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A new tridentate and rigid ligand containing S,N-hetero donor, the 1H-1,8-naphthyridine-2-thione (Hnpt), is designed and developed to build up the first homonuclear nickel string supported by the m...

We report the syntheses, structures, magnetic and electrochemical properties of MRhRh metal cores helically wrapped by four dpa− (2,2′-dipyridylamide) ligands. We successfully synthesized the precursor Rh2(dpa)4 (1) in high yield and characterized its structure including its oxidized form (1+) which facilitated the syntheses of this series of metal springs. By the reactions of (1) and the metal ions of group 7 to group 12 (M = Mn(2), Fe(3), Co(4), Ni(5), Cu(6), Pd(8), Pt(9), Ru(10), Ir(11) and Rh(12)), ten MRh2(dpa)4Cl2 complexes were successfully isolated. Note that Cd(7) can only be obtained by the one-pot method. The yield of Rh3(dpa)4Cl2 (12) is also improved by this stepwise method. The oxidized complexes [MRh2(dpa)4Cl2](PF6) (M: Ni(5+), Ru(10+), Ir(11+)) are also synthesized for the studies of electronic structures and magnetic properties. The X-ray diffraction technique is applied to characterize all of their structures. The results of these structural, magnetic, and electrochemical studies provide us with in-depth knowledge and comprehensive insight into metal–metal bonds and interactions for this new series of metal strings. In particular, four metal–metal bonds with short distances are found: Pd–Rh (2.372(13) A), Pt–Rh (2.385(7) A), Ru–Rh (2.33(3) A), and Ir–Rh (2.373(5) A). The remaining ones show no evidence of covalent metal bonds judging from their metal–metal distances, magnetic behaviour, and redox couples in electrochemical analysis. Besides, two unique tetranuclear MRhRhM(dpa)4X2 (M: Cu+(13) and Ag+(14)) complexes with a Rh2(dpa)4 framework are developed. Four metals are aligned linearly. This coordination mode of metal strings provides a unique synthetic route for constructing longer metal chains from a smaller number of dentate ligands.

The electronic and vibrational structures of trinickel metal string complexes [Ni3(dpa)4X2]1-,0,1+ (X = Cl, NCS) were investigated using both theoretical calculations and spectroscopic methods. We used the density functional theory (DFT) method B3LYP*-D3, including less exact exchange energy and the van der Waals interaction of metal ions, to obtain the geometries and vibrational structures, which were found to be in excellent agreement with the experimental data. The ground state of Ni3(dpa)4X2 is an antiferromagnetic (AF) singlet state, and the next state is a quintet state, which was detected using temperature-dependent Raman spectroscopy under a magnetic field. The vibrational structure of the quintet state is nearly identical to that of the AF state, according to the measured Raman spectra, except that the stretching of Ni-Cl is blue-shifted from 282.5 cm-1 in the AF state to 283.8 cm-1 in the quintet state. Two oxidized Ni3 complexes were found to have [Ni3]7+ cores, the doublet [Ni3(dpa)4]3+ without axial ligands and the quartet [Ni3(dpa)4X2]+. Complex [Ni3(dpa)4X2]-, which was produced from a reduction reaction by gold nanoparticles at room temperature, consists of a quartet state as the ground state and a doublet state lying nearby.

Five heterometallic pentanuclear metal strings were prepared by stepwise synthesis from two to three and four kinds of metals aligned in one chain. In particular, NiPtCo2Pd(tpda)4Cl2 (5) possesses four different metals, and the SQUID measurement shows that Ni2+ is the only magnetically active center. Besides, the shortest Co(ii)-Co(ii) single bond (2.105(9) A), so far, is reported.

