Filtration Coefficient of the Axon Membrane As Measured with Hydrostatic and Osmotic Methods

The hydraulic conductivity of the membranes surrounding the giant axon of the squid, Dosidicus gigas, was measured. In some axons the axoplasm was partially removed by suction. Perfusion was then established by insertion of a second pipette. In other axons the axoplasm was left intact and only one pipette was inserted. In both groups hydrostatic pressure was applied by means of a water column in a capillary manometer. Displacement of the meniscus in time gave the rate of fluid flowing across the axon sheath. In both groups osmotic differences across the membrane were established by the addition of a test molecule to the external medium which was seawater. The hydraulic conductivity determined by application of hydrostatic pressure was 10.6 ± 0.8.10^-8 cm/sec cm H₂O in perfused axons and 3.2 ± 0.6.10^-8 cm/sec cm H₂O in intact axons. When the driving force was an osmotic pressure gradient the conductivity was 4.5 ± 0.6 x 10^-10 cm/sec cm H₂O and 4.8 ± 0.9 x 10^-10 cm/sec cm H₂O in perfused and intact axons, respectively. A comparable result was found when the internal solution was made hyperosmotic. The fluid flow was a linear function of the hydrostatic pressure up to 70 cm of water. Glycerol outflux and membrane conductance were increased 1.6 and 1.1 times by the application of hydrostatic pressure. These increments do not give an explanation of the difference between the filtration coefficients. Other possible explanations are suggested and discussed.     

Effect of osmolality on the hydraulic permeability coefficient of red cells

The osmotic water permeability coefficient, L_p, for human and dog red cells has been measured as a function of medium osmolality, and found to depend on the osmolality of the bathing medium. In the case of human red cells L_p falls from 1.87 x 10^-11 cm³/dyne sec at 199 mOSM to 0.76 x 10^-11 cm³/dyne sec at 516 mOSM. A similar decrease was observed for dog red cells. Moreover, L_p was independent of the direction of water movement and the nature of the solute used to provide the osmotic pressure gradient; it depended only on the final osmolality of the medium. Furthermore, L_p was not affected by pH in the range of 6 to 8 nor by the presence of drugs such as valinomycin (1 x 10^-6 M) and tetrodotoxin (3.2 x 10^-6 M). The instantaneous nature of the response to changes in external osmolality suggests that the hydraulic conductivity of the membrane is controlled by a thin layer at the outer face of the membrane.     

Comparative nuclear magnetic resonance studies of diffusional water permeability of red blood cells from different species. V—Rabbit (Oryctolagus Cuniculus)

• 1.1. The diffusional water permeability (P_d) of rabbit red blood cell (RBC) membrane has been monitored by a doping nuclear magnetic resonance (NMR) technique on control cells and following inhibition with p-chloromercuribenzene sulfonate (PCMBS).
• 2.2. The values of P_d were around 6.3 × 10⁻³ cm/sec at 15°C, 7.0 × 10⁻³cm/sec at 20°C, 8.0 × 10⁻³ cm/sec at 25°C, 9.1 × 10⁻³ cm/sec at 30°C and10.7 × 10⁻³ cm/sec at 37°C.
• 3.3. Systematic studies on the effects of PCMBS on water diffusion indicated that the maximal inhibition was reached in 15 min at 37°C with 0.5 mM PCMBS.
• 4.4. The values of maximal inhibition were around 71–74% at all temperatures.
• 5.5. The basal permeability to water was estimated as 1.6 × 10⁻³cm/sec at 15°C, 2.0 × 10⁻³cm/sec at 20°C, 2.4 × 10⁻³cm/sec at 25°C, 2.6 × 10⁻³cm/sec at 30°C, and 3.1× 10^{−3 cm/secat 37°C}.
• 6.6. The activation energy of water diffusion was around 18 kJ/mol and increased to 27 kcal/mol after incubation with PCMBS in conditions of maximal inhibition of water diffusion.
• 7.7. The membrane polypeptide electrophoretic pattern of rabbit RBCs has been compared with its human counterpart.
• 8.8. The rabbit membrane contained a higher amount of spectrin (bands 1 and 2), while the band 6 (glyceraldehyde-3-phosphate dehydrogenase) was markedly less intense.
• 9.9. Considerable differences in the electrophoretic patterns of the two sources of RBC membranes appeared in the bands migrating in the band 4.5 region and in front of band 7, where some polypeptides were apparent in higher amounts in the rabbit RBC membrane.

