Ruthenium-azoimine-chloranilates Synthesis,Spectra and Electrochemistry of Ruthenium(II)-1-alkyl-2-(arylazo)imidazole-chloranilate Complexes

Ag⁺-assisted dechlorination of blue cis-trans-cis Ru(R-aai-R′)₂Cl₂ followed by the reaction with chloranilic acid (H₂CA) in the presence of Et₃N, gives a neutral mononuclear violet complex [Ru(R-aai-R′)₂(CA)]. [R-aai-R′=p-R-C₆H₄—N=N—C₃H₂—NN, abbreviated as an N,N′ chelator where N(imidazole) and N(azo) represent N and N′, respectively; R = H (a), OMe (b), NO₂ (c) and R′= Me (4), Et(5), Bz(6)]. All the complexes exhibit strong intense MLCT transitions in the visible region and weak broad bands at higher wavelength (>700 nm). Visible transitions (580–595 nm) show a negative solvatochromic effect. The cyclic voltammograms show two quasireversible to irreversible couples positive to SCE and are due to CA⁻/CA²⁻ (1.2–1.35 V) and Ru(III)/Ru(II) (1.6–1.8 V) redox processes. Three couples, negative to SCE, are assigned to CA²⁻/CA³⁻ (−0.2 to −0.3 V), and azo reductions (−0.5 to −0.7, −0.8 to −0.9 V) of the chelated R-aai-R′.     

Nitric oxide and singlet oxygen photo-generation by light irradiation in the phototherapeutic window of a nitrosyl ruthenium conjugated with a phthalocyanine rare earth complex

The photochemical, photophysical and photobiological studies of a mixture containing cis-[Ru(H-dcbpy⁻)₂(Cl)(NO)] (H₂-dcbpy = 4,4′-dicarboxy-2,2′-bipyridine) and Na₄[Tb(TsPc)(acac)] (TsPc = tetrasulfonated phthalocyanines; acac = acetylacetone), a system capable of improving photodynamic therapy (PDT), were accomplished. cis-[Ru(H-dcbpy⁻)₂(Cl)(NO)] was obtained from cis-[Ru(H₂-dcbpy)₂Cl₂]·2H₂O, whereas Na₄[Tb(TsPc)(acac)] was obtained by reacting phthalocyanine with terbium acetylacetonate. The UV–Vis spectrum of cis-[Ru(H-dcbpy⁻)₂(Cl)(NO)] displays a band in the region of 305 nm (λ_max in 0.1 mol L⁻¹ HCl)(π–π*) and a shoulder at 323 nm (MLCT), while the UV–Vis spectrum of Na₄[Tb(TsPc)(acac)] presents the typical phthalocyanine bands at 342 nm (Soret λ_max in H₂O) and 642, 682 (Q bands). The cis-[Ru(H-dcbpy⁻)₂(Cl)(NO)] FTIR spectrum displays a band at 1932 cm⁻¹ (Ru–NO⁺). The cyclic voltammogram of the cis-[Ru(H-dcbpy⁻)₂(Cl)(NO)] complex in aqueous solution presented peaks at E = 0.10 V (NO^+/0) and E = −0.50 V (NO^0/−) versus Ag/AgCl. The NO concentration and ¹O₂ quantum yield for light irradiation in the λ > 550 nm region were measured as [NO] = 1.21 ± 0.14 μmol L⁻¹ and ø_OS = 0.41, respectively. The amount of released NO seems to be dependent on oxygen concentration, once the NO concentration measured in aerated condition was 1.51 ± 0.11 μmol L⁻¹ The photochemical pathway of the cis-[Ru(H-dcbpy⁻)₂(Cl)(NO)]/Na₄[Tb(TsPc)(acac)] mixture could be attributed to a photoinduced electron transfer process. The cytotoxic assays of cis-[Ru(H-dcbpy^-)₂(Cl)(NO)] and of the mixture carried out with B16F10 cells show a decrease in cell viability to 80% in the dark and to 20% under light irradiation. Our results document that the simultaneous production of NO and ¹O₂ could improve PDT and be useful in cancer treatment.     

