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Igor O Koshevoy, Kristina S Kisel, Alexei S Melnikov, Elena V Grachova, Pipsa Hirva, Sergey P Tunik
The bifunctional aminopyridine ligands H2N-(CH2)n-4-C5H4N (n = 0, L1; 1, L2; 2, L3) have been utilized for the preparation of rhenium complexes [Re(phen)(CO)3(L1-L3)]+ (1-3). 2 and 3 with NH2-coordinated L2/L3 were coupled with cycloplatinated motifs {Pt(ppy)Cl} and {Pt(dpyb)}+ to give the bimetallic species [Re(phen)(CO)3(μ-L2/L3)Pt(ppy)Cl]+ (4, 6) and [Re(phen)(CO)3(μ-L2/L3)Pt(dpyb)]2+ (5, 7). In solution, complexes 4 and 6 show 3MLCT {Re}-based emission at 298 K, which changes the parentage to 3IL(ppy) state at 77 K...
June 21, 2017: Chemistry: a European Journal
Karina P Morelli Frin, Rafael M de Almeida
Mono-nuclear fac-[Re(CO)3(ph2phen)(4,4'-bpy)](+) and di-nuclear [(ph2phen)(CO)3Re(4,4'-bpy)Re(ph2phen)(CO)3](2+) complexes, ph2phen = 4,7-diphenyl-1,10-phenanthroline and 4,4'-bpy = 4,4'-bipyridine, were synthesized and characterized by (1)H NMR, UV-visible and FT-IR spectroscopy. Also, their photophysical properties were investigated using steady-state and time-resolved emission spectroscopy. Both complexes showed UV absorption assigned to intraligand, (1)ILph2phen, and metal-to-ligand charge transfer, (1)MLCTRe→ph2phen, transitions, and typical (3)MLCTRe→ph2phen emission (ϕ = 0...
June 14, 2017: Photochemical & Photobiological Sciences
Masayuki Naruto, Santosh Agrawal, Katsuaki Toda, Susumu Saito
Carboxylic acids (CAs) are one of the most ubiquitous and important chemical feedstocks available from biorenewable resources, CO2, and the petrochemical industry. Unfortunately, chemoselective catalytic transformations of CH n CO2H (n = 1-3) groups into other functionalities remain a significant challenge. Herein, we report rhenium(V) complexes as extremely effective precatalysts for this purpose. Compared to previously reported heterogeneous and homogeneous catalysts derived from high- or low-valent metals, the present method involves a α-C-H bond functionalization, a hydrogenation, and a hydrogenolysis, which affords functionalized alcohols with a wide substrate scope and high chemoselectivity under relatively mild reaction conditions...
June 13, 2017: Scientific Reports
Lucas Prieto, Jeremie Rossier, Katarzyna Derszniak, Jakub Dybas, René M Oetterli, Emmanuel Kottelat, Stefan Chlopicki, Felix Zelder, Fabio Zobi
This communication describes the anti-platelet effects of a new class of cis-rhenium(ii)-dicarbonyl-vitamin B12 complexes (B12-ReCORMs) with tuneable CO releasing properties.
June 22, 2017: Chemical Communications: Chem Comm
Gisela D Hess, Tobias Fiedler, Frank Hampel, John A Gladysz
Reactions of Re(CO)5(X) (X = Cl, Br) or [Re2(CO)4(NO)2(μ-Cl)2(Cl)2] and the phosphines P((CH2)mCH═CH2)3 (m = 6, a; 7, b; 8, c) give mer,trans-Re(CO)3(X)(P((CH2)mCH═CH2)3)2 (53-95%) or cis,trans-Re(CO) (NO) (Cl)2(P((CH2)6CH═CH2)3)2 (57%), respectively. Additions of Grubbs' catalyst (5-10 mol %, 0.0010-0.0012 M) and subsequent hydrogenations (PtO2, ≤5 bar) yield the gyroscope-like complexes mer,trans-R e(CO)3(X)(P((CH2)n)3 P) (n = 2m + 2; X = Cl, 7a,c; Br, 8a,c; 18-61%) or cis,trans-R e(CO)(NO)(Cl)2(P((CH2)14)3 P) (14%), respectively, and/or the isomers mer,trans-R e(CO)3(X)( P(CH2)n-1 CH2)((CH2)n)( P(CH2)n-1 CH2) (X = Cl, 7'a-c; Br, 8'b; 6-27%)...
