4,449 research outputs found
High-uniformity TiN/Ti/TiN multilayers for the development of Microwave Kinetic Inductance Detectors
No full textMicrowave Kinetic Inductance Detectors (MKIDs) are a class of superconducting cryogenic detectors that simultaneously exhibit energy resolution, time resolution and spatial resolution. The pixel yield of MKID arrays is usually a critical figure of merit in the characterisation of an MKIDs array. Currently, for MKIDs intended for the detection of optical and near-infrared photons, only the best arrays exhibit a pixel yield as high as 75-80%. The uniformity of the superconducting film used for the fabrication of MKIDs arrays is often regarded as the main limiting factor to the pixel yield of an array. In this paper we will present data on the uniformity of the TiN/Ti/TiN multilayers deposited at the Tyndall National Institute and compare these results with a statistical model that evaluates how inhomogeneities affect the pixel yield of an array
Cellular Detection of a Mitochondria Targeted Brominated Vinyl Triphenylamine Optical Probe (TP−Br) by X‐Ray Fluorescence Microscopy
No full textInternational audienceTriphenylamine (TP) derivatives such as two-branch cationic vinylbenzimidazolium triphenylamine TP−2Bzim are promising turn-on fluorescent probes suitable for two-photon imaging, labelling mitochondria in live cells. Here, we designed two TP−2Bzim derivatives as bimodal probes suitable for X-ray fluorescence imaging. The conjugation of the TP core with a rhenium tricarbonyl moiety in the TP−RePyta probe altered the localisation in live cells from mitochondria to lysosomes. The introduction of bromine on the TP core generated the TP−Br probe retaining good photophysical properties and mitochondria labelling in live cells. The influence of calcium channels in the uptake of TP−Br was studied. Synchrotron Radiation X-ray Fluorescence (SXRF) imaging of bromine enabled the detection of TP−Br and suggested a negligible presence of the probe in an unbound state in the incubated cells, a crucial point in the development of these probes. This study paves the way towards the development of TP probes as specific organelle stainers suitable for SXRF imagin
Relationship between biodistribution of a novel thymidine phosphorylase (TP) imaging probe and TP expression levels in normal mice
No full textObjective: Thymidine phosphorylase (TP) is a key enzyme in the pyrimidine nucleoside salvage pathway and its expression is upregulated in a wide variety of solid tumors. In mice, we previously observed high and specific accumulation levels of our TP imaging probe, radioiodinated 5-iodo-6-[(2-iminoimidazolidinyl)methyl]uracil (IIMU) not only in high-TP-expressing tumors, but also in the liver and small intestine. To clarify the reason for the high accumulation levels of radioiodinated IIMU in the liver and small intestine, we investigated the expression levels of TP in mice in comparison with the biodistribution of radioiodinated IIMU (123I-IIMU). Methods: BALB/cCrSlc mice were injected with 123I-IIMU, and the radioactivity levels [%ID/g (normalized to a mouse of 25 g body weight)] in the tissues of interest were determined 0.5, 1, 3 and 24 h after the injection (n = 5, each time point). To determine the expression levels of TP, BALB/cCrSlc and ddy mice (n = 3/each strain) were euthanized, and the heart, liver, lung, spleen, kidney, stomach, small intestine, large intestine and brain were collected. The mRNA and protein expression levels of TP in these organs were