Spectrophotometric determination of cobalt(II) with 2-(3′-sulfobenzoyl)pyridine benzoylhydrazone

A simple method has been described for the Spectrophotometric determination of cobalt(II) with 2-(3′-sulfobenzoyl)pyridine benzoylhydrazone (SBPBH). In aqueous solution, cobalt(II) reacts with SBPBH to form a yellow complex, which is not destroyed even by the addition of 3.8 M perchloric acid. The absorption maximum of the complex in 1.5 M perchloric acid medium was found to be 400 nm; the molar absorptivity was 2.17 × 10⁴ liters mol⁻¹ cm⁻¹. The proposed method is fairly selective and has been applied to the determination of cobalt in standard alloy steel samples.     

Syntheses and characterization of Co(pydc)(H2O)2 and Ni(pydc)(H2O) (pydc = 3,5-pyridinedicarboxylate)

The hydrothermal reaction of 3,5-pyridinedicarboxylic acid (pydcH₂) and Co(NO₃)₂ or Ni(NO₃)₂ in the presence of 4,4′-bipyridine results in two novel compounds Co(pydc)(H₂O)₂ (1) and Ni(pydc)(H₂O) (2). Crystal data: 1, monoclinic, C2/c, a=9.900(2), b=11.984(2), c=7.3748(15) Å, β=105.37(3)°, V=843.7(3) Å³, Z=4; 2, monoclinic, P2₁/c, a=7.7496(6), b=15.0496(11), c=6.4224(5) Å, β=108.437(1)°, V=710.59(9) Å³, Z=4. The structure of 1 is composed of honeycomb layers built up from {CoO₄N} trigonal bipyramids and 3,5-pyridinedicarboxylate bridges. The structure of 2 adopts a three-dimensional framework structure in which the Ni atoms are coordinated by the pydc bridges both within the honeycomb layer and between the layers. The magnetic properties of 1 and 2 have been investigated.     

Synthesis, DNA-binding and photocleavage studies of [Ru(phen)2(pbtp)] and [Ru(bpy)2(pbtp)] (phen = 1,10-phenanthroline; bpy = 2,2′-bipyridine; pbtp = 4,5,9,11,14-pentaaza-benzo[b]triphenylene)

Based on the ligand dppz (dppz = dipyrido-[3,2-a:2′,3′-c]phenazine), a new ligand pbtp (pbtp = 4,5,9,11,14-pentaaza-benzo[b]triphenylene) and its polypyridyl ruthenium(II) complexes [Ru(phen)₂(pbtp)]²⁺ (1) (phen = 1,10-phenanthroline and [Ru(bpy)₂(pbtp)]²⁺ (2) (bpy = 2,2′-bipyridine) have been synthesized and characterized by elemental analysis, ES-MS and ¹H NMR spectroscopy. The DNA-binding of these complexes were investigated by spectroscopic methods and viscosity measurements. The experimental results indicate that both complexes 1 and 2 bind to CT-DNA in classical intercalation mode, and can enantioselectively interact with CT-DNA. It is interesting to note that the pbtp ruthenium(II) complexes, in contrast to the analogous dppz complexes, do not show fluorescent behavior when intercalated into DNA. When irradiated at 365 nm, both complexes promote the photocleavage of pBR 322 DNA.     

Electrochemical, spectroelectrochemical and theoretical studies on the reduction and deprotonation of the photovoltaic sensitizer [(H3-tctpy)Ru(NCS)3] (H3-tctpy=2,2′:6′,2′′-terpyridine-4,4′,4′′-tricarboxylic acid)

