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121.
122.
Dr. Richard D. Adams Dr. Vitaly Rassolov Yuen Onn Wong 《Angewandte Chemie (International ed. in English)》2014,53(41):11006-11009
The electronically unsaturated dirhenium complex [Re2(CO)8(µ‐AuPPh3)(µ‐Ph)] ( 1 ) was obtained from the reaction of [Re2(CO)8{µ‐η2‐C(H)?C(H)nBu}(µ‐H)] with [Au(PPh3)Ph]. The bridging {AuPPh3} group was replaced by a bridging hydrido ligand to yield the unsaturated dirhenium complex [Re2(CO)8(µ‐H)(µ‐Ph)] ( 2 ) by reaction of 1 with HSnPh3. Compound 2 reductively eliminates benzene upon addition of NCMe at 25 °C. The electronic structure of 2 and the mechanism of the reductive elimination of the benzene molecule in its reaction with NCMe were investigated by DFT computational analyses. 相似文献
123.
Structure–Activity Studies of Cysteine‐Rich α‐Conotoxins that Inhibit High‐Voltage‐Activated Calcium Channels via GABAB Receptor Activation Reveal a Minimal Functional Motif 下载免费PDF全文
Dr. Bodil B. Carstens Dr. Géza Berecki James T. Daniel Han Siean Lee Kathryn A. V. Jackson Dr. Han‐Shen Tae Dr. Mahsa Sadeghi Dr. Joel Castro Tracy O'Donnell Dr. Annemie Deiteren Prof. Stuart M. Brierley Prof. David J. Craik Prof. David J. Adams Dr. Richard J. Clark 《Angewandte Chemie (International ed. in English)》2016,55(15):4692-4696
α‐Conotoxins are disulfide‐rich peptides that target nicotinic acetylcholine receptors. Recently we identified several α‐conotoxins that also modulate voltage‐gated calcium channels by acting as G protein‐coupled GABAB receptor (GABABR) agonists. These α‐conotoxins are promising drug leads for the treatment of chronic pain. To elucidate the diversity of α‐conotoxins that act through this mechanism, we synthesized and characterized a set of peptides with homology to α‐conotoxins known to inhibit high voltage‐activated calcium channels via GABABR activation. Remarkably, all disulfide isomers of the active α‐conotoxins Pu1.2 and Pn1.2, and the previously studied Vc1.1 showed similar levels of biological activity. Structure determination by NMR spectroscopy helped us identify a simplified biologically active eight residue peptide motif containing a single disulfide bond that is an excellent lead molecule for developing a new generation of analgesic peptide drugs. 相似文献
124.
Paolo Ravarino Dr. Santanu Panja Simona Bianco Dr. Todor Koev Dr. Matthew Wallace Prof. Dave J. Adams 《Angewandte Chemie (International ed. in English)》2023,62(4):e202215813
We use a pH-driven annealing process to convert between co-assembled and self-sorted networks in multicomponent gels. The initially formed gels at low pH are co-assembled, with the two components coexisting within the same self-assembled structures. We use an enzymatic approach to increase the pH, resulting in a gel-to-sol transition, followed by a hydrolysis to lower the pH once again. As the pH decreases, a self-sorted network is formed by a two-stage gelation process determined by the pKa of each component. This approach can be expanded to layered systems to generate many varied systems by changing composition and rates of pH change, adapting their microstructure and so allowing access to a far greater range of morphologies and complexity than can be achieved in single component systems. 相似文献
125.
Chris J. Adams Michael I. Bruce Brian W. Skelton Allan H. White 《Journal of Cluster Science》1994,5(3):419-441
The reactions between Ru5(
5-C2PPh2)(gm-PPh2(CO)13 (1) and cyclopentadienes afforded the hexanuclear clusters Ru6(
6-C)(
3-PPh2)2(CO)10(-C5
R
5) [R
5 = H5 (2), H4Me (3), Me5 (4)] which contain an encapsulated carbide and a face-capping
3-CH group, formed by cleavage of CC and CP bonds of the C2PPh2 moiety in1. In the reaction with cyclopentadiene, the unusual ligand C13H12O, formed by combination of C2, CO and two molecules of C5H6 (or one molecule of dicyclopentadien), was characterized in the complex Ru5(
4-PPh) (
4-C13H12O)(-PPh2(CO)11(-C5H5) (5). In the reaction with pentamethylcyclopentadiene, the vinylidene complex Ru5(
3-CCHPh)(
4-PPh)(
4-PPh) (-PPh2)(CO)9(-C5Me5) (6) was also formed. 相似文献
126.
