[RuCl(H)(CO)(PPh3)3] (2) was found to catalyze, in the presence of H2C=CHSiMe3(3), the trimerisation of aldehydes RCHO [R=Et (4a), i-Bu (4b)] yielding 1,3,5-trioxanes (5) and the aldol condensation yielding α,β-unsaturated aldehydes (6). When (4a) was used as a reactant, from these reaction mixtures, the ruthenium complex [RuCl2(CO)(PPh3)2(i-BuCHO-κO)] (7) having the aldol condensation product as the ligand crystallized. In the analogous reaction with (4b), the complex [RuCl2(CO)(PPh3)2(i-BuCHO-κO)] (8) with the aldehyde as ligand was obtained. The constitution of these complexes was established by single-crystal X-ray diffraction measurements. The ruthenium centers are octahedrally coordinated having the aldehyde and the carbonyl ligand in mutually trans positions (coordination index: OC-6-12). The aldehydes are monodentately coordinated via the carbonyl oxygen atom (κO). The coordination induced elongations of the C=O double bonds [1.242(4) Å (7), 1.234(4) Å (8)] indicate an activation of the aldehydes. Furthermore, the Ru-CO bond lengths [1.842(4) Å (7), 1.823(4) Å (8)] exhibit a relatively low trans influence of the aldehyde ligands. The formation of the complexes (7) and (8) give an indication that the Lewis acidity of the ruthenium center is of importance for aldehyde activation in the catalytic process. 相似文献
Aldehyde dehydrogenases (ALDHs) catalyze the oxidation of aldehydes to carboxylic acids. Elevated ALDH expression in human cancers is linked to metastases and poor overall survival. Despite ALDH being a poor prognostic factor, the non-invasive assessment of ALDH activity in vivo has not been possible due to a lack of sensitive and translational imaging agents. Presented in this report are the synthesis and biological evaluation of ALDH1A1-selective chemical probes composed of an aromatic aldehyde derived from N,N-diethylamino benzaldehyde (DEAB) linked to a fluorinated pyridine ring either via an amide or amine linkage. Of the focused library of compounds evaluated, N-ethyl-6-(fluoro)-N-(4-formylbenzyl)nicotinamide 4 b was found to have excellent affinity and isozyme selectivity for ALDH1A1 in vitro. Following 18F-fluorination, [18F] 4 b was taken up by colorectal tumor cells and trapped through the conversion to its 18F-labeled carboxylate product under the action of ALDH. In vivo positron emission tomography revealed high uptake of [18F] 4 b in the lungs and liver, with radioactivity cleared through the urinary tract. Oxidation of [18F] 4 b , however, was observed in vivo, which may limit the tissue penetration of this first-in-class radiotracer. 相似文献
Ribonucleotide reductases (RNRs) are essential enzymes required for DNA synthesis. In class Ib Mn2 RNRs superoxide (O2.?) was postulated to react with the MnII2 core to yield a MnIIMnIII‐peroxide moiety. The reactivity of complex 1 ([MnII2(O2CCH3)2(BPMP)](ClO4), where HBPMP=2,6‐bis{[(bis(2‐pyridylmethyl)amino]methyl}‐4‐methylphenol) towards O2.? was investigated at ?90 °C, generating a metastable species, 2 . The electronic absorption spectrum of 2 displayed features (λmax=440, 590 nm) characteristic of a MnIIMnIII‐peroxide species, representing just the second example of such. Electron paramagnetic resonance and X‐ray absorption spectroscopies, and mass spectrometry supported the formulation of 2 as a MnIIMnIII‐peroxide complex. Unlike all other previously reported Mn2‐peroxides, which were unreactive, 2 proved to be a capable oxidant in aldehyde deformylation. Our studies provide insight into the mechanism of O2‐activation in Class Ib Mn2 RNRs, and the highly reactive intermediates in their catalytic cycle. 相似文献
Biotinylated polymers with side‐chain aldehydes were prepared for use as multifunctional scaffolds. Two different biotin‐containing chain transfer agents (CTAs) and an aldehyde‐containing monomer, 6‐oxohexyl acrylate (6OHA), are synthesized. Poly(ethylene glycol) methyl ether acrylate (PEGA) and 6OHA are copolymerized by reversible addition‐fragmentation chain transfer (RAFT) polymerization in the presence of the biotinylated CTAs. The resulting polymers are analyzed by GPC and1H NMR spectroscopy. The polymer end groups contained a disulfide bond, which could be readily reduced in solution to remove the biotin. Reactivity of the aldehyde side chains is demonstrated by oxime and hydrazone formation at the polymer side chains, and conjugate formation of fluorescently labeled polymers with streptavidin is investigated by gel electrophoresis.
