃(H₂O)₂] · 2ClO₄ · H₂O}_n (1), {[Mn(bpdc)(dpe)] · CH₃OH · 2H₂O}_n (2), {[Cu(bpdc)(H₂O)₂]}_n (3), {[Zn(bpdc)(H₂O)₂]}_n (4), {[Cd(bpdc)(H₂O)₃] · 2H₂O}_n (5), and {[Co(bpdc)(H₂O)₃] · 0.5dpe · H₂O}_n (6) (H₂bpdc = 2,2′-bipyridine-3,3′-dicarboxylic acid, bpy = 2,2′-bipyridine, dpe = 1,2-di(4-pyridyl) ethylene), have been synthesized and characterized. Compound 1 forms 1D helical chain structure containing two unique Mn^II ions. In 2, the bridging ligand dpe links Mn-bpdc double zigzag chains to generate a layer possesses rectangular cavities. In 3, bpdc²⁻ ligand connects to three metal centers forming a 2D network. Different from the above compounds, 4 displays a 1D double-wavelike chain. Compound 5 features a helical chain. Compound 6 also displays a helical chain with guest molecule dpe existing in the structure. These diverse structures illustrate rational adjustment of metal ions and the second ligand is a good method for the further design of helical compounds with novel structures and properties. In addition, the magnetic properties of 2, 3 and 6, the thermal stabilities and photoluminescence properties of 4 and 5 were also studied.     

Copper(II) complexes with monocarboxylate ligands bearing different substituent groups: Synthesis and spectroscopic studies

In our continuing efforts to explore the effects of substituent groups of ligands in the formation of supramolecular coordination structures, seven new Cu^II complexes formulated as [Cu₂(L¹)₄(DMF)₂] (1), {[Cu₂(L¹)₄(Hmta)](H₂O)_0.75}_∞ (2), [Cu₂(L²)₄(2,2′-bipy)₂] (3), [Cu₂(L³)₄(H₂O)₂] (4), [Cu₂(L³)₄(Hmta)]_∞ (5), [Cu₂(L³)₄(Dabco)]_∞ (6) and [Cu₂(L³)₄(Pz)]_∞ (7) with three monocarboxylate ligands bearing different substituent groups HL¹-HL³ (HL¹ = phenanthrene-9-carboxylic acid, HL² = 2-phenylquinoline-4-carboxylic acid, HL³ = adamantane-1-carboxylic acid, Hmta = hexamethylenetetramine, 2,2′-bipy = 2,2′-bipyridine, Dabco = 1,4-diazabicyclo[2.2.2] octane and Pz = pyrazine), have been prepared and characterized by X-ray diffraction. In 1, 2 and 4-7, each Cu^II ion is octahedrally coordinated, and carboxylate acid acts as a syn-syn bridging bidentate ligand. While each Cu^II ion in 3 is penta-coordinated in a distorted square-pyramidal geometry. 1 and 4 both show a dinuclear paddle-wheel block, while 2, 5, 6 and 7 all exhibit an alternated 1D chain structure between dinuclear paddle-wheel units of the tetracarboxylate type Cu₂-(RCO₂)₄ and the bridging auxiliary ligands Hmta, Dabco and Pz. Furthermore, 3 has a carboxylic unidentate and μ_1,1-oxo bridging dinuclear structure with the chelating auxiliary ligand 2,2′-bipy. Moreover, complexes 1-6 were characterized by electron paramagnetic resonance (EPR) spectroscopy.     

Two three-dimensional cyano-bridged bimetallic cadmium(II) and copper(II)-copper(I) mixed-valence polymer compounds: Crystal structures and thermal stability analysis and magnetic properties

Two cyano-bridged cadmium(II) and copper(II)-copper(I) mixed-valence polymer compounds 1 and [Cu^II(en)₂]_0.5[CdCu^I(CN)₃] · Cl · H₂O 2 (en = 1,2-ethanediamine) through systematically varying the solution environment have been synthesized and structurally characterized by single crystal X-ray diffraction analysis. The cyano anions connected the copper and cadmium centres with bidentate or tridentate bridging modes resulting in two complicated 3D networks for 1 and 2. Compound 1 has a rare 5,6-connected network, while compound 2 can be reduced to a 6-connected α-Po net. The magnetic and thermal properties of 1 and 2 are also studied.