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Peter V Simpson, Ilaria Casari, Silvano Paternoster, Brian W Skelton, Marco Falasca, Massimiliano Massi
Rhenium and ruthenium complexes containing N-heterocylic carbene (NHC) ligands and conjugated to indomethacin were prepared. The anticancer properties were probed against pancreatic cell lines, revealing a remarkable activity of the rhenium fragment as anticancer agent. The ruthenium complexes were found to be inactive against the same pancreatic cancer cell lines, either alone or in conjugation with indomethacin. An in depth biological study revealed the origin of the anticancer properties of the rhenium tricarbonyl fragment, of which a complete elucidation had yet to be achieved...
March 23, 2017: Chemistry: a European Journal
Marta Roqué I Figuls, Maria José Martinez-Zapata, Martin Scott-Brown, Pablo Alonso-Coello
BACKGROUND: This is an update of the review published in Issue 4, 2003. Bone metastasis cause severe pain as well as pathological fractures, hypercalcaemia and spinal cord compression. Treatment strategies currently available to relieve pain from bone metastases include analgesia, radiotherapy, surgery, chemotherapy, hormone therapy, radioisotopes and bisphosphonates. OBJECTIVES: To determine efficacy and safety of radioisotopes in patients with bone metastases to improve metastatic pain, decrease number of complications due to bone metastases and improve patient survival...
March 23, 2017: Cochrane Database of Systematic Reviews
Mitchell Ashley Klenner, Giancarlo Pascali, Bo Zhang, Tiffany Russel Sia, Lawson Kyle Spare, Anwen M Krause-Heuer, Janice Aldrich-Wright, Ivan Greguric, Adam Guastella, Massimiliano Massi, Benjamin Hugh Fraser
Azeotropic distillation is typically required to achieve fluorine-18 radiolabelling during the production of positron emission tomography (PET) imaging agents. However, this time consuming process also limits fluorine-18 incorporation, due to radioactive decay of the isotope and its adsorption to the drying vessel. In addressing these limitations, we herein report the fluorine-18 radiolabelling of one model rhenium(I) complex, which is significantly improved under conditions that do not require azeotropic drying...
March 22, 2017: Chemistry: a European Journal
Allen M Lunsford, Kristina F Goldstein, Matthew A Cohan, Jason A Denny, Nattamai Bhuvanesh, Shengda Ding, Michael B Hall, Marcetta Y Darensbourg
The bipyridine ligand is renowned as a photo- and redox-active ligand in catalysis; the latter has been particularly explored in the complex Re(bipy)(CO)3Cl for CO2 reduction. We ask whether a bidentate, redox-active MN2S2 metallodithiolate ligand in heterobimetallic complexes of Mn and Re might similarly serve as a receptor and conduit of electrons. In order to assess the electrochemical features of such designed bimetallics, a series of complexes featuring redox active MN2S2 metallodithiolates, with M = Ni(2+), {Fe(NO)}(2+), and {Co(NO)}(2+), bound to M'(CO)3X, where M' = Mn and Re, were synthesized and characterized using IR and EPR spectroscopies, X-ray diffraction, cyclic voltammetry, and density functional theory (DFT) computations...
March 21, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
Damaris E Pérez, Jessica L Smeltz, Roger D Sommer, Paul D Boyle, Elon A Ison
A series of novel cationic Re(iii) complexes [(DAAm)Re(CO)(NCCH3)2][X] [DAAm = N,N-bis(2-arylaminoethyl)methylamine; aryl = C6F5 (a), Mes (b)] [X = OTf (2), BAr(F)4 [BAr(F)4 = tetrakis[3,5-(trifluoromethyl)phenyl]borate] (3), BF4 (4), PF6 (5)], and their analogue [(DAmA)Re(CO)(Cl)2] [DAmA = N,N-bis(2-arylamineethyl)methylamino; aryl = C6F5] (6) were synthesized. The catalytic efficiency for the hydrosilylation reaction of aldehydes using 4a (0.03 mol%) has been demonstrated to be significantly more active than rhenium catalysts previously reported in the literature...