The effects of glutaric aldehyde concentration CGA(in the range from 0.07 to 0.2 wt %) and temperature T(from 20 to 65°C) on the kinetics of an increase in the effective viscosity effof aqueous solutions of chitosans (CCH= 2.4 wt %, pH 3.6, and ionic strength I= 0.05) with molecular masses equal to 33 × 104and 55 × 104and the degrees of substitution at N-acetyl and amino groups of 0.08 and 0.90, respectively were studied. The kinetic curves eff(t) exhibited the induction periods of a relatively slight increase in the viscosity of chitosan–glutaric aldehyde mixed solutions with time followed by the periods of a drastic increase in the viscosity. The former periods correspond to the formation of gel clusters; the latter periods, to the gelation over the whole volume of a solution. Optimal ranges of the parameters CGAand Twere determined for the preparation of spherical gel particles of slightly cross-linked chitosan, which are used for the sorption of heavy metals from low-concentrated solutions. 相似文献
A simple, sensitive, and accurate liquid-chromatographic method with UV detection has been developed for simultaneous determination
of spinosin, danshensu, and protocatechuic aldehyde in traditional Chinese Zaoren-an-shen capsules. Chromatographic separation
was achieved on a C18 column. Vanillin was used as internal standard and the UV detection wavelength was 280 nm. Excellent linear behavior was
observed over the concentration ranges investigated, with R values higher than 0.9997 for all the analytes. The limits of quantification for spinosin, danshensu, and protocatechuic
aldehyde were 1.31, 0.74, and 0.27 μg mL−1, respectively. This validated method can be used for routine quality control of Zaoren-an-shen capsules. 相似文献
The aldehyde moiety in the title complex, chloro(2‐pyridinecarboxaldehyde‐N,O)(2,2′:6′,2′′‐terpyridine‐κ3N)ruthenium(II)–chloro(2‐pyridinecarboxylic acid‐N,O)(2,2′:6′,2′′‐terpyridine‐κ3N)ruthenium(II)–perchlorate–chloroform–water (1.8/0.2/2/1/1), [RuCl(C6H5NO)(C15H11N3)]1.8[RuCl(C6H5NO2)(C15H11N3)]0.2(ClO4)2·CHCl3·H2O, is a structural model of substrate coordination to a transfer hydrogenation catalyst. The title complex features two independent RuII complex cations that display very similar distorted octahedral coordination provided by the three N atoms of the 2,2′:6′,2′′‐terpyridine ligand, the N and O atoms of the 2‐pyridinecarboxaldehyde (pyCHO) ligand and a chloride ligand. One of the cation sites is disordered such that the aldehyde group is replaced by a 20 (1)% contribution from a carboxylic acid group (aldehyde H replaced by carboxyl O—H). Notable dimensions in the non‐disordered complex cation are Ru—N 2.034 (2) Å and Ru—O 2.079 (2) Å to the pyCHO ligand and O—C 1.239 (4) Å for the pyCHO carbonyl group. 相似文献
V2O3(OH)4(g), Proof of Existence, Thermochemical Characterization, and Chemical Vapor Transport Calculations for V2O5(s) in the Presence of Water By use of the Knudsen-cell mass spectrometry the existence of V2O3(OH)4(g) is shown. For the molecules V2O3(OH)4(g), V4O10(g), and V4O8(g) thermodynamic properties were calculated by known Literatur data. The influence of V2O3(OH)4(g) for chemical vapor transport reactions of V2O5(s) with water ist discussed. ΔBH°(V2O3(OH)4(g), 298) = –1920 kJ · mol–1 and S°(V2O3(OH)4(g), 298) = 557 J · K–1 · mol–1, ΔBH°(V4O10(g), 298) = –2865,6 kJ · mol–1 and S°(V4O10(g), 298) = 323.7 J · K–1 · mol–1, ΔBH°(V4O8(g), 298) = –2465 kJ · mol–1 and S°(V4O8(g), 298) = 360 J · K–1 · mol–1. 相似文献
