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International audience; We present a time-resolved study of the evolution of the spin-wave intensity and phase in a local parametric spin-wave amplifier at pumping powers close to the threshold of parametric generation. We show that the phase of the amplified spin waves is determined by the phase of the incoming signal-carrying spin waves and that it can be preserved on long time scales as long as the energy input by the input spin waves is provided. In contrast, the phase-information is lost in such a local spin-wave amplifier as soon as the input spin-wave is switched off. These findings are an important benchmark for the use of parametric amplifiers in logic circuits relying on the spin-wave phase as information carrier.

In this paper, graphene oxides graft poly citric acid was synthesized. In first step grahene oxide was prepared. In oxidation process Mildly oxidation technique and a modified Hummer's method which used a lower concentration of oxidizing agent were used to prepare the graphene oxide. Two types of graphene oxides were investigated including Hummer's Graphene Oxide (HGO) and Mildly Graphene Oxide (MGO). Subsequent the surface of graphene oxides were modified by grafting (poly citric acid (PCA)) by using radical polymerization. Polymerized graphene oxides (HGO-graft-PCA and MGO-graft-PCA) were prepared and characterized by using various microscopic and spectroscopic analyses including FTIR, SEM, TEM, UV–Visible, and XPS. The results were consistent with PCA being grafted onto the surface of the graphene oxide. Our results show that polymerization of MGO is better than HGO with the polymerized MGO better able to dissolve in organic and aqueous solvents. Finally, the MGO and MGO-g-PCA were used as nanoelectrocatalysts and coated on electrode surfaces successfully.

The issue of localization/delocalization of electron spin density in Metal-to-Ligand Charge Transfer (MLCT) excited states of [Ru(bpy) 3 ] 2+ (bpy = 2,2′-bipyridine) has been debated for almost four decades. Localization/delocalization of MLCT excited states specifically addresses the question regarding electron configuration in the excited state and whether the excited electron in the dπ 5 π ∗1 excited state was localized on one ligand, [Ru III (bpy)(bpy − )] 2+∗ , or delocalized over all three, [Ru III (bpy − 1/3 ) 3 ] 2+∗ . This contribution outlines the results of a detailed meta-analysis of available experimental data to delineate the factors that govern how the excited state electron density evolves over the time from excitation until final excited state equilibration. Given the nature of the analysis, a number of interwoven issues are discussed in this article. A cohesive evaluation of the existing data leads to a detailed mechanistic understanding of the events that accrue following excitation of [Ru(bpy) 3 ] 2+ . The results of the meta-analysis are both remarkably systematic and consistent with existing theories of dynamic processes.

PMID: 27664317; Cytochrome cbb3 (also known as C-type) oxidases belong to the family of heme-copper terminal oxidases which couple at the end of the respiratory chain the reduction of molecular oxygen into water and the pumping of protons across the membrane. They are expressed most often at low pressure of O2 and they exhibit a low homology of sequence with the cytochrome aa3 (A-type) oxidases found in mitochondria. Their binuclear active site comprises a high-spin heme b3 associated with a CuB center. The protein also contains one low-spin heme b and 3 hemes c. We address here the redox properties of cbb3 oxidases from three organisms, Rhodobacter sphaeroides, Vibrio cholerae and Pseudomonas stutzeri by means of electrochemical and spectroscopic techniques. We show that the redox potential of the heme b3 exhibits a relatively low midpoint potential, as in related cytochrome c-dependent nitric oxide reductases. Potential implications for the coupled electron transfer and proton uptake mechanism of C-type oxidases are discussed.

Using renewable energy to facilitate the Haber-Bosch process is of significant importance. In this issue of Chem, Wang et al. report an ingenious approach for the design of an electrode-solution-reactant interface for efficient, light-assisted N2 reduction in aqueous solution.

Widespread implementation of renewable energy technologies, while preventing significant increases in greenhouse gas emissions, appears to be the only viable solution to meeting the world's energy demands for a sustainable energy future. The final energy mix will include conservation and energy efficiency, wind, geothermal, biomass, and others, but none more ubiquitous or abundant than the sun. Over several decades of development, the cost of photovoltaic cells has decreased significantly with lifetimes that exceed 25 years and there is promise for widespread implementation in the future. However, the solar input is intermittent and, to be practical at a truly large scale, will require an equally large capability for energy storage. One approach involves artificial photosynthesis and the use of the sun to drive solar fuel reactions for water splitting into hydrogen and oxygen or to reduce CO2 to reduced carbon fuels. An early breakthrough in this area came from an initial report by Honda and Fujishima on photoelectrochemical water splitting at TiO2 with UV excitation. Significant progress has been made since in exploiting semiconductor devices in water splitting with impressive gains in spectral coverage and solar efficiencies. An alternate, hybrid approach, which integrates molecular light absorption and catalysis with the band gap properties of oxide semiconductors, the dye-sensitized photoelectrosynthesis cell (DSPEC), has been pioneered by the University of North Carolina Energy Frontier Research Center (UNC EFRC) on Solar Fuels. By utilizing chromophore-catalyst assemblies, core/shell oxide structures, and surface stabilization, the EFRC recently demonstrated a viable DSPEC for solar water splitting.