The electrochemical reduction of the black dye photosensitizer [(H₃-tctpy)Ru^II(NCS)₃]⁻ (H₃-tctpy=2,2′:6′,2′′-terpyridine-4,4′,4′′-tricarboxylic acid) used in photovoltaic cells has been found to be a complex process when studied in dimethylformamide. At low temperatures, fast scan rates and at a glassy carbon electrode, the chemically reversible ligand based one-electron reduction process [(H₃-tctpy)Ru(NCS)₃]⁻+e⁻[(H₃-tctpy√⁻)Ru(NCS)₃]²⁻ is detected. This process has a reversible half-wave potential (E^r_1/2) of −1585±20 mV versus Fc/Fc⁺ at 25°C. Under other conditions, a deprotonation reaction occurs upon reduction, which produces [(H_3−x-tctpy^x−)Ru(NCS)₃]^(1+x)− and hydrogen gas. Mechanistic pathways giving rise to the final products are discussed. The E^r_1/2-value for the ligand based reductions of the deprotonated complex is 0.70 V more negative than for [(H₃-tctpy)Ru(NCS)₃]⁻. Consequently, data obtained from molecular orbital calculations are consistent with the reaction [(H₃-tctpy)Ru(NCS)₃]⁻+e⁻→[(H₂-tctpy⁻)Ru(NCS)₃]²⁻+1/2H₂ yielding the monodeprotonated complex as the major product obtained after electrochemical reduction of [(H₃-tctpy)Ru(NCS)₃]⁻. The E^r_1/2-values for the metal based Ru^II/III process differ by 0.30 V when data obtained for the protonated and deprotonated forms of the black dye are compared. Electronic spectra obtained during the course of experiments in an optically transparent thin layer electrolysis configuration are consistent with the overall reaction scheme proposed on the basis of voltammetric measurements and molecular orbital calculations. Reduction studies on the free ligand, H₃-tcpy, are consistent with results obtained with [(H₃-tctpy)Ru(NCS)₃]⁻.     

Syntheses, structures, spectroscopic, electrochemical properties and DFT calculation of Ru(II)–thioarylazoimidazole complexes

The reaction of 1-alkyl-2-{(o-thioalkyl)phenylazo}imidazoles (SRaaiNR) (2a/2b) with Ru(II) has synthesized [Ru(SRaaiNR)₂](ClO₄)₂ (3a/3b) in 2-methoxyethanol. The reaction in methanol, however, has synthesized [Ru(SRaaiNR)(SRaaiNR)Cl](ClO₄) (4a/4b). The solid phase reaction of SRaaiNR and RuCl₃ on silica gel surface upon microwave irradiation has synthesized [Ru(SRaaiNR)(SaaiNR)](PF₆) (5a/5b) [SRaaiNR represents tridentate N,N′,S-chelator; SRaaiNR is N,N′-bidentate chelator where S does not coordinate and SaaiNR refers N,N′,S-chelator where S refers to thiolato binding]. The structural characterization of [Ru(SEtaaiNEt)(SEtaaiNEt)Cl](ClO₄) (4b) and [Ru(SEtaaiNEt)(SaaiNEt)](PF₆) (5b) has been confirmed by single crystal X-ray diffraction study. The IR, UV–Vis, and ¹H NMR spectral data also support the stereochemistry of the complexes. The complexes show metal oxidation, Ru(III)/Ru(II), and ligand reductions (azo/azo⁻, azo⁻/azo). The molecular orbital diagram has been drawn by density functional theory (DFT) calculation. Normal mode of analysis has been performed to correlate calculated and experimental frequencies of representative complexes. The electronic movement and assignment of electronic spectra have been carried out by TDDFT calculation both in gas and acetonitrile phase.     

Heterometallic clusters arising from cubic Ni3M′O4 (M′=K and Na) entity: Solvothermal synthesis with/without the assistance of microwave

Solvothermal reaction assisted with microwave leads to the formation of two unique heterometallic cubic clusters [Ni₃M′(L)₃(OH)(CH₃CN)₃]₂·CH₃CN (M′=K for 1 and M′=Na for 2, where L is an anion of 2-[(2-hydroxy-3-methoxy-benzylidene)-amino]-ethanesulfonate) with higher efficiency, yields and purity than those without it. The 6-metallacrown-3 [Ni₃(OH)(L)₃]⁻ groups exhibit interesting ion trapping and self-assembly of size-different Na⁺ and K⁺ through form recognition and coordination activity in 1 and 2. The magnetic studies for 1 and 2 suggest that the {Ni₃M′O₄} (M′=K and Na) cores both display dominant ferromagnetic interactions from the nature of the binding modes of μ₃-O (oxidophenyl) and μ₃-OH.     

Diffuse reflectance spectra of iron(III) vanadates

The electronic spectra of solid iron(III) vanadates FeVO₄ and Fe₂V₄O₁₃ were investigated by the diffuse reflectance technique in the spectral range 12 500–50 000 cm⁻¹. The spectra of investigated vanadates contain 2–3 intensive CT bands in the UV region and two lowest energy d–d bands in the 12 000–22 000 cm⁻¹ range. The presence of the weak bands for FeVO₄ and Fe₂V₄O₁₃ at 16 500 cm⁻¹ and 20 500 cm⁻¹ points to the lattice deffects (oxygen deficiency and the presence of the V⁴⁺ ions) in the structure of investigated vanadates.     

