共查询到20条相似文献,搜索用时 15 毫秒
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D. Szopkó É. Darkó I. Molnár K. Kruppa B. Háló A. Vojtkó M. Molnár-Láng S. Dulai 《Photosynthetica》2017,55(2):317-328
The photosynthetic responses to salt stress were examined in a wheat (Triticum aestivum L. cv. Asakaze)–barley (Hordeum vulgare L. cv. Manas) 7H addition line having elevated salt tolerance and compared to the parental wheat genotype. For this purpose, increasing NaCl concentrations up to 300 mM were applied and followed by a 7-day recovery period. Up to moderate salt stress (200 mM NaCl), forcible stomatal closure, parallel with a reduction in the net assimilation rate (P N), was only observed in wheat, but not in the 7H addition line or barley. Since the photosynthetic electron transport processes of wheat were not affected by NaCl, the impairment in P N could largely be accounted for the salt-induced decline in stomatal conductance (g s), accompanied by depressed intercellular CO2 concentration and carboxylation efficiency. Both, P N and nonstomatal limitation factors (Lns) were practically unaffected by moderate salt stress in barley and in the 7H addition line due to the sustained g s, which might be an efficient strategy to maintain the efficient photosynthetic activity and biomass production. At 300 mM NaCl, both P N and g s decreased significantly in all the genotypes, but the changes in P N and Lns in the 7H addition line were more favourable similar to those in wheat. The downregulation of photosynthetic electron transport processes around PSII, accompanied by increases in the quantum yield of regulated energy dissipation and of the donor side limitation of PSI without damage to PSII, was observed in the addition line and barley during severe stress. Incomplete recovery of P N was observed in the 7H addition line as a result of declined PSII activity probably caused by enhanced cyclic electron flow around PSI. These results suggest that the better photosynthetic tolerance to moderate salt stress of barley can be manifested in the 7H addition line which may be a suitable candidate for improving salt tolerance of wheat. 相似文献
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《Inorganica chimica acta》1988,143(2):223-227
The kinetics and mechanism of the oxidative addition of CH3I to [Rh(β-diketone)(P(OPh)3)2] complexes was studied in acetone medium at various temperatures. The experimental rate law is R = k[Rh(β-diketone)(P(OPh3)2][CH3I]. The order of the effect of the β-diketone on the reactivity of the complexes is acac >; BA >; DBM >; TFAA >; TFBA >; HFAA indicating that electronegative substituents of the β-diketone decrease the reactivity of the complexes towards oxidative addition reactions. The volume of activation for some of the reactions was determined in various solvents. The large negative values of the volume and entropy of the activation indicated a mechanism which occurs via a polar transition state. 相似文献
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Ch. Nageswara Rao Bogi Srinu V. Gowri Kumari 《Chemical Speciation and Bioavailability》2016,28(1-4):66-71
Chemical speciation of binary complexes of Pb(II) and Cd(II) ions with maleic acid have been studied pH metrically in the concentration range of 0–50% v/v ethylene glycol (EG)–water mixtures maintaining an ionic strength of 0.16 molL?1 at 303 K. Alkalimetric titrations were carried out in different relative concentrations of metal and maleic acid. Stability constants of various models of binary complexes were refined with MINIQUAD75. The best-fit chemical models were selected based on statistical parameters and residual analysis. The species detected are ML2, ML3, and ML2H for Pb(II) and Cd(II). The chemical speciation, metal bioavailability, and transportation are explained based on the distribution diagrams. 相似文献
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Floriane Malvolti Olivier Cador Jean-François Halet Loic Toupet Stéphane Cordier 《Inorganica chimica acta》2011,374(1):288-301