March 21, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
Alexander Wilting, Thorsten Stolper, Ricardo A Mata, Inke Siewert
Herein, we present the reduction chemistry of a dinuclear α-diimine rhenium complex, 1, [Re2(L)(CO)6Cl2], with a proton responsive ligand and its application as a catalyst in the electrochemical CO2 reduction reaction (L = 4-tert-butyl-2,6-bis(6-(1H-imidazol-2-yl)-pyridin-2-yl)phenol). The complex has a phenol group in close proximity to the active center, which may act as a proton relay during catalysis, and pyridine-NH-imidazole units as α-diimine donors. The complex is an active catalyst for the electrochemical CO2 reduction reaction...
March 20, 2017: Inorganic Chemistry
Tara Mastren, Valery Radchenko, Hong T Bach, Ethan R Balkin, Eva R Birnbaum, Mark Brugh, Jonathan W Engle, Matthew D Gott, James Guthrie, Heather M Hennkens, Kevin D John, Alan R Ketring, Marina Kuchuk, Joel R Maassen, Cleo M Naranjo, F Meiring Nortier, Tim E Phelps, Silvia S Jurisson, D Scott Wilbur, Michael E Fassbender
INTRODUCTION: Rhenium-186g (t1/2 = 3.72 d) is a β(-) emitting isotope suitable for theranostic applications. Current production methods rely on reactor production by way of the reaction (185)Re(n,γ)(186g)Re, which results in low specific activities limiting its use for cancer therapy. Production via charged particle activation of enriched (186)W results in a (186g)Re product with a higher specific activity, allowing it to be used more broadly for targeted radiotherapy applications. This targets the unmet clinical need for more efficient radiotherapeutics...
March 3, 2017: Nuclear Medicine and Biology
Shigeyuki Takagi, Yuki Iijima, Toyoto Sato, Hiroyuki Saitoh, Kazutaka Ikeda, Toshiya Otomo, Kazutoshi Miwa, Tamio Ikeshoji, Shin-Ichi Orimo
Ninefold coordination of hydrogen is very rare, and has been observed in two different hydride complexes comprising rhenium and technetium. Herein, based on a theoretical/experimental approach, we present evidence for the formation of ninefold H- coordination hydride complexes of molybdenum ([MoH9](3-)), tungsten ([WH9](3-)), niobium ([NbH9](4-)) and tantalum ([TaH9](4-)) in novel complex transition-metal hydrides, Li5MoH11, Li5WH11, Li6NbH11 and Li6TaH11, respectively. All of the synthesized materials are insulated with band gaps of approximately 4 eV, but contain a sufficient amount of hydrogen to cause the H 1s-derived states to reach the Fermi level...
March 13, 2017: Scientific Reports
Mostafa Erfani, Nasim Rahmani, Alireza Doroudi, Mohammad Shafiei
OBJECTIVE: Rhenium-188-hydroxyethylidene diphosphonate ((188)Re-HEDP) as a first generation bisphosphonate has been widely used for bone seeking radiopharmaceutical in cases of metastatic bone disease. No study has been yet reported on preparing a complex of (188)Re with pamidronate (3-aminohydroxypropylidene-1,1-bisphosphonic acid) (PMA) as a second generation bisphosphonate. Based on this fact, it was hypothesized that a bone-seeking (188)Re-PMA radiopharmaceutical could be developed as an agent for palliative radiotherapy of bone pain due to skeletal metastases...
February 24, 2017: Nuclear Medicine and Biology
John K Nganga, Christian R Samanamu, Joseph M Tanski, Carlos Pacheco, Cesar Saucedo, Victor S Batista, Kyle A Grice, Mehmed Z Ertem, Alfredo M Angeles-Boza
A series of rhenium tricarbonyl complexes coordinated by asymmetric diimine ligands containing a pyridine moiety bound to an oxazoline ring were synthesized, structurally and electrochemically characterized, and screened for CO2 reduction ability. The reported complexes are of the type Re(N-N)(CO)3Cl, with N-N = 2-(pyridin-2-yl)-4,5-dihydrooxazole (1), 5-methyl-2-(pyridin-2-yl)-4,5-dihydrooxazole (2), and 5-phenyl-2-(pyridin-2-yl)-4,5-dihydrooxazole (3). The electrocatalytic reduction of CO2 by these complexes was observed in a variety of solvents and proceeds more quickly in acetonitrile than in dimethylformamide (DMF) and dimethyl sulfoxide (DMSO)...