The novel bulky diphosphite (P∩P) ligands ( 3 and 4 ) based on the 2,7,9,9‐tetramethyl‐9H‐xanthene‐4,5‐diol ( 2 ) backbone were investigated in the Rh‐catalyzed hydroformylation of oct‐1‐ene, styrene, and (E)‐oct‐2‐ene. These diphosphites gave rise to very active and selective catalysts for the hydroformylation of oct‐1‐ene to nonanal with average rates>10000 (mol aldehyde)(mol Rh)−1h−1 (P(CO/H2)=20 bar, T=80°, [Rh]=1 mM ) and maximum selectivities of 79% for the linear product. Relatively high selectivities towards the linear aldehyde (up to 70%, linear/branched up to 2.3) but very high activities (up to 39000 (mol aldehyde)(mol Rh)−1h−1) were observed for the hydroformylation of styrene in the presence of these bidentate ligands (P(CO/H2)=2 – 10 bar, T=120°, [Rh]=0.2 mM ). Remarkable activities (up to 980 (mol aldehyde)(mol Rh)−1h−1) were achieved with these diphosphites for the hydroformylation of (E)‐oct‐2‐ene with selectivities for the linear product of 74% (l/b up to 2.8, P(CO/H2)=2 bar, T=120°, [Rh]=1 mM ). A detailed study of the solution structure of the catalyst under catalytic conditions was performed by NMR and high‐pressure FT‐IR. The spectroscopic data revealed that under hydroformylation conditions, the bidentate ligands rapidly formed stable, well‐defined catalysts with the structure [RhH(CO)2(P∩P)]. All the ligands showed a preference for an equatorial‐apical ( ea ) coordination mode in the trigonal bipyramidal Rh‐complexes, indicating that a bis‐equatorial ( ee ) coordination is not a prerequisite for highly selective catalysts. 相似文献
The computed chemical shifts of transition‐metal complexes with dimetridazole (= 1,2‐dimethyl‐5‐nitro‐1H‐imidazole; 1 ), a prototypical nitro‐imidazole‐based radiosensitizer, are reported at the GIAO‐BP86 and ‐B3LYP levels for BP86/ECP1‐optimized geometries. These complexes comprise [MCl2( 1 )2] (M = Zn, Pd, Pt), [RuCl2(DMSO)2( 1 )2], and [Rh2(O2CMe)4( 1 )2]. Available δ(1H) and δ(15N) values, and Δδ(1H) and Δδ(15N) coordination shifts are well‐reproduced theoretically, provided solvation and relativistic effects are taken into account by means of a polarizable continuum model and suitable methods including spin–orbit (SO) coupling, respectively. These effects are particularly important for the metal‐coordinated N‐atom, where the contributions from solvation and relativity can affect δ(15N) and Δδ(15N) values up to 10–20 ppm. The 195Pt chemical shifts of cis‐ and trans‐[PtCl2( 1 )2] are well‐reproduced using the zero‐order regular approximation including SO coupling (ZORA‐SO). Predictions are reported for 99Ru and 103Rh chemical shifts, which suggest that these metal centers could be used as additional, sensitive NMR probes in their complexes with nitro‐imidazoles. 相似文献
Crystal Structures, Normal Coordinate Analyses, and 15N NMR and 77Se NMR Chemical Shifts of trans ‐[OsO2(NCO)4]2–, trans ‐[OsO2(NCS)4]2–, and trans ‐[OsO2(SeCN)4]2– The crystal structures of trans‐(Ph3PNPPh3)2[OsO2(NCO)4] ( 1 ) (orthorhombic, space group Pbca, a = 19.278(3), b = 16.674(4), c = 19.982(2) Å, Z = 4), trans(n‐Bu4N)2[OsO2(NCS)4] ( 2 ) (triclinic, space group P1, a = 12.728(3), b = 12.953(3), c = 16.255(6) Å, α = 97.39(4), β = 105.62(2), γ = 95.25(3)°, Z = 2) and trans‐(n‐Bu4N)2[OsO2(SeCN)4] ( 3 ) (tetragonal, space group I4/m, a = 13.406(2), c = 12.871(1) Å, Z = 2) have been determined by single‐crystal X‐ray diffraction analysis, showing the bonding of NCO and NCS via the N atom but the coordination of SeCN via the Se atom to osmium. Based on the molecular parameters of the X‐ray determinations the vibrational spectra have been assigned by normal coordinate analyses. The valence force constants are for 1 fd(OsO) = 6.43, fd(OsN) = 3.32, fd(NC) = 14.50, fd(CO) = 12.80, for 2 fd(OsO) = 6.56, fd(OsN) = 1.75, fd(NC) = 15.00, fd(CS) = 5.50, and for 3 fd(OsO) = 6.75, fd(OsSe) = 0.99, fd(SeC) = 3.23, fd(CN) = 15.95 mdyn/Å. The observed NMR shifts are δ(15N) = –386.6 ( 1 ), δ(15N) = –294.7 ( 2 ) and δ(77Se) = 108.8 ppm ( 3 ). 相似文献