Facile strategies for the synthesis and crystallization of linear trinuclear nickel(II)-Schiff base complexes with carboxylate bridges: Tuning of coordination geometry and magnetic properties

Three new linear trinuclear nickel(II) complexes, [Ni₃(salpen)₂(OAc)₂(H₂O)₂]·4H₂O (1) (OAc = acetate, CH₃COO⁻), [Ni₃(salpen)₂(OBz)₂] (2) (OBz = benzoate, PhCOO⁻) and [Ni₃(salpen)₂(OCn)₂(CH₃CN)₂] (4) (OCn = cinnamate, PhCHCHCOO⁻), H₂salpen = tetradentate ligand, N,N′-bis(salicylidene)-1,3-pentanediamine have been synthesized and characterized structurally and magnetically. The choice of solvent for growing single crystal was made by inspecting the morphology of the initially obtained solids with the help of SEM study. The magnetic properties of a closely related complex, [Ni₃(salpen)₂(OPh)₂(EtOH)] (3) (OPh = phenyl acetate, PhCH₂COO⁻) whose structure and solution properties have been reported recently, has also been studied here. The structural analyses reveal that both phenoxo and carboxylate bridging are present in all the complexes and the three Ni(II) atoms remain in linear disposition. Although the Schiff base ligand and the syn–syn bridging bidentate mode of the carboxylate group remain the same in complexes 1–4, the change of alkyl/aryl group of the carboxylates brings about systematic variations between six- and five-coordination in the geometry of the terminal Ni(II) centres of the trinuclear units. The steric demand as well as hydrophobic nature of the alkyl/aryl group of the carboxylate is found to play a crucial role in the tuning of the geometry. Variable-temperature (2–300 K) magnetic susceptibility measurements show that complexes 1–4 are antiferromagnetically coupled (J = −3.2(1), −4.6(1), −3.2(1) and −2.8(1) cm⁻¹ in 1–4, respectively). Calculations of the zero-field splitting parameter indicate that the values of D for complexes 1–4 are in the high range (D = +9.1(2), +14.2(2), +9.8(2) and +8.6(1) cm⁻¹ for 1–4, respectively). The highest D value of +14.2(2) and +9.8(2) cm⁻¹ for complexes 2 and 3, respectively, are consistent with the pentacoordinated geometry of the two terminal nickel(II) ions in 2 and one terminal nickel(II) ion in 3.     

Spectrophotometric study of pseudopurpurin-Pd(II) dimer complex. Spectrophotometric determination of traces of Pd(II)

We have studied spectrophotometrically the Pseudopurpurin-Pd(II) complex in an ethanolic-water medium ¦Ethanolamine ¦_optimum = 4 × 10⁻¹M; λ = 670 nm; 20% H₂O; stable for at least 4 hr; ¦Reagent¦_optimum = 5 × 10⁻⁵M; stoichiometry 2:2; log K = 17.7. A new method for the spectrophotometric determination of Pd traces is proposed for concentrations between 0.30 and 2.40 ppm. The relative error and the interferences of the method have been investigated.     

Coordination chemistry of di-2-pyridylketone. Synthesis, spectroscopic investigations, X-ray studies and DFT calculations of Re(III) and Re(V) complexes

The paper presents a combined experimental and computational study of Re(III) and Re(V) complexes containing di-2-pyridylketone and its gem-diol form – [ReCl₃(dpk-N,O)(PPh₃)] (1), [ReCl₃(dpk-N,N′)(OPPh₃)] (2) and [ReOBr₃(dpk-OH)]·2(dpkH⁺Br⁻) (3). All the complexes have been characterized spectroscopically and structurally (by single-crystal X-ray diffraction). The complex 2 has been additionally studied by magnetic measurement. The magnetic behavior of 2 is characteristic of mononuclear octahedral Re(III) complex with d⁴ low-spin (³T_1g ground state) and arise because of the large spin–orbit coupling (ζ = 2500 cm⁻¹), which gives diamagnetic ground state. DFT and time-dependent (TD)DFT calculations have been carried out for [ReCl₃(dpk-N,N′)(OPPh₃)] and [ReOBr₃(dpk-OH), and their UV–vis spectra have been discussed on this basis.     

