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A plausible reaction path for synthesizing pyrazolylamidino Cu(ii) complexes is established. Cu(pzH)4X2 (X = ClO4−, BF4−, or NO3−), usually considered as an inert species for the pyrazole-nitrile coupling reaction, actually is more reactive.

The first anionic Fe(iii) monosulfenato (Fe–S(O)R) complex, as a possible intermediate species in the catalytic intramolecular N–S bond formation, is isolated and structurally determined.

Compounds with the benzisothiazol-3-one (BIT) skeleton perform excellently in the pharmaceutical field, although current synthetic methods remain limited in terms of synthetic efficiency. Herein, we report the catalytic intramolecular N-S bond formation for BITs from easily prepared disulfide precursors by an Fe(III) dithiolate through O

Carbon monoxide (CO) plays an important role in signaling in cells, making its use as a therapeutic tool highly intriguing. Reduced burst emissions are important to avoid the cytotoxicity and tissue damage caused by CO. Here, we developed a stable diiron carbonyl [FeFe] hydrogenase agent that enables prolonged CO release activity (half-life of over 9 h) in cells. The integrated analysis allowed the identification of the key intermediate sites and CO accumulations with subcellular resolution. We observed that the [FeFe]

Nuclear resonance vibrational spectroscopy (NRVS) and density functional theory (DFT) are complementary tools for studying the vibrational and geometric structures of specific isotopically labeled molecular systems. Here we apply NRVS and DFT to characterize the trans-[57Fe(η2-H2)(H)(dppe)2][BPh4] [dppe = 1,2-bis(diphenylphosphino)ethane] complex. Heretofore, most NRVS observations have centered on the spectral region below 1000 cm-1, where the 57Fe signal is strongest. In this work, we show that state-of-the-art synchrotron facilities can extend the observable region to 2000 cm-1 and likely beyond, in measurements that require less than 1 day. The 57Fe-H stretch was revealed at 1915 cm-1, along with the asymmetric 57Fe-H2 stretch at 1774 cm-1. For a small fraction of the H2-dissociated product, the 57Fe-H stretch was detected at 1956 cm-1. The unique sensitivity to 57Fe motion and the isolated nature of the Fe-H/H2 stretching modes enabled NRVS to quantitatively analyze the sample composition.

To study whether the methylation status of cervical secretions can reflect the ability of the endometrium to allow embryo implantation.Case-control study.In vitro fertilization centers.Women undergoing embryo transfer cycles, in which at least 1 good-quality embryo was transferred.Collection of cervical secretions during the procedure of embryo transfer.Methylation profiles of cervical secretions in relation to pregnancy outcomes.Genome-wide methylation profiles differ between cervical secretions from pregnancy and nonpregnancy cycles. Clustering analysis on the basis of the top 2,000 differentially methylated probes of cervical secretions from 28 pregnancy and 29 nonpregnancy cycles correctly categorized 86.0% of the samples in terms of conceptional status, which was verified in selected genes by quantitative methylation-specific polymerase chain reaction and validated in another independent sample set. The combination of selected genes was estimated to predict pregnancy outcomes with a maximal area under the receiver operating characteristic curve of 0.83.The methylation profiles of cervical secretions were associated with pregnancy outcomes in embryo transfer cycles. Although not clinically useful at present, deoxyribonucleic acid methylation in cervical secretions may shed new light on the less invasive assessment of endometrial receptivity.

Nuclear resonance vibrational spectroscopy (NRVS) and density functional theory (DFT) are complementary tools for studying the vibrational and geometric structure of specific isotopically-labeled molecular systems. Here we apply NRVS and DFT to characterize the trans-[(57)Fe(η(2)-H(2))(H)(dppe)(2)][BPh(4)] complex. Heretofore, most NRVS observations have centered on the spectral region below 1000 cm(−1) where the (57)Fe signal is strongest. In this work, we show that state-of-the-art synchrotron facilities can extend the observable region to 2000 cm(−1) and likely beyond, in measurements that require less than one day. The (57)Fe–H stretch was revealed at 1915 cm(−1), along with the asymmetric (57)Fe–H(2) stretch at 1774 cm(−1). For a small fraction of the H(2)-dissociated product, the (57)Fe–H stretch was detected at 1956 cm(−1). The unique sensitivity to (57)Fe motion and the isolated nature of the Fe–H/H(2) stretching modes enabled NRVS to quantitatively analyze the sample composition.