     

Cuticular control of diffusional water permeability

The diffusional water permeability (P_d) in various gut structures of the fleshfly, Sarcophaga bullata, was measured using tritiated water. Water P_d in the larval hindgut was 3.91 × 10^?6 cm/sec, whereas in the adult hindgut it was 4.4 × 10^?4 cm/sec. The presence of cuticle in various parts of the gut apparently controls the water permeabilities of these structures. Furthermore, the water permeability of the cuticle may be correlated with the mechanism for the production of a hyperosmotic excretion in the hindgut.     

Partial Purification and Properties of an Alkaline alpha-Galactosidase from Mature Leaves of Cucurbita pepo

A fourth molecular from of α-galactosidase, designated L_IV, an alkaline α-galactosidase, was isolated from leaves of Cucurbita pepo and purified 165-fold. It was active over a narrow pH range with optimal hydrolysis of p-nitrophenyl-α-d-galactoside and stachyose at pH 7.5. The rate of stachyose hydrolysis was 10 times that of raffinose. K_m determinations in McIlvaine buffer (200 millimolar Na₂-phosphate, 100 millimolar citric acid, pH 7.5) for p-nitrophenyl-α-d-galactoside, stachyose, and raffinose were 1.40, 4.5, and 36.4 millimolar, respectively. L_IV was partially inhibited by Ca²⁺, Mg²⁺, and Mn²⁺, more so by Ni²⁺, Zn²⁺, and Co²⁺, and highly so by Cu²⁺, Ag²⁺, Hg²⁺ and by p-chloromercuribenzoate. It was not inhibited by high concentrations of the substrate p-nitrophenyl-α-d-galactoside or by myo-inositol, but α-d-galactose was a strong inhibitor. As observed for most other forms of α-galactosidase, L_IV only catalyzed the hydrolysis of glycosides possessing the α-d-galactose configuration at C₁, C₂, and C₄, and did not hydrolyze p-nitrophenyl-α-d-fucoside (α-d-galactose substituted at C₆). The enzyme was highly sensitive to buffers and chelating agents. Maximum hydrolytic activity for p-nitrophenyl-α-d-galactoside was obtained in McIlvaine buffer (pH 7.5). In 10 millimolar triethanolaminehydrochloride-NaOH (pH 7.5) or 10 millimolar Hepes-NaOH (pH 7.5), hydrolytic activity was virtually eliminated, but the addition of low concentrations of either ethylenediaminetetraacetate or citrate to these buffers restored activity almost completely. Partial restoration of activity was also observed, but at higher concentrations, with pyruvate and malate. Similar effects were found for stachyose hydrolysis, but in addition some inhibition of L_IV in McIlvaine buffer, possibly due to the high phosphate concentration, was observed with this substrate. It is questionable whether the organic acid anions possess any regulatory control of L_IVin vivo. It was possible that the results reflected the ability of these anions, and ethylene-diaminetetraacetate, to restore L_IV activity through coordination with some toxic cation introduced as a buffer contaminant.     