Synthesis and characterization of half-sandwich iridium(III) and rhodium(III) complexes bearing organochalcogen ligands

Reactions of [Cp*M(μ-Cl)Cl]₂ (M = Ir, Rh; Cp* = η⁵-pentamethylcyclopentadienyl) with bi- or tri-dentate organochalcogen ligands Mbit (L1), Mbpit (L2), Mbbit (L3) and [Tm^Me]⁻ (L4) (Mbit = 1,1′-methylenebis(3-methyl-imidazole-2-thione); Mbpit = 1,1′-methylene bis (3-iso-propyl-imidazole-2-thione), Mbbit = 1,1′-methylene bis (3-tert-butyl-imidazole-2-thione)) and [Tm^Me]⁻ (Tm^Me = tris (2-mercapto-1-methylimidazolyl) borate) result in the formation of the 18-electron half-sandwich complexes [Cp*M(Mbit)Cl]Cl (M = Ir, 1a; M = Rh, 1b), [Cp*M(Mbpit)Cl]Cl (M = Ir, 2a; M = Rh, 2b), [Cp*M(Mbbit)Cl]Cl (M = Ir, 3a; M = Rh, 3b) and [Cp*M(Tm^Me)]Cl (M = Ir, 4a; M = Rh, 4b), respectively. All complexes have been characterized by elemental analysis, NMR and IR spectra. The molecular structures of 1a, 2b and 4a have been determined by X-ray crystallography.     

Simultaneous determination of pethidine and methadone by capillary electrophoresis with electrochemiluminescence detection of tris(2,2′-bipyridyl)ruthenium(II)

In this paper, we described a simple and rapid method, capillary electrophoresis with electrochemiluminescence (CE–ECL) detection using tris(2,2′-bipyridyl)ruthenium(II) (Ru(bpy)₃²⁺), to simultaneously detect pethidine and methadone. Analytes were injected to separation capillary of 67.5 cm length (25 μm i.d., 360 μm o.d.) by electrokinetic injection for 10 s at 10 kV. Under the optimized conditions: ECL detection at 1.20 V, 30 mM sodium phosphate (pH 6.0) as running buffer, separation voltage at 14.0 kV, 5 mM Ru(bpy)₃²⁺ with 50 mM sodium phosphate (pH 6.5) in the detection cell, the linear range from 2.0 × 10^− 6 to 2.0 × 10^− 5 M for pethidine and 5.0 × 10^− 6 to 2.0 × 10^− 4 M for methadone and detection limits of 0.5 μM for both of them were achieved (S/N = 3). Relative standard derivations of the ECL intensity were 2.09% and 6.59% for pethidine and methadone, respectively.     

An unprecedented Cu–Schiff base complex existing as two different trinuclear units with strong antiferromagnetic couplings

A new tetradentate N₂O₂ donor Schiff base ligand [OHC₆H₄CHNCH₂CH₂CH(CH₂CH₃)NCHC₆H₄OH = H₂L ] was obtained by 1:2 condensation of 1,3-diaminopentane with salicylaldehyde and has been used to synthesise an unusual copper(II) complex whose asymmetric unit presents two structurally different almost linear trinuclear units [Cu₃(μ-L)₂(ClO₄)₂] [Cu₃(μ-L)₂(H₂O)(ClO₄)₂] (1). The ligand and the complex were characterised by elemental analysis, FT-IR, ¹H NMR and UV–Vis spectroscopy in addition electrochemical and single crystal X-ray diffraction studies were performed for the complex. The magnetic properties of 1 reveal the presence of strong intra-trimer (J₁ = −202(3) cm⁻¹ and J₂ = −233(3) cm⁻¹) as well as very weak inter-trimer (zJ′ = −0.11(1) cm⁻¹) antiferromagnetic interactions.     

