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1.
Abdul Ghany M. Al-Daher Kenneth W. Bagnall Carla Bisi Castellani Franco Benetollo Gabriella Bombieri 《Inorganica chimica acta》1984,95(5):269-277
The complexes M(NCS)4·xL (x = 2, M = U, L = Me3CCON(Pri)2(dippva); x = 3, M = Th, L = Me2CHCON(Pri)2(dipiba) and dippva, M = U, L = EtCON(Pr1)2(dippa), dipiba and dippva; x = 4, M = Th, L = MeCON(Pri)2(dipa), dippa and dipiba, M = U, L = dipa, dippa) and the solvates M(NCS)4·4dipa·CH2Cl2 (M = Th, U) have been prepared. Their i.r. and u.v.-visible (M = U only) spectra are reported. The crystal and molecular structure of U(NCS)4(dipa)4· CH2Cl2 has been determined by the heavy-atom method from X-ray diffractometer data and refined by least squares to R 0.029 for 1135 independent reflections. The crystal is tetragonal, space group P21c, with Z = 2, a = 15.663(4) and c = 10.512(3) Å. The coordination geometry about the 8-coordinate uranium atom is dodecahedral with the N atoms of the NCS groups occupying the dodecahedral A sites and the ‘dipa’ O atoms the B sites. The bonding distances of UO and UN are 2.363(8), and 2.444(11) Å respectively. 相似文献
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Complexes of the formula cis-[Pt(H~N)(L)Cl2], where (H~N) are the protonated diamines including 3-aminoquinuclidine, N-aminopiperidine, piperazine, N-methylpiperazine, 1,1,4-trimethylpiperazine, and N-methyl-1,4-diazabicyclo [2,2,2] octane (N-methyl-dabco) and L = SCN?, NO2?, Br?, and F?, were synthesized from the protonated diamine complexes, [Pt(H~N)Cl3]. The antitumor activities of the complexes were evaluated in vitro against L1210 murine leukemia cells, and ID50 values for the L-substituted complexes were compared to values of the parent complexes. In each case it was found that replacement of a chloride ion by SCN?, NO2?, Br?, or F?, either reduced or completely eliminated antitumor activity. This effect is explained in terms of the trans-directing ability of the ligand, L, compared to chloride. The NO2-substituted complex of 3- aminoquinuclidine was tested in vivo and found to exhibit little or no antitumor activity. 相似文献
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《Inorganica chimica acta》1986,115(2):169-172
2-(Methylamino)pyridine reacts with RuCl2(CO)3 to give a carbamoyl complex, [)Cl(CO)2], which yields with pyridine (py) and acetylacetone (Hacac), respectively, [)Cl(CO)2(py)] and [)(CO)2(acac)]. These complexes are characterized spectroscopically. The amino group of the ligand is carbonylated and the resulted carbamoyl ligand is chelating through a pyridine ring-N and a carbamoyl-C atom. 2-Aminopyridine and 2-aminopyrimidine react similarly with RuCl2(CO)3 to give the corresponding carbamoyl complexes. 相似文献
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《Inorganica chimica acta》2001,312(1-2):7-14
The synthesis and spectroscopic characterization of new transition metal complexes containing the heterocyclic nitrogen ligand 4′-phenyl-2,2′:6′,2″-terpyridine are reported. Complexes of the [XM(CO)3(L)] type (M=Re(I), Mn(I), Mo(0), or W(0); X=Br or CO; and L=4′-phenyl-2,2′:6′,2″-terpyridine) were prepared by photosubstitution or by thermolytic reactions. Aspects of the IR, UV–Vis, proton NMR spectra and electrochemistry of the complexes are discussed. Special attention is given to the fact that the heterocyclic nitrogen ligand ph-tpy acts as a bidentate or terdentate chelate in complexes of this type and shows the fluxionality in the coordination. Correlations between redox potentials and spectroscopic measurements indicate the various interactions of the ligand and the metal center, and allow the evaluation of the metal–ligand back-donation. 相似文献
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Jean-Pierre Girault Jean-Claude Chottard Eric R. Guittet Jean-Yves Lallemand Tam Huynh-Dinh Jean Igolen 《Biochemical and biophysical research communications》1982,109(4):1157-1163
The stoichiometric reaction between d-TpGpGpCpCpA (d(T-G-G-C-C-A)) and -[Pt(NH3)2(H2O)2](NO3)2 (8.4 × 10?6 to 1.3 × 10?4M in water at pH 5.5–6) gives a single complex. High pressure gel permeation chromatography and pH-dependent 1H NMR analyses of the nonexchangeable base protons, show that it is a platinum chelate with the -PtII(NH3)2 moiety bound to the two N7 atoms of the adjacent guanines. A 3 × 10?3M reaction gives the same platinum chelate, via the formation of intermediate complexes, together with unsoluble adducts. 相似文献
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Cooperativity in ligand binding: a new graphic analysis. 总被引:16,自引:0,他引:16