Interaction of the Laburnum anagyroides lectin with fucoantigens

We studied interaction of the lectin from the bark of Golden Rain shrub (Laburnum anagyroides, LABA) with a number of basic fucose-containing carbohydrate antigens by changes in its tryptophan fluorescence. The strongest LABA binding was observed for the trisaccharide H of type 6 [α-L-Fucp-(1-2)-β-D-Galp-(1-4)-D-Glc, K _a = 4.2 × 10³ M^?1]. The following antigens were bound with a weaker affinity: H-disaccharide α-L-Fucp-(1-2)-D-Gal, a glucoanalogue of tetrasaccharide Le^y α-L-Fucp-(1-2)-β-D-Galp-(1-4)-[α-L-Fucp-(1-3)]-D-Glc, and 6-fucosyl-N-acetylglucosamine, a fragment of core of the N-glycans family (K _a 1.1?1.7 × 10³ M^?1). The lowest binding was observed for L-fucose (K _a = 2.7 × 10² M^?1) and trisaccharide Le^a, (β-Galp-(1-3)-[α-L-Fucp-(1-4)]-GlcNAc (K _a = 6.4 × 10² M^?1). The Le^d, Le^a, and Le^x pentasaccharides and Le^b hexasaccharide were not bound to LABA.     

Studies on the reactions of ruthenium(II) substrates with tridentate (N,N,O) azo ligands

Reactions of 1-{[2-(arylazo)phenyl]iminomethyl}-2-phenol, HL_sal, 1, [where H represents the dissociable protons upon complexation and aryl groups of HL_sal are phenyl for HL¹_sal, p-methylphenyl for HL²_sal, and p-chlorophenyl for HL³_sal], ligands with Ru(H)(CO)(Cl)(PPh₃)₃ afforded complexes of composition [(L_sal)Ru(CO)(Cl)(PPh₃)] and (L_sal)₂Ru where the N,N,O donor tridentate (L_sal)⁻ ligands coordinated the metal centre facially and meridionally, respectively. Stepwise formation of [(L_sal)₂Ru] has been ascertained. Reaction of 1-{[2-(arylazo)phenyl]iminomethyl}-2-napthol, HL_nap, 2, [where H represents the dissociable protons upon complexation and aryl groups of HL_nap are phenyl for HL¹_nap, p-methylphenyl for HL²_nap, and p-chlorophenyl for HL³_nap], ligands with Ru(H)(CO)(Cl)(PPh₃)₃ afforded exclusively the complexes of composition [(L_nap)Ru(CO)(Cl)(PPh₃)], where N,N,O donor tridentate (L_nap)⁻ was facially coordinated. The ligand 1-{[2-(phenylazo)phenyl]aminomethyl}-2-phenol, HL, 3, was prepared by reducing the aldimine function of HL¹_sal. Reaction of HL with Ru(PPh₃)₃Cl₂ afforded new azosalen complex of Ru(III) in concert with regiospecific oxygenation of phenyl ring of HL. All the new ligands were characterized by analytical and spectroscopic techniques. The complexes were characterized by analytical and spectroscopic techniques and subsequently confirmed by the determination of X-ray structures of selected complexes.     

Diurnal changes in volume and solute transport coefficients of phaseolus roots

Volume (J_v) and solute (J_s) fluxes through Phaseolus root systems were observed over a 24-hour period. The volume flux was varied in a pressure chamber by altering the hydrostatic pressure in 10 steps, from 0 to 0.41 megapascals. All root systems showed strong diurnal peaks in volume flux. The five transport coefficients (σ, ω, J_s^*, L_p, and π^*) were estimated from a nonlinear least squares algorithm. Analysis of the data revealed that all the coefficients exhibited a diurnal rhythm. When the total differential of the volume flux was considered it was possible to show that the diurnal changes in volume flux were due to a complex interaction between the diurnally shifting coefficients with the role of each highly dependent on the level of volume flux. At low volume fluxes, ω, J_s^*, and π^* accounted for nearly all the diurnal change in volume flux. At high volume fluxes, however, the major influence shifted to L_p and π^*, while ω and J_s^* became relatively unimportant. Thus, π^* was the only coefficient of interest across the entire range of J_v and appeared to be the single most important one in determining the diurnal rhythm of J_v under conditions of a constant applied pressure.     