We report the synthesis of a novel heteroheptanuclear metal string complex (HMSC) [Ni3Ru2Ni2(μ7-teptra)4(NCS)2](PF6) 1 supported by tetra-pyridyl-tri-amine (H3teptra) ligands. We employed X-ray diffraction and other spectroscopic techniques to characterize the complex. The observed remarkably short Ru-Ru distance of 2.2499(3) A for 1 is indicative of a unique metal-metal interaction in the mixed-valence [Ru2]5+ (S = 3/2) unit. The complex exhibits a relatively high magnetic moment value of 4.55 B.M. at 4 K, which increases rapidly to 6.00 B.M. at 30 K and remains at 6.11 B.M. from 50 to 300 K as shown by SQUID measurements, indicating a high spin (S≥ 3/2) system which is further supported by the analyses of EPR spectra at low temperatures. These magnetic behaviors can be ascribed to the result of spin-exchange interactions among multi-spin centers.

We report the syntheses, structures, magnetic and electrochemical properties of MRhRh metal cores helically wrapped by four dpa- (2,2'-dipyridylamide) ligands. We successfully synthesized the precursor Rh2(dpa)4 (1) in high yield and characterized its structure including its oxidized form (1+) which facilitated the syntheses of this series of metal springs. By the reactions of (1) and the metal ions of group 7 to group 12 (M = Mn(2), Fe(3), Co(4), Ni(5), Cu(6), Pd(8), Pt(9), Ru(10), Ir(11) and Rh(12)), ten MRh2(dpa)4Cl2 complexes were successfully isolated. Note that Cd(7) can only be obtained by the one-pot method. The yield of Rh3(dpa)4Cl2 (12) is also improved by this stepwise method. The oxidized complexes [MRh2(dpa)4Cl2](PF6) (M: Ni(5+), Ru(10+), Ir(11+)) are also synthesized for the studies of electronic structures and magnetic properties. The X-ray diffraction technique is applied to characterize all of their structures. The results of these structural, magnetic, and electrochemical studies provide us with in-depth knowledge and comprehensive insight into metal-metal bonds and interactions for this new series of metal strings. In particular, four metal-metal bonds with short distances are found: Pd-Rh (2.372(13) Å), Pt-Rh (2.385(7) Å), Ru-Rh (2.33(3) Å), and Ir-Rh (2.373(5) Å). The remaining ones show no evidence of covalent metal bonds judging from their metal-metal distances, magnetic behaviour, and redox couples in electrochemical analysis. Besides, two unique tetranuclear MRhRhM(dpa)4X2 (M: Cu+(13) and Ag+(14)) complexes with a Rh2(dpa)4 framework are developed. Four metals are aligned linearly. This coordination mode of metal strings provides a unique synthetic route for constructing longer metal chains from a smaller number of dentate ligands.

We report the synthesis of a novel heteroheptanuclear metal string complex (HMSC) [Ni

Five heterometallic pentanuclear metal strings were prepared by stepwise synthesis from two to three and four kinds of metals aligned in one chain. In particular, NiPtCo2Pd(tpda)4Cl2 (5) possesses four different metals, and the SQUID measurement shows that Ni2+ is the only magnetically active center. Besides, the shortest Co(ii)-Co(ii) single bond (2.105(9) Å), so far, is reported.

The CoRu2(dpa)4Cl2 (1) (dpa: 2,2′-dipyridylamide) is synthesized by the reaction of Ru2(OAc)4Cl and Co3(dpa)4Cl2. By mixing 1 with NH3, Co2+ can be removed and result in the formation of unique binuclear complex 4,0-Ru2(dpa)4Cl (2) featuring one coordination pocket supported by free pyridine groups. Hence, this complex can act as an outstanding precursor for the formation of heterotrimetallic chains with MRu2 cores. A series of M–Ru25+ complexes (M = Co2+ (3), Ag+ (4), Mn2+ (5), Fe2+ (6), Zn2+ (7), Cd2+ (8), Pd2+ (9), Rh2+ (10), and Ir2+ (11)) were prepared and isolated, representing the most complete series of heterotrimetallic chains to date. All these metal string complexes are in a linear trimetallic framework helically wrapped by four dpa− ligands, characterized by X-ray diffraction measurements. The bending of the trinuclear metal cores in RhRu2 (10) and IrRu2 (11) (∠Ru–Ru–Rh: 167.58° and ∠Ru–Ru–Ir: 167.61°) indicates that a heterometallic metal–metal bonds (Ru–Rh; Ru–Ir) are generated. The studies from DFT calculation of 10 and 11 coincide with the experimental results. Furthermore, the M⋯Ru25+ distances are regulated by the factors including the bonding force of M–pyridyl and the static repulsion between M and Ru25+ unit. Interestingly, the trend for these distances is in line with that observed in trans-M(py)4Cl2 complexes.