The presence of asymmetric cysteine sulfur-oxygenation donors, consisting of sulfenate (SO), sulfinate (SO2), and thiolate (S), around a trivalent iron is essential for the catalytic function of Fe- or Co-type nitrile hydratase (NHase). To gain insight into the role of this asymmetric ligation, an octahedral bisthiolate low-spin FeIII complex and two of its S-oxygenation derivatives, unprecedented mixed sulfinate/thiolate and O-bound bissulfinate complexes, were generated. The placement of anionic nitrogen atoms trans to the thiolates in the bisthiolate complex caused the axial imino C=N bonds to be more polarized and thus resembled the activation of bound nitrile in nitrile hydratase. The polarization was found to be even more severe in the monosulfinate species, and hydration of the Fe-bound C=N bond by HO– was observed. The generation of an O-bound bissulfinate octahedral complex implied that the equatorial carboxamido and axial thiolate ligation in Fe-NHase provided greater electron buffering capacity in keeping the electron density of the FeIII ion constant even in the presence of equatorial S-oxygenations.

An effective and quick approach to selectively separate sulfate anions from ethanol solution or water/EtOH mixture (1 : 1, v/v) based on the precipitation of the neutral sulfate complex, without the slow crystallization process and by utilizing a positive-charged and low-solubility receptor, is illustrated in this paper. The cationic receptor [HL1]+ with the tris(aminomethyl)ethane platform appended with three pyrrolic arms is capable of selectively separating HSO4− or H2PO4− anions in the form of precipitates from EtOH. The mono-protonated tetrapodal receptor [HL2]+, based upon a cyclic C4N2 six-member chair-form platform equipped with four pyrrolic moieties, was constructed in situ through anion-templated chemical synthesis from L1 and pyrrole-2-carboxaldehyde. This receptor shows the capability of selectively precipitating sulfate anions in EtOH or ethanol/water solution. A minor structural modification from L1 to L2 through chemical synthesis in situ leads to an increase of selectivity for sulfate binding and precipitation. The solid-state crystal structure of the precipitates [HL2]2[SO4] after recrystallization shows the encapsulation of a single sulfate within a cavity embraced by two receptors, thereby forming a supramolecular capsule. This tetrapodal receptor exhibits high affinity for sulfate anions as also revealed by a chloroform–water extraction experiment, and can be recycled after NaOH(aq) treatment for continuous usage.

Dioxygen activation by FeII thiolate complexes is relatively rare in biological and chemical systems because the sulfur site is at least as vulnerable as the iron site to oxidative modification. O2 activation by FeII-SR complexes with thiolate bound trans to the O2 binding site generally affords the FeIV[double bond, length as m-dash]O intermediate and oxidized thiolate. On the other hand, O2 activation by Fe(ii)-SR complexes with thiolate bound cis to the O2 binding site generates FeIII-O-FeIII or S-oxygenated complexes. The postulated FeIV[double bond, length as m-dash]O intermediate has only been identified in isopenicillin N synthase recently. We demonstrated here that O2 activation by a dinuclear FeII thiolate-rich complex produces a mononuclear FeIII complex and water with a supply of electron donors. The thiolate is bound cis to the postulated dioxygen binding site, and no FeIII-O-FeIII or S-oxygenated complex was observed. Although we have not detected the transient intermediate by spectroscopic measurements, the FeIV[double bond, length as m-dash]O intermediate is suggested to exist by theoretical calculation, and P-oxidation and hydride-transfer experiments. In addition, an unprecedented FeIII-O2-FeIII complex supported by thiolates was observed during the reaction by using a coldspray ionization time-of-flight mass (CSI-TOF MS) instrument. This is also supported by low-temperature UV-vis measurements. The intramolecular NHO[double bond, length as m-dash]FeIV hydrogen bonding, calculated by DFT, probably fine tunes the O2-activation process for intramolecular hydrogen abstraction, avoiding the S-oxygenation at cis-thiolate.