Causes of root growth retardation induced by ultraviolet-B irradiation of shoots in Barley seedlings

In barley seedlings (Hordeum vulgare L.) during two days after irradiation of shoots with UV-B (0.5 W/m², 6 h), the rate of elongation of primary roots decreased 2–3 times compared to that in control plants. The modulus of elasticity of roots (ε) increased at most twofold in 12 h after the onset of irradiation; the hydraulic conductivity (L _p) diminished by a factor of two in 12 h, and the root osmotic pressure gradually decreased by 0.08 MPa in 24 h. Changes in ε and L _p were shown to be related to oxidative stress in growing roots, which was evidenced from the increase in H₂O₂ level up to 15-fold increase in 6 h and in activity of guaiacol peroxidase (3.5-fold in 12 h). After 48 h, the characteristics of oxidative metabolism and root characteristics ε and L _p became identical in untreated and treated plants. On the third day, the rate of root growth in treated plants reached its initial value. It is concluded that the main causes of retardation of root growth under these conditions were as follows: the increase in cell wall rigidity related to formation of oxidative cross-links in the apoplast and the decrease in root osmotic pressure due to limited transport of assimilates from irradiated leaves. After the intensity of UV-B irradiation applied to shoots was enhanced (1.6 W/m², 4 h), another physiological status of roots was observed on the 2nd day characterized by twofold increase in L _p, tenfold decreased root elongation rate, and by a progressing increase of root diameter in growing roots. The comparison of root responses induced by irradiation of shoots with the root responses to sodium salicylate and ABA suggests that both agents might participate in the transmission of signals from irradiated leaves to roots.     

Prevalence and Associated Factors for Dual Form of Malnutrition in Mother-Child Pairs at the Same Household in the Gaza Strip-Palestine

Background

In many developing countries nutritional, and epidemiological transitions are emerging into continuing undernutrition and escalating overnutrition, giving rise to the double burden of the malnutrition phenomenon.

Objectives

This study aims to determine the prevalence of the dual form of malnutrition (overweight mother/underweight child) in the same household and its associated factors in the Gaza Strip.

Methods

A total of 357 mother-child pairs from the same households were surveyed from three different geographical locations in the Gaza Strip, namely, El Remal urban area, Jabalia refugee camp, and Al Qarara rural area. The height and weight of mothers aged 18–50 years were measured, and their body mass index (BMI) was computed. The mothers were categorized according to the criterion of the World Health Organization (WHO) for BMI as overweight if they have a BMI ≥ 25 kg/m². Anthropometric indices were measured for children aged two to five years to classify the underweight children Z-score <-1.

Results

The results showed the prevalence of the dual form of malnutrition in the Gaza Strip was 15.7%, and its associated factors were child’s birth order (OR_adj, 1.50, 95% CL, 1.22, 1.82; p = <0.001), father’s educational (low or medium) levels (OR_adj, 3.19, 95% CL, 1.07, 9.5; p = 0. 036), or (OR_adj, 3.4, 95% CL, 1.12, 10.37; p = 0. 031), high scores of mothers'' nutrition knowledge (OR_adj, 1.23, 95% CL, 1.01, 1.52; p = 0. 048), and low monthly income (OR_adj, 0.28, 95% CL, 0.09, 0.88; p = 0. 030).

Conclusions

The results from this study showed the dual form of malnutrition in the same household was prevalent in the Gaza Strip. This is a public health issue that must be understood and addressed and policy makers must implement an appropriate nutrition action plan to control dual form of malnutrition based on the underlying specific risk factors in the study population. In addition, interventions are needed to help individuals to translate their nutrition knowledge into healthy dietary behaviors.     

Magnesium influx in dialyzed squid axons

Summary The influx of magnesium from seawater into squid giant axons has been measured under conditions where internal solute control in the axon was maintained by dialysis. Mg influx is smallest (1 pmol/cm² sec) when both Na and ATP have been removed from the axoplasm by dialysis. The addition of 3mm ATP to the dialysis fluid gives a Mg influx of 2.5 pmol/cm² sec while the addition of [Na] _i and [ATP] _i gives 3 pmol/cm² sec as a value for Mg influx; this corresponds well with fluxes measured in intact squid giant axons.The Mg content of squid axons is 6 mmol/kg axoplasm; this is unaffected by soaking axons in Li or Na seawater for periods of up to 100 min.     