New membrane-protein based electrodes were prepared incorporating cytochrome bo3 from Escherichiacoli and gold nanoparticles. Direct electron transfer between the electrode and the immobilized enzymes was achieved, resulting in an electrocatalytic activity in presence of O2. The size of the gold nanoparticles was shown to be important and smaller particles were shown to reduce the overpotential of the process. Keywords: Membrane protein, Gold nanoparticles, Direct electron transfer, Electrocatalysis

In many of the chemical steps in photosynthesis and artificial photosynthesis, proton coupled electron transfer (PCET) plays an essential role. An important issue is how excited state reactivity can be integrated with PCET to carry out solar fuel reactions such as water splitting into hydrogen and oxygen or water reduction of CO2 to methanol or hydrocarbons. The principles behind PCET and concerted electron–proton transfer (EPT) pathways are reasonably well understood. In Photosystem II antenna light absorption is followed by sensitization of chlorophyll P680 and electron transfer quenching to give P680+. The oxidized chlorophyll activates the oxygen evolving complex (OEC), a CaMn4 cluster, through an intervening tyrosine–histidine pair, YZ. EPT plays a major role in a series of four activation steps that ultimately result in loss of 4e−/4H+ from the OEC with oxygen evolution. The key elements in photosynthesis and artificial photosynthesis – light absorption, excited state energy and electron transfer, electron transfer activation of multiple-electron, multiple-proton catalysis – can also be assembled in dye sensitized photoelectrochemical synthesis cells (DS-PEC). In this approach, molecular or nanoscale assemblies are incorporated at separate electrodes for coupled, light driven oxidation and reduction. Separate excited state electron transfer followed by proton transfer can be combined in single semi-concerted steps (photo-EPT) by photolysis of organic charge transfer excited states with H-bonded bases or in metal-to-ligand charge transfer (MLCT) excited states in pre-associated assemblies with H-bonded electron transfer donors or acceptors. In these assemblies, photochemically induced electron and proton transfer occur in a single, semi-concerted event to give high-energy, redox active intermediates.

Structural changes between [OsIIL3]2+ and [OsIIIL3]3+ (L: 2,2′-bipyridine; 1,10-phenanthroline) and molecular and electronic structures of the OsIII complexes [OsIII(bpy)3]3+ and [OsIII(phen)3]3+ are discussed in this paper. Mid-infrared spectra in the ν(bpy) and ν(phen) ring stretching region for [OsII(bpy)3](PF6)2, [OsIII(bpy)3](PF6)3, [OsII(phen)3](PF6)2, and [OsIII(phen)3](PF6)3 are compared, as are X-ray crystal structures. Absorption spectra in the UV region for [OsIII(bpy)3](PF6)3 and [OsIII(phen)3](PF6)3 are dominated by very intense absorptions (e = 40 000–50 000 M−1 cm−1) due to bpy and phen intra-ligand π → π∗ transitions. In the visible region, relatively narrow bands with vibronic progressions of ∼1500 cm−1 appear, and have been assigned to bpy or phen-based, spin–orbit coupling enhanced, 1π → 3π∗ electronic transitions. Also present in the visible region are ligand-to-metal charge transfer bands (LMCT) arising from π(bpy) → t2g(OsIII) or π(phen) → t2g(OsIII) transitions. In the near infrared, two broad absorption features appear for oxidized forms [OsIII(bpy)3](PF6)3 and [OsIII(phen)3](PF6)3 arising from dπ–dπ interconfigurational bands characteristic of dπ5OsIII. They are observed at 4580 and 5090 cm−1 for [OsIII(bpy)3](PF6)3 and at 4400 and 4990 cm−1 for [OsIII(phen)3](PF6)3. The bpy and phen infrared vibrational bands shift to higher energy upon oxidation of Os(II) to Os(III). In the cation structure in [OsIII(bpy)3](PF6)3, the OsIII atom resides at a distorted octahedral site, as judged by ∠N–Os–N, which varies from 78.78(22)° to 96.61(22)°. Os–N bond lengths are also in general longer for [OsIII(bpy)3](PF6)3 compared to [OsII(bpy)3](PF6)2 (0.010 A), and for [OsIII(phen)3](PF6)3 compared to [OsII(phen)3](PF6)2 (0.014 A). Structural changes in the ligands between oxidation states are discussed as originating from a combination of dπ(OsII) → π∗ (bpy or phen) backbonding and charge redistribution on the ligands as calculated by natural population analysis.