Treatment of [Ru]–CCPh (1, [Ru] = (η5-C5H5)(dppe)Ru, dppe = Ph2PCH2CH2PPh2) with trimethylsilyl azide afforded the cationic nitrile complex {[Ru]NCCH2Ph}[N3] (2) and the further cycloaddition of 2 with trimethylsilyl azide at 60 °C afforded the N(2)-bound tetrazolato complex [Ru]N4CCH2Ph (3). The regiospecific alkylation of 3 gave a series of cationic N(2)-bound N(4)-alkylated-5-benzyl tetrazolato complexes {[Ru]N4(CH2R)CCH2Ph}[Br] (4a, R = C6F5; 4b, R = Ph; 4c, R = 4-CN-C6H4; 4d, R = 2,6-F2-C6H3; 4e, R = 6-CH2Br-C5NH3) and the subsequent cleavage of the Ru–N bond of 4a–4e gave N(1)-alkylated-5-benzyl tetrazoles N4(CH2R)CCH2Ph (5a–5e) in good to excellent yields and [Ru]–Br, which, on reacting with phenylacetylene, resulted in the formation of 1 thus forming a reaction cycle. The structures of 2, 3, 4a, 4c and 5a were confirmed by single-crystal X-ray diffraction analysis.

Redox reaction was photoinduced on metal nanoparticle (NP) with diruthenium complexes absorbing on the surface. Surface enhanced Raman scattering (SERS) was employed to detect the vibrational wavenumber of the Ru–Ru stretching mode νRu–Ru,str. During reaction, the local environment remains roughly unaltered; the variation of bonding strength of Ru–Ru related to its valence state can be measured. The heterometal extended metal atom chain (EMAC) complexes diruthenium nickel dipyridylamide [Ru2Ni(dpa)4Cl2]0,1+ (dpa = dipyridylamide) display the Raman νRu–Ru,str at 327 (broad) and 333 cm–1 in solid form for the neutral and oxidized complexes, respectively, but red-shift to 312 cm–1 on gold NP substrate and to 328 cm–1 on AgNP. According to the oxidation potentials from voltammogram, and the Raman shifts obtained for the model complex Ru2(OAc)4Cl we assign the diruthenium core with charge +5/+4 and +6, respectively for the neutral and oxidized diruthenium nickel dipyridylamide in solid form. On substrate AuNP ...

The heterotrimetallic complexes [FeMFe(dpa)4 Cl2 ] (M=Ni (1), Pd (2), and Pt (3); dpa- =dipyridylamido) featuring two high-spin iron centers linked by Group 10 metals were synthesized and their physical properties were investigated. Oxidation of 1-3 with suitable oxidants in CH2 Cl2 solution yielded the mixed-valent species [1]+/2+ -[3]+/2+ . The solution properties of [1]0/+/2+ -[3]0/+/2+ were characterized by 1 H NMR and UV/Vis/NIR spectroscopy as well as spectroelectrochemisty. The mixed-valent states of [1]+ -[3]+ obtained by electrochemical or chemical oxidation are classified as class II valence delocalization. The solid-state structures of 1-3, [1]+ , [3]+ , and [1]2+ were determined by single-crystal X-ray diffraction analysis, exhibiting a linear metal framework with an approximate D4 symmetry. The spin states and magnetic properties were studied by using SQUID magnetometry, EPR and Mossbauer spectroscopy, and DFT calculations. Antiferromagnetic interactions between terminal high-spin iron centers are present within [1]0/+/2+ -[3]0/+/2+ and the |J| values increase with the central metal ion changing from Ni to Pt. The DFT calculations reproduce the antiferromagnetic coupling and ascribe it to a σ-type exchange pathway. The substitution of the central metal not only influences the spin-spin interactions but also the degree of electronic delocalization between the terminal iron sites along the Fe-M-Fe chains.