Delmulle B De Saeger S Adams A De Kimpe N Van Peteghem C 《Rapid communications in mass spectrometry : RCM》2006,20(5):771-776
The development of a liquid chromatography/tandem mass spectrometry (LC/MS/MS) method for the simultaneous determination of 16 mycotoxins possibly related to the 'Sick Building Syndrome' on filters and in fungal cultures is described. Fungi-surface sampling as regards the 'Sick Building Syndrome' preferably happens by scraping off fungal material and vacuuming onto cellulose filters. Therefore, these two media were used as samples. They were spiked with nivalenol, deoxynivalenol, zearalenone, diacetoxyscirpenol, T-2 toxin, verrucarol, verrucarin A, neosolaniol, sterigmatocystin, roridin A, ochratoxin A, aflatoxin B1, aflatoxin B2, aflatoxin G1 and aflatoxin G2, which can be produced by isolates from fungi-damaged buildings. Deepoxy-deoxynivalenol was used as internal standard. Samples were extracted with organic solvents and the different mycotoxins were separated by high-performance liquid chromatography (HPLC) using a C18 reversed-phase SunFire analytical column and a mobile phase of variable mixtures of ammonium acetate (10 mM) and sodium acetate (20 microM) in water (solvent A) and in methanol (solvent B). The samples were run on-line with a Micromass Quattro Micro triple quadrupole mass spectrometer in positive electrospray ionisation mode using multiple reaction monitoring (MRM). The detection limits of the procedure varied from 50 to 0.009 pg/microL for filter samples and from 75 to 0.04 pg/microL for fungal culture samples. As the method includes few and non-labourious sample treatment steps, it should allow for a high throughput of samples. 相似文献
127.
López-Torres M Fernández A Fernández JJ Suárez A Pereira MT Ortigueira JM Vila JM Adams H 《Inorganic chemistry》2001,40(18):4583-4587
Reaction of cyclometalated halide-bridged Pd(II) complexes 1-4 with the tertiary triphosphine ligand (Ph2PCH2CH2)2PPh (triphos) yielded complexes [((Ph2PCH2CH2)2PPh-P,P,P)Pd(N(Cy)=(H)C)C6H2(C(H)=N(Cy))Pd((Ph2PCH2CH2)2PPh-P,P,P)][ClO4]2 5, [Pd(C6H4-N=NC6H5)((Ph2PCH2CH2)2PPh-P,P,P)][ClO4] 6, and [Pd(R-C6H3C(H)=NCy)((Ph2PCH2CH2)2PPh-P,P,P)][ClO4] (7; R = 4-CHO, 8; 3-CHO). Spectroscopic and analytic data suggest five-coordination on the palladium atom, which, for complexes 5, 6, and 7, was confirmed by X-ray crystallography. The geometry around palladium may be view as a distorted trigonal bipyramid, with the palladium, nitrogen, and terminal phosphorus atoms in the equatorial plane. Compound 5 is the first doubly cyclometalated palladium(II) compound with two pentacoordinated metal centers. The structure of 6 comprises two discrete cations with slightly different geometries, showing the importance of crystal packing forces in order to determine the coordination arrangement. 相似文献
128.
Ronson TK Adams H Harding LP Pope SJ Sykes D Faulkner S Ward MD 《Dalton transactions (Cambridge, England : 2003)》2007,(10):1006-1022
A set of three potentially bridging ligands containing two tridentate chelating N,N',O-donor (pyrazole-pyridine-amide) donors separated by an o, m, or p-phenylene spacer has been prepared and their coordination chemistry with lanthanide(III) ions investigated. Ligand L(1) (p-phenylene spacer) forms complexes with a 2:3 M:L ratio according to the proportions used in the reaction mixture; the Ln(2)(L(1))(3) complexes contain two 9-coordinate Ln(III) centres with all three bridging ligands spanning both metal ions, and have a cylindrical (non-helical) 'mesocate' architecture. The 1:1 complexes display a range of structural types depending on the conditions used, including a cyclic Ln(4)(L(1))(4) tetranuclear helicate, a Ln(2)(L(1))(2) dinuclear mesocate, and an infinite one-dimensional coordination polymer in which metal ions and bridging ligands alternate along the sequence. ESMS studies indicate that the 1:1 complexes form a mixture of oligonuclear species {Ln(L(1))}(n) in solution (n up to 5) which are likely to be cyclic helicates. In contrast, ligands L(2) and L(3) (with o- and m-phenylene spacers, respectively) generally form dinuclear Ln(2)L(2) Ln(III) complexes in which the two ligands may be arranged in a helical or non-helical architecture about the two metal ions. These complexes also contain an additional exogenous bidentate bridging ligand, either acetate or formate, which has arisen from hydrolysis of solvent molecules promoted by the Lewis-acidity of the Ln(III) ions. Luminescence studies on some of the Nd(III) complexes showed that excitation into ligand-centred pi-pi* transitions result in the characteristic near-infrared luminescence from Nd(III) at 1060 nm. 相似文献
129.