Decrease in membrane hydraulic conductance of rhizodermal cells under nitrate deficit is related to acidification at the root surface

Barley seedlings (Hordeum vulgare L.) were grown on porous plates submerged in Knop medium at pH 6.0 (control) and in a similar nutrient solution where NO ₃ ^? was replaced with Cl^? (treatment); in some treatments Mes buffer (10–20 mM, pH 6.0) was added to the medium. In the absence of buffer, the pH of the medium shifted towards the alkaline region in the presence of NO ₃ ^? and to the acidic region in the presence of Cl^?, with the total shift of no more than 0.3 pH units per day. The replacement of NO ₃ ^? with Cl^? (in a buffer-free medium) decreased the hydraulic membrane conductance of rhizodermal cells (L _p) within a 4-h period; after one day L _p settled at approximately 50% of its initial value observed in untreated plants. When the removal of nitrate from the medium was accompanied by the addition of buffer, no changes in L _p were observed over a 1-day period. The perfusion of external solution (at a rate of 10 mm/s) made it possible to control pH in the proximity to root surface (pH_s). These experiments showed that L _p was independent of the surface pH in the pH_s range 7.0–5.0, whereas at pH_s = 4.5 L _p decreased within 15 min to a steady-state level of about 50% of the control value. It is concluded that the reduction of L _p under nitrate deficit was related to acidification of the medium near the root surface. The acidic pH shift could be caused by the cessation of proton/nitrate symport and by activation of the plasmalemma H⁺-pump, related to changes in the cytosolic pH-stat.     

Synthesis and characterization of a dinuclear ferric complex with redox-active ligands

A dinuclear ferric complex with the redox-active ligand (L^Cl₂)^2- (H₂L^Cl₂ = N,N′-dimethyl-bis(3,5-dichloro-2-hydroxybenzyl)-1,2-diaminoethane), was synthesized and characterized. The two iron(III) ions are six-coordinate in a distorted octahedral environment of the donor set of one (L^Cl₂)²⁻ and one amine and one phenolate donor of a second (L^Cl₂)²⁻, which bridges the two complex halves. The relatively low-symmetric complex 1 crystallizes in the space group R. The crystal structure contains hexagonal, one-dimensional channels parallel to the c axis with diameters of ∼13 Å. The absorption spectrum of 1 exhibits strong characteristic features of p_π → d_π^∗, p_π → d_σ^∗, phenolate-to-metal CTs, and π → π^∗ ligand transitions. Electrochemical studies on 1 reveal the redox-activity of the coordinated ligand (L^Cl₂)²⁻ by showing irreversible oxidative electron-transfer waves. The reductive electron transfers at negative potentials seem to originate from metal-centered processes. A detailed comparison to complexes with similar donor sets provides new insights into the electrochemical properties of these kinds of complexes.     

Temporal dynamics of soil spatial heterogeneity in sagebrush-wheatgrass steppe during a growing season

Variability in five soil resources essential for plant growth (NH₄ ⁺, NO₃ ^-, P, K and soil moisture) was quantified using univariate, multivariate and geostatistical techniques in a sagebrush-grass steppe ecosystem at three times (early April, June and August) during the 1994 growing season. Samples were collected every meter in a 10 × 10-m ‘macrogrid’, every 20 cm within nested 1 × 1-m ‘minigrids’, and every 3 cm within additionally nested 15 × 15-cm ‘microgrids’. Strong autocorrelation for all variables in the three sample periods was only found over distances less than 2 m, indicating that patches of high internal uniformity in this soil were smaller than 2 m during the growing season. Differences in semivariograms between sample periods were most pronounced for NO₃ ^-, NH₄ ⁺ and soil moisture, variables that we consider to primarily limit plant growth in this system. The distance over which sample points were autocorrelated for NO₃ ^-, NH₄ ⁺ and soil moisture increased from April to June. In contrast P and K, which are relatively more abundant at the study site, exhibited relatively constant semivariance patterns over the three sample periods. Weak correlation was found between samples collected in the three sample periods for N and soil moisture indicating that the spatial pattern of these limiting resources changed between sample periods. However, P and K had highly significant correlations (p<0.00001) among sample periods, indicating that the distributional patterns of these relatively more abundant resources remained rather constant. There were strong negative correlations between P and K and distance from the base of shrubs for all sample times (p<0.001), indicating an increase in P and K close to shrubs. Similar strong negative correlations were not found between distance from the shrubs and levels of NH₄ ⁺, NO₃ ^-, or soil moisture, nor for any soil variable and distance from perennial tussock grasses. Changes in patterns of nutrient and soil moisture variability within a growing season suggest that not only must plants acquire soil resources that vary in time and space, but that they may also have to adjust to different scales of resource patchiness during the season.     