Transient infrared spectroscopy (or time-resolved infrared spectroscopy, TRIR) on the nanosecond and faster timescales has continued to evolve as a routine and, sometimes, definitive tool both for elucidation of electronic and molecular structures in metal complex excited-states. This review examines examples from the literature since 1998 and discusses experimental methods for performing transient infrared experiments and recent novel applications of TRIR to the excited states of transition metal complexes. While the interrogation of “reporter” ligands such as ν(CO) and ν(CN) modes in metal carbonyl and cyanide complexes and ν(C O) ligand modes, has grown extensively toward the identification of excited states and important features of their bonding, there have been many exciting extensions of the transient infrared technique in recent years. TRIR has been increasingly applied to many types of excited states, resulting in a well-established methodology for assigning excited-state identities. The usefulness of this method has been demonstrated in the unraveling of the sometimes complicated photophysical behavior associated with the complex interplay of multiple excited states, such as closely-spaced MLCT, intra- (IL) and interligand, and dd (ligand-field (LF)) excited states. In recent years, efforts to relate ground-to-excited state vibrational band shifts with other excited state properties (such as the ground-to-excited state energy gap), and medium effects have brought new insights to the understanding of electronic structure in excited states. Application of electronic structure calculations, such as density functional theory approaches, has proven to be a very powerful tool when combined with TRIR in this regard. Relatively new developments, such as non-linear 2D infrared (T2D-IR) spectroscopy, spectroscopic extension into the near infrared, and time-resolved dynamic imaging methods offer exciting possibilities for future applications, and have already presented new capabilities for providing additional insight into the excited states of transition metal complexes.

Application of time-resolved near-infrared spectroscopy (TRNIR) to Os ( phen ) 3 2 + in CD3CN, following visible (450 nm) laser flash excitation, reveals an absorption feature at ν ¯ max = 5460 cm - 1 (emax ⩾ 5000 M−1 cm−1, Δ ν ¯ 1 / 2 = 1840 cm - 1 ) for the MLCT excited state Os ( phen ) 3 2 + ∗ . Based on an electronic structure model, including spin–orbit coupling, the absorption is tentatively assigned to three overlapping ligand-to-ligand charge transfer (LLCT) bands two of which have dπ → dπ interconfigurational character. This assignment is consistent with the results of a solvent dependence study and an analysis of predicted band energies.

Purpose: In chemoradiation for pancreatic carcinoma three-dimensional target volume definitions could maximize tolerability and therapeutic effect at the same time because toxicity correlates with treatment volume. We aimed to define guidelines for elective treatment of nodal areas based on pathologic nodal involvement to optimize treatment volume for this tumor. Methods and Materials: Pathologic patterns of regional nodal spread in 175 patients who underwent primary pancreatoduodenectomy with ≥10 assessed nodes and literature data on para-aortic spread were the base of the definition of the target volume. Significant correlations between spread to lymphatic areas and tumor characteristics were determined using Fisher's exact test. Computed tomography scans and a Pinnacle 3 (Philips, Best, The Netherlands) system were used for treatment planning. Results: Among 175 resected tumors without pretreatment, 76% had regional nodal metastasis and 22% had spread to distant nodes. High-risk lymphatic areas were identified and selected for elective treatment. A standardized planning procedure was derived and tested under treatment conditions. Conclusions: Histopathologic data allowed us to develop recommendations for standardized treatment planning for ductal carcinoma of the pancreatic head. These are proposed for quality assurance in multicenter studies and routine use.

The metal-to-ligand charge transfer (MLCT) excited states of polypyridyl complexes of the d 6 ions Ru(II), Os(II), and Re(I) have provided the basis for many studies on photochemical electron and energy transfer. In this account, a brief review of photochemical electron transfer by [Ru(bpy) 3 ] 2+* is given, followed by an update on MLCT excited state molecular and electronic structure, and an introduction to photochemical electron and energy transfer in molecular assemblies. The majority of the account is devoted to describing the evolution of two approaches to preparing complex molecular assemblies for the study of photochemical electron and energy transfer both inspired by the demands of achieving artificial photosynthesis. The first approach involves the derivatization of preformed polystyrene by added chromophores and electron or energy transfer donors or acceptors and three generations of polymers differing in polymer content and linkage strategies. The second approach has exploited solid-state peptide synthesis and the stepwise preparation of oligopeptides with spatial control of added groups and alignment on the resulting helical scaffolds.