June 9, 2017: Inorganic Chemistry
Rebeca Arévalo, Christopher M Vogels, Gregory A MacNeil, Lucía Riera, Julio Pérez, Stephen A Westcott
The first examples for the rhenium-catalysed hydroboration of aldehydes, ketones and aldimines, including heteroaromatic quinoline, are reported herein. Reactions are remarkably chemoselective and tolerant of several functional groups. A wide array of rhenium complexes were efficient pre-catalysts for these hydroborations, including new low-valent complexes of the formula [Re(N-N)(CO)3(L)]X (N-N = bipy derivative, L = labile ligand/solvent, and X = [BAr(F)4](-) and [B(3,5-di-tBu-cat)2](-)), which have been characterized fully including an X-ray diffraction study for [Re(bipy)(CO)3(quin)][BAr(F)4] (2)...
June 7, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
Xiaolin Chen, Chuangang Ning
It was believed that the rhenium anion Re(-) was not stable, just like Mn(-). We report the observation of Re(-) in the laser ablation ion source and the further confirmation via the high-resolution photoelectron spectra of Re(-). The ground state of Re(-) ions is 5d(6)6s(2 5)D4. The electron affinity of rhenium is determined to be 487.13(51) cm(-1) or 60.396(63) meV.
June 15, 2017: Journal of Physical Chemistry Letters
Jan Philip Kraack, Angelo Frei, Roger Alberto, Peter Hamm
We investigate the ultrafast vibrational dynamics of monolayers from adsorbed rhenium-carbonyl CO2-reduction catalysts on a semiconductor surface (indium-tin-oxide (ITO)) with ultrafast two-dimensional attenuated total reflection infrared (2D ATR IR) spectroscopy. The complexes are partially equipped with isotope-labeled ((13)C) carbonyl ligands to generate two spectroscopically distinguishable forms of the molecules. Ultrafast vibrational energy transfer between the molecules is observed via the temporal evolution of cross-peaks between their symmetric carbonyl stretching vibrations...
May 22, 2017: Journal of Physical Chemistry Letters
Alice Brink, John R Helliwell
Multiple possibilities for the coordination of fac-[Re(CO)3(H2O)3](+) to a protein have been determined and include binding to Asp, Glu, Arg and His amino-acid residues as well as to the C-terminal carboxylate in the vicinity of Leu and Pro. The large number of rhenium metal complex binding sites that have been identified on specific residues thereby allow increased target identification for the design of future radiopharmaceuticals. The core experimental concept involved the use of state-of-art tuneable synchrotron radiation at the Diamond Light Source to optimize the rhenium anomalous dispersion signal to a large value (f'' of 12...
May 1, 2017: IUCrJ
Joanna Skiba, Tytus Bernaś, Damian Trzybiński, Krzysztof Woźniak, Giarita Ferraro, Daniela Marasco, Antonello Merlino, Marsel Z Shafikov, Rafał Czerwieniec, Konrad Kowalski
Two new neutral fac-[Re(CO)₃(phen)L] compounds (1,2), with phen = 1,10-phenanthroline and L = O₂C(CH₂)₅CH₃ or O₂C(CH₂)₄C≡CH, were synthetized in one-pot procedures from fac-[Re(CO)₃(phen)Cl] and the corresponding carboxylic acids, and were fully characterized by IR and UV-Vis absorption spectroscopy, ¹H- and (13)C-NMR, mass spectrometry and X-ray crystallography. The compounds, which display orange luminescence, were used as probes for living cancer HeLa cell staining. Confocal microscopy revealed accumulation of both dyes in mitochondria...