Structures and IR absorption spectra of the conformational isomers of perfluorinated aldehyde hydrates, n-CxF2x+1CH(OH)2, (x = 1-4) have been calculated using density functional theory (DFT) and compared to experimental FT-IR measurements. Two absorption peaks around 3600-3700 cm−1 were observed and are assigned to OH stretching modes of OH groups with, and without, intramolecular hydrogen bonding. For n-C3F7CH(OH)2, two absorption bands around 900-1000 cm−1 were observed in the experimental spectra, whereas only a single in-phase stretching mode of the (CF3)(C2F4CH(OH)2) and (C3F7)(CH(OH)2) bonds was calculated for each conformer. The experimental spectra were well described by composite spectra of the thermal equilibrium mixture of different conformational isomers of n-CxF2x+1CH(OH)2 calculated by DFT. 相似文献
Synthesis, Crystal Structure, Vibrational Spectra, and Normal Coordinate Analysis of cis‐ and trans‐(n‐Bu4N)2[PtF2(ox)2] and (n‐Bu4N)2[PtF4(ox)] By treatment of trans‐(n‐Bu4N)2[PtCl2(ox)2] and (n‐Bu4N)2[PtCl4(ox)] with XeF2 in propylene carbonate cis‐ and trans‐(n‐Bu4N)2[PtF2(ox)2] ( 1 , 2 ) and (n‐Bu4N)2[PtF4(ox)] ( 3 ) are formed which have been isolated by ion exchange chromatography on diethylaminoethyl cellulose. The crystal structure of trans(n‐Bu4N)2[PtF2(ox)2] ( 2 ) (tetragonal, space group P42/n, a = 15.5489(9), b = 15.5489(9), c = 17.835(1)Å, Z = 4) und Cs2[PtF4(ox)] ( 3 ) (monoclinic, space group C2/m, a = 14.5261(7), b = 6.2719(4), c = 9.6966(9)Å, β = 90.216(8)°, Z = 4) reveal complex anions with nearly D2h and C2v point symmetry. The average bond lengths in the symmetrical coordinated axes are Pt—F = 1.93 ( 2 , 3 ) and Pt—O = 1.987 ( 2 ) and in the F•—Pt—O′‐axes Pt—F• = 1.957 and Pt—O′ = 1.977Å ( 3 ). The oxalato ligands are nearly planar with a maximum displacement of the ring atoms of 0.05 ( 2 ) und 0.01Å ( 3 ) to the calculated best planes. In the vibrational spectra the symmetric and antisymmetric PtF stretching vibrations are observed at 583 and 586 ( 2 ) and 576 and 568 cm—1 ( 3 ). The PtF• modes appear at 565 and 562 ( 1 ) and 560 cm—1 ( 3 ). The PtO and PtO′ stretching vibrations are coupled with internal modes of the oxalato ligands and appear in the range of 400—800 cm—1. Based on the molecular parameters of the X‐ray determinations ( 2 , 3 ) and estimated data ( 1 ) the IR and Raman spectra are assigned by normal coordinate analysis. The valence force constants are fd(PtF) = 3.55 ( 2 ) and 3.38 ( 3 ), fd(PtF•) = 3.23 ( 1 ) and 3.20 ( 3 ), fd(PtO) = 2.65 ( 1 ) and 2.84 ( 2 ) and fd(PtO′) = 2.97 ( 1 ) and 3.00 mdyn/Å ( 3 ). Taking into account increments of the trans influence a good agreement between observed and calculated frequencies is achieved. The NMR shifts are δ(195Pt) = 8485 ( 1 ), 8597 ( 2 ) and 10048 ppm ( 3 ), δ(19F) = —350 ( 2 ) and —352 ( 3 ) and δ(19F•) = —323 ( 1 ) and —326 ppm ( 3 ) with the coupling constants 1J(PtF) = 1784 ( 2 ) and 1864 ( 3 ) and 1J(PtF•) = 1525 ( 1 ) and 1638 Hz ( 3 ). 相似文献
