Dynamics of 4-benzylamino-7-nitrobenzofurazan in the 1-propanol/water binary solvent system. Evidence for composition-dependent solvent organization

We report on the fluorescence lifetime and rotational diffusion dynamics of 4-benzylamino-7-nitrobenzofurazan (BBD) in a series of 1-propanol/water binary solvent systems. The fluorescence lifetime of BBD increases monotonically with increasing 1-propanol concentration. The rotational diffusion dynamics of BBD also vary with solution 1-propanol content, but this variation is not monotonic. Comparison of the BBD rotational diffusion time constant to solution viscosity and 1-propanol composition reveals the presence of a solution composition dependence of solvent-solute interactions, with a relative decrease in solvent-solute interaction strength for solvent system compositions where the 1-propanol/water azeotrope is known to exist. These data point collectively to the existence of microscopic heterogeneity in these binary solvent systems.     

Dispersion and size control of layered double hydroxide nanoparticles in aqueous solutions

We report a simple but efficient method to prepare stable homogeneous suspensions containing monodispersed MgAl layered double hydroxide (LDH) nanoparticles that have wide promising applications in cellular drug (gene) delivery, polymer/LDH nanocomposites, and LDH thin films for catalysis, gas separation, sensing, and electrochemical materials. This new method involves a fast coprecipitation followed by controlled hydrothermal treatment under different conditions and produces stable homogeneous LDH suspensions under variable hydrothermal treatment conditions. Moreover, the relationship between the LDH particle size and the hydrothermal treatment conditions (time, temperature, and concentration) has been systematically investigated, which indicates that the LDH particle size can be precisely controlled between 40 and 300 nm by adjusting these conditions. The reproducibility of making the identical suspensions under identical conditions has been confirmed with a number of experiments. The dispersion of agglomerated LDH aggregates into individual LDH crystallites during the hydrothermal treatment has been further discussed. This method has also been successfully applied to preparing stable homogeneous LDH suspensions containing various other metal ions such as Ni(2+), Fe(2+), Fe(3+), Co(2+), Cd(2+), and Gd(3+) in the hydroxide layers and many inorganic anions such as Cl(-), CO(3)(2-), NO(3)(-), and SO(4)(2-).     

Reactions involving di-trans-[12]annulenes

The low temperature complete dehydrohalogenation of pentabromocyclododecene (C12H17Br5) with potassium tert-butoxide in THF followed by exposure to potassium metal leads to the formation of the anion radical of 1,5-di-trans-[12]annulene, which loses hydrogen and undergoes ring closure to form the anion radical of 11,12-dihydro-[8]annuleno-[6]annulene. This product can, in turn, be isolated as its neutral molecule via reoxidation with iodine. A [12]annulene obtained via the dimerization of 1,5-hexadiyne in the presence of 18-crown-6 and potassium tert-butoxide undergoes ring closure, with concomitant loss of hydrogen, to yield the heptalene anion radical. It follows that the heptalene anion radical precursor was the 1,7-di-trans isomer of [12]annulene.     

A robust small-molecule microarray platform for screening cell lysates

Herein we report the expanded functional group compatibility of small-molecule microarrays to include immobilization of primary alcohols, secondary alcohols, phenols, carboxylic acids, hydroxamic acids, thiols, and amines on a single slide surface. Small-molecule "diversity microarrays" containing nearly 10,000 known bioactive small molecules, natural products, and small molecules originating from several diversity-oriented syntheses were produced by using an isocyanate-mediated covalent capture strategy. Selected printed bioactive compounds were detected with antibodies against compounds of interest. The new surface of the diversity microarrays is highly compatible with approaches involving cellular lysates. This feature has enabled a robust, optimized screening methodology using cellular lysates, allowing the detection of specific interactions with a broad range of binding affinity by using epitope-tagged or chimeric fluorescent proteins without prior purification. We believe that this expanded research capability has considerable promise in biology and medicine.     

Stable suspension of layered double hydroxide nanoparticles in aqueous solution

Seriously aggregated LDH agglomerates can be dispersed by a hydrothermal treatment into homogeneous stable suspensions that contain LDH particles in the range of 50-300 nm.     

Nonchromatographic "stir and filter approach" (SAFA) for isolating Sc3N@C80 metallofullerenes

Separation difficulties have led to a paucity of purified metallic nitride fullerenes (MNFs). Fundamental research and application development has been hampered with limited sample availability. Separation techniques designed to remove contaminant empty-cage fullerenes (e.g., C(60), C(70)...C(2)(n)) and classical metallofullerenes (e.g., non-MNFs) traditionally require expensive and tedious chromatographic methods. Our motivation is an alternative purification approach to minimize dependence on HPLC. Herein we report the use of cyclopentadienyl (CPD) and amino functionalized silica to selectively bind contaminant fullerenes. This "Stir and Filter Approach" (SAFA) provides purified MNF samples at ambient and reflux conditions. Under reflux conditions, purified MNFs (80% recovery, 41 h) are obtained using CPD silica. However, at room temperature, there is an equilibrium established between fullerenes and CPD silica, and no purified MNF samples are obtained using SAFA. In contrast, purified MNF samples (99+%) are readily obtained at room temperature using amino, diamino, and triamino silica at recoveries of 93% (11 h), 76% (9 h), and 50% (6 h), respectively.     

Isoscalar monopole strength in 100Mo: an indicator for static triaxial deformation in the ground state

We perform deformation constraint symmetry-unrestricted three-dimensional time-dependent density functional theory (TDDFT) calculations for the isoscalar monopole (ISM) mode in ¹⁰⁰Mo. Monopole moments are obtained as a function of time using time propagating states based on different deformations. A Fourier transform is then performed on the obtained response functions. The resulting ISM strength functions are compared with experimental data. For the static potential-energy-surface (PES) calculations, the results using the SkM* and UNEDF1 energy-density functionals (EDFs) show spherical ground states and considerable softness in the triaxial deformation. The PES obtained with the SLy4 EDF shows static triaxial deformation. The TDDFT results based on different deformations show that a quadrupole deformation (characterized by \begin{document}$ \beta_2 $\end{document}) value of 0.25–0.30 gives a two-peak structure of the strength functions. Increasing triaxial deformation (characterized by γ) from 0\begin{document}$ ^{\circ} $\end{document} to 30\begin{document}$ ^{\circ} $\end{document} results in the occurrence of an additional peak between the two, making the general shape of the strength functions closer to that of the data. Our microscopic TDDFT analyses suggest that ¹⁰⁰Mo is triaxially deformed in the ground state. The calculated isoscalar \begin{document}$ Q_{20} $\end{document} and \begin{document}$ Q_{22} $\end{document} strength functions show peaks at lower energies. The coupling of these two modes with the ISM mode is the reason for the three-peak/plateau structure in the strengths of ¹⁰⁰Mo.