March 9, 2017: Inorganic Chemistry
Xiaoxiao Qiao, Qiqi Li, Richard N Schaugaard, Benjamin W Noffke, Yijun Liu, Dongping Li, Lu Liu, Krishnan Raghavachari, Liang-Shi Li
Improving energy efficiency of electrocatalytic and photocatalytic CO2 conversion to useful chemicals poses a significant scientific challenge. We report on using a colloidal nanographene to form a molecular complex with a metal ion to tackle this challenge. In this work, a well-defined nanographene-Re complex was synthesized, in which electron delocalization over the nanographene and the metal ion significantly decreases the electrical potential needed to drive the chemical reduction. We show the complex can selectively electrocatalyze CO2 reduction to CO in tetrahydrofuran at -0...
March 8, 2017: Journal of the American Chemical Society
Patrick Piehl, Miguel Peña-López, Anna Frey, Helfried Neumann, Matthias Beller
A novel rhenium complex bearing a non-innocent PNP pincer ligand was prepared. This novel catalyst is active in hydrogen autotransfer reactions to form new C-C and C-N bonds. More specifically, valuable alkylations of ketones and sulfonamides with primary alcohols are herein presented. In addition, the first examples of rhenium-catalysed synthesis of pyrroles are described by dehydrogenative coupling of diols, amines and ketones.
March 18, 2017: Chemical Communications: Chem Comm
Zhi Li, Agustin E Pierri, Po-Ju Huang, Guang Wu, Alexei V Iretskii, Peter C Ford
We describe a new strategy for triggering the photochemical release of caged carbon monoxide (CO) in aerobic media using long-wavelength visible and near-infrared (NIR) light. The dinuclear rhenium-manganese carbonyl complexes (CO)5ReMn(CO)3(L), where L = phenanthroline (1), bipyridine (2), biquinoline (3), or phenanthrolinecarboxaldehyde (4), each show a strong metal-metal-bond-to-ligand (σMM → πL*) charge-transfer absorption band at longer wavelengths. Photolysis with deep-red (1 and 2) or NIR (3 and 4) light leads to homolytic cleavage of the Re-Mn bonds to give mononuclear metal radicals...
March 5, 2017: Inorganic Chemistry
Justin M Hoffman, Allen G Oliver, Seth N Brown
The rhenium(V) oxo complex oxo(triphenylphosphine) (bis(3,5-di-tert-butyl-2-phenoxo)amido)rhenium(V), (ONO(Cat))ReO(PPh3), reacts with molecular oxygen to give triphenylphosphine oxide and the dimeric rhenium(VII) complex fac,anti-(ONO(Cat))Re(O)(μ-O)2Re(O)(ONO(Cat)). The ONO ligand adopts an unusual fac geometry, presumably to maximize π donation to rhenium; strong π donation is substantiated by the intraligand bond distances (metrical oxidation state = -2.24(9)). Addition of the N-heterocyclic carbene ligand IMes to fac,anti-(ONO(Cat))Re(O)(μ-O)2Re(O)(ONO(Cat)) cleaves the dimer into monomeric C1-symmetric fac-(ONO(Cat))ReO2(IMes)...
March 16, 2017: Journal of the American Chemical Society
M S McDonald, A D Gallimore, D M Goebel
We present an improved heater design for thermionic cathodes using a rhenium filament encased in a boron nitride ceramic sleeve. This heater is relatively simple to fabricate, yet has been successfully used to reliably and repeatably light a lanthanum hexaboride (LaB6) hollow cathode based on a previously published design without noticeable filament degradation over hundreds of hours of operation. The high decomposition temperature of boron nitride (2800 C for inert environments) and melting point for rhenium (3180 C) make this heater especially attractive for use with LaB6, which may require operating temperatures upwards of 1700 C...