The CoRu

Invited for the cover of this issue is the group of Shie-Ming Peng at the National Taiwan University in Taipei, Taiwan. The cover image shows a “vending machine” that generates heteronuclear metal string complexes. By inserting coins, representing suitable ligands, into the machine and selecting the desired combination of buttons, representing the metal ions, tailored complexes can be prepared! These chain-like complexes offer an excellent electron-transporting platform with potential applications as functional molecular wires.

We report the infrared, Raman, and surface-enhanced Raman scattering (SERS) spectra of triruthenium dipyridylamido complexes and of diruthenium mixed nickel metal-string complexes. From the results of analysis on the vibrational modes, we assigned their vibrational frequencies and structures. The infrared band at 323–326 cm−1 is assigned to the Ru3 asymmetric stretching mode for [Ru3(dpa)4Cl2]0–2+. In these complexes we observed no Raman band corresponding to the Ru3 symmetric stretching mode although this mode is expected to have substantial Raman intensity. There is no frequency shift in the Ru3 asymmetric stretching modes for the complexes with varied oxidational states. No splitting in Raman spectra for the pyridyl breathing line indicates similar bonding environment for both pyridyls in dpa– , thus a delocalized structure in the [Ru3]6–8+ unit is proposed. For Ru3(dpa)4(CN)2 complex series, we assign the infrared band at 302 cm−1 to the Ru3 asymmetric stretching mode and the weak Raman line at 285 cm−1 to the Ru3 symmetric stretching. Coordination to the strong axial ligand CN– weakens the Ru-Ru bonding. For the diruthenium nickel complex [Ru2Ni(dpa)4Cl2]0–1+, the diruthenium stretching mode νRu-Ru is assigned to the intense band at 327 and 333 cm−1 in the Raman spectra for the neutral and oxidized forms, respectively. This implies a strong Ru-Ru metal-metal bonding.

In this paper, the development of a portable polymerase chain reaction (PCR) device is presented. Integrating electromagnetic mini-actuators for bi-directional fluid transport, the proposed device, whose dimension is 67mm × 66mm × 25mm, can be fully operated with a 5V DC voltage. The device consists of four major parts: A disposable channel chip in which PCR mixture is manipulated and reacted, a heater chip which generates different temperature zones for PCR reaction, a linear actuator array for pumping PCR mixture, and a circuit module for controlling and driving the system. The advantages of the device include the rapid temperature responses associated with continuous-flow-type PCR devices, as well as the programmable thermal cycling associated with chamber-type PCR devices. The thermal characteristics are measured and discussed. PCR amplification is successfully performed for the 122 bp segment of MCF-7/adr cell line. Due to its small footprint, this self-contained system potentially can be employed for point-of-care (POC) applications.

A combined experimental and theoretical electron density study of the shortest trichromium metal wire, Cr3(dpa)4Cl2·(C2H5OC2H5)(x)(CH2Cl2)(1-x) (1, dpa = bis(2-pyridyl)amido), is reported. High resolution X-ray diffraction data has been collected both at 100 K using a conventional X-ray source (DS1) and at 15 K using a synchrotron X-ray source (DS2). The linear chromium string is terminated by Cl(-) ions at both ends, and each Cr atom is also coordinated by four N atoms from bridging dpa ligands. The two Cr-Cr bond distances are unequal at 100 K (with d(Cr1-Cr2) being 0.029 A shorter than d(Cr2-Cr3)) but at 15 K they are almost equal (0.002 A difference). Analysis of the slightly elongated thermal ellipsoids of the Cr2 atom suggests that it is not due to disorder, but the presence of a shallow potential energy surface. Laplacian maps clearly show local valence shell charge concentration (VSCC) in the electron density along the bisector of the equatorial Cr-N bonds. Integration over the atomic basins indicates that Cr2 has smaller atomic charge and volume than Cr1 and Cr3. The topological characterization of the Cr-Cr bonds indicates partly covalent characters with electron density at the bond critical point of ∼0.3 e A(-3) and negative total energy density. The delocalization index of Cr-Cr is 0.8 for Cr1-Cr2 and 0.08 for Cr1-Cr3. Second-order perturbation analysis shows high stabilization energy of the Cr-Cr bonds (E(2) ∼ 190 kcal mol(-1)). Delocalization indices and source function and natural bond orbital analyses are all indicative of localized Cr-Cr bonding interactions.