Molecular mechanisms underlying the repair of nitrosylated [Fe-S] clusters by the microbial protein YtfE remain poorly understood. The X-ray crystal structure of YtfE, in combination with EPR, magnetic circular dichroism (MCD), UV, and (17) O-labeling electron spin echo envelope modulation measurements, show that each iron of the oxo-bridged Fe(II) -Fe(III) diiron core is coordinatively unsaturated with each iron bound to two bridging carboxylates and two terminal histidines in addition to an oxo-bridge. Structural analysis reveals that there are two solvent-accessible tunnels, both of which converge to the diiron center and are critical for capturing substrates. The reactivity of the reduced-form Fe(II) -Fe(II) YtfE toward nitric oxide demonstrates that the prerequisite for N2 O production requires the two iron sites to be nitrosylated simultaneously. Specifically, the nitrosylation of the two iron sites prior to their reductive coupling to produce N2 O is cooperative. This result suggests that, in addition to any repair of iron centers (RIC) activity, YtfE acts as an NO-trapping scavenger to promote the NO to N2 O transformation under low NO flux, which precedes nitrosative stress.

This paper proposes a complementary metal–oxide–semiconductor (CMOS) digitized gas transducer with noise shaping for CO2 concentration monitoring applications. The proposed chip is attractive, because, when combined with various CO2 sensors, it can monitor the present CO2 concentration and then quickly communicate with controllers or computers. The output format of the proposed chip is a type of pulse stream. It can easily be sent over a wide range of transmission media, such as package switch networks, radio, optical, infrared, and ultrasonic. Unlike previous works, the proposed chip is suitable for processing at a wide range of CO2 concentrations, and enables noise shaping of intrinsic sensor noise for CO2 concentration monitoring applications. On the basis of device parameters of 0.35- $\mu \text{m}$ 2P4M CMOS technology with a 3 V power supply, the functions and performance of the proposed digitized gas transducer were successfully tested, measured, and confirmed to be applicable to office meeting rooms. The measured range of CO2 concentration was 382–989 ppm, and its corresponding measured signal-to-noise-distortion ratio was 83.3–65.1 dB. The chip area is 1.18 mm $\times $ 2.48 mm. The proposed chip is suitable for CO2 concentration monitoring devices, such as wireless sensor network devices.

The reaction of Ni(ClO4)2 with 4 equiv of pyrazole (pzH) in MeCN leads to [Ni(pzH)2(HN═C(Me)pz)2](ClO4)2 via the intermediate [Ni(MeCN)2(pzH)4](ClO4)2, which is the first pyrazole−nitrile coupling reaction activated by a Ni(II) complex. The reaction is also successfully conducted with other nitriles RCN bearing an electron-donating group (R = Et, Bz) and is counteranion-specific. The reaction proceeds more quickly with NO3− as counteranion than with ClO4−, and BF4− is found to be unsatisfactory for the coupling reaction. As for the X-ray crystal structures, [Ni(MeCN)2(pzH)4](ClO4)2 possesses stronger pyrazolyl NH···anion hydrogen-bonding interactions than does [Ni(MeCN)2(pzH)4](BF4)2. The same trend is also observed by solution IR (pyrazolyl NH) analysis. The supramolecular structure of the complex [Ni(pzH)2(HN═C(Me)pz)2](ClO4)2 displays a two-dimensional network dominated by cooperative face-to-face π−π stacking and edge-to-face CH···π bonding interactions. In addition, a mechanism based on anion-mediate...

Two neutral group 12 metal complexes, bis(pyrrol-2-ylmethyleneaminoethylthio)zinc(II) (1) and bis(pyrrol-2-ylmethyleneaminoethylthio)mercury(II) (2), with the (Nimine)2S2 coordination mode were synthesized by using metal-templated Schiff base condensation, and their molecular structures were determined by X-ray diffraction analysis. Complex 1 exhibits a distorted tetrahedral geometry around the metal, whereas the metal center has a bisphenoidal configuration in complex 2. Both mononuclear complexes possess intramolecular NH⋯S hydrogen bonds, as evidenced by IR, 1H NMR and X-ray crystallography. The hydrogen-bond donor (H–Npyrrole) and acceptor (S atom) are coming from different ligands within a single molecule. Complex 2 represents the first example of a mercury complex in the N2S2 coordination mode with intramolecular NH⋯S hydrogen-bond interactions. An investigation of the effects of the NH⋯S hydrogen bonding on the stability of 1 and 2, using an N-methyl pyrrolyl analogue, demonstrated that the N–H hydrogen-bond donor from the pyrrolyl moiety probably played a role in the stability of 1, but not 2.