Aims: A considerable number of melanoma patients present with clinically evident regional lymph node metastases. Factors influencing prognosis following therapeutic lymph node dissection (TLND) were evaluated. Methods: In total 140 patients (68 women, 72 men, median age 53 years) with established regional lymph node metastases, but without clinically detectable distant metastases, received cervical, axillary or ilioinguinal TLND between 1978 and 1997 and were retrospectively reviewed. Uni- and multivariate survival analysis was performed. Results: Median survival for all 140 patients was 25 months; the observed overall 5 year survival rate was 30%. Age greater than 50 years, primary tumour site on the trunk, more than three lymph node metastases and extracapsular spread were associated with a poor prognosis. In multivariate analysis age (≤50 years vs >50 years, P =0.02), location of the primary tumour (non-truncal vs truncal, P =0.005), number of lymph nodes involved ( n ≤3 vs n >3, P =0.01) and extracapsular spread (none vs present, P =0.04) proved to be independent prognostic factors. Conclusions: TLND is worthwhile and offers a potential chance of cure in about one-third of melanoma patients with established regional lymph node metastases. There are subgroups with a particularly poor prognosis in whom the benefit of radical surgery alone is limited.

Spectroscopic evidence is presented for different structural isomers of trans -[Ru(bpy) 2 (L 1 )(L 1 )] 2+ (L 1 or L 2 =4-Etpy ( 1 ), py-PTZ) in which bpy is planar or nonplanar compared to cis -[Ru(bpy) 2 (py) 2 ] 2+ or [Ru(bpy) 3 ] 2+ in which bpy is planar. The nonplanar form is dominant in the ground states in low temperature glasses. The two forms appear to be in a temperature dependent equilibrium in 4:1 (v/v) ethanol/methanol at higher temperatures. The nonplanar form is converted into the planar form in the MLCT excited state(s) of 1 .

Treatment of systemic diseases by means of the inhalation route is hampered by uncertainties of the drug dose applied by inhalation. In this study, the hypothesis was tested that by standardization of the breathing maneuver used for inhalation, the interindividual variability of the dose deposited intrathoracically can be reduced. Therefore, breathing pattern during routine inhalations with jet nebulizers was measured in 18 patients with lung disease. Using monodisperse 3 μm particles, total deposition was then assessed for the measured spontaneous and for three controlled, slow breathing patterns. Particle deposition for the three controlled breathing patterns was additionally measured in 14 healthy subjects. The study has shown that within the study population the inhaled air volume and flow rate were quite different. Consequently, total particle deposition varied between 20 and 95%, depending on breathing pattern. For controlled, slow breathing patterns, deposition was on average higher, intersubject variability of deposition was smaller, and differences in deposition between healthy subjects and patients were negligible. Therefore, to perform efficient systemic treatment with aerosolized drugs, controlled, slow breathing patterns should be used. © 2000 Wiley‐Liss, Inc. and the American Pharmaceutical Association J Pharm Sci 89: 724–731, 2000

The synthesis of a new electron transfer donor and two new ruthenium chromophores are described based on coupling to derivatized proline residues for the purpose of constructing molecular assemblies capable of undergoing photoinduced electron transfer.

Objective Patients with lung emphysema show increased aerosol-derived dimensions of peripheral airspaces and increased aerosol bolus dispersion (AD). To apply these tests in epidemiologic studies, the objective of this pilot study was to investigate whether morphometric changes caused by lung fibrosis can be distinguished from those caused by emphysema. Design This study was designed as a cross-sectional study in which airspace dimensions and AD in patients with emphysema and in patients with fibrosis were compared. Forty patients participated in the study: 20 patients had high-resolution CT (HRCT)-proved lung emphysema and 20 patients had HRCT-proved lung fibrosis. All patients underwent conventional lung function tests, aerosol-derived airway morphometry (ADAM), and AD measurements. Results Patients with lung emphysema showed normal dimensions of small airways but enlarged airspace dimensions in the lung periphery. Patients with fibrosis showed in all lung depths increased airspace dimensions. AD was increased in patients with emphysema but was normal in patients with fibrosis. Conclusions These results show that when using ADAM and AD, morphometric changes caused by emphysema can be distinguished from those caused by fibrosis with high sensitivity and specificity.