Structure determination from powder diffraction data and thermal behaviour of layered lead nitrate oxalate hydrate, Pb2(NO3)2(C2O4).2H2O

The mixed lead nitrate oxalate, Pb₂(NO₃)₂(C₂O₄).2H₂O, has been obtained in a polycrystalline form in the course of a study on precursors of nanocrystalline PZT-type oxides. Its crystal structure has been solved from powder diffraction data collected using a monochromatic radiation from a conventional X-ray source. The symmetry is monoclinic, space group P2₁/c (No. 14), the cell dimensions are a=10.623(2) Å, b=7.9559(9) Å, c=6.1932(5) Å, β=104.49(1)° and Z=4. The structure consists of a stacking of complex double sheets parallel to (1 0 0), forming layers held together by hydrogen bonds. The sheets result from the condensation of PbO₁₀ polyhedra, in which the oxalate and nitrate groups, as well as water molecules, play a major role. The structure is discussed in terms of Pb---O distances, polyhedra shape and lead coordination, with emphasis on the dimensional polymerisation role of water molecules. The thermal behaviour of this layered compound is carefully described from temperature-dependent powder diffraction and thermogravimetric measurements. The enthalpy, Δ_rH=232(3) kJ mol⁻¹, and entropy, Δ_rS=532(8) J K⁻¹ mol⁻¹, of the dehydration reaction have been determined. The high value of Δ_rH demonstrates that the water molecules are strongly bonded in the structure. The complex decomposition proceeds through the crystallisation and decomposition of Pb(NO₃)₂(C₂O₄) into Pb(NO₃)₂ and PbC₂O₄, and, finally, various lead oxides.     

Synthesis of unsymmetrical compartmental oxime nickel(II) and copper(II) complexes: spectral, electrochemical and magnetic studies

A new series of binuclear unsymmetrical compartmental oxime complexes (1–5) [M₂L] [M=Cu(II), Ni(II)] have been synthesized using mononuclear complex [ML] (L=1,4-bis[2-hydroxy-3-(formyl)-5-methylbenzyl]piperazine), hydroxylamine hydrochloride and triethylamine. In this system there are two different compartments, one has piperazinyl nitrogens and phenolic oxygens and the other compartment has two oxime nitrogens and phenolic oxygens as coordinating sites. The complexes were characterized by elemental and spectral analysis. Electrochemical studies of the complexes show two step single electron quasi-reversible redox processes at cathodic potential region. For copper complexes E¹ _pc=−0.18 to −0.62 and E² _pc=−1.18 to −1.25 V, for nickel complexes E¹ _pc=−0.40 to −0.63 and E² _pc=−1.08 to −1.10 V and reduction potentials are sensitive towards the chemical environment around the copper and nickel atoms. The nickel(II) complexes undergo two electrons oxidation. The first one electron oxidation is observed around +0.75 V and the second around +1.13 V. ESR Spectra of the binuclear copper(II) complexes [Cu₂L](ClO₄), [Cu₂L(Cl)], [Cu₂L(NO₃)] shows a broad signal at g=2.1 indicating the presence of coupling between the two copper centers. Copper(II) complexes show a magnetic moment value of μ_eff around 1.59 B.M at 298 K and variable temperature magnetic measurements show a −2J value of 172 cm⁻¹ indicating presence of antiferromagnetic exchange interaction between copper(II) centres.     

Electrochemical and DNA-binding properties of dipyridophenazine complexes of osmium(II)

A transition metal complex as an electrochemical probe of a DNA sensor must have an applicable redox potential, high binding affinity and chemical stability. Some complexes with the dipyrido[3,2-a:2′,3′-c]phenazine (DPPZ) ligand have been reported to have high binding affinity for DNA. However, it was difficult to detect the targeted DNA electrochemically using these complexes because of the relatively high redox potential. In this work, a combination of bipyridine ligands with functional groups (---NH₂, ---CH₃ and ---COOH) and the DPPZ ligand were studied. The introduction of electron-donating groups was effective for controlling the redox potential of the DPPZ-type osmium complex. The [Os(DA-bpy)₂DPPZ]²⁺ complex (DA-bpy; 4,4′-diamino-2,2′-bipyridine) had a lower half-wave potential (E_1/2) of 147 mV (vs. Ag AgCl) and higher binding affinity with DNA {binding constant, K=3.1×10⁷ M⁻¹ in 10 mmol dm⁻³ Tris–HCl buffer with 50 mmol dm⁻³ NaCl (pH 7.76)} than those of other complexes. With the single stranded DNA (ssDNA) modified gold electrode, the hybridization signal (ΔI) of the [Os(DA-bpy)₂DPPZ]²⁺ complex was linear in the concentration range of 1.0 pg ml⁻¹–0.12 μg ml⁻¹ for the targeted DNA with a regression coefficient of 0.999. The detection limit was 0.1 pg ml⁻¹.     