The new thiocyanato- (5) and azido- (6) complexes were synthesized and studied under their Fe(II) and Fe(III) redox states. For the first time among the various [Fe(η5-C5Me5)(η2-dppe)]-based cationic radicals studied so far, the magnitude and spatial orientation of the g-tensor diagonal values were experimentally determined for 5[PF6]. These data are in good agreement with those issued from a DFT modelization. The changes experienced by the electronic structure of the Fe(II) complexes subsequent to oxidation are reminiscent of these previously observed for the known arylalkynyl analogues, albeit some differences can be pointed out. Thus, the differences observed in the 1H NMR spectra of 5[PF6] and 6[PF6] are attributed to a slower electronic spin relaxation and to the differently oriented magnetic anisotropy. The sizeable spin density evidenced by DFT on the terminal atom of the ligands of the Fe(III) complexes renders these new paramagnetic metallo-ligands quite appealing for accessing larger polynuclear molecular assemblies with magnetically interacting centers. 相似文献
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《Inorganica chimica acta》1986,122(2):149-151
The pKb for the equilibria NiL(OH)+ ⇄ NiL2+ + OH− for L1,4,7,10-tetraazacyclotridecane, 1,4,8, 12-tetraazacyclopentadecane, C-β-racemic-5,7,7,12, 14,14-hexamethyl-l,4,8,11-tetraazacyclotetradecane and C-β-racemic-1,4,5,7,7,8,11,12,14,14,-decamethyl- 1,4,8,112-tetraazacyclotetradecane are 0.95, 1.9, 0.2 and 0.65 respectively. The results are compared with data for analogous complexes reported earlier. The results indicate that the main factors affecting these equilibrium constants are the in plane ligand field strengths of the square planar complexes and steric factors. 相似文献
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Carla P. Da Costa Danuta Krajewska Andrzej Okruszek Wojciech J. Stec Helmut Sigel 《Journal of biological inorganic chemistry》2002,7(4-5):405-415
The acidity constants of twofold protonated methyl thiophosphate (MeOPS(2-)) and of monoprotonated uridine 5'- O-thiomonophosphate (UMPS(2-)) have been determined in aqueous solution (25 degrees C; I= 0.1 M, NaNO(3)) by potentiometric pH titration. The stability constants of their 1:1 complexes formed with Pb(2+), i.e. Pb(MeOPS) and Pb(UMPS), have also been measured. The results show that replacement of a phosphate oxygen by a sulfur atom increases the acidity by about 1.4 p K units. On the basis of recently established log versus plots ( = simple phosphate or phosphonate ligands where R is a non-coordinating residue), it is shown that the stability of the Pb(thiophosphate) complexes is by log Delta= 2.43+/-0.09 larger than expected for a Pb(2+)-phosphate interaction. The identity of the stability increase (log Delta) observed for Pb(MeOPS) and Pb(UMPS) shows that the nucleobase residue in the Pb(UMPS) complex has no influence on complex formation. To be able to carry out the mentioned comparisons, we have also determined the stability constant of the complex formed between Pb(2+) and methyl phosphate; the corresponding data for Pb(UMP) were already known from our earlier studies. The present results allow an evaluation of other Pb(2+) complexes formed with thiophosphate derivatives and they are applied now to the Pb(2+) complexes of adenosine 5'- O-thiomonophosphate (AMPS(2-)). The stability constants of the Pb(H;AMPS)(+) and Pb(AMPS) complexes were measured and it is shown that, within the error limits, the stability of the Pb(AMPS) complex is determined by the basicity of the thiophosphate group of AMPS(2-); in other words, no hint for macrochelate formation involving N7 was observed. More important, with the aid of micro-stability-constant considerations it is concluded that the structure of the dominating isomer of the Pb(H;AMPS)(+) species is the one where the proton is located at the N1 site of the adenine residue and Pb(2+) is coordinated to the deprotonated thiophosphate group. The insights gained from this study with regard to thiophosphate-altered single-stranded nucleic acids and their affinity towards Pb(2+) are discussed. 相似文献