The crystal and molecular structures of OsIII(tpy)(Cl)3 (1) (tpy=2,2′:6′,2″-terpyridine) and (PPN)[OsIII(Tp)(Cl)3] (2) (PPN+=bis-(triphenylphosphoranylidene) ammonium cation, Tp=hydrido tris(1-pyrazolyl)borate anion) are reported. In trans-OsIII(tpy)(Cl)3 (1) Os–Cl bond lengths are in the range 2.3604(10)–2.3833(9) A. In (PPN)[OsIII(Tp)(Cl)3] (2) Os–Cl bond lengths are in the range 2.3789(19)–2.4082(17) A. These bond lengths are consistent with OsIII as compared with similar values in chloro-containing Os compounds found in the literature.

A protected form of 3,5-bis(phosphonomethyl)benzoic acid (Bpb-OH), a metal oxide surface bivalent anchor, has been synthesized, coupled to an amine functionality, deprotected, and shown to bind to metal oxide surfaces. The protected anchor, 3,5-bis(dimethoxyphosphinylmethyl)benzoic acid (Me4Bpb-OH) was synthesized in 23% yield over four steps, coupled to a proline-chromophore, deprotected with a solution of iodotrimethylsilane (TMSI) in acetonitrile and adsorbed to Tin(IV)-doped indium oxide and nanocrystalline TiO2 electodes at surface coverages of 1.5 × 10−10 mol cm−2 and 4.9 × 10−11 mol cm−2, respectively. Finally, Me4Bpb-OH was converted to an amino derivative by attaching a diamino butane linker.

Rapid reactions occur between [Os VI (tpy)(Cl) 2 (N)]X (X = PF 6 − , Cl − , tpy = 2,2′:6′,2″-terpyridine) and aryl or alkyl phosphi nes (PPh 3 , PPh 2 Me, PPhMe 2 , PMe 3 and PEt 3 ) in CH 2 Cl 2 or CH 3 CN to give [Os IV (tpy)(Cl) 2 (NPPh 3 )] + and its analogs. The reaction between trans -[Os VI (tpy)(Cl) 2 (N)] + and PPh 3 in CH 3 CN occurs with a 1:1 stoichiometry and a rate law first order in both PPh 3 and Os VI with k (CH 3 CN, 25°C) = 1.36 ± 0.08 × 10 4 M − s −1 . The products are best formulated as paramagnetic d 4 phosphoraniminato complexes of Os IV based on a room temperature magnetic moment of 1.8 μ B for trans -[Os IV (tpy)(Cl) 2 (NPPh 3 )](PF 6 ), contact shifted 1 H NMR spectra and UV-Vis and near-IR spectra. In the crystal structures of trans -[Os IV (tpy)(Cl) 2 ( NPPh 3 )](PF 6 )·CH 3 CN (monoclinic, P 2 1 / n with a = 13.384(5) A, b = 15.222(7) A, c = 17.717(6) A, β = 103.10(3)°, V = 3516(2) A 3 , Z = 4, R w = 3.40, R w = 3.50) and cis -[Os IV (tpy)(Cl) 2 (NPPh 2 Me)]-(PF 6 )·CH 3 CN (monoclinic, P 2 1 / c , with a = 10.6348(2) A, b = 15.146(9) AA, c = 20.876(6) A, β = 97.47(1)°, V = 3334(2) A 3 , Z = 4, R = 4.00, R w = 4.90), the long Os-N(P) bond lengths (2.093(5) and 2.061(6) A), acute Os-N-P angles (132.4(3) and 132.2(4)°), and absence of a significant structural trans effect rule out significant Os-N multiple bonding. From cyclic voltammetric measurements, chemically reversible Os V/IV and Os IV/III couples occur for trans -[Os IV (tpy)(Cl) 2 (NPPh 3 )](PF 6 ) in CH 3 CN at +0.92 V (Os V/IV ) and −0.27 V (Os IV/III ) versus SSCE. Chemical or electrochemical reduction of trans -[Os IV (tpy)(Cl) 2 (NPPh 3 )](PF 6 ) gives isolable trans -Os III (tpy)(Cl) 2 (NPPh 3 ). One-electron oxidation to Os V followed by intermolecular disproportionation and PPh 3 group transfer gives [Os VI (tpy)Cl 2 (N)] + , [OS III (tpy)(Cl) 2 (CH 3 CN)] + and [Ph 3 =N=PPh 3 ] + (PPN + ). trans -[Os IV (tpy)(Cl) 2 (NPPh 3 )](PF 6 ) undergoes reaction with a second phosphine under reflux to give PPN + derivatives and Os II (tpy)(Cl) 2 (CH 3 CN) in CH 3 CN or Os II (tpy)(Cl) 2 (PR 3 ) in CH 2 Cl 2 . This demonstrates that the Os VI nitrido complex can undergo a net four-electron change by a combination of atom and group transfers.