Adams CJ Connelly NG Onganusorn S 《Dalton transactions (Cambridge, England : 2003)》2007,(19):1904-1910
Two series of stable cyanide-bridged linkage isomers, namely [(o-O2C6Cl4)(Ph3P)(OC)2Ru(mu-XY)MnL(NO)(eta-C5Me5)] (XY = CN or NC, L = CNBu(t) or CNXyl) and [(o-O2C6Cl4)L(OC)2Ru(mu-XY)M(CO)(PhC-CPh)Tp'] {M = Mo or W, L = PPh3 or P(OPh)3, Tp' = hydrotris(3,5-dimethylpyrazolyl)borate} have been synthesised; pairs of isomers are distinguishable by IR spectroscopy and cyclic voltammetry. The molecular structure of [(o-O2C6Cl4)(Ph3P)(OC)2Ru(mu-NC)Mo(CO)(PhC-CPh)Tp'] has the catecholate-bound ruthenium atom cyanide-bridged to a Mo(CO)(PhC[triple band]CPh)Tp' unit in which the alkyne acts as a four-electron donor; the alignment of the alkyne relative to the Mo-CO vector suggests the fragment (CN)Ru(CO)2(PPh3)(o-O2C6Cl4) acts as a pi-acceptor ligand. The complexes [(o-O2C6Cl4)(Ph3P)(OC)2Ru(mu-XY)Mn(NO)L(eta-C5Me5)] undergo three sequential one-electron oxidation processes with the first and third assigned to oxidation of the ruthenium-bound o-O2C6Cl4 ligand; the second corresponds to oxidation of Mn(I) to Mn(n). The complexes [(o-O2C6Cl4)L(OC)2Ru(mu-XY)M(CO)(PhC[triple band]CPh)Tp'] are also first oxidised at the catecholate ligand; the second oxidation, and one-electron reduction, are based on the M(CO)(PhC[triple band]CPh)Tp' fragment. Chemical oxidation of [(o-O,C6Cl4)(Ph3P)(OC)2Ru(mu-XY)MnL(NO)(eta-C5Me5)] with [Fe(eta-C5H4COMe)(eta-C5H5)][BF4], or of [(o-O2C6Cl4)L(OC)2Ru(mu-XY)M(CO)(PhC[triple band]CPh)Tp'] with AgBF4, gave the paramagnetic monocations [(o-O2C6Cl4)(Ph3P)(OC)2Ru(mu-XY)MnL(NO)(eta-C5Me5)]+ and [(o-O2C6Cl4)L(OC)2Ru(mu-XY)M(CO)(PhC[triple band]CPh)Tp']+, the ESR spectra of which are consistent with ruthenium-bound semiquinone ligands. Linkage isomers are distinguishable by the magnitude of the 31P hyperfine coupling constant; complexes with N-bound Ru(o-O2C6Cl4) units also show small hyperfine coupling to the nitrogen atom of the cyanide bridge. 相似文献
130.
Amarante D Cherian C Catapano A Adams R Wang MH Megehee EG 《Inorganic chemistry》2005,44(24):8804-8809
Five new mixed diimine 1,1'-dithiolate or dithiocarbamate ligand complexes of the form [Rh(bpy)2(SS)][PF6]n, where bpy = 2,2'-bipyridine and SS = various substituted dialkyldithiocarbamates or 1,1'-dithiolates, were synthesized from cis-[Rh(bpy)2(OTf)2][OTf]. The triflate ligands are easily displaced by other ligands and allow these syntheses to proceed in high yields (80-90% overall) under relatively mild reaction conditions and to give high purity products. Electrochemistry shows irreversible two-electron reduction of Rh(III) to Rh(I) and a concomitant loss of one bipyridine ligand; this is followed by reversible one-electron reduction of the remaining 2,2'-bipyridine ligand. The electronic characterizations of these complexes are consistent with significant delocalization of the sulfur electron density onto the empty metal d orbitals. The 1,1'-dithiolate ligands induce larger red shifts in the absorption and emission spectra than the dithiocarbamates as the 1,1'-dithiolates have a more extensive conjugation system. 相似文献