May 15, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
Swagat Sahu, Po Ling Cheung, Charles W Machan, Steven A Chabolla, Clifford P Kubiak, Nathan C Gianneschi
A series of polymeric frameworks with functional assemblies were designed to alter the catalytic activity of covalently bound Re(I) electrocatalysts. Norbornenyl polymers containing positively charged quaternary ammonium salts, neutral phenyl, or negatively charged trifluoroborate groups were end-labelled with a Re(I) fac-tricarbonyl bipyridine electrocatalyst via cross metathesis. Electrochemical studies in acetonitrile under an inert atmosphere and with saturated CO2 indicate that the quaternary ammonium polymers exhibit a significantly lower potential for CO2 reduction to CO (ca...
May 3, 2017: Chemistry: a European Journal
Indranil Chakraborty, Jorge Jimenez, P K Mascharak
A photo-active luminescent rhenium carbonyl complex namely, [Re(CO)3(phen)(pyAl)](CF3SO3) was grafted on a biocompatible carboxymethyl chitosan (CMC) matrix through Schiff base condensation reaction. The light-induced CO delivery from ReCMC has been shown to eradicate human colorectal adenocarcinoma cells (HT-29) very efficiently in a dose-dependent fashion. The onset of CO-induced apoptosis was realized by caspase-3,-7 detection aided by fluorescence confocal microscopy. ReCMC represents a unique example of a biocompatible and biodegradable antineoplastic agent that could find its use in cancer photopharmacology...
May 3, 2017: Chemical Communications: Chem Comm
Jana Rohacova, Osamu Ishitani
We developed new cyclic Re(i)-based trinuclear redox photosensitizers with both high oxidation power in the excited state and strong reduction power in the reduced form. These excellent properties were achieved by introducing electron-donating groups on the diimine ligand of the Re(i) metal centre and by connecting each Re(i) unit with polyphenyl-bisphosphine bridging ligands. These Re-rings were applied to homogenous visible light-driven photocatalytic CO2 reduction in conjunction with various mononuclear catalysts, such as Re(i), Ru(ii) and Mn(i) metal complexes, employing a relatively weak sacrificial electron donor, triethanolamine...
November 1, 2016: Chemical Science
Jing-Kai Qin, Wen-Zhu Shao, Cheng-Yan Xu, Yang Li, Dan-Dan Ren, Xiao-Guo Song, Liang Zhen
Substitutional doping of transition metal dichalcogenide two-dimensional materials has proven to be effective in tuning their intrinsic properties, such as band gap, transport characteristics, and magnetism. In this study, we realized substitutional doping of monolayer rhenium disulfide (ReS2) with Mo via chemical vapor deposition. Scanning transmission electron microscopy demonstrated that Mo atoms are successfully doped into ReS2 by substitutionally replacing Re atoms in the lattice. Electrical measurements revealed the degenerate p-type semiconductor behavior of Mo-doped ReS2 field effect transistors, in agreement with density functional theory calculations...
May 1, 2017: ACS Applied Materials & Interfaces
Marharyta I Kharlova, Kseniia O Piletska, Kostiantyn V Domasevitch, Alexander V Shtemenko
In the title compound, [ReBr(C16H16N4O3)(CO)3]·CH3OH, the Re(I) atom adopts a distorted octa-hedral coordination sphere with a facial arrangement of the three carbonyl ligands. Two N atoms of the chelating 5-(3,4,5-tri-meth-oxy-phen-yl)-3-(pyridin-2-yl)-1H-1,2,4-triazole ligand and two carbonyl ligands define the equatorial plane of the complex, with the third carbonyl ligand and the bromide ligand in axial positions. Conventional hydrogen bonds including the methanol solvent mol-ecules assemble the complex mol-ecules through mutual N-H⋯O-H⋯Br links [N⋯O = 2...