Although it is estimated that > 1 billion passengers travel by air worldwide each year, the incidence of in-flight emergencies is low. However, due to nonstandardized reporting requirements for in-flight medical emergencies, the true incidence of pulmonary barotrauma in airplane passengers is unknown. We describe the case of a passenger with an asymptomatic intrapulmonary cyst in whom a severe case of cerebral gas embolism developed during an aircraft flight. The decrease in ambient pressure during the aircraft climb resulted in expansion of the cyst volume based on Boyle's law (pressure x volume = constant). Due to the cyst expansion, we believe tears in the wall led to the leakage of air into the surrounding vessels followed by brain gas emboli. Adult patients with intrapulmonary cysts should be strongly considered for cyst resection or should at least be advised to abstain from activities leading to considerable changes in ambient pressure.

Time-resolved resonance Raman and infrared spectroscopies have been applied to a variety of problems arising in excited states and molecular assemblies based on polypyridyl complexes of Re(I), Ru(II) and Os(II). Application of transient resonance Raman spectroscopy has been used to assign the acceptor ligand in heteroleptic Ru(II) complexes and to characterize molecular structure in acceptor ligands. It has been applied to intramolecular electron transfer in chromophore-quencher complexes and molecular assemblies and to intramolecular energy transfer in polynuclear complexes. Time-resolved infrared spectroscopy has opened new avenues for the study of excited-state electronic structure and dynamics by the observation of ν(CO) and ν(CN) bands in transient absorption difference spectra. This technique has been applied to distinguishing between metal-to-ligand charge transfer and ligand-based ππ ∗ states in Re(I) complexes and to intramolecular energy transfer in cyano-bridged oligomers.

The syntheses of three bridging electron transfer donor ligands are described based on coupling of the electron transfer donor, N, N′-dimethylbenzidine with two 2,2′-bipyridines. Two different coupling strategies are used: coupling between an acid and an amine with formation of an amide, and nucleophilic coupling between an amine and an electrophilic bipyridine.

By a condensation of 1,10-phenanthroline-5,6-dione and 1,2-diamino antraquinone, the new acceptor polypiridine ligand, 10,11-[1,4 naphtalendione]dipyrido[3,2-a;2′,3′-c]phenazine, was obtained. A new synthetic route for the 1,10phenanthroline-5,6-dione precursor is also reported.

The synthesis and characterization of the complex [Ru(tppz)(4,4′-(CH 3 ) 2 bpy)Cl] + , where tppz = 2,3,5,6-tetrakis(2-pyridyl)pyrazine, is reported. The ion was obtained in a one pot synthesis by reduction of Ru(4,4′-(CH 3 ) 2 bpy)Cl 4 with triethylamine in the presence of tppz, and isolated as the hexafluorophosphate salt. The structure of [Ru(tppz)(4,4′-(CH 3 ) 2 bpy)Cl](PF 6 ), 1 , was established by X-ray diffraction. The ruthenium atom is in a highly distorted octahedral environment with the 4,4′-(CH 3 ) 2 bpy nitrogens, the pyrazine central nitrogen of tppz, and chlorine defining the best mean equatorial plane. The axial positions are occupied by the nitrogens of the coordinated pyridyl rings of tppz. The Ru—N(tppz) bond to the central ring is short [1.962(9) A], while the Ru—N(4,4′(CH 3 ) 2 bpy) bond trans to it is lengthened towards a single bond distance [2.096(10) A]. This enhances the distortion in coordination of the octahedron, mainly produced by the bite angle of tppz. The distortions in 1 are evident in the 1 H-NMR spectra by the shifts of characteristic resonances upfield and downfield relative to the ligand.