Two aminopyrroles, 2-(t-butylaminomethyl)pyrrole (HL1) and 2,5-di(t-butylaminomethyl)pyrrole (HL2), were synthesized and the hydrogen-bond interactions were observed in the single-crystal X-ray structures of HL1·HCl and HL2. Bis[2-(t-butylaminomethyl)pyrrole]nickel(II) [Ni(L1) 2 ] was prepared by treatment of the NiCl 2 with 2 equiv. of mono-deprotonated HL1 in THF solvent. The solid-state structure of Ni(L1) 2 shows the N 4 -coordinated nickel atom, with a geometry corresponding to a square-planar structure, in which two intramolecular C-H···Ni interactions are present at the axial positions with contact distances of 2.77 A. The complex displays an irreversible reduction response at -0.66 V (vs. Fc + /Fc) in CH 3 CN. Furthermore, 1 H, 13 C-HSQC NMR experiments performed at room temperature revealed that the two methylene protons of the chelating L1 -1 are chemically nonequivalent and one of them is coupled to the amino proton. The coupling constants (J HH' ) observed are close to the values predicted from the vicinal Karplus correlation diagram.

A unique trithiol macromolecule, with an intrinsic conformational propensity for dimerization (cage) instead of oligomerization upon oxidation, was prepared straightforwardly through rational design. The quantitative conversion and the reversibility between the cage and trithiols through redox reactions were assayed by 1H NMR spectroscopic analysis. The X-ray structure of the synthesized cage-type molecule represents the first successful example of a redox-controlled reversible dimeric capsule linked through covalent disulfide bonds. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

Nitrosylation of the chelate-thiolate-containing dinitrosyliron complex (DNIC) [(S(CH(2))(3)S)Fe(NO)(2)](-) triggers nitric oxide (NO) activation to generate the homoleptic nitrosyl {Fe(NO)(2)}(9) DNIC [Fe(NO)(4)](-) (1) made up of two nitroxyls (or two NO anions) attached to a delocalized {Fe(NO)(2)}(9) motif. The significantly longer N3-O3/N4-O4 [1.380(12) and 1.280(12) Å] and Fe1-N3/Fe1-N4 [2.008(11) and 2.045(10) Ǻ] bond distances reflect that N3-O3 and N4-O4 of complex 1 may act as the nitroxyl-coordinated ligands. That is, the electronic structure of the DNIC 1 is best described as a {Fe(NO)(2)}(9) motif coordinated by two nitroxyl (NO(-)) ligands.

A simple organic molecular container can selectively encapsulate the volatile and highly reactive MeI through hydrogen-bonding interactions in solution. The remarkable encapsulation of MeI without self-methylation of the container appears to be determined by the complementary binding sites and the rigidity of the hydrogen-bonding array constrained by the molecular framework.

In the title compound, C14H13NOS2, the S atom with the methyl group is involved in an intramolecular hydrogen bond with the amido H atom. In the crystal, the sulfanyl H atoms form intermolecular hydrogen bonds with the O atoms, connecting the molecules into zigzag chains along thecaxis. The two aromatic rings exhibit a small interplanar angle of 16.03 (9)°.

The symmetrical title compound, C(20)H(20)N(6)S(2), contains a disulfide bond of 2.0884 (6) Å. The C-S-S-C torsion angle is -59.57 (7)°. In the crystal, classical N-H⋯N and non-classical C-H⋯N hydrogen bonds link the compounds into chains along the a axis.

A simple shape-persistent organic molecular container is capable of selective absorption and storage of I(2(g)) over water vapor and NO gas even in its amorphous solid state. In addition, the strongly associated I(2) can be efficiently released from the charged container in organic solvents under ambient conditions.

In the title complex, [Ni(CH(3)CN)(2)(C(3)H(4)N(2))(4)](NO(3))(2), the cation lies on an inversion center and adopts an octa-hedral coordination geometry about the Ni atom. The two acetonitrile ligands are in a trans conformation. N-H⋯O hydrogen bonds between cations and anions link the complex mol-ecules into one-dimensional chains running parallel to [100].