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《Inorganica chimica acta》2006,359(11):3671-3676
Reaction of the salt [Rh(PMe3)4]Cl (1) with p-F3C–C6H4–CC–CC–C6H4-p-CF3 (2) in THF gives a mixture of two related neutral π-bound diyne complexes of [Rh(PMe3)3Cl], each having two distinct CF3 resonances of equal intensity in the in situ 19F{1H} NMR spectrum. The ratio of the two products can be varied by varying the stoichiometry of the reagents. On the basis of the spectroscopic data and literature precedent, we propose Rh(PMe3)3(Cl)((1,2-η2)-p-F3C–C6H4–CC–CC–C6H4-p-CF3) (3a) and [Rh(PMe3)3(Cl)]2(μ-(1,2-η2):(1,2-η2)-p-F3C–C6H4–CC–CC–C6H4-p-CF3) (3b) as the most likely structures of the species in solution. However, upon standing overnight, single crystals of the unusual, dinuclear complex [Rh(PMe3)3(Cl)]2(μ-(1,2-η2):(3,4-η2)-p-F3C–C6H4–CC–CC–C6H4-p-CF3) (4), an isomer of 3b, form reproducibly and in good yield as two different solvates from THF/C6D6 solution. The centrosymmetric structure of 4, obtained from single-crystal X-ray diffraction data, displays a transoid orientation of the bridging diarylbutadiyne ligand. 相似文献
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Liang Junxi Wang Yanbin Zhang Qiang Li Yu Geng Zhiyuan Wang Xiuhong 《Journal of molecular modeling》2013,19(4):1739-1750
Gas-phase reactions of ClO–/BrO– with RCl (R = CH3, C2H5, and C3H7) have been investigated in detail using the popular DFT functional BHandHLYP/aug-cc-pVDZ level of theory. As a result, our findings strongly suggest that the type of reaction is firstly initiated by a typical SN2 fashion. Subsequently, two competitive substitution steps, named as SN2-induced substitution and SN2-induced elimination, respectively, would proceed before the initial SN2 product ion-dipole complex separates, in which the former exhibits less reactivity than the latter. Those are consistent with relevant experimental results. Moreover, we have also explored reactivity difference for the title reactions in term of some factors derived from methyl group, p-π electronic conjugation, ionization energy (IE), as well as molecular orbital (MO) analysis. Figure
Energy profiles for the ClO– reactions and BrO–reactions, respectively 相似文献
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《Inorganica chimica acta》1986,121(1):67-69
Spontaneous resolution in the formation of the [HgI3]− salts of the copper complex of racemic lysine was previously reported. X-ray and IR studies were used to support this conclusion. Gas chromatographic studies using a chiral phase on the crystals originally studied, and on newly formed crystals using D,L-lysine, do not substantiate the suggestion that spontaneous resolution occurs. 相似文献
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《Inorganica chimica acta》1986,125(3):173-182
The pre-resonance Raman spectra of 2-formylpyridine thiosemicarbazone have been measured at three pH values corresponding to the fully protonated (H2FPT+), half protonated (HFPT) and deprotonated (FPT−) forms of the ligand. Assignments of the vibrations coupled with the π→π* transition have been made by comparison with the spectrum of the deuterated form (DFPT). The pre-resonance Raman spectra of the Zn(II) and Cu(II) complexes, [ZnFPT]+, [CuFPT]+ and [CuHFPT]2+, have also been measured. The spectral pattern of the Cu(II) complexes shows resonance enhancement of vibrations coupled with the π→π*, as well as with the ligand to metal charge transfer transitions. In addition, it is consistent with coordination through thiolate sulfur in [CuFPT]+ and thione sulfur in [CuHFPT]2+. 相似文献
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《Inorganica chimica acta》1987,138(3):205-214