Preparation and Properties of Soluble and Polysiloxane-Supported (Ether-Phosphine)ruthenium(II) Complexes Phosphine-modified Polysiloxanes of the type x SiO2 · [SiO3/2(CH2)6P(Ph)R] (x = 0 – 3, I–IV ) were prepared by hydrolytic condensation of (MeO)3Si(CH2)6P(Ph)R [ 1 ; R = CH2CH2OMe ( a ), CH2C4H7O ( b ), CH2C4H7O2 ( c ), Ph ( d )]. Crosslinking was achieved by cocondensation of 1 and Si(OEt)4. 2 SiO2 · [SiO3/2(CH2)6P(Ph)CH2CH2OMe] ( IIIa ) was investigated by means of 31P and 29Si CP-MAS-NMR-spectroscopy, especially in view of a quantification of silyl species which revealed the following ratios: T2:T4:Q2:Q3:Q4 = 76:158:48:135:82. Reaction of RuCl2(PPh3)3 with 3 moles of 1a gave fluxional RuCl2(P∩O)(P～O)2 ( 4a ). From its temperature dependent 31P{1H}-NMR spectrum the temperatures of coalescence and the corresponding activation enthalpies could be estimated at -25°C (46 kJ · mol?1) and +20°C (55 kJ · mol?1). Soluble 1a-d as well as their insoluble counterparts I-IV were treated with [RuCl2(CO)2]n to give all-trans-RuCl2(CO)2(PR3)2 ( 6 ). On heating (120°C) 6 could be transformed into isomeric cis, cis, trans-RuCl2(CO)2(PR3)2 ( 7 ). Decarbonylation occurred on irradiation of 6 . Polysiloxane-supported ruthenium complexes were proved to be active in the heterogeneous hydrogenation of crotonaldehyde. Thus, at p(H2) = 50 bat, T = 120°C, reaction time = 190 min, and at a molar ratio of aldehyde: Ru = 250:1, all-trans-RuCl2(CO)2(P～O)2 ( 6f , O,P = IIIa ) effected a conversion of 50%, crotyl alcohol being formed in comparatively high selectivities. Moreover, no loss of metal or ligand from the support could be observed. 相似文献
Based on the tripodal 1,3,5‐tris(imidazol‐1‐yl)benzene (tib) ligand, four transition metal coordination polymers, namely, {[Ni3(tib)2(H2O)12] · (SO4)3}n ( 1 ), {[Co1/6(tib)1/3] · (O)1/3}n ( 2 ), and [M(tib)(hip)]n (M = Mn for 3 , and M = Co for 4 ) (hip = 5‐hydroxyisophthalic acid), were synthesized through solvothermal method. Their structures were defined by single‐crystal X‐ray diffraction analyses and further characterized by elemental analyses (EA), IR spectra, powder X‐ray diffraction (PXRD), and thermogravimetric analyses (TGA). Complex 1 displays a 2D 3‐connected (63) hcb net. Complex 2 is a 2D (3,6)‐connected (43)2(46.66.83) kgm net. Complex 3 and 4 present similar 2D 4‐connected (44.62) sql net. Moreover, the solid state luminescence properties of complexes 1 and 3 were investigated. 相似文献
The title compound, dibromo(3‐hydroxy‐5‐hydroxymethyl‐2‐methyl‐4‐pyridinecarboxaldehyde semicarbazone‐κ3N1,O3,O3′)copper(II), [CuBr2(C9H12N4O3)], consists of discrete complex units with the tridentate pyridoxal semicarbazone ligand as a zwitterion in an almost planar configuration. The CuII ions are in a distorted square‐pyramidal coordination, with the equatorial Br atom at a distance of 2.4017 (6) Å and the apical Br atom at a distance of 2.6860 (6) Å. 相似文献
The synthesis and characterization of platinum(II) and palladium(II) complexes of the type [PtX2(nPr-N(Ph2P)2)] (X = Cl, I) and [PdCl2(R-N(Ph2P)2)] {R = nPr, p-OMe(C6H4)} containing aminodiphosphine P,P-bidentate ligands is described. Complexes of the type [PtCl2(R-N(Ph2P)2)] (where R = benzyl, 2-picolyl and nPr) catalyzed the hydroformylation of 1-octene, albeit at low activities and slightly elevated regioselectivities toward the
linear aldehyde, when compared with analogous compounds containing small bite angles. 相似文献
Reactions of monooxidized thioyl and selenoyl bis(phosphanyl)amine ligands C10H7‐1‐N(P(E)Ph2)(PPh2) [E = S ( 1 ), Se ( 2 )] with Mo(CO)4(pip)2 and W(CO)4(cod) afforded the complexes [M(CO)4{ 1 ‐κ2P,S}] [M = Mo ( 3 ), W ( 4 )] and [M(CO)4{ 2 ‐κ2P,Se}] [M = Mo ( 5 ), W ( 6 )]. Complexes 3 – 6 were characterized by multinuclear NMR (1H, 13C, 31P, and 77Se NMR) and IR spectroscopy. Crystal‐structure determinations were carried out on 3 , 5 , and 6 , which represent the first examples of structurally characterized complexes of such ligands with group‐6 metal carbonyls. 相似文献
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