When analyzing binding of ligands to macromolecules, the existence of site-site interactions complicates a straightforward interpretation of the binding parameters obtained through classical analytical methods, such as the Scatchard plot. For describing site-site interactions, we propose a new parameter, the of the receptor sites, , calculated as . Plotting as a function of fractional occupancy (), reveals that: (1) at very low occupancy a limiting high is obtained (e) (“empty sites” conformation); (2) when the fraction of sites filled increases above a certain threshold, begins to fall due to increasing site-site interactions until (3) a limiting low (f) is obtained (“filled sites” conformation). This method has been successfully applied to the negative cooperativity of insulin receptors. 相似文献
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Werner Jahn Kenan Yünlü Wolfgang Oroschin Hans-Dieter Amberger R.Dieter Fischer 《Inorganica chimica acta》1984,95(2):85-104
The main objective of this survey is to demonstrate that by extensive assessment of variable temperature 1H NMR data obtained on paramagnetic f-element complexes in solution, not only valuable information on details of the molecular structure, but also on the electronic structure may be deduced. One of the most informative quantities to arrive at is the paramagnetic anisotropy term, χ∥ - χ⊥, of axially symmetric molecules from which, if the bulk susceptibility is also known, the crystal-field sensitive parameters χ∥ and χ⊥ can be derived.The majority of the examples considered belong to the widely studied type [Cp3fMLn]q (Cp = η5C5H4R); fM = Pr(III), Nd(III), Yb(III) and U(IV); n = 0, 1 and 2; q = 0 or ?1) and to the uranocene family. The survey also includes the two sub-classes of novel anionic complexes [Cp3LnL]? and [(Cp3Ln)2(μ-L)]?, respectively, and different isomers of the general composition [Cp3UXY]q (L = lanthanoid). 相似文献
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Proton and 13C magnetic resonance studies are reported on the synthetic polypentapeptide of elastin, HCO-(Val(1)-Pro(2)-Gly(3)-Val(4)-Gly(5))n-Val-OMe, where n ∼- 18. Temperature and solvent dependence of peptide N chemical shift and solvent dependence of peptide carbonyl chemical shift were used to delineate these moieties preliminary to identification of secondary structure.Based on these studies it is proposed, for the organic solvents of dimethyl sulfoxide, methanol, and low-temperature trifluoroethanol, that dynamic hydrogen bonds form in order of decreasing frequency of occurrence between the Val(1)O and the Val(4) N (a β-turn), between the Gly(3) N and the Gly(5)O (an 11-atom, hydrogen-bonded ring), and a more limited interaction between the Gly(3)O and the Gly(5) N (a γ-turn).Arguments are presented that relate the conformational features proposed above to the coacervate, which is a filamentous state. 相似文献
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K.N. Thimmaiah G.T. Chandrappa Winston D. Lloyd Cyril Párkányi 《Inorganica chimica acta》1985,107(1):1-4
4-Acetyl-2-(acetylamino)-5-dimethyl-Δ2-1,3,4-thiadiazole (AAT) has been used to obtain the complexes of the general formula [M(AAT)X2]·H2O where M(II) = Zn, Hg, Cd and Cu, and X Cl or SO4. The complexes have been characterized on the basis of their elemental analysis, molar conductance, magnetic susceptibility and spectral data. Probable structures for the complexes have been proposed on the basis of their physico-chemical properties. The fungitoxicity of AAT and the isolated complexes has been tested on pathogenic fungi. 相似文献
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In this contribution, the synthesis and characterisation of a series of complexes of the type [Ru(L-L′)(CO)2Cl2] are reported, where L-L′ are the chelating ligands L1-L8, 2-(4H-[1,2,4]triazol-3′-yl)-pyridine (L1); 2-(4H-[1,2,4]triazol-3′-yl)-pyrazine; (L2); 2-(1-methyl-4H-[1,2,4]-triazol-3-yl)pyridine (L3); 2-(5-pyridin-2-yl-4H-[1,2,4]-triazole-3-yl)phenol (L4); 3-(5-methylphenyl)-pyridin-2-yl-1,2,4-triazole (L5); 3-(4-methylphenyl)-pyridin-2-yl-1,2,4-triazole (L6); 3-(4-methoxyphenyl)-pyridin-2-yl-1,2,4-triazole (L7); 3,6-bis[(4-methoxyphenyl)iminomethyl]pyridazine (L8). L1-L7 are triazole-based ligands, which provide two distinct bidentate coordinate modes (via N2 or N4 of the triazole) whereas L8 is pyridazine-based and contains two identical bidentate binding pockets. The products obtained are analysed using infrared and NMR spectroscopy. The X-ray and molecular structures of the complexes with the ligands L2, L6, L7 and L8 are reported. These structures are the first to be reported for triazole based ruthenium chloro and ruthenium pyridazine imine complexes. The data show that the triazole ring in L2, L6 and L7 is coordinated via the N2 atom, and that the pyridazine-based ligand L8 uses only one binding pocket hence accommodating only one ruthenium(II) centre. For all compounds the cis(CO)transCl conformation is obtained. The results obtained are compared with those obtained for other similar compounds. 相似文献