April 1, 2017: Acta Crystallographica. Section E, Crystallographic Communications
Lisa Suntrup, Sinja Klenk, Johannes Klein, Sebastian Sobottka, Biprajit Sarkar
Bidentate ligands containing at least one triazole or triazolylidene (mesoionic carbene, MIC) unit are extremely popular in contemporary chemistry. One reason for their popularity is the similarities as well as differences in the donor/acceptor properties that these ligands display in comparison to their pyridine or other N-heterocyclic carbene counterparts. We present here seven rhenium(I) carbonyl complexes where the bidentate ligands contain combinations of pyridine/triazole/triazolylidene. These are the first examples of rhenium(I) complexes with bidentate 1,2,3-triazol-5-ylidene-containing ligands...
April 21, 2017: Inorganic Chemistry
Qaisar Nadeem, Yunjun Shen, Muhammad Farooq Warsi, Gulfam Nasar, Muhammad Abdul Qadir, Roger Alberto
The present study reports the syntheses of half-sandwich complexes of the type [M(η(5) -C5 H4 CONH-R)(CO)3 ] (M = Re,(99m) Tc;R = cyclic RGD peptide (cRGDyK) for potential imaging of αv β3 integrin expression. The (99m) Tc complex was prepared directly from the reaction of [(99m) Tc(OH2 )3 (CO)3 ](+) with cRGDyK, doubly conjugated to Thiele's acid [(C5 H5 COOH)2 ] in water. This approach extends the viability of metal-mediated retro Diels-Alder reactions for the preparation of small molecules such as linear tripeptides to a more complex cyclic peptide carrying a [(η(5) -C5 H4 )(99m) Tc(CO)3 ] tag...
April 21, 2017: Journal of Labelled Compounds & Radiopharmaceuticals
Allan R Petersen, Peter Fristrup
The deoxydehydration (DODH) reaction remains one of the most efficient methods of reducing the oxygen content of biomass while keeping important functionality in place. This reaction is traditionally catalysed by high-valent oxorhenium species. Recent research into heterogeneous rhenium-based catalysts for DODH demonstrates their ability to rival and in some cases surpass their homogeneous counterparts. Furthermore, catalysts based on the metals molybdenum and vanadium show great potential as inexpensive alternatives to rhenium catalysts...
April 17, 2017: Chemistry: a European Journal
Joyce M van Dodewaard-de Jong, John M H de Klerk, Haiko J Bloemendal, Daniela E Oprea-Lager, Otto S Hoekstra, H Pieter van den Berg, Maartje Los, Aart Beeker, Marianne A Jonker, Joe M O'Sullivan, Henk M W Verheul, Alfons J M van den Eertwegh
BACKGROUND: Rhenium-188-HEDP is a beta-emitting radiopharmaceutical used for palliation of metastatic bone pain. We investigated whether the addition of rhenium-188-HEDP to docetaxel/prednisone improved efficacy of chemotherapy in patients with CRPC. METHODS: Patients with progressive CRPC and osteoblastic bone metastases were randomised for first-line docetaxel 75 mg/m(2) 3-weekly plus prednisone with or without 2 injections of rhenium-188-HEDP after the third (40 MBq/kg) and after the sixth (20 MBq/kg) cycle of docetaxel...
April 18, 2017: European Journal of Nuclear Medicine and Molecular Imaging
Zhongkai Zhang, Bian Tian, Qiuyue Yu, Peng Shi, Qijing Lin, Na Zhao, Weixuan Jing, Zhuangde Jiang
A thermal stress range analysis of tungsten-rhenium thin film thermocouples based on ceramic substrates is presented to analyze the falling off and breakage problems caused by the mismatch of the thermal stresses in thin film thermocouples (TFTCs) and substrate, and nano-indentation experiments are done to measure and calculate the film stress to compare with the simulation results. Optimal design and fabrication of tungsten-rhenium TFTCs based on ceramic substrates is reported. Static high temperature tests are carried out, which show the optimization design can effectively reduce the damage caused by the thermal stress mismatch...
April 14, 2017: Sensors
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