The chiral binaphthyl Schiff-base manganese complexes [MnL(X)] [H2L = 2,2′-bis(3-R1-5-R2-2-hydroxybenzylideneimino)-1,1′-binaphthyl; R1 = R2 = Cl, X = O2CMe 1; R1 = Et, R2 = NO2, X = O2CMe 2; R1 = R2 = Cl, X = acac (acetylacetonate) 3] and an iron analogue [FeL(acac)] 4 (R1 = R2 = Cl) have been prepared. The crystal structures of the racemic forms of 3·CH2Cl2 and 4·2H2O exhibit non-planar cis-β configurations with dihedral angles of 85.5 and 72.1° respectively between the two naphthalene rings. Complexes (R)-1 to 3 are active catalysts for the asymmetric epoxidation of alkenes by PhIO. The oxidation of cis-β-methylstyrene by (R)-2 in toluene at –20 °C gave an enantiomeric excess of 76%.

This communication provides a practical strategy for the synthesis of heterotrimetallic extended metal atom chains with supported dpa(-) ligands. The transformation of the CoCoRh to a NiCoRh trinuclear complex can be achieved by direct metallic replacement. Furthermore, the first (CoRh)(4+) metal-metal bond is described here.

The synthesis, crystal structure, magnetic properties, and single-molecule conductance of two new trinuclear metal string complexes, [Ni(3)(dzp)(4)(NCS)(2)] (2) and [Co(3)(dzp)(4)(NCS)(2)] (3), containing the rigid Hdzp ligand (1, 1,9-diazaphenoxazine) are reported. X-ray structural analyses show that compounds 2 and 3 exhibit smaller torsion angles and longer metal-metal distances than those exhibited by the corresponding dpa(-) analogues (dpa(-) = dipyridylamido anion) due to the rigidity of Hdzp ligands. The longer metal-metal distance observed for 2 and 3 results in variations in their magnetic properties. The exchange interaction (J = -160 cm(-1)) between two high spin (HS) Ni(II) ions in 2 decreases slightly in comparison with those of trinickel dpa(-) analogues. The doublet-quartet gap of 3 is smaller than that of [Co(3)(dpa)(4)(NCS)(2)] (4), which causes compound 3 to show spin-crossover behavior even at low temperature.

This work presents the development of a reliable capacitive tactile sensing array which will be tailored as the artificial skins for a humanoid robot. The proposed capacitive sensing element include of two sensing electrodes and a common floating electrode. The sensing electrodes as well as the metal interconnect for signal scanning are implemented on the FPCB, while the floating electrode is patterned on one of the PDMS structures. This special design can effectively reduce the complexity of device structure and thus makes the device highly manufacturable. The measured maximum sensitivity is about 14.5%/kPa. Pressure distribution is captured using a scanning circuit. The deployment of the skin on a humanoid robot is also demonstrated.

A sensitive liquid chromatography/tandem mass spectrometry (LC/MS/MS) method was developed and evaluated for the determination of pitavastatin in human plasma and urine. Samples were extracted using solid-phase extraction (SPE). The major benefit of the present method was the high sensitivity, with a lower limit of quantification (LLOQ) of 0.08 ng/mL. Pitavastatin and internal standard (IS, rosuvastatin) were separated on a C18 column with a mobile phase consisted of methanol/water (75:25, v/v) with 0.05% formic acid. Drug and IS were detected by LC/MS/MS with positive electrospray ionization (ESI). Accuracy and precision for the assay were determined by calculating the intra- and inter-batch variation of quality control (QC) samples at three concentration levels, with relative standard deviations (R.S.D.s) of less than 15%. The developed method was successfully applied to determine pitavastatin in human plasma and urine, and was proved to be suitable for use in Phase I clinical pharmacokinetic study after oral administration of pitavastatin (1, 2 and 4 mg) in healthy Chinese volunteers.