The use of electrochemical methods for the detection of various biological substances has provided real-time measurements giving insights into their roles in various physiological functions. The discovery that nitric oxide (NO) plays critical regulatory roles in a variety of physiological processes has prompted development of analytical techniques for the detection of this diatomic molecule in biological systems. This report will address the use of electrochemical techniques for the detection of NO. Several NO-sensitive electrodes have been fabricated and we present a discussion on the advantages and disadvantages of these techniques that will enable the reader to evaluate the best technique for a particular use. The fabrication of NO-sensitive devices for the electrochemical oxidation of solutions containing certain porphyrins (nickel tetra-N-methylpyridiniumporphyrin chloride, Ni(TMPP) and the corresponding apoporphyrin is described here. A key finding is that the lowering of the potential for oxidation of NO can be attributed to modification of the carbon surface and not the porphyrin film. The porphyrin does appear to improve the signal-to-noise ratio. An evaluation of various potential interferences will be discussed. Biological substances that potentially interfere with this type of electrode can be excluded by coating the electrode with Nafion membrane. A description of the coating procedure is presented and methods of distinguishing between NO and other substances such as nitrite, ascorbate, and catecholamines are discussed.

Redox-active amino acids were synthesized for incorporation into peptide assemblies to study photoinitiated electron or energy transfer. 4′-Methyl-2,2′-bipyridine-4-carboxylic acid was obtained in 72% yield by consecutive SeO2 and Ag2O oxidation without isolation of intermediates. The side chain e-amino group of Boc-l-lysine methyl ester or γ-carboxyl group of Boc-l-glutamic acid α-methyl ester was coupled to a redox moiety (transition-metal chromophore, electron donor, electron acceptor, metal ligand, or triplet-energy transmitter) using 4-(dimethylamino)pyridine, (1-benzotriazoleoxy)tris(dimethylamino)phosphonium hexafluorophosphate, N-methylmorpholine, and 1-hydroxybenzotriazole. Use of one equivalent of 4-(dimethylamino)pyridine provided the amide coupling product in 80–97% isolated yield. Selective hydrolysis of the methyl esters with lithium hydroxide provided the redox Boc-amino acids in 70–98% yield. These redox modules are suitable for solid-phase assembly of light-harvesting peptides, as illustrated by the synthesis of the partially α-helical 11-residue redox triad that contains a phenothiazine electron donor, a ruthenium(II)tris(bipyridine) chromophore, and an anthraquinone electron acceptor. Upon laser excitation at 420 nm, the peptide triad underwent photoinduced electron transfer to create a charge-separated state with a lifetime of 53 ns and decayed with a first-order rate constant of 1.9 × 108 s−1.

Although the architectures of several membrane proteins in respiration as well as the basic chemical reactions have been described, the interactions on molecular level, the high diversity and the high efficiency of mechanisms, are under discussion. Experiments have been developed which reveal how protons and other ions are drawn through proteins and how they are coupled to electron transfer.An electrochemical approach on proteins immobilized on gold nano particles was used to get insight into the redox properties in the presence and absence of substrate and inhibitors to the proton channels (Zn2+).1 Two approaches are presented to functionally probe the enzymes against substrates and inhibitors: i) The redox reaction was IR spectroscopically studied in solution and ii) the proteins are immobilized via their His-Tag on a gold layer, deposited on an ATR-crystal and studied by surface enhanced IR spectroscopy (SEIRAS). 2 The combination of the electrochemical and IR spectroscopic approach allowed the observation of protein action at the level of single functional groups within the large protein studied and thus provides essential knowledge's for the understanding of the mechanism of the studied enzymes.References1. Meyer, T.; Melin, F.; Xie, H.; von der Hocht, I.; Choi, S. K.; Noor, M. R.; Michel, H.; Gennis, R. B.: Soulimane, T.; Hellwig, P. (2014) J. Am. Chem. Soc., 136, 10854-10852. Kriegel, S., Uchida, T., Osawa, M., Friedrich, T., Hellwig, P. (2014) Biochemistry 53(40):6340-7.

The analysis of average molecular masses and molecular mass distributions by means of liquid chromatography is usually performed with size-exclusion columns. With mathematical methods the average molecular mass of the sample and its distribution are then calculated by comparison with standards. For polyethylene glycols (PEGs), a simple way to separate the oligomer species by isocratic elution with reversed phase columns was found. They can be identified and analysed quantitatively. The measurements were performed for PEGs with molecular masses from 300 up to 2000 g/mol. The results for several commercially available PEGs are presented. A comparison between a large-scale PEG and a PEG standard is shown, which demonstrates that polymer standards must be handled with care.

