Microwave spectrum,structure, and chemical bonding of trimethylbromosilane

The microwave spectrum of trimethylbromosilane (trimethylsilylbromide) has been investigated in the 26.5–40.0-GHz region. Spectra of several isotopic species have been observed, including the previously unreported spectrum of the ¹H¹²C³⁰Si⁸¹Br species, which yielded a B rotational constant of 1440.92 ± 0.02 MHz. From the experimental data it has been possible to derive the following structural parameters: SiBr = 2.235 ± 0.002 Å, SiC = 1.856 ± 0.010 Å, and ∠CSiBr = 107.5 ± 0.1°. The results have been compared to other relevant data and discussed in terms of prevailing chemical bonding principles.     

Synthesis of zerovalent nanophase metal particles stabilized with poly(ethylene glycol)

Concurrent sonolysis of iron pentacarbonyl and poly(ethylene glycol)-400 (PEG-400) in hexadecane solvent proceeds via zero-order kinetics and results in Fe nanoparticles encapsulated in PEG-400 (Fe-PEG). The transmission electron microscopy images show Fe-PEG consisting of <3 nm Fe particles that are evenly dispersed in the PEG matrix. M?ssbauer and X-ray absorption fine structure/X-ray absorption near-edge structure data reveal an ordered PEG assembly that helps protect the zerovalent Fe core. The Fe nanoparticles in Fe-PEG are superparamagnetic with a magnetization value of 45 emu/g-Fe at 10 KOe. The rheology of the synthesized material shows an unusual increase in viscosity with temperature that is likely due to lower critical saturation temperature phase segregation over 40 degrees C. The low-temperature mobility of the PEG-400 moiety in Fe-PEG would allow facile ligation of the Fe0 core with biologically and chemically active groups.     

Bioinspired synthesis of new silica structures

Silicon and oxygen are the two most abundant elements in the Earth's crust but despite the vast scientific literature on crystalline and amorphous silica, new chemistries, structures and applications continue to be discovered for compounds formed from these elements--thus we present here for the first time the formation of new amorphous silica structures that were uniquely synthesized by a bioinspired synthetic system.     

Custom‐Fit Ruthenium(II) Metallopeptides: A New Twist to DNA Binding With Coordination Compounds

A new bipyridine building block has been used for the solid‐phase synthesis of dinuclear DNA‐binding ruthenium(II) metallopeptides. Detailed spectroscopic studies suggest that these compounds bind to the DNA by insertion into the DNA minor groove. Moreover, the potential of the solid‐phase peptide synthesis approach is demonstrated by the straightforward synthesis of an octaarginine derivative that shows effective cellular internalization and cytotoxicity linked with strong DNA interaction, as evidenced by steady‐state fluorescence spectroscopy and AFM studies.