examined by quantitative reverse transcription-polymerase chain reaction and western blot analyses, respectively. Results: In BALB/cCrSlc mice administered 123I-IIMU, markedly high radioactivity levels were observed in the liver [1.568 ± 0.237 (%ID/g)] and small intestine [0.506 ± 0.082 (%ID/g)], whereas those in the other tissues were fairly low [<0.010 ± 0.003 (%ID/g)] 30 min after the injection. The highest expression levels of TP mRNA were also observed in the liver and small intestine among the tissues tested. Immunoblotting showed intense immunoreactive bands of the TP protein for the liver and small intestine, whereas no notable bands were detected for other tissues. Similar expression profiles of TP mRNA and protein were observed in ddy mice. Conclusion: We confirmed TP expression in various tissues of mice at the mRNA and protein levels: high TP expression levels were observed in the liver and small intestine. These high TP expression levels are consistent with the high accumulation levels of 123I-IIMU in these tissues. Our results may provide important information about the physiological accumulation of 123I-IIMU, which may be useful for the clinical diagnostic imaging of TP
K⊂{[Fe(Tp)(CN)][Co(Tp)][Co(Tp)]}: a neutral soluble model complex of photomagnetic Prussian blue analogues
No full textStraightforward access to a new cyanide-bridged {FeCo} “molecular box” containing a potassium ion, namely K⊂{[Fe(Tp)(CN)][Co(Tp)][Co(Tp)]} (1) (with Tp and Tp = tris- and tetrakis(pyrazolyl)borate, respectively), is provided, alongside its full characterisation. A detailed analysis of the molecular structure (X-ray diffraction, mass spectrometry, NMR spectroscopy) and electronic properties (EPR spectroscopy, SQUID magnetometry, UV/Vis spectroscopy, cyclic voltammetry) reveals that 1 shows slow magnetic relaxation and a remarkable photomagnetic effect at low temperature which is reminiscent of some FeCo Prussian Blue Analogues (PBAs), and is ascribed to a photo-induced electron transfer. However, in contrast with these inorganic polymers, the overall neutral compound 1 is soluble and remarkably stable in organic solvents such as CH2Cl2. Moreover, 1 shows interesting redox versatility, with electrochemical experiments revealing the possible access to six stable redox states
Synthesis and X-ray crystal structures of hydridotris(3,5- dimethylpyrazolyl)borate (Tp′) molybdenum(VI) bis(imido) complexes
No full textThe reaction between the bridged bis(imido) complexes {[(CH 2)n(2-C6H4N)2]MoCl 2(dme)} (n=1,2); dme=1,2-dimethoxyethane) and one equivalent of potassium hydridotris(3,5-dimethylpyrazolyl)borate (KTp′) in refluxing thf gives {[(CH2)n(2-C6H4N) 2](Tp′)MoCl} (n=1 (1), n=2 (2)) as red crystalline solids in good yields. Similarly, the reaction between [Mo(NAr)2Cl 2(dme)] or [Mo(NAr)(NBut)Cl2(dme)] (Ar=2,6-Pr2iC6H3) and KTp′ gives green [Tp′Mo(NAr)2Cl] (3) or brown/black [Tp′Mo(NAr)(NBut)Cl] (4), respectively. X-ray crystal structures of the compounds 1, 3 and 4 have been determined. All have octahedral structures with fac coordination for the tridentate Tp′ ligands and near-linear imido groups. \ua9 2003 Elsevier Ltd. All rights reserved
Mononuclear sulfido-tungsten(V) complexes: completing the Tp*MEXY (M = Mo, W; E = O, S) series