February 2017: Review of Scientific Instruments
Baptiste Laramée-Milette, Nelsi Zaccheroni, Francesco Palomba, Garry Shawn Hanan
A [n x 1] head-to-tail bonding strategy was used for the synthesis of Re(I) metallacycles. From the k3N-dicarbonyl precursor, a single discrete [4 x 1] square assembly was isolated and characterized while the k2N-tricarbonyl precursor led to two major species, a square and a [3 x 1] triangular assembly. A solid-state X-ray diffraction study confirmed the high angular distortion (71° to 96°) of the k2N precursors. The electrochemical reversibility of the triangular (5) and the squares (6, 7) assemblies is increased over that of their precursors...
February 27, 2017: Chemistry: a European Journal
Tatsuhiko Mukuta, Peter V Simpson, Jamila G Vaughan, Brian W Skelton, Stefano Stagni, Massimiliano Massi, Kazuhide Koike, Osamu Ishitani, Ken Onda
We carried out time-resolved infrared (TR-IR) and emission lifetime measurements on a Re(I) carbonyl complex having an N-heterocyclic carbene ligand, namely, fac-[Re(CO)3(PyImPh)Br], under photochemically reactive (in solution in acetonitrile) and nonreactive (in solution in dichloromethane) conditions to investigate the mechanism of photochemical ligand substitution reactions. The TR-IR measurements revealed that no reaction occurs on a picosecond time scale and the cationic product, namely, fac-[Re(CO)3(PyImPh)(MeCN)](+), is produced on a nanosecond time scale only in solution in acetonitrile, which indicates that the reaction proceeds thermally from the excited state...
February 27, 2017: Inorganic Chemistry
Esteban Rodríguez Arce, Ignacio Machado, Belén Rodríguez, Michel Lapier, María Carolina Zúñiga, Juan Diego Maya, Claudio Olea Azar, Lucía Otero, Dinorah Gambino
American Trypanosomiasis is a chronic infection discovered and described in 1909 by the Brazilian scientist Carlos Chagas. It is caused by the protozoan parasite Trypanosoma cruzi. Although it affects about 10million people in Latin America, the current chemotherapy is still inadequate. The discovery of new drugs is urgently needed. Our group is focused on the development of prospective metal-based drugs mainly based on bioactive ligands and pharmacologically interesting metal ions. In this work three new rhenium(I) tricarbonyl compounds fac-[Re(I)(CO)3Br(HL)] where HL=5-nitrofuryl containing thiosemicarbazones were synthesized and fully characterized in solution and in the solid state...
January 23, 2017: Journal of Inorganic Biochemistry
H Y Vincent Ching, Xia Wang, Menglan He, Noemi Perujo Holland, Régis Guillot, Cyrine Slim, Sophie Griveau, Hélène C Bertrand, Clotilde Policar, Fethi Bedioui, Marc Fontecave
A series of [Re(N^N)(CO)3(X)] (N^N = diimine and X = halide) complexes based on 4-(2-pyridyl)-1,2,3-triazole (pyta) and 1-(2-pyridyl)-1,2,3-triazole (tapy) diimine ligands have been prepared and electrochemically characterized. The first ligand-based reduction process is shown to be highly sensitive to the nature of the isomer as well as to the substituents on the pyridyl ring, with the peak potential changing by up to 700 mV. The abilities of this class of complexes to catalyze the electroreduction and photoreduction of CO2 were assessed for the first time...
February 21, 2017: Inorganic Chemistry
Maruthupandiyan Priyatharsini, Bhaskaran Shankar, Malaichamy Sathiyendiran, Navaneethakrishnan Srinivasan, Rajaputi Venkatraman Krishnakumar
The title dinuclear complex, [Re2(C13H8NOS)2(CO)6], crystallizes in two polymorphs where the 2-(1,3-benzo-thia-zol-2-yl)phenolate ligands and two carbonyl groups are trans- (I) or cis-arranged (II) with respect to the [Re2O2(CO)4] core. Polymorphs I and II exhibit a crystallographically imposed centre of symmetry and a twofold rotation axis, respectively. The structures may be described as being formed by two octa-hedrally distorted metal-coordinating units fused through μ-oxido bridges, leading to edge-sharing dimers...
February 1, 2017: Acta Crystallographica. Section E, Crystallographic Communications
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