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The low temperature optical spectra in the region of the Q00 (α-band) and Q01 (β-band) transitions of model heme complexes for - and c-type cytochromes were measured and the results discussed in terms of the similarities and differences to the spectra of horse heart cytochrome and other hemeproteins. Comparisons of the resolved vibronic components of the Q01 and β′ bands were made to the recent resonance Raman spectra of hemeproteins. Tentative assignment of the β′ band to Q02 type transitions has been proposed. 相似文献
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A new method for decomposing fluorescence emission spectra into their elementary components, based on the simultaneous recording of fluorescence intensity and lifetime vs. the emission wavelength, has been applied to the spectra of algal cells at liquid nitrogen temperature. A model of Gaussian components fits both τ(λ) and F(λ) spectra with the same parameters. The fluorescence lifetimes have been measured by phase fluorimetry at two modulation frequencies: 29 and 139 MHz. The final Gaussian decomposition is able to describe both the 29 and 139 MHz spectra. The following conclusions concerning the fluorescence spectra of Chlorella cells at 77 K can be drawn. These conclusions are also valid with minor changes for the other examined species. (1) An overlapping of different emitting bands occurs in all the spectra; therefore, a direct lifetime reading from phase delay measurement necessitates measurements being made at several frequencies. (2) At the Fmax fluorescence level, the lifetime values of the two emissions usually associated with variable fluorescence are 0.53 ns (for B′1; λ peak 688 nm), and 1.46 ns (for B′2; λ peak 698 nm); these lifetimes are shorter than those we have measured at room temperature (approx. 1.8 ns). (3) Superimposed on B′1 and B′2 and with approximatively the same peak location, two long-lifetime components (B″1, 4.8 ns; B″2, 5.6 ns) are present. Two hypotheses can be proposed to explain these emissions: (i) the long-lifetime components arise from subsets of chlorophyll a disconnected from the functional antenna by the cooling process; and (ii) charge recombination in reaction centers leads to delayed fluorescence. (4) In the λ > 710 nm region, two main bands are required to describe the so-called Photosystem I emission: B3 (0.8 ns; λ peak 715 nm) and B4 (3.3 ns; λ peak 724 nm). The former band, usually unresolved in the amplitude fluorescence spectra, is a specific finding from lifetime measurements and has been associated with the antenna core of Photosystem I. No additional information has been obtained for B4. A supplementary small band (B5, 0.40 ns; ) is necessary to take into account the frequency effect and the τ(λ) decrease in the λ > 740 nm spectral range. 相似文献
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Acylated des-(Ala1-Gly2)-somatostatin analogs: prolonged inhibition of growth hormone secretion 总被引:1,自引:0,他引:1
P Brazeau W Vale J Rivier R Guillemin 《Biochemical and biophysical research communications》1974,60(4):1202-1207
The following eight analogs of somatostatin were synthesized by solid phase: des-[Ala1-Gly2]-somatostatin (I); des-[Ala1-Gly2]-H2somatostatin (II); -acetyl-Cys3-somatostatin (III); -acetyl-Cys3-H2somatostatin (IV); -pyvalyl-Cys3-H2somatostatin (V); -acrylyl-Cys3-H2somatostatin (VI); -benzoyl-Cys3-H2somatostatin (VII); -hexanoyl-Cys3-H2somatostatin (VIII). Deletion of the N-terminal dipeptide Ala1-Gly2 is compatible with high biological activity. A single s.c. injection of these analogs as a microsuspension in saline inhibits for 24–72 hours (depending on the compound) the secretion of growth hormone normally stimulated in rats by pentobarbital. 相似文献
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Structures and luminescent sensors of mixed‐counterions based salen‐type lanthanide coordination polymers
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Jin‐Long Du Xin‐Yu Wang Xiao‐Yan Zou Yu‐Xin Li Wei‐Zuo Li Xu Yao Guang‐Ming Li 《Luminescence》2018,33(6):1040-1047
Reactions of N,N′‐bis (salicylidene)‐1,2‐cyclohexanediamine (H2L) with mixed lanthanide counterions of LnCl3·6H2O and Ln (NO3)3·6H2O afford six H2L lanthanide coordination polymers, e.g. {[Pr(H2L)2(NO3)2Cl]·2CH2Cl2}n ( 1 ); {[Ln(H2L)1.5(NO3)3]2·5CHCl3·mCH3OH}n [Ln = Sm ( 2 ), Eu ( 3 ), Gd ( 4 ), Tb ( 5 ) and Yb ( 6 ); m = 1 ( 2 – 5 ); m = 0 ( 6 )]. X‐ray crystallographic analysis reveals that complex 1 exhibits three‐dimensional diamondoid topologic structure and complexes 2 – 6 are of two‐dimensional structure. Luminescent spectra show that complexes 1 and 6 have characteristic near‐infrared (NIR) emission of praseodymium (III) and ytterbium (III) ions and complexes 2 – 5 emit luminescence in the visible region. Complexes 3 and 6 reveal sensitive luminescence responses to formaldehyde. 相似文献