Electronic and 57Fe Mössbauer spectra are reported for two new water-soluble porphyrinato iron(III) complexes. Equilibrium constants for μ-oxo bishaem formation are calculated assuming two protons are released.Comparisons are made of the data with other porphyrinato iron(III) systems and it is shown that, in the absence of well-defined fifth ligands, the mononuclear species in acidic solution probably contain two axial water ligands. The μ-oxo bishaems do not contain water or hydroxide coordinated to iron but may hold water by hydrogen-bonding to the oxygen bridge or possibly by aquation of the porphyrin ligands.μ-Oxo bridge formation is controlled by the acid strength of the water coordinated to the iron in the mononuclear species, low pKa values assisting oxo-bridge formation. Such low pKa values are assisted by electron-attracting substituents on the porphyrin periphery. It is noted that this same property assists the stabilisation of iron(II) complexes. Steric inhibition of oxo-bridge formation requires large substituents, unsubstituted phenyl groups being apparently not large enough. 相似文献
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《Inorganica chimica acta》1988,143(1):59-70
Complexes η-C5R5Fe(CO)2(η1-SC(S)OEt) (RH, (1) and RCH3 (2)) have been analysed by X-ray diffraction techniques. 1: P212121 11.3560(5), 10.8595(4), 10.1158(3) Å, Z=4; 1023 observed reflexions, R and Rw 0.069 and 0.073. 2: Pbca, 15.6907(11), 15.4566(13), 14.3083(11) Å, Z=8; 2271 observed reflexions, R and Rw being 0.071, 0.073. The coordination is quite similar for both compounds with the xanthate monodentate ligand almost perpendicular to the ring planes and a relative twist, one from each other of about 10°. The reductive electrochemistry of both complexes has been examined by cyclic voltammetry and coulometry. In a carbon electrode the first-one electron reduction step can be ascribed to the formation of corresponding carbonyl dimers. In a mercury electrode, the first reduction step of 1 leads to a bond rupture process with formation of a mercury compound [CpFe(CO)2]2Hg and further reduction to the anion CpFe(CO)2−. However, the behaviour of the pentamethylcyclopentadienyl complex (2) is quite different, and it is reduced in a three step process. 相似文献
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《Inorganica chimica acta》1987,130(1):61-63
A new high yielding synthesis of the seven-coordinate complexes [MI2(CO)3{Ph2P(CH2)nPPh2}] (M = Mo and W; n = 1–6) is described. The procedure involves reacting the complexes [MI2(CO)3(NCMe)2] in CH2Cl2 with an equimolar amount of the bidentate phosphorus ligand. The low temperature (−70 °C) 13C NMR spectra of the complexes [Wl2(CO)3{Ph2P(CH2)nPPh2}] (n = 3 and 5) indicates that the geometry is capped octahedral with a carbonyl ligand in the unique capping position. 相似文献
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《Inorganica chimica acta》1988,149(2):193-208
The reactions of Fe(CO)3(R-DAB; R1, H(4e)) (1a: R = i-Pr, R1 = H; 1b: R = t-Bu, R1 = H; 1c: R = c-Hex, R1 = H; 1e: R = p-Tol, R1 = H; 1f: R = i-Pr, R1 = Me) with Ru3(CO)12 and of Ru(CO)3(R-DAB; R1, H(4e)) (2a: R = i-Pr, R1 = H; 2d: R = CH(i-Pr)2, R1 = H) with Fe2(CO)9 in refluxing heptane both afforded FeRu(CO)6(R-DAB; R1, H(6e)) (3) in yields between 50 and 65%.The coordination mode of the ligand has been studied by a single crystal X-ray structure determination of FeRu(CO)6(i-Pr-DAB(6e)) (3a). Crystals of 3a are monoclinic, space group P21/a, with four molecules in a unit cell of dimensions: a = 22.436(3), b = 8.136(3), c = 10.266(1) Å and β = 99.57(1)°. The structure was refined to R = 0.049 and Rw = 0.052 using 3045 reflections above the 2.5σ(I) level. The molecule contains an FeRu bond of 2.6602(9) Å, three terminally bonded carbonyls to Fe, three terminally bonded carbonyls to Ru and bridging 6e donating i-Pr-DAB ligand. The i-Pr-DAB ligand is coordinated to Ru via N(1) and N(2) occupying an apical and equatorial site respectively (RuN(1) = 2.138(4) RuN(2) = 2.102(3) Å). The C(2)N(2) moiety of the ligand is η2-coordinated to Fe with C(2) in an apical and N(2) in an equatorial site (FeC(2) = 2.070(5) and FeN(2) = 1.942(3) Å).The 1H and 13C NMR data indicate that in all FeRu(CO)6(R-DAB(6e)) complexes (3a to 3f) exclusively