Thermodynamic Stability and Physicochemical Characterization of Ligand (4S)‐4‐Benzyl‐3,6,10‐tris(carboxymethyl)‐3,6,10‐triazadodecanedioic Acid (H5[(S)‐4‐Bz‐ttda]) and Its Complexes Formed with Lanthanides,Calcium(II), Zinc(II), and Copper(II) Ions

A derivative of H₅ttda (=3,6,10‐tris(carboxymethyl)‐3,6,10‐triazadodecanedioic acid=N‐{2‐[bis(carboxymethyl)amino]ethyl}‐N‐{3‐[bis(carboxymethyl)amino]propyl}glycine), H₅[(S)‐4‐Bz‐ttda] (=(4S)‐4‐benzyl‐3,6,10‐tris(carboxymethyl)‐3,6,10‐triazadodecanedioic acid=N‐{(2S)‐2‐[bis(carboxymethyl)amino]‐3‐phenylpropyl}‐N‐{3‐[bis(carboxymethyl)amino]propyl}glycine; 1 ) carrying a benzyl group was synthesized and characterized. The stability constants of the complexes formed with Ca²⁺, Zn²⁺, Cu²⁺, and Gd³⁺ were determined by potentiometric methods at 25.0±0.1° and 0.1M ionic strength in Me₄NNO₃. The observed water proton relaxivity value of [Gd{(S)‐4‐Bz‐ttda}]²⁻ was constant with respect to pH changes over the range pH 4.5–12.0. From the ¹⁷O‐NMR chemical shift of H₂O induced by [Dy{(S)‐4‐Bz‐ttda}]²⁻ at pH 6.80, the presence of 0.9 inner‐sphere water molecules was deduced. The water proton spin‐lattice relaxation rate for [Gd{(S)‐4‐Bz‐ttda}]²⁻ at 37.0±0.1° and 20 MHz was 4.90±0.05 mM ⁻¹ s⁻¹. The EPR transverse electronic relaxation rate and ¹⁷O‐NMR transverse‐relaxation time for the exchange lifetime of the coordinated H₂O molecule (τ_M), and ²H‐NMR longitudinal‐relaxation rate of the deuterated diamagnetic lanthanum complex for the rotational correlation time (τ_R) were thoroughly investigated, and the results were compared with those previously reported for the other lanthanide(III) complexes. The exchange lifetime (τ_M) for [Gd{(S)‐4‐Bz‐ttda}]²⁻ (2.3±1.3 ns) was significantly shorter than that of the [Gd(dtpa)(H₂O)]²⁻ complex (dtpa=diethylenetriaminepentaacetic acid). The rotational correlation time τ_R for [Gd{(S)‐4‐Bz‐ttda}]²⁻ (70±6 ps) was slightly longer than that of the [Gd(dtpa)(H₂O)]²⁻ complex. The marked increase of relaxivity of [Gd{(S)‐4‐Bz‐ttda}]²⁻ mainly resulted from its longer rotational time rather than from its fast water‐exchange rate. The noncovalent interaction between human serum albumin (HSA) and the [Gd{(S)‐4‐Bz‐ttda}]²⁻ complex containing the hydrophobic substituent was investigated by measuring the solvent proton relaxation rate of the aqueous solutions. The association constant (K_A) was less than 100 M ⁻¹, indicating a weaker interaction of [Gd{(S)‐4‐Bz‐ttda}]²⁻ with HSA.     

Adaptation on the space of finite signed measures

Given an i.i.d. sample from a probability measure P on ℝ, an estimator is constructed that efficiently estimates P in the bounded-Lipschitz metric for weak convergence of probability measures, and, at the same time, estimates the density of P — if it exists (but without assuming it does) — at the best possible rate of convergence in total variation loss (that is, in L ¹-loss for densities).      

Periodic arrays of interfacial cylindrical reverse micelles

We report an approach for the fabrication of periodic molecular nanostructures on surfaces. The approach involves biomimetic self-organization of synthetic wedge-shaped amphiphilic molecules into multilayer arrays of cylindrical reverse micelles. The films were characterized by atomic force microscopy and X-ray reflectivity. These nanostructured films self-assemble in solution but remain stable upon removal and exposure to ambient conditions, making them potentially suitable for a variety of dry pattern transfer methods. We illustrate the generality of this approach by using two distinct molecular systems that vary in size by a factor of 2.     

Structural Evolution and Fluorescence Properties of Dy<Superscript>3+</Superscript>: Silica Matrix

Silica glasses doped with Dy³⁺ were prepared by sol–gel method. The FTIR and thermo gravimetric analysis (TGA) clearly show complete densification (density = 2.2 gm/cm³) of the gels around 1000C. The fluorescence properties of Dy³⁺ ion are utilized to study the structural changes during the gel to glass transition of the silica xerogels. The fluorescence intensity and full width at half maximum (FWHM) of the emission bands show an increasing tendency with heat treatment. This is attributed to a glassy silica network with an asymmetric environment. The (Y/B) ratio for the Dy³⁺ ion is found to be less sensitive to site symmetry effects.     

A new C(1)-auxiliary for anomeric stereocontrol in the synthesis of alpha-sialyl glycosides

The installation of the novel N,N-dimethylglycolamide ester auxiliary onto the C(1)-position of protected neuraminic acid donors allows for the exploitation of C(1)-neighboring group participation to generate sialoside conjugates with good to excellent alpha-selectivity under a variety of sialylation protocols, including those that would otherwise lead to nonselective or beta-selective sialoside products.     

Doppler shapes of the γ line in the <Superscript>9</Superscript>Be(α, nγ)<Superscript>12</Superscript>C reaction in plasma at temperatures <Emphasis Type="Italic">T</Emphasis><Subscript>α</Subscript> < 0.6 MeV

A parametrization of the partial cross section of the ⁹Be(α, nγ)¹²C reaction in the α-particle energy range of 0.3–7.9 MeV is presented, along with the count rates of γ quanta. The need to consider subbarrier (Eα < 1.9 MeV) α-particles in plasma for temperatures T _α < 0.2 MeV is substantiated. The shapes of the Doppler-broadened 4.44 MeV γ line and the count rates of γ quanta in the plasma of the JET tokamak are measured for the first time and compared to the calculated values. An estimated T _α ≲ 160 keV is obtained.