Nitrogen and potassium variation on contaminant removal for a vertical subsurface flow lab scale constructed wetland

Lab scale constructed wetlands were used to evaluate organic load removal efficiency. Bioreactors were fed with synthetic wastewater (SW) with varying concentrations of nitrogen and potassium. Reactors were planted with species Phragmites australis. Fed theoretic COD was adjusted to 240.0 mg-O₂ L⁻¹, nitrogen levels were 10 and 40 mg-N L⁻¹ (ammonium sulfate), potassium levels were 5 and 31 mg-K L⁻¹ (potassium monobasic phosphate). The higher biomass yield, for 0.5 and 0.775 N:K ratios, was related with higher organic load removal. The ratio N:K showed significant differences for organic load abatement, when 1:0.5 and 1:0.775 N:K ratios were applied, 96.8% efficiency was obtained, whereas N:K ratio of 1:0.125 had efficiency of 92.1% and N:K ratio of 1:3.1 showed an efficiency of 90.5%. For planted bioreactor E_H decreased in 162.7 mV from sample port to 5 cm down to 35 cm depth, while for the bioreactor without plant showed an E_H decrement of only 17.7 mV.     

Temperature-Dependent Water and Ion Transport Properties of Barley and Sorghum Roots : II. Effects of Abscisic Acid

Water flux through excised roots (J_v) is determined by root hydraulic conductance (L_p) and the ion flux to the xylem (J_i) that generates an osmotic gradient to drive water movement. These properties of roots are strongly temperature dependent. Abscisic acid (ABA) can influence J_v by altering L_p, J_i, or both. The effects of root temperature on responses to ABA were determined in two species differing in their temperature tolerances. In excised barley (Hordeum vulgare L.) roots, J_v was maximum at 25°C; 10 micromolar ABA enhanced J_v, primarily by increasing L_p, at all temperatures tested (15-40°C). In sorghum (Sorghum bicolor L.) roots, J_v peaked at 35°C; ABA reduced this optimum temperature for J_v to 25°C by increasing L_p at low temperatures and severely inhibiting J_i (dominated by fluxes of K⁺ and NO₃⁻) at warm temperatures. The inhibition of K⁺ flux by ABA at high temperature was mostly independent of external K⁺ availability, implying an effect of ABA on ion release into the xylem. In sorghum, ABA enhanced water flux through roots at nonchilling low temperatures but at the expense of tolerance of warm temperatures. These effects imply that ABA may shift the thermal tolerance range of roots of this heat-tolerant species toward cooler temperatures.     

Complexes of hybrid ligands. Synthesis of mixed-ligand,phosphino-alkoxide complexes of Pd2+: the crystal and molecular structure of the complex Ph2 PCH2C(CF3 )2OPdCl(PPh2Me)