η2-CN coordination to the Fe atom and not to the Ru atom is present irrespective of whether 3 was prepared by reaction of Fe(CO)3(R-DAB(4e)) (1) with Ru3(CO)12 or by reaction of Ru(CO)3(R-DAB(4e)) (2) with Fe2(CO)9. In the case of FeRu(CO)6(i-Pr-DAB; Me, H(6e)) (3f) the NMR data show that only the complex with the C(Me)N moiety of the ligand σ-N coordinated to the Ru atom and the C(H)N moiety η2-coordinated to the Fe atom was formed. Variable temperature NMR experiments up to 140 °C showed that the α-diimine ligand in 3a is stereochemically rigid bonded.FeRu(CO)6(R-DAB(6e)) (3a and 3e) reacted with allene to give FeRu(CO)5(R-DAB(4e))(C3H4) (4a and 4e). A single crystal X-ray structure determination of FeRu(CO)5(i-Pr-DAB(4e))(C3H4) (4a) was performed. Crystals of 4a are triclinic, space group P1, with two molecules in a unit cell of dimensions: a = 9.7882(7), b = 12.2609(9), c = 8.3343(7) Å, α = 99.77(1)°, β = 91.47(1)° and γ = 86.00(1)°. The structure was refined to R = 0.028 and Rw = 0.043 using 4598 reflections above the 2σ(I) level. The molecule contains an FeRu bond of 2.7405(7) Å and three terminally bonded carbonyls to iron. Two carbonyls are terminally bonded to the Ru atom together with a chelating 4e donating i-Pr-DAB ligand [RuN = 2.110(1) (mean)]. The allene ligand is coordinated in an η3-allylic fashion to the Fe atom while the central carbon of the allene moiety is σ-bonded to the Ru atom (FeC(14) = 2.166(3), FeC(15) = 1.970(2), FeC(16) = 2.127(3) and RuC(15) = 2.075(2) Å). The 1H and 13C NMR data show that in solution the coordination modes of the R-DAB and the allene ligands are the same as in the solid state.Thermolysis reactions of 3a with R-DAB or carbodiimides gave decomposition and did not afford C(imine)C(reactant) coupling products. Thermolysis reactions of 3a with M3(CO)12 (M = Ru, Os) and Me3NO gave decomposition. When the reaction of 3a with Me3NO was performed in the presence of dimethylacetylenedicarboxylate (DMADC) the known complex FeRu(CO)4(i-Pr-DAB(8e))(DMADC) (5a) was formed in low yield. In 5a the R-DAB ligand is in the 8e coordination mode with both the imine bonds η2-coordinated to iron. The acetylene ligand is coordinated in a bridging fashion, parallel with the FeRu bond. 相似文献
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Cui-Li Yuan An-Guo Zhang Ze-Bo Zheng 《Journal of biomolecular structure & dynamics》2013,31(3):316-330
A phenylthiophenyl-bearing Ru(II) complex of [Ru(bpy)2(Hbptip)](PF6)2 {bpy?=?2,2′-bipyridine, Hbptip?=?2-(4-phenylthiophen-2-yl)-1H-imidazo[4,5-f][1,10]phenanthroline} was synthesized and characterized by elemental analysis, 1H NMR spectroscopy, and electrospray ionization mass spectrometry. The ground- and excited-state acid–base properties of the complex were studied by UV–visible absorption and photoluminescence spectrophotometric pH titrations and the negative logarithm values of the ground-state acid ionization constants were derived to be pK a1?=?1.31?±?0.09 and pK a2?=?5.71?±?0.11 with the pK a2 associated deprotonation/protonation process occurring over 3 pK a units more acidic than thiophenyl-free parent complex of [Ru(bpy)2(Hpip)]2+ {Hpip?=?2-phenyl-1H-imidazo[4,5-f][1,10]phenanthroline}. The calf thymus DNA-binding properties of [Ru(bpy)2(Hbptip)]2+ in Tris–HCl buffer (pH 7.1 and 50?mM NaCl) were investigated by DNA viscosities and density functional theoretical calculations as well as UV–visible and emission spectroscopy techniques of UV–visible and luminescence titrations, steady-state emission quenching by [Fe(CN)6]4?, DNA competitive binding with ethidium bromide, DNA melting experiments, and reverse salt effects. The complex was evidenced to bind to the DNA intercalatively with binding affinity being greater than those for previously reported analogs of [Ru(bpy)2(Hip)]2+, [Ru(bpy)2(Htip)]2+, and [Ru(bpy)2(Haptip)]2+ {Hip?=?1H-imidazo[4,5-f][1,10]phenanthroline, Htip?=?2-thiophenimidazo[4,5-f][1,10]phenanthroline, Haptip?=?2-(5-phenylthiophen-2-yl)-1H-imidazo[4,5-f][1,10]phenanthroline}. 相似文献