No full textOrange Tp*WSCl2 has been synthesized from the reactions of Tp*WOCl2 with boron sulfide in refluxing toluene or Tp*WS2Cl with PPh3 in dichloromethane at room temperature. Mononuclear sulfido-tungsten(V) complexes, Tp*WSXY {X = Y = Cl, OPh, SPh, SePh; X = Cl, Y = OPh; XY = toluene-3,4-dithiolate (tdt), quinoxaline-2,3-dithiolate (qdt); and Tp* = hydrotris(3,5-dimethylpyrazol-1-yl)borate} were prepared by metathesis of Tp*WSCl2 with the respective alkali metal salt of X–/XY2–, or [NHEt3]2(qdt). The complexes were characterized by microanalysis, mass spectrometry, electrochemistry, and infrared (IR), electron paramagnetic resonance (EPR) and electronic absorption spectroscopies. The molecular structures of Tp*WS(OPh)2, Tp*WS(SePh)2, and Tp*WS(tdt) have been determined by X-ray crystallography. The six-coordinate, distorted-octahedral W centers are coordinated by terminal sulfido (W≡S = 2.128(2) – 2.161(1) Å), terdentate facial Tp*, and monodentate/bidentate O/S/Se-donor ligands. The sulfido-W(V) complexes are characterized by lower energy electronic transitions, smaller giso, and larger Aiso(183W) values, and more positive reduction potentials compared with their oxo-W(V) counterparts. This series has been probed by sulfur K-edge X-ray absorption spectroscopy (XAS), the spectra being assigned by comparison to Tp*WOXY (X = Y = SPh; XY = tdt, qdt) and time-dependent density functional theoretical (TD-DFT) calculations. This study provides insight into the electronic nature and chemistry of the catalytically and biologically important sulfido-W unit
Synthesis and reactivity in salt metathesis reactions of trivalent [La(Tp(Me2))(2)X] (X = Cl, I) complexes: crystal structures of [La(Tp(Me2))(2)Cl] and [La(Tp(Me2))(2)(kappa(2)-pz(Me2))]
No full textReaction of LaX3(THF)(n) (X = Cl, 1) with two equiv. of K(Tp(Me2)) gave good yields of the bis-Tp complexes [La(Tp(Me2))(2)X] (X = Cl (1); I (3)). However, the formation of 1 and 3 is always accompanied by significant amounts of La(Tp(Me2))(2)(kappa(2)-pz(Me2)) ([pz(Me2)](-) = 3,5-dimethyl-pyrazolato) (2). The pyrazolato complex 2, which presumably arises from decomposition of the [Tp(Me2)](-) moiety during salt metathesis, was independently prepared in good yield from 1 and in situ generated [pz(Me2)](-). The solid-state structures of 1 and 2 were determined by single-crystal X-ray diffraction studies. Subsequent reactions of halogeno-Tp(Me2) complexes 1 and 3 with various alkali metal salts MR (M = Li, R = CH2SiMe3, Ph, N(SiMe3)(2); M = K, R = OAr) gave M(Tp(Me2)) as the major product. Alternatively, the mono-Tp bis(aryloxide) derivatives [Ln(Tp(Me2))(OC6H2-2,6-'Bu-4-Me)(2)] (Ln = La (4); Nd (5)) were obtained in high yields by salt metathesis of [Ln(OC6H2-2,6-'Bu-4-Me)(3)] with one equiv. of K(Tp(Me2)). (C) 2004 Elsevier Ltd. All rights reserved.Univ Fed Rio Grande Sul, Inst Quim, Lab Catalise Mol, BR-90501970 Porto Alegre, RS, BrazilUNESP, Inst Quim Araraquara, BR-14800900 Araraquara, SP, BrazilUniv Rennes 1, CNRS, UMR 6626, Grp Matiere Condensee & Mat, F-35042 Rennes, FranceUniv Rennes 1, CNRS, UMR 6509, Lab Organomet & Catalyse, F-35042 Rennes, FranceUNESP, Inst Quim Araraquara, BR-14800900 Araraquara, SP, Brazi
Substitution and Hydrogenation Reactions on Rhodium(I)−Ethylene Complexes of the Hydrotris(pyrazolyl)borate Ligands Tp‘ (Tp‘ = Tp, Tp<sup>Me2</sup>)<sup>†</sup>
No full textThe bis(ethylene) Rh species TpMe2Rh(C2H4)2 (1*) (TpMe2 = tris(3,5-dimethyl-1-pyrazol-1-yl)hydroborate) has
been obtained from [RhCl(C2H4)2]2 and KTpMe2. Complex 1* easily decomposes in solution to give mainly the
butadiene species TpMe2Rh(η4-C4H6). In the solid state its thermal decomposition follows a different course and