The hybrid, bidentate, diarylphosphino-alkoxide ligand PPh₂CH₂C(CF₃)₂O⁻, L¹, gives the Pd²⁺ bis- complex Pd(L¹)₂, from which the chloride-bridged dinuclear complex [(L¹)Pd(μ-Cl)₂Pd(L¹)] is made by reaction with PdCl₂(PhCN)₂. Cleavage of the dinuclear complex with monodentate ligands L² then gives Pd(L¹)Cl(L²) (L² =PPh₃, PPh₂Me, PPhMe₂, PMe₃, SMe₂, or pyridine); NMR data show that PR₃ is cis to the phosphine site in L¹ in these complexes, but SMe₂ or pyridine are probably trans.A complete crystal and molecular structural determination has been made for cis-Pd(L¹)Cl(PPh₂Me). Crystals are monoclinic, space group P2₁/c, a = 10.821(1), b = 14.600(1), c = 18.674(2) Å, β = 101.25(1)°, V = 2893 ų, Z = 4. Least-squares refinement on F of 361 variables using 3977 observations converged at a conventional agreement factor R = 0.025. The complex is square-planar, with the two phosphines cis; the 5-membered chelate ring is in a dissymmetric envelope conformation. The PdP bonds differ in length, with that to the unidentate phosphine, 2.259(1) Å, being significantly longer than that to the phosphine on the chelating ligand, 2.231(1) Å.     

Comparison of crystal field dependent and independent methods to analyse lanthanide induced NMR shifts in axially symmetric complexes. Part I. Systems with a C3 symmetry axis

A critical analysis of the lanthanide induced paramagnetic shift (LIS) data for several series of Ln³⁺ complexes of C₃ symmetry in terms of structural changes, crystal-field effects and/or variation of hyperfine constants along the lanthanide series was undertaken using a combination of the two-nuclei and three-nuclei techniques together with the classical one-nucleus technique. The crystal-field independent two-nuclei technique to study the isostructurality of a series of lanthanide complexes, is usefully complemented by the three nuclei shift ratio method, which is based exclusively on the experimental shift data, requiring no knowledge of B₀², 〈S_z〉 or C_j values. However, this later method cannot provide quantitative values for F_i and G_i. The combined use of the three methods was found to be a powerful analytical tool of the solution structure of lanthanide complexes. Isostructurality of whole series of complexes, either with no change of the F_i, G_i and B₀² parameters (L⁵ and L⁶), or with changes of the F_i and B₀² parameters (L⁷ and L⁸), is clearly defined by the combination of the two first methods. In these cases, the three-nuclei method sometimes fully supports such an isostructurality (L⁶, L⁸), but in other cases, due to the high structural sensitivity of its α and β parameters, it is able to detect small, unnoticed, structural changes in the complexes of L⁵ and L⁷. Clear structural changes, involving the F_i, G_i and B₀² parameters, are observed for the series of complexes of (L⁹), where the three methods agree, involving hydration and carboxylate coordination changes. More subtle structural changes, involving the internal dynamics of the bound ligands, are proposed in other cases (L¹-L⁴). These could also result from a magnification, by the present graphical analysis, of the breaks expected from the gradual structural changes along the series due to the lanthanide contraction.     

Ethylenediamine- and propylenediaminediacetic acid derivatives as ligands for the “fac-[M(CO)3]” core (M = Re, Tc)

The reaction of Re(CO)₅Cl with o- or p-N-(nitrophenyl)ethylenediaminediacetic acid (H₂L¹, H₂L²) and o- or p-N-(nitrophenyl)propylenediaminediacetic acid (H₂L³, H₂L⁴) in methanol leads to the formation of stable anionic [Et₃NH][Re(CO)₃(L)] · H₂O complexes 1-4. These compounds have been characterized by means of IR, mass spectrometry, elemental analysis, NMR and conductimetry, as well as X-ray crystallography for 2 and 3. The [Re(CO)₃]⁺ moiety is coordinated via the nitrogen of the iminodiacetic acid unit and two oxygens of monodentate carboxylate groups. In each case, the nitro group of the aromatic ring remains uncoordinated. The analogous technetium-99m complexes 1′ and 3′ were also prepared quantitatively by the reaction of H₂L¹ and H₂L³, respectively, with the fac-[^99mTc(CO)₃(H₂O)₃]⁺ precursor in ethanol. The corresponding Re and ^99mTc compounds were shown to possess the same structure by means of HPLC studies. The high affinity of these ligands for the Tc(I) or Re(I) core, coupled with the easiness of their derivatization (by reduction of the nitro group in amino group), implies that the utilization of this ligand system to develop target-specific radiopharmaceuticals for diagnosis and therapy is promising.