Novel M(II)–Hg(II) coordination polymers generated from metal-containing building blocks M(2-pyrazinecarboxylate)2 · (H2O)2 (M=Cu, Ni, Co) and HgCl2

A new class of M(II)–Hg(II) (M=Cu(II), Co(II), Ni(II)) mixed-metal coordination polymers, Cu(2-pyrazinecarboxylate)₂HgCl₂ (4), [Co(2-pyrazinecarboxylate)₂(HgCl₂)₂] · 0.61H₂O (5) and [Ni(2-pyrazinecarboxylate)₂(HgCl₂)₂] · 0.77H₂O (6), have been prepared by self assembly of metal-containing building blocks, M(2-pyrazinecarboxylate)₂ · (H₂O)₂(M=Cu(II), Co(II), Ni(II)), with HgCl₂. Compounds 4–6 were characterized fully by IR, elemental analysis and single crystal X-ray diffraction. Compound 4 crystallized in the monoclinic space group C2/c, with a=17.916(5) Å, b=7.223(2) Å, c=13.335(4) Å, β=128.726(3)°, V=1346.2(6) ų, Z=4. It contains alternating Hg(II) and Cu(II) metal centers that are cross-linked by 2-pyrazinecarboxylate spacers and chlorine co-ligands to generate a unique three-dimensional Hg(II)–Cu(II) mixed metal framework. Compound 5 crystallized in the triclinic space group P , with a=6.3879(7) Å, b=6.6626(8) Å, c=13.2286(15) Å, α=96.339(2)°, β=91.590(2)°, γ=113.462(2)°, V=511.71(10) ų, Z=1. Compound 6 also crystallized in the triclinic space group P , with a=6.3543(8) Å, b=6.6194(8) Å, c=13.2801(16) Å, α=96.449(2)°, β=92.263(2)°, γ=113.541(2)°, V=506.67(11) ų, Z=1. Compounds 5 and 6 are isostructural and in the solid state the Hg(II)M(II)Hg(II) units are connected by Hg₂Cl₂ linkages to produce a novel M(II)–Hg(II) (M=Co(II), Ni(II)) zigzag mixed-metal chain, in which a new type of M–M′–M′–M array was observed. The metal containing building blocks, M(2-pyrazinecarboxylate)₂ · (H₂O)₂ (M=Cu(II), Co(II), Ni(II)), exhibit different connectivities to HgCl₂ depending on the metal cation contained within them.     

Spectroscopic investigations on AsH(XΣ) radical using CCSD(T) theory in combination with correlation-consistent quintuple basis set

The equilibrium internuclear separations, harmonic frequencies and potential energy curves of the AsH(X³Σ⁻) radical have been calculated using the coupled-cluster singles–doubles–approximate-triples [CCSD(T)] theory in combination with the series of correlation-consistent basis sets in the valence range. The potential energy curves are all fitted to the Murrell–Sorbie function, which are used to reproduce the spectroscopic parameters such as D_e, ω_eχ_e, α_e, B_e and D₀. The present D₀, D_e, R_e, ω_e, ω_eχ_e, α_e and B_e obtained at the cc-pV5Z basis set are of 2.8004 eV, 2.9351 eV, 0.15137 nm, 2194.341 cm⁻¹, 43.1235 cm⁻¹, 0.2031 cm⁻¹ and 7.3980 cm⁻¹, respectively, which almost perfectly conform to the measurements. With the potential obtained at the UCCSD(T)/cc-pV5Z level of theory, a total of 18 vibrational states is predicted when the rotational quantum number J is set to equal zero (J = 0) by numerically solving the radial Schrödinger equation of nuclear motion. The complete vibrational levels, classical turning points, inertial rotation and centrifugal distortion constants are determined when J = 0 for the first time, which are in excellent agreement with the experiments.