Polypyridyl complexes of Fe II and Zn II containing the ligand 4-methyl-2,2′-bipyridyl-4′-carboxaldehyde(4-CH 3 -4′-CHO-bpy) have been prepared. Upon electrochemical reduction of these complexes coupling reactions occur at the ligands, yielding thin metal-complex-containing polymeric films on the electrode surfaces. The polypyridyl ligands that form in a polymerized film of [Zn(4-CH 3 -4′-CHO-bpy) 3 ] 2+ have been isolated following chemical degradation and characterized using fast atom bombardment mass spectrometry and 1 H nuclear magnetic resonance. These and other results are consistent with a mechanism for polymerization that involves radical—radical coupling at the aldehyde substituents following reduction. The coupling occurs with the formation of a 1,2-diol linkage between the bipyridine ligands which creates a basis for network polymerization.

Night-to-night variability of apneas on overnight polymnography exists in patients with documented obstructive sleep apnea (OSA). In this study, we evaluated the possibility that this variability may be severe enough to miss the diagnosis of OSA in patients clinically at risk for the disease. We prospectively studied 11 patients who were deemed on clinical grounds to have probable OSA, but had a negative result on overnight polysomnography. Six of the 11 patients were found to have a positive second study with a significant rise in the apnea/hypopnea index (AHI) from 3.1 +/- 1.0 to 19.8 +/- 4.7 (mean +/- SEM, p < 0.01). The cause of the negative first study in these patients is unclear, but it does not seem related to risk factor pattern, sleep architecture, or test interval. The change in AHI was not found to be rapid eye movement (REM)-dependent. This study demonstrates that a negative first-night study is insufficient to exclude OSA in patients with one or more clinical markers of the disease.

In soluble polystyrene polymers that contain polypyridyl complexes of Ru II or Os II it has been possible to demonstrate the existence of intrastrand photochemical electron and energy transfer.

The temperature effect on mutual solubility data for 81 binary systems has been studied by means of UNIQUAC and extended UNIQUAC models. The energy parameters of the models are expressed by a quadratic function of temperature. Among the systems studied 61 systems have an upper critical point, 14 systems have a closed partial miscibility and in six systems the mutual solubility increases with decreasing temperature. The extended UNIQUAC model shows significant improvement for some systems and therefore slightly better results, on average, than the original UNIQUAC model.

Cell walls prepared from Bacillus Calmette-Guerin (BCG) and associated with oil droplets have been shown to protect mice from aerosol infection with the virulent H37Rv strain of Mycobacterium tuberculosis. A combination of the peptidoglycolipid cell wall skeleton (CWS-I), prepared by exhaustive organic solvent extraction of BCG cell walls, and P3, isolated by centrifugal microparticulate bed chromatography from the free lipids of the mycobacterial cell wall, gave protection comparable to that provided by whole BCG cell wall. Neither component by itself was capable of protecting mice. The mechanism of protection based upon the chemistry of the mycobacterial components is discussed.

Flash photolysis studies on Mn2(CO)10 in cyclohexane and THF show that the dominant photochemistry involves photolytic formation of 2 Mn(CO)5 followed by recombination at rates near the diffusion-controlled limit. A second, relatively, long-lived intermediate is also observed and earlier observations of photodecomposition and photodisproportionation can be accounted for in terms of secondary photolysis of this intermediate. For the equilibrium: Mn2(CO)10 ⇌ 2 Mn(CO)5 △H ∼ 36 kcal/mol, △S ∼ 32 e.u., and K(25°C) ∼ 10−20 where the thermodynamic values have been estimated from kinetic measurements.

The ability of certain mycobacterial cell wall components, when attached to minute droplets of oil, to induce granulomatous inflammation in mouse lung and guinea pig skin has been studied for clues to the mechanisms by which these components protect mice against aerosol challenge with virulent tubercle bacilli and are useful in immunotherapy of dermal tumors of guinea pigs. Fractions examined were the following: the cell wall skeleton (CWS-I), which consisted of a polymeric peptidoglycolipid; wax D, which contained mono- or oligomeric peptidoglycolipid; and trehalose mycolates (P3). A combination of CWS-I and P3 induced more granuloma in mouse lungs than either of these two entities alone. Similarly, when wax D was separated into a chloroform-methanol-insoluble portion (CMI), which contained the mono- or oligomeric peptidoglycolipid, and the soluble portion (CMS), which contained P3, it was found that both moieties were required to produce maximal granulomatous inflammation. The degree of granuloma induced by these nonliving vaccines, as measured by an increase in lung weight following intravenous inoculation, could be correlated with the degree of protection produced in mice against airborne infection with M. tuberculosis H37Rv and with the degree of regression of skin tumors in guinea pigs upon intralesional inoculation. Even though quantitation of the granulomatous response in the skin of guinea pigs is difficult, it would appear that intradermal inoculation of cell walls, CWS-I, or CMI produced comparable granuloma, whereas CMS or P3 alone was essentially inactive.