the allyl TpMe2RhH(syn-C3H4Me) is cleanly obtained as a mixture of exo and endo isomers. The complexes Tp‘Rh(C2H4)2 (Tp‘ = Tp, TpMe2) afford the monosubstituted species Tp‘Rh(C2H4)(PR3) upon reaction with PR3 but
react differently with L = CO or CNR: the Tp compound gives dinuclear [TpRh]2(μ-L)3 complexes, while, in
the case of 1*, TpMe2Rh(C2H4)(L) species are obtained. The ethylene ligand of complexes TpMe2Rh(C2H4)(PR3)
is labile, and several peroxo compounds of composition TpMe2Rh(O2)(PR3) have been isolated by their reaction
with O2. All the mononuclear Rh(I) complexes are formulated as 18e- trigonal bipyramidal species on the basis
of IR and NMR spectroscopic studies. A series of dihydride complexes of Rh(III) of formulation Tp‘RhH2(PR3)
have been prepared by the hydrogenation of the corresponding ethylene derivatives. Complexes [TpRh]2(μ-CNCy)3,
TpMe2Rh(C2H4)(PEt3), and TpMe2Rh(O2)(PEt3) have been further characterized by X-ray diffraction studies
Synthesis and Reactivity of [Tp‘(CO)(PhC⋮CMe)WNPh]<sup>+</sup> (Tp‘ = Hydridotris(3,5-dimethylpyrazolyl)borate)
No full textThe tungsten(IV) nitrene complex
[Tp‘(CO)(PhC⋮CMe)WNPh]+ (cation of
1; Tp‘ =
hydridotris(3,5-dimethylpyrazolyl)borate) has been prepared
by oxidation of the amido
complex Tp‘(CO)(PhC⋮CMe)W(NHPh) (2) with
elemental iodine in the presence of triethylamine. Oxidation in the absence of base also forms the aniline
complex [Tp‘(CO)(PhC⋮CMe)W(NH2Ph)]+
(3), which has been independently synthesized. Reaction
of 1 with
1 equiv of KBH4 adds hydride to the nitrene ligand to give
the amido complex 2. Reaction
of 1 with Li[HBEt3] forms the formyl
adduct Tp‘(NPh)(PhC⋮CMe)W(η1-C(O)H)
(4) as an
intermediate, which ultimately yields the hydride complex
Tp‘(NPh)(PhC⋮CMe)W(H) (5)
with loss of CO. The hydride complex is also formed from reaction
of 1 with 10 equiv of
KBH4. Addition of acid to the hydride complex
5 protonates the nitrene nitrogen to form
[Tp‘(H)(PhC⋮CMe)W(NHPh)][BAr‘4]
(6). Both 5 and 6 exhibit
surprisingly low-field hydride
resonances in the 1H NMR (13.5 and 20.6 ppm, respectively).
Addition of methylmagnesium
bromide to the nitrene complex leads to the methyl acyl intermediate
Tp‘(NPh)(PhC⋮CMe)W(η1-C(O)Me) (7), which readily adds a
proton and cyclizes to
[Tp‘(NHPh)W(C(Ph)C(Me)C(O)Me][BAr‘4] (8). Reaction of
1 with phenyllithium forms the phenyl acyl complex
Tp‘(NPh)(PhC⋮CMe)W(η1-C(O)Ph) (9).
X-ray crystal structures have been determined for 1 and
8.
The ring in complex 8 exhibits a structure similar to a
folded envelope, with the flap
containing the Cα, W, and O atoms. The ring is
bonded in an η4 fashion to the metal center
Coupling of transition metal carbynes with a methylene arsane moiety: Structure of Tp '(CO)(2)W C-As=C(NMe2)(2) [Tp ' = HB(3,5-Me2HC3N2)(3)]
No full textWeber L, Dembeck G, Boese R, Bläser D. Coupling of transition metal carbynes with a methylene arsane moiety: Structure of Tp '(CO)(2)W C-As=C(NMe2)(2) [Tp ' = HB(3,5-Me2HC3N2)(3)]. Organometallics. 1999;18(22):4603-4607.Condensation of Tp'(CO)(2)M=CCl [1a, M = Mo; 1b, W; Tp' = HB(3,5-Me2HC3N2)(3)] with the arsaalkene Me3SiAs=C(NMe2)(2) afforded the novel arsaalkenyl carbyne complexes Tp'-(CO)(2)M=C-As=C(NMe2)(2) (2a) (M = Mo) and 2b (M = W). Methylation of 2a and 2b, occurred at the arsenic atom to give the complexes [Tp'(CO)(2)M=CAs(Me)C(NMe2)(2)](SO3CF3) 3a (M = Mo) and 3b (M = W). Compounds 2a,b and 3a,b have been characterized by IR and H-1 and C-13 NMR spectroscopy. In addition, the molecular structure of 2b has been determined by a single-crystal X-ray structural analysis
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