Materials Literature
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The use of DAB-Am-64 amine dendrimer as a single-molecule template to produce mesoporous cavities in silica sol−gels is reported. The method is meant to afford the synthesis of spheroidal cavities and is likely to enjoy generality, since there are a number of dendritic molecules commercially available today. X-ray dif…
Exposure to ultrasonic acoustic waves can greatly enhance various chemical reactions. Ultrasonic acoustic irradiation of organic compounds in aqueous solution results in oxidation of these compounds. The mechanism producing this behavior is the inducement of the growth and collapse of cavitation bubbles driven by the…
We present first-principles calculations of electron-electron scattering rates of low-energy electrons in Au. Our full band-structure calculations indicate that a major contribution from occupied d states participating in the screening of electron-electron interactions yields lifetimes of electrons in Au with energies…
The magnetic interaction between a 5f element and a 3d transition metal in a molecular compound was investigated with a novel class of complexes in which the central UIV ion is associated with two MII ions by means of a hexadentate Schiff base ligand (see picture). The comparative study of the Cu2U, Zn2U, and Cu2Zr co…
We present a study of the adsorption of two peptides at the octane-water interface. The first peptide, Lac21, exists in mixed monomer-tetramer equilibrium in bulk solution with an appreciable monomer concentration. The second peptide, Lac28, exists as a tetramer in solution, with minimal exposed hydrophobic surface. A…
The electronic structure of successive redox states of two series of thienylenevinylene oligomers (nTVs, n=4, 5, 6, 8, and 12) that carry hexyl substituents at the alpha- or beta-positions in order to increase the solubility was investigated in detail by means of UV/ Vis/near-IR and ESR spectroscopy in solution. The n…
Compounding extruders are still designed based on experience and time-consuming experimental examinations. This work investigates the morphology development of incompatible polyblends along a mixing zone at the end of a corotating twin-screw extruder. During the process, the samples are taken from the running extruder…
Concerted cleavage of two C−C single bonds provides the basis for a novel concept for the storage and release of electrons. Electron transfer, mediated by metal ions, occurs between the cyclopropyl ring of a Ni porphyrinogen and the interligand C−C bond of a bis(Ni-salophen) complex (see scheme).
Reaction of the thiol-terminated fourth-generation dendrimer 2-G4 (96 SH groups) with the gold cluster compound Au55(PPh3)12Cl6 in a 3:1 molar ratio in dichloromethane results in the formation of bare Au55 clusters. The cuboctahedrally shaped Au55 particles coalesce to well-formed microcrystals (Au55) infinity. The ro…
The by no means trivial, solid-state reaction for the condensation of {(Mo)Mo5}12Fe30 giant spheres commences through the water ligands and leads to oxo (or hydroxo) bridging. As the discrete icosahedral units approach each other, their oxygen atom bridges ultimately form covalent bonds (Fe−Fe 3.79 Å, see picture) to…
Es wird eine chemische Betrachtung spinmagnetischer Phänomene in abgeschlossenen (Atome und Moleküle) und unendlich großen Systemen (Übergangsmetalle und ihre Legierungen) vorgestellt, die auf den Konzepten von Bindung und elektronischer Abschirmung basiert. Der Ansatz soll als halbquantitative Richtschnur für die Syn…
The role of the ligand's structure and absolute configuration in the supramolecular chirality induction in achiral bis(zinc porphyrin) has been studied. The amines with bulkier substituents resulted in stronger CD signals due to increased helical displacement in the anti conformer. All the amines with an R absolute co…
Thirty electrons are frozen on the O = Mo(H2O) groups which function as spacer units between the {(Mo)Mo5} building units of the giant {Mo102} sphere 1 (the picture shows a wireframe representation in which the spacer units are represented as a darker shade).
A detailed multifrequency high-field-high-frequency EPR (95-285 GHz) study has been performed on the single-molecule magnet of formula [Fe8O2(OH)12(tacn)6]Br8 x 9H2O, in which tacn = 1,4,7-triazacyclononane. Polycrystalline powder spectra have allowed the estimation of the zero-field splitting parameters up to fourth…
Silole-2,5-diboronic acid derivatives 1 serve as new precursors for silole-based π-conjugated polymers 2. The Suzuki–Miyaura coupling of the diboronic acids with 2,5-bis(bromothienyl)silole affords silole–thiophene alternating copolymers, which have a particularly narrow band gap owing to the effects of the ring silic…
Architecture in minature: Fréchet-type monodendrons functionalized on their periphery with the 3,4-bis(n-dodecan-1-yloxy)benzyl ether minidendron exhibit flat tapered (at generations two (G2) and three (G3)), disclike (G4), and conical (G5) shapes that self-assemble into cylindrical (G2–4) and spherical (G5) supramole…
Complicated, alternating ferromagnetic/antiferromagnetic interactions in homometallic, one-dimensional MnII-azido systems permit an unprecedented ferrimagnetic response. One new kind of ferrimagnet with a surprising ferrimagnetic behavior in a system with ground state ST = 0 (see picture) was observed and related to t…
The partitioning of Zn to the pyrophyllite surface was studied as a function of surface loading for periods up to 4 months. Examination of the reaction products using X-ray absorption fine structure spectroscopy (XAFS) indicated the formation of a Zn precipitate at each surface loading. Comparison of the local structu…
The world record in ground state spin value “S = 51/2” belongs to a ferromagnetically coupled, cyano-bridged pentadecanuclear Mn cluster (see picture). This molecule has 51 unpaired electrons. Magnetic dipole–dipole interactions together with exchange interactions resulting from the specific three dimensional crystal…
Recent high pressure work has suggested that elemental barium forms a high pressure self-hosting structure (Ba IV) involving two `types' of barium atom. Uniquely among reported elemental structures it cannot be described by a single crystalline lattice, instead involving two interpenetrating incommensurate lattices. I…