Bis(tosyl)imidoruthenium(VI) porphyrin complexes are prepared and characterised by spectroscopic means; [Ru VI - (tpp)(NTs) 2 ] can undergo imido group transfer reactions with alkenes to afford aziridines, as well as C–H bond oxidation of benzyl alcohol to give benzaldehyde; a tosylamido ruthenium(IV) complex is also isolated and characterised by X-ray diffraction.

A series of chiral Schiff bases, 2,2′-bis(3-R1-5-R2-2-hydroxybenzylideneamino)-1,1′-binaphthyl H2L (R2= Cl, R1= Cl, Me, Et or NO2; R2= Me, R1= But; R2= NO2, R1= H, Me, Et, Pri, But or Cl), and their complexes [CuL1]1 and [Mn2L12(OMe)2]2(R1= R2= Cl) have been prepared. The crystal structure of the racemic form of 1 has been determined. Complex 1 is an active catalyst for the oxidation of alkenes by tert-butyl hydroperoxide. On the contrary, 2 is inert towards alkene epoxidation by PhIO. However, upon mixing Mn(O2CMe)3·xH2O and H2L in acetonitrile a green solution was obtained which could effect asymmetric epoxidation of alkenes by PhIO. The effects of the steric and electronic effects of the R1 and R2 substituents, temperature, and the addition of donors like N-methyl- and 2-methyl-imidazole and pyridine N-oxide on the catalytic activity of the MnIII+(S)-H2L systems towards alkene epoxidation have been investigated. When R1= Et and R2= NO2 the best enantiomeric excesses of 58 and 43% were found for epoxidation of cis-β-methylstyrene to (1S,2R)-cis-β-methylstyrene oxide and 4-chlorostyrene to 4-(S)-chlorostyrene oxide respectively.

An experimental and theoretical charge density study, based on Bader’s Quantum Theory: Atoms in Molecule (QTAIM), on a trichromium metal string complex, Cr3(dpa)4Cl2(C2H5OC2H5)x(CH2Cl2)1-x (1, dpa- = bis(2-pyridyl)amido)) is performed. The structure and multipole model of 1 are performed by using experimental X-ray diffraction data which are collected at both 100 K using conventional X-ray source (DS1) and 15 K using synchrotron source (DS2). The three chromium metal string is bridged by four dpa- ligands. These tri-chromium metal ions are bonded to each other and terminated by two Cl- ions on the both ends, forming a [Cl(1)Cr(1)Cr(2)Cr(3)Cl(2)] linear string. Each Cr atoms are coordinated by four N atoms of each dpa- ligand. This metal string is slightly unsymmetrical at both data sets. The bond distance, from DS1 (DS2), of Cr(1)Cr(2), 2.3480(2) (2.3669(1)) Å, is 0.03 (0.003) Å shorter than Cr(2)Cr(3), 2.3773(2) (2.3689(1)) Å. Furthermore, the Cr(1)Cl(1) is 0.04 (0.04) Å longer than Cr(3)Cl(2) (2.5481(2) (2.5335(2)) and 2.5065(2) (2.4947(2)), respectively). The bond characterization of CrCr bonds indicate that the (3,-1) bond critical points are located at the center of CrCr bonds with small value of electron density, ρb ~ 0.25 e/Å3 and small positive value of total energy density, Hb ~ 0.03 H/Å3. The Laplacian density maps of Cr atoms show obviously local valence shell charge concentration (VSCC) along the bisection of CrN bonds. The total d-orbital populations of Cr atoms have similar value of 4.76 e for Cr(1) and Cr(3) but has slightly larger value of 4.8 e for Cr(2). The charge difference becomes larger at 15 K (4.61 for Cr(2) and 4.3 for Cr(1) and Cr(3). The electron populations of each five d-orbitals are populated unevenly. The dx2-y2 orbital which points to CrN bonds has smallest population in all three Cr atoms. This is consistent to the observation of Laplacian density of Cr atoms. The theoretical charge density analyses show good agreement with experimental one. A